INTRODUCTION TO ANATOMY
 The word ‘anatome’ is Greek origin meaning cutting
up (ana- up; tome – process of cutting).
 Anatomy is the basic medical science, which deals
of the structure of human body and their
relationship.
 Anatomy is subdivided according to the method of
description into:
1) Gross (macroscopic) anatomy
 Regional anatomy
 Systemic anatomy
1
2) Microscopic anatomy ( = Histology)
3) Other subdivisions:

Clinical anatomy
 Surgical anatomy

Surface anatomy

Radiological anatomy

Developmental anatomy
Embryology
2
Gross (macroscopic) anatomy:
 which deals with the body details which are seen by
the naked eye. It is studied by means of dissection of
the body. It is further subdivided into.
a) Regional anatomy: study of a discrete portion of
the body. E.g. upper limb, lower limb, thorax etc
b) Systemic anatomy: study of a particular system as
it is traced throughout the whole body, e.g.
Reproductive system, Respiratory system…etc.
Microscopic anatomy:
 which deals with the fine details of the body (cells
and tissues). It is studied by the use of microscopic
techniques
- is also called Histology
3
• Other subdivisions of anatomy:
Applied (Clinical) anatomy:
– emphasizes aspects of body structure and
function important in the practice of medicine,
dentistry, and the allied health sciences.
– It stresses clinical application.
Surgical anatomy:
– is the study of anatomy in connection with
surgical operations and surgical procedures
(e.g. anatomy of surgical incisions, anatomy of
surgical exposures…..).
4
Surface anatomy
• is the study of the surface landmarks of the
underlying body points, muscles and tendons.
e.g. surface anatomy of the heart, the lung or the
main nerves and vessels).
Radiological anatomy:
• is the study of anatomy using radiological techniques
e.g. X-rays, CT scan, ultrasound and MRI to
demonstrate the bones or some internal organs as the
heart, lungs, kidneys, stomach and intestine.
5
Body planes (coronal , sagittal, oblique, and transverse)
6
RMCP
LMCP
L1
L5
Four quadrants
Nine regions
7
CELLS
– Cells are the basic structural and functional unit of the
living organism showing a variety of functional
specializations which to perform all the activities
necessary for the survival, growth and
reproduction of the organism.
– Cells are the smallest entities capable of
independent life.
• Activity 1: Enumerate as many human body
cells as you can.
Cells are diverse in
– Number (around 100 trillion [1012]cells)
– Type (around 250 named cell types)
– Shape (round, oval, columnar, multipolar,
polyhedral, cylindrical, fusiform, pyramidal, pyriform,
etc.)
– Size (3µm - 120µm in diameter)
– Diverse functions
Blood cells are
examples of round
cells
250
Diverse Cellular Functions
Specialized Cell(s)
1. Movement
Muscle & other contractile cells
2. Form adhesive and tight junctions
between cells to form membranes
Epithelial cells
3. Synthesize & secrete components of the Fibroblasts, cells of bone and
ECM
cartilage
4. Convert physical & chemical stimuli into
Neurons and sensory cells
action potentials
5. Synthesis & secretion of enzymes
Cells of digestive glands
6. Synthesis & secretion of mucous
substances
Mucous-gland cells, goblet cells
7. Synthesis & secretion of steroids
adrenal cortex, testis, & ovary
8. Ion transport
Cells of the kidney & salivary gland
ducts, stomach parietal cells
9. Intracellular digestion
10. Lipid storage
11. Metabolite absorption
Macrophages & some WBC
Fat cells (adipocytes)
Cells lining the intestine
Organization of the Cell
– A typical cell, as seen by the light
microscope has two major parts: the
nucleus and cytoplasm.
– The nucleus is separated from the
cytoplasm by a nuclear membrane,
and the cytoplasm is separated from
the extracellular environment by a cell
membrane, also called the plasma
membrane.
– The different substances that make up
the cell are collectively called
protoplasm.
– Protoplasm is composed mainly of six
basic substances: water, electrolytes
(ions), proteins, lipids,
carbohydrates, and nucleic acids.
•A membrane similar to the cell membrane surrounds
such important cytoplasmic organelles as nucleus,
mitochondria, endoplasmic reticulum, Golgi complex,
lysosomes, and peroxisomes.
•Organelles that are not surrounded by membranes
include ribosomes, basal bodies, centrioles, and
centrosomes.
.
17
Systems of the body
• The 11 human systems
• Integumentary
• Skeletal
• Muscular
• Nervous
• Endocrine
• Circulatory
• Cardiovascular
• Lymphatic
• Respiratory
• Digestive
• Urinary
• Reproductive
• Immune
18
1.The cardiovascular system
• consists of
– the heart
– blood vessels
The cardiovascular system
• Heart
– hollow, muscular, 4 chambered organ
– Cardiology is a discipline of which deals with heart
– Weighs about 300 g in adults (about the size of a clenched
fist)
– 2 cm long, 9cm wide & 6 c m thick
– it rests on the diaphragm near the mid line of the thoracic
cavity in the mediastinum
• 2/3rd portion of the heart is located in the left side of the body,
– the heart has a pointed end the apex, and a broad portion
opposite to the apex called base
The Heart: Surfaces
21
The Heart: Surfaces
22
Structure of the heart
• Pericardium (peri = around)
– is a protective and surrounding membrane of the heart
– it consists of two principal portion:
• the fibrous pericardium
• the serous pericardium
• Fibrous pericardium
– is tough inelastic, dense irregular connective tissue, which
looks like a bag.
– It rests & attaches to the diaphragm:
– its open end is fused to the vessels entering and leaving the
heart.
– Function of fibrous pericardium
• prevents overstretching of the heart
• provides protection and
• anchors the heart in the mediastinum
• The serous pericardium
– is a thinner membrane which forms a double layer
– parietal layer –
• is the outer serous pericardium
– visceral layer• The inner serous pericardium
• adheres tightly to the surface of the heart.
– pericardial fluid.
• is a fluid In the cavity b/n two layers of pericardium
• is important to reduce friction b/n the heart and the outer layers and
also prevent the heart from external pressure.
• Layers of the heart wall
– contain 3 distinct layers:
– Epicardium –
• thin, external membrane around the heart
• allow protection against friction by rubbing organs
– Myocardium –
• thickest layer; consists of cardiac muscle. i.e the bulk of
the heart wall.
• It is involuntary muscle
• responsible for the ability of the heart to contract
– Endocardium –
• a thin innermost layer; a unique type of epithelial tissue
that lines the entire circulatory system
• Chambers of the heart
– The heart has four chambers
• two - atria (entry halls or chambers)
• two ventricles (little bellies)
• Right atrium
– forms the right border of the heart
– it receives blood from
• superior vena cava
• inferior vena cava and
• coronary sinus
– Interatrial septum- is a thin partition between right
and left atriums.
– blood passes from the right atrium in to the right
ventricle through a valve called tricuspid valve, it
consists of three leaflets of cusps
• Heart Valves:
– prevent back flow of blood and ensure that blood
flows in the proper direction through the heat.
– The valves function to maintain blood flow in one
direction.
– Valves open and close in response to changes in
pressure:
• 4 heart valves
– Atrioventricular (AV) valves
• tricuspid and
• bicuspid valves
– Semilunar valves
• Aortic valve
• Pulmonary valve
Heart Sounds
• Lub
– first heart sound
– occurs during ventricular systole
– A-V valves closing
• Dub
– second heart sound
– occurs during ventricular diastole
– pulmonary and aortic semilunar valves closing
• Murmur – abnormal heart sound
Surface Anatomy of the Heart
31
• Conducting System
– Sino atrial (SA) node –pacemaker
– atrioventricular (AV) node
– AV bundle
– right and left bundle branches
– Purkinje fibers
Conduction System of the Heart
• Two circulatory routes:
–pulmonary circulation:
• right ventricle ----pulmonary artery---lungs----pulmonary vein----- left atrium
–systemic circulation:
• left ventricle ----- aorta-----body-----superior and inferior vena cava------right
atrium
• Coronary circulation is part of the systemic
circulation and supplies blood to the heart
tissues via coronary arteries and veins.
Principal Arteries of the body
• aorta
• ascending aorta
– ascends from the heart (left ventricle)
– The coronary arteries are the only branch of
the ascending aorta
• Aortic arch
– Three vessels arise from the aortic arch:
• the brachiocephalic artery–supplies the
upper limbs and head regions
• left common carotid artery
• left subclavian artery
• brachiocephlic artery
– bifurcates into:
• the right common carotid artery
(supplies the right side of hand and
neck) and the
• subclavian artery (supplies the right
upper limb)
• The left common carotid artery and the
left subclavian artery
– branch directly from the aortic arch.
• Arteries of the neck and head
• Common carotid artery
– ascends upwards in the neck lateral to
trachea
– Divides slightly below the angle of the
mandible into
• the internal carotid artery and
• the external carotid artery
Arteries of the upper limbs
• Right subclavian- from brachiocephalic.and
• left subclavian- from aortic arch.
• It has the several branches in the thorax but
becomes the axillary artery as it passes in the
axilla.
• It becomes the brachial artery in the arm.
– Site for BP(blood pressere measurement)
• Branches of the abdominal portion of aorta
– Abdominal aorta is the segment between
diaphragm and L4
– Has three main unpaired branches
– Other paired branches
• unpaired
• Celiac trunk –
– short, thick, branch, which divides into three
vessels:
• Splenic artery (to spleen)
• Left gastric artery ( to stomach)
• Common hepatic (to liver)
• Superior mesenteric artery– to the small intestine (except the duodenum),
cecum, appendix, transverse, and ascending colons
• Inferior mesenteric artery –
– last major, anterior, unpaired branch just before
bifurcation into the common iliac arteries.
• Supplies the descending, and sigmoid colons,
rectum
• Paired branches
– Renal artery– to kidney
– Suprarenal artery - to adrenal glands
– Testicular artery - to testes
– ovarian artery- to ovaries
• Arteries of the pelvis and lower limbs
–the abdominal aorta terminates by
bifurcating into
• right common iliac arteries
• left common iliac arteries
–The common iliac divides into
• the internal iliac and
• external iliac artery
• The external iliac artery–
– passes out of pelvis beneath the inguinal
ligament to become the femoral artery
• Femoral artery –
– passes through the femoral triangle on the
upper medial portion of the thigh.
– At this point it is close to the surface, hence
for pulpation and pressure.
– the femoral artery becomes the popliteal
artery as it passes across the posterior
aspect of the knee.
Venous drainage of the body
• Veins Draining the neck and head
• External jugular vein
– from scalp, portions of face, superficial neck region
– drain into right and left subclavian vein.
• Internal jugular vein
– from brain, meniges, deep regions of face and neck
– larger and deeper than the external jugular vein
– passes in carotid sheath with the common carotid
and vagus nerve beneath sternocleidomastoid
muscle
• subclavian vein and internal jugular unite to form the
brachiocephalic vein
• the two brachiocephalic veins merge to form the
superior vena cava, w/h empties into the right atrium
Veins of the upper extremity
• Consists of superficial and deep venous drainage
• Deep veins
•
accompany the arteries and bear their names / region
– radial vein + ulnar vein
• both drain from deep and superficial palmar
arches
• radial and ulnar veins join in the cubital fossa to
form the brachial vein, which continues up on the
medial side of the arm.
– Brachial vein -axiliary → subclavian → internal
jugular → brachiocephalic
superficial veins
• are the basilic and
– cephalic veins
• basilic vein
– drains blood from ulnar side of forearm,
medial side of arm
– merges with brachial vein near the head of
the humerus to form the axillary vein
• cephalic vein
– drains superficial region of hand and forearm
on radial side
– joins axillary vein in the shoulder region
– median cubital vein ascends from the
cephalic vein to join basilic vein on radial
side. It is a site of venipuncture
• Veins of the thorax
• Superior vena cava
– receives blood from the right and left
brachiocephalic veins, which drain head, neck, and
upper limb as well as from azygous veins.
– lacks valves which are characteristics of most veins
• The azygous vein
– extends superiorly along the dorsal abdominal and
thoracic walls on the right side of the vertebral
column
• The superficial vein include
–small saphenous vein :
• arises from the lateral side of the foot,
courses posteriorly along the surface of
the calf of the leg and enters deep into the
popliteal vein behind the knee.
–Great saphenous vein :
• longest vessel in the body, originates at
the arch of the foot and ascends
superiorly along the medial aspect of the
leg and thigh before draining into the
femoral vein.
THE DIGESTIVE SYSTEM
Introduction
• The organs of the digestive system are
specialized for the digestion and
absorption of food.
• Anatomically and functionally, the digestive system
can be divided into:
– a tubular digestive tract, or (GI tract)
– accessory organs.
• The GI tract
– is approximately 9m long and
– extends from the mouth to the anus.
– It include
• oral cavity
-stomach
• pharynx
-small intestine,
• esophagus
-large intestine.
• Accessory digestive organs
– it include
• the teeth
• tongues
• salivary glands
-liver
- gallbladder
- pancreas.
• Palate:– the roof of the oral cavity and consists of the bony
• soft palate– the mobile fibromuscular part (posterior 2/3 rd)
– attached to the posterior edge of the hard palate.
• hard palate
– anterior 2/3 rd and
– is formed by the palatine process of maxilla and the
horizontal plate of palatine bone.
• The uvula –
– is a conical process (cone-shaped projection) suspended
from the middle inferior border of the soft palate.
– The soft palate and uvula are drawn upward against the wall
of the pharynx,
– thereby closing the nasophaynx and preventing food and
fluid from entering the nasal cavity (regurgitation).
Abdominal visceral organs
68
Histological Layers of the GIT
• Esophagus
– This is a collapsible muscular tube (25cm) that connects the
pharynx to the stomach, and located posterior to the
trachea.
– It passes through the diaphragm is an opening called
esophageal hiatus.
– The esophagus is lined with a nonkeratinzed stratified
squamous epithelium.
– The upper third of the esophagus contains skeletal muscle,
the middle third contains both skeletal and smooth muscle,
and the terminal portion contains only smooth muscle.
– The lumen of the terminal portion of the esophagus is
slightly narrowed due to the presence of the lower
esophageal (gastroesophageal) sphincter.
– This prevents regurgitation of stomach contents into the
esophagus.
• Stomach
–The stomach is a J-shaped pouch and is
the most distensible part of the GIT.
–The functions of the stomach are:
• to store food as it is mechanically churned
with gastric secretions
• to initiate the digestion of proteins
• to carry out limited absorption
• to move food into the small intestine as a
chyme (pasty material)
• Secration of gastric juice
 The stomach is divided into
four regions
– Cardiac: - the narrow
upper region immediately
below the
gastroesophangeal
sphincter
– Fundus: - the dome
shaped portion to the left
and in direct contact with
diaphragm
– Body: - the lager central
portion
– Pylorus:- the funnel
shaped terminal portion.
• Small intestine
• It is the portion of the GIT b/n the pyloric
sphincter of the stomach and the ileocecal
valve opening into the large intestine.
– is the site where digestion is completed and
nutrients are absorbed.
– The surface area of the intestinal wall is increased
by villi, and microvilli.
• The functions the small intestine are
– the reception of the secretions from the liver and
pancreas,
– mechanical breakdown of chime,
– absorption of nutrients and
– transportation of the remaining undigested material
to the large intestine.
• The small intestine is divided into three regions
• These are
– the duodenum,
– jejunum and
– ileum.
Small intestine
Small Intestine:
• longest part of the GIT &
extends from pyloric
orifice of stomach to
ileocecal fold.
• is about 6-7 m long with
a narrowing diameter
from beginning to end
• Major digestive organ
• Primary site for absorption
• consists of duodenum
(25 cm), jejunum (2.5 m)
& ileum (3.6 m).
• first part of small intestine
is duodenum.
75
Jejunum and Ileum
• Jejunum begins at
duodeno-jejunal
flexure
• Has intraperitoneal
course.
• Ileum ends at
ileocecal junction.
• Most jejunum lies in
LUQ
• while most ileum lies
in RLQ.
• Small coils of small
76
Jejunum & Ileum
Jejunum:
• is about 2.5m long &
represents proximal two-fifths.
• It is mostly in the left upper
quadrant of the abdomen
• It is larger in diameter and
has a thicker wall than the
ileum.
• less prominent arterial
arcades & longer vasa recta
(straight arteries), compared
to those of ileum, are a unique
characteristic of jejunum .
Jejunum
Ileum
77
Jejunum & Ileum
Ileum:
• is about 4m long & makes up
distal three-fifths of Small
Intestine
• is mostly in right lower
quadrant.
• Compared to jejunum, ileum
has thinner walls, shorter
vasa recta, more arterial
arcades & more mesenteric
fat
• ileum opens into large intestine
78
Distinguishing Characteristics of
Jejunum and Ileum in Living
Persons(summary)
Characteristics
Jejunum
Ileum
•Caliber
2 - 4 cm
2 - 3 cm
•Wall
Thick & heavy
Thin & light
•Vascularity
Greater
Less
•Vasa recta
Long
Short
•Arcades
A few large loops
Many short loops
•Fat in mesentery
Less
More
•Lymphoid nodules (Peyer
patches)
•Color
Few
Many
Red
Pale
79
• The large intestine is structurally divided into
– the cecum
– colon
– rectum
– anal canal.
• The cecum
– is the dilated pouch that hangs inferiorly slightly
below the ileocecal valve.
– The ileocecal valve is a fold of mucus membrane at
the junction of the small and large intestine that
prohibits the back flow of chyme.
– The appendix (9cm) is attached to the inferior
medial margin of the cecum.
– It has an abundance of lymphatic tissue which
serves to resist infection.
The large intestine
• The colon
– consists of ascending, transverse, descending, and
sigmoid portions.
– The ascending colon extends superiorly from the cecum
along the right abdominal wall to the interior surface of the
liver.
– Hence the colon bends sharply to the left at the hepatic
flexure (right colic flexure) and transversely crosses the
upper abdominal cavity as the transverse colon.
– At the left abdominal wall, it bends at a right angel called the
splenic flexure (or left colic flexure).
– The latter marks the beginning of the descending colon.
– This passes inferiorly along the left abdominal wall to the
pelvic region where it bends medially from the pelvic brim to
form an S- shaped curve called the sigmoid colon..
• The terminal (20cm) portion of the GIT is the
rectum of which the last 2 to 3 cm is called the
anal canal.
• The anus is the external opening of the anal
canal.
• Two sphincter muscles guard the anal opening:
– the internal anal
– external anal sphincter
• composed of smooth muscle fibers and the
composed of skeletal muscle.
• The mucus membrane of the anal canal is a
ranged into highly vascular longitudinal folds
called anal columns
Accessory digestive glands
– These organs aid in the chemical break down
of food.
– These are
• the liver
• gallbladder, and
• pancreas.
– The liver and pancreas function as exocrine
glands in this process because their
secretions are transported to the lumen of the
GIT via ducts.
The Liver
• Liver is the largest gland in the body
 It normally weighs about 1.5kg.
• accounts for about one-fortieth of
the body weight in the adult.
• At birth, it represents one-twentieth
of weight of the body
• In the adult, it is concealed under
the costal margin and cannot be felt
or palpated.
• The Liver lies principally in the right
hypochondrium & epigastrium &
extends into left hypochondrium.
RUQ
86
Surface anatomy of liver
• Liver has two
surfaces:–
diaphragmatic &
visceral
surfaces which are
separated by an
irregular, inferior
border.
• Diaphragmatic
surface :
• is smooth & is
related to the
diaphragm.
87
Ligaments of liver
• On the diaphragmatic
surface
– Coronary ligament –bare
area
– Falciform ligament – right
and left lobe
On the visceral surface
• Round ligaments of
liver(ligamentum
teres)
• Ligamentum venous
88
– The porta of the liver is where the hepatic artery,
portal vein, lymphatic, and nerves enter the liver
and where the hepatic ducts exit.
• The liver carries out numerous functions:
– synthesis, storage, and release of vitamins;
– synthesis, storage, and release of glycogen;
– synthesis of blood proteins;
– phagocytosis of old red blood cells and certain
bacteria;
– removal of toxic substances; and
– production of bile.
• Gall bladder
– is a sack like organ attached to the inferior surface
of the liver.
– It stores and concentrates bile, which drains to it
from the liver by way of the bile ducts, hepatic duct,
and cystic duct, respectively.
– Bile is a yellowish-green fluid containing
– bile salts bilirubin (a product resulting from a
breakdown of blood), cholesterol and other
compounds.
– Bile is continuously produced by the liver and drains
through the hepatic and common bile ducts to the
duodenum for the emulsification and absorption of
fats.
– When the small intestine is empty of food, the
sphincter of ampulla (Oddi) constricts and bile is
• Pancreas
– The pancreas (12.5cm long and 2.5cm thick)
– is a soft, lobulated, glandular organ that has both
exocrine and endocrine function.
– The endocrine function is performed by clusters of
cells called the pancreatic islets (islets of
langerhans) that secrete the hormones insulin and
glucagons into the blood.
– The pancreas, as an exocrine gland, also secretes
pancreatic juice through the pancreatic duct into the
duodenum.
– It is positioned along the posterior abdominal wall,
adjacent to the greater curvature of the stomach.
– It has an expanded head near the duodenum, a
centrally located body, and a tapering tail near the
spleen.
Respiratory System
Functions
1. Provides extensive gas exchange
surface area between air and circulating
blood
2. Moves air to and from exchange
surfaces of lungs
3. Protects respiratory surfaces from
outside environment
4. Produces sounds-speaking, singing
5. Participates in olfactory sense
The Respiratory Tract
• Consists of a conducting portion:
– from nasal cavity to terminal bronchioles
• Consists of a respiratory portion:
– the respiratory bronchioles and alveoli - Are
air-filled pockets within the lungs
• where all gas exchange takes place
The Trachea & Bronchial Tree
95
Anatomy of the Larynx
Figure 23–4
Cartilages of the Larynx
• 3 large, unpaired
cartilages form the
larynx:
– the thyroid cartilage
– the cricoid cartilage
– the epiglottis
The Thyroid Cartilage
• Also called the Adam’s
apple
• Is a hyaline cartilage
• Forms anterior and
lateral walls of larynx
• Ligaments attach to
hyoid bone, epiglottis,
and laryngeal cartilages
The Cricoid
Cartilage
• Is a hyaline
cartilage
• Form posterior
portion of larynx
• Ligaments attach
to first tracheal
cartilage
• Articulates with
arytenoid
cartilages
The Epiglottis
• Composed of
elastic cartilage
• Ligaments
attach to thyroid
cartilage and
hyoid bone
Cartilage Functions
• Prevents entry of food and liquids into
respiratory tract
– During swallowing:
– the larynx is elevated
– the epiglottis folds back over glottis
• Thyroid and cricoid cartilages support and
protect:
– the glottis
– the entrance to trachea
The Glottis
Figure 23–5
Sound Production
• Air passing through glottis:
– vibrates vocal folds
– produces sound waves
Sound Variation
• Sound is varied by:
– tension on vocal folds
The Trachea
• Also called the
windpipe
• Extends from
the cricoid
cartilage into
mediastinum
– where it
branches into
right and left
pulmonary
bronchi
The Tracheal Cartilages
• 15–20 tracheal cartilages:
– strengthen and protect airway
– discontinuous where trachea contacts
esophagus
• Ends of each tracheal cartilage are
connected by:
– an elastic ligament and trachealis muscle
The Primary Bronchi
• Right and left primary bronchi:
– separated by an internal ridge (the carina)
The Right Primary Bronchus
• Is larger in diameter than the left
• Descends at a steeper angle
Structure of Primary Bronchi
• Each primary bronchus:
– travels to a groove (hilus) along medial
surface of the lung
Hilus
• Where pulmonary nerves, blood vessels, and
lymphatics enter lung
• Anchored in meshwork of connective tissue
The Lungs
• Left and right
lungs:
– are in left and right
pleural cavities
• The base:
– inferior portion of
each lung rests on
superior surface of
diaphragm
Root of the Right Lung
Right lung:
is wider
is displaced upward
by liver
109
Root of the Left Lung
• Left lung:
– is longer
– is displaced
leftward by
the heart
forming the
cardiac
notch
110
Secondary Bronchi
• Branch to form tertiary
bronchi, also called the
segmental bronchi
• Each segmental
bronchus:
– supplies air to a
single
bronchopulmonary
segment
An Alveolus
• Has an
extensive
network of
capillaries
• Is
surrounded
by elastic
fibers
Alveolar Epithelium
• Consists of simple
squamous
epithelium
• Patrolled by
alveolar
macrophages,
also called dust
cells
• Contains septal
cells (Type II
cells) that produce
surfactant
Surfactant
• Is an oily
secretion
• Contains
phospholipids
and proteins
• Coats alveolar
surfaces and
reduces surface
tension
• Tracheotomy – an operation to make an
opening into trachea
• Intubation – a tube is inserted into the mouth or
nose and passed inferiorly through larynx and
trachea to maintain an open airway or to serve
as a conduit through which to administer certain
drugs
Urinary system
– consists of:
– Two kidneys
– Two ureters
– The urinary bladder &
– The urethra
– Responsible for water &
electrolytes homeostasis: by
eliminating excess water &
electrolytes from the body
Functions of urinary system
– The maintenance of water and electrolyte balance
– Excretion of many toxic metabolic waste products
– The end product of urinary system is urine
kidneys
ureters
urinary bladder
urethra
outside of the body
– In female
– urethra is solely a urinary duct
– In male
– it also serves as the pathway for ejaculation of
the semen in addition to urine
– Two Kidneys
– Perform all functions except actual
excretion.
– Two Ureters
– Convey urine from Kidneys to Urinary
Bladder
– Urinary Bladder
– Holds Urine until excretion/void
– Urethra
– Conveys urine from bladder to outside of
body (discharge)
The kidneys
– are a pair of reddish brown, bean shaped organs
Position
–
–
–
–
–
–
in the posterior wall of the abdominal region.
lie on either side of the vertebral column,
below the diaphragm and liver,
are retroperitoneal
the right is slightly lower than the left due to liver
capped by the adrenal gland
CT coverings
– Pararenal fat
– Renal fascia: binds to abdominal wall
– Adipose capsule: cushions kidney
Covering of kidney are:
– Pararenal fat tissue of the posterior
abdominal wall
– Renal fascia: dense fibrous CT anchors
kidneys/or adrenal gland to the
surroundings fat tissues or thin layer of
dense irregular connective tissue that
anchors the kidney to the abdominal
wall.
– Adipose capsule: is a mass of a
perirenal fatty tissue surrounding the
renal capsule.
– Renal capsule: closely related to the
kidney cortical surface
– It serves as a barrier against trauma and
helps maintain the shape of the kidney
Renal capsule
Microscopic Structure of the kidney
The nephron
– is the functional unit of the kidney
– consists of the blood processing unit which serves to
produce urine
– to produce urine, nephrons and collecting tubules and
ducts perform three basic processes: glomerular
filtration, tubular reabsorption, and tubular secretion
– there are more than a million nephrons per kidney
– consists of a renal corpuscle and tubules, and small blood
vessels.
• Renal blood vessels
• Arterial blood enters the kidney
through the renal artery →
Segmental arteries→ interlobar
arteries→ the arcuate
arteries→ interlobular →
afferent arterioles.
• deliver blood into glomeruli
capillary
• efferent arterioles →
peritubular capillaries →inter
lobular veins→ arcuate veins
→interlobar veins → renal
veins→ inferior vena cava.
URETER
– Cylindrical tube, 3- 4 mm in
diameter, 25-30 cm in length
Urethra
– a single tubular structure that conveys
urine from urinary bladder to outside.
– communicates the urinary bladder
with the outside
– its wall contains mucus secreting
urethral glands
– consists of two muscular sphincters:
– Internal urethral sphincter
– External urethral sphincter
– Male urethra is longer than female
urethra and also functions as a route
for semen
Female Urethra
– relatively short.
– about 4cm long and 5-6 mm in diameter
– empties urine through urethral orifice into the
vestibule b/n the labia minora.
– positioned immediately anterior to the vaginal
orifice, and 2.5cm posterior to the root of clitoris
The Male Urethra
– is about 18-20 cm long. serves both as urinary and
reproductive systems
– conveys urine from urinary bladder and an exit for semen
– S-shaped because of the shape of penis
– Four parts:
1. The Prostatic Part (3-4 cm )- during orgasm receives
semen
2. The Membranous Part (1-2 cm) - passes through
pelvic diaphragm
3. The spongy (penile) part – within the penis (penile)
4. Fossa Navicularis part: in the glans penis
– opens to exterior
Kidney stones
–
A hard granule of calcium, phosphate, uric acid and
protein.
–
Form in renal pelvis and get lodged in pelvis or ureter.
–
Caused by urinary tract infections, dehydration, pH
imbalances, or an enlarged prostate gland.
–
Treated with stone dissolving drugs, surgical removal, or
lithotripsy (ultrasonic vibrations)
Reproductive system
132
INTRODUCTION
• Sexual reproduction involves production of offsprings
with a genetic makeup inherited from parents.
• Function of male reproductive system:
– to produce the male gamete, or spermatozoa,
– to transfer it to the female through coitus.
• Function of female reproductive system:
– to produce female gamete, or ova
– receive the sperm from the male during coitus.
– a site for
• fertilization,
• implantation, development of the embryo,
– facilitate delivery of the baby during parturition.
– Provides a means of nourishing the baby through secretions
133
from mammary glands after birth.
• The reproductive system is a unique body system
in three respects:
– To perpetuate the species by passing genetic
material from generation to generation [other body
systems function to sustain the individual)
– The anatomy and physiology of the reproductive
organs constitute the major d/c b/n the male and
female species (other systems have minor gender
differences)
– It undergoes latent development under hormonal
control (others function at birth but the reproductive
system does not until puberty).
134
• THE MALE REPRODUCTIVE ANATOMY
– can be categorized on functional basis as follows:
• Primary sex organs (= gonads = testes in scrotum)
• Secondary sex organs
– transporting ducts;
• Epididymides
• ductus deferens
• ejaculatory ducts
• urethra.
– accessory glands
• seminal vessicle
• prostate
• bulbourethral glands.
– compulatory organ
• penis (contains erectile tissue).
135
136
137
• The Ductus Deferens
• also known as vas deferens
• is a thick-walled muscular tube
• begins in the tail of the epididymis and
• ends by joining the duct of the seminal vesicle
to form the ejaculatory duct.
• It is about 45 cm long and ascends in the
spermatic cord.
• in its course no other structure intervenes b/n it
and the peritoneum.
138
139
140
• The Ejaculatory Ducts
– formed by the union of the ducts of the seminal
vesicle and ductus deferens.
– are about 2.5 cm long
– They run anteroinferiorly through the posterior part
of the prostate along the sides of the prostatic
utricle.
– open in to the posterior wall of the prostatic urethra.
141
• The seminal vesicles
– is a thin-walled, Blind-ending tube about 5 cm long;
– located b/n the fundus of the bladder and the
rectum.
– do not store sperm cells.
– Provide most of the volume of the semen (a thick
yellowish alkaline fluid)
142
143
• The prostate gland
– Largest accessory gland of the male repr. system
– Partly glandular & partly fibromucular
– Surrounds the prostatic urethra.
• The prostate has
– base
– apex
– 4 surfaces
• posterior
• anterior
• 2 inferolateral surfaces
– 4 lobes
• Anterior lobe
• Posterior lobe
• Middle lobe
• Lateral lobes
144
• Bulbourethral Glands
– are two pea-size glands (Cowper glands).
– lie posterolateral to the intermediate part of
the urethra,
– largely embedded within the external urethral
sphincter
– The ducts of the bulbourethral glands open
into the proximal part of the spongy urethra in
the bulb of the penis.
– Their mucus-like secretion enters the urethra
during sexual arousal.
145
146
147
• Distal structures of the body,
• Glans penis(head)
– is distal expansion of the corpus spongiosum of the
penis
– Is cone shape
– Contain higher concentration of sensory nerves
– Sensitive to physical stimuli
– has :
• Corona
– margin of the glans projects beyond the ends of the
corpora cavernosa
• The corona overhangs the neck of the glans
148
THE FEMALE REPRODUCTIVE ANATOMY
– Include:• the Vagina
• Uterus
• Uterine tubes
• Ovaries
149
• VAGINA
– a musculomembranous(7-9cms) tube
– extends from the cervix to the vestibule
– Its posterior wall is ~1cm longer than the anterior
– Serves:
• as a canal for menstrual fluid.
• Forms birth canal.
• sexual intercourse.
– The vagina is usually collapsed except at its superior end,
where the cervix holds them apart.
– 4 muscles compress the vagina and act like
sphincters:
– pubovaginalis
– external urethral sphincter
– urethrovaginal sphincter
– bulbospongiosus
150
• UTERUS
– The uterus (womb) is a thick-walled, pearshaped, hollow muscular organ.
– The non-gravid uterus lies in the lesser
pelvis,
– The normal adult uterus position is
anteverted. and anteflexed (flexed or bent
anteriorly) so that its mass lies over the
bladder.
151
152
B)abnormal positions
153
Cervix
• cylindrical, lower part of uterus whose inferior part
projects into vagina;
– the cavity of the cervix (cervical canal)
communicates with uterine cavity & vagina through
its internal os & external os respectively.
– pierces ant. wall of vagina divided into supravaginal
& vaginal parts
– paras cx is d/t from that of non para.
154
155
The wall of the uterus
• 3 layers:
• Perimetrium:
– the outer serous coat
– Made up of peritoneum.
• Myometrium:
– the middle muscular coat of smooth muscle
– greatly distended during pregnancy
– blood vessels and nerves of the uterus are located in
this coat.
• Endometrium:
– the inner mucous coat, which firmly adheres to the
myometrium
– is actively involved in the menstrual cycle
– differ in structure with each stage
– site of implantation
– if no conception it shed as menstrual
156
• Supports of the Uterus
• normal positions of uterus is maintained
by
• ligaments
• muscles
• fibromuscular structures
• peritoneal folds
• Ligaments of the Uterus
– Broad ligament
– Round ligament
– Cardinal (transverse cervical) ligament
– Uterosacral ligament
157
• The Uterine Tubes
– These are 10 cm long and 1 cm in diameter.
– They extend laterally from the cornua of the uterus.
– Each tube opens to horn of the uterus proximaly
– opens into the peritoneal cavity near the ovary at its distal
end
• Function:
– carry oocytes from the ovaries to the fertilisation site&
– sperm from Ux. to fertilisation site
– conveys the dividing zygote to the uterine cavity. Serve
as fertilisation site
– The uterine tube has 4 parts:
– infundibulum
– ampulla
– isthmus
– Intramural
158
• The infundibulum
– is the funnel-shaped distal end
– opens into the peritoneal cavity.
– has finger-like processes called the fimbriae
• The ampulla
– begins at the medial end of the infundibulum.
– the widest & longest part,
– is site of fertilization
• The isthmus
– b/n ampulla & intramural part
– narrow part
• Intramural part
– is the short segment that opens into the uterine cavity at the
uterine horn.
159
Ectopic pregnacy Sites
Ampulla (95%)
Isthmus (8%)
Cornua (< 2%)
Ovary (< 2%)
Abdomen (< 2%)
Cervix (< 2%)
160
• Tubal Ligation
– Ligation of the uterine tubes is a surgical method of
birth control.
– performed through a short suprapubic incision
made just at the pubic hairline.
161
OVARY
• Position
– located in the ovarian fossa
– Lies close to appendix on the right
– Bounded anteriorly by medial umbilical ligament
– Its anterior border is attached to post border of
broad ligament by mesovarium
– Attached to uterus by the ligament of ovary which
runs in the mesovarium of the broad ligament
– not covered by peritoneum-- oocyte is released into
peritoneal cavity during ovulation
• Has two parts
– Cortex
162
163
Female External Genitalia(vulva)
• include
– mons pubis
– labia majora
–labia minora
– clitoris
– bulbs of the vestibule
–greater and lesser vestibular glands.
– hymen
164
vulva
165
• Mons Pubis (L. mountain)
– is a rounded fatty elevation anterior to the
pubic symphysis.
– The amount of fat increases during puberty
and decreases after menopause.
– covered with coarse pubic hairs during
puberty, which also decrease after
menopause.
– The typical female distribution of pubic hair
has a horizontal superior limit across the
pubic region
166
167
• The Labia Majora (L. large lips)
– are two symmetrical folds of fat & skin
– provide protection for the urethral and vaginal orifices
– The labia majora meet anteriorly at the anterior labial
commissure.
– They do not join posteriorly but a transverse bridge of skin
called the posterior labial commissure passes between
them.
The Labia Minora (L. small lips)
– are thin, delicate folds of fat-free hairless skin.
– They are located between the labia majora.
– It contains many sensory nerve endings.
– Sebaceous and sweat glands open on both of their surfaces.
– The labia minora enclose the vestibule of the vagina
– They meet just superior to the clitoris to form a fold of skin
called the prepuce (clitoral hood).
– In young females the labia minora are usually united
posteriorly by a small fold of the skin, the frenulum of the
labia minora.
168
• The Vestibule of the Vagina
– is the space b/n the labia minora.
– The urethra, vagina, and ducts of the greater vestibular
glands open into the vestibule.
• The External Urethral Orifice
– located 2 to 3 cm posterior to the clitoris and
– immediately anterior to the vaginal orifice.
– the paraurethral glands (Skene's glands) ducts open On
each side of this orifice
– These glands are homologous to the prostate in the male.
• The Vaginal Orifice
– inferior and posterior to the much smaller external urethral
orifice.
– The size and appearance of the vaginal orifice varies with
the condition of the hymen
169
vestibular glands
• The Greater Vestibular Glands(B.G )
– located on each side of the vestibule of the vagina,
– posterolateral to the vaginal orifice.
– ducts open into the vestibule of the vagina on each side of
the vaginal orifice.
– secrete a small amount of lubricating mucus into the
vestibule of the vagina during sexual arousal.
– homologous with the bulbourethral glands in the male.
The Lesser Vestibular Glands
– are small glands on each side of the vestibule of the
vagina.
– They open into it b/n the urethral and vaginal
orifices.
– also secrete mucus into the vestibule, w/c moistens
170
the labia and the vestibule.
The Clitoris
• is an erectile organ 2 to 3 cm in length.
• It is homologous with the penis and.
• Unlike the penis, is not traversed by the
urethra;therefore it has no corpus spongiosum.
• It is usually hidden by the labia when it is flaccid.
• It is suspended by a suspensory ligament.
• enlarge upon tactile stimulation, like the penis
• but it does not lengthen significantly.
• It is highly sensitive and very important in the sexual
arousal of a female.
171
• The clitoris consists of
• a root and
• a body that are composed of
– two crura,
– two corpora cavernosa,
– a glans
• the prepuce of the clitoris
– formed from The parts of the labia minora passing anterior to
the clitoris
– homologous with the male prepuce.
• frenulum of the clitoris
– formed from the parts of the labia passing posterior to the
clitoris
– is homologous with the frenulum of the penile prepuce.
172
173
174
HYMEN
• the ancient Greek god of marriage.
• A thin fold of mucous membrane that covers all
or part of the entrance to the vagina
175
D/t SHAPES OF HYMEN
Annular hymen
Cribriform hymen
Crescentic hymen
Experianced hymen
Parous hymen
Imperforated hymen
176
Skeletal
system(Osteology)
• The skeletal system includes all
the bones in the body, the
ligaments and the cartilages
associated with the bone
• The adult human has 206
bones(80+126)
• Provides the framework for the
body
• Protects and supports body
organs
• Site of blood cell formation
• Stores minerals
• Allows for body movement
177
Bone Tissue
• Two Kinds:
•
Compact bone tissue- the bone’s shaft
and the outer portion of its two ends.
– Compact bone forms in thin, circular layers
with small canals at their centers, which
contain blood vessels and nerves.
– Cells communicate with each other through
the canals.
•
Spongy bone tissue- inside the shaft of
long bones.
178
• Much of it is composed of a cylinder of dense white
osseous tissue called compact bone.
- it inclose a medulary cavity/marrow cavity
which contain a bone marrow.
• At the end of a bone, a central space is occupied by a
more loosely organized tissue ,spongy bone.
• Principal parts of long bone has:
- a shaft/diphysis- the middle region
- epiphysis- located at the two ends
Where one bone meets another is covered by a hyaline
cartilage
Articular cartilage
179
Spongy bone
tissue
Central canal
compact bone
tissue
spongy bone
tissue
compact bone
outer layer of dense
180
connective tissue
• 3.2 Shapes of bones
•
classified into four principal types.
– Long bones:
• are longer than wide
• function as levers.
• E.g most of the bones of the upper and lower
limbs.
– Short bones:
• cube-shaped and are found in confined spaces
where they transfer forces.
• E.g.wrist and ankle bones.
– Flat bones:
• have broad, dense surface for muscle
attachment or protection of underlying organs.
• E.g. the cranium, ribs, and bones of the shoulder
181
girdle.
• Irregular bones:
– have varied shapes and have many surface
markings for muscle attachment.
– E.g.the facial bones and vertebrae.
• Sesamoid bones:
– round or oval nodules that develop in certain
tendons
– e.g. the patella.
– found commonly where tendons cross the ends of
long bones in the limbs
• Accessory bones:
– develop when additional ossification centers appear
and give rise to extra bones.
– E.g sutural (wormian) bones of the skull and 182
accessory bones of the foot.
Divisions of the skeletal system.
• consists of 206 bones in the adult
• It is divided into
– the axial
– the appendicular portions
• THE AXIAL SKELETON
– consists of the bones that form the axis of the body
– Form skeleton of the head, neck and trunk.
• Skull
– the cranial bones
– the facial bones
• Auditory ossicles
– malleus
– incus
– stapes
183
• Hyoid bone - located above the larynx and below the
• Vertebral column or back bone
– 5 group of bones(C7,T12,L5,S1,C1)
• Rib cage or thoracic cage
– 12 ribs
– the sternum.
– T12
184
• The appendicular skeleton
–Pectoral girdle
– scapulae
– clavicles.
–the upper limb
–the pelvic girdles.
–lower limb
185
•Upper limbs
– consist of
• humerus
• ulna
• radius
• carpal
• metacarpal
• phalanges
186
Pelvic girdle
formed by
– two hipbones
–
sacrum of the
– coccyx
Lower limbs
• Contain
– femur
– patella.
– tibia
– fibula
– tarsal
– metatarsal
– phalanges
189
• The Axial Skeleton
• A. The Skull
–consists of cranial bones and facial
bones.
–The cranial bones
• 8 in number.
– The facial bones
• 14 in number.
190
191
The Adult Skull – lateral view
192
• Facial Bones
– with certain cranial bones (frontal and portions of
the ethmoid and temporal bones) provide the basic
shape of the face.
– support the teeth and provide attachments for
various muscles that move the jaw and cause facial
expressions.
– All are paired except the vomer and mandible.
– Maxillae form upper jaw.
– Mandible or lower jaw is the only moveable bone of
the skull.
– It is attached to the skull by the temporomandibular
joint.
– Other bones of the face include the palatine bones,
zygomatic bones, lacrimal bones, nasal bones, 193
vomer, and inferior nasal conchae
194
• B. The vertebral column
– composed of 33 individual
vertebrae;
–7 cervical,
–12 thoracic,
–5 lumbar,
–5 fused sacral and
–4 or 5 fused coccygeal vertebrae,
– of which 26 are moveable and the
rest are fused.
195
196
C. Rib Cage
• This consists of the
– thoracic vertebrae,
– 12 paired ribs, costal cartilages and
– the sternum.
• It supports the pectoral girdle and upper limbs,
protects and supports the thoracic and upper
abdominal viscera, and plays a major role in
breathing.
197
• Ribs
– There are 12 pairs, each pair being attached
posteriorly to a thoracic vertebra.
– Anteriorly, the 1st seven pairs are anchored to
the sternum by individual costal cartilages and
are called true ribs.
– The remaining five pairs (8,9,10,11 and 12) are
termed false ribs
– The last two pairs of false ribs (11 and 12) do not
attach at all to the sternum, and are called
floating ribs.
• Each of the first ten ribs has a head and a tubercle for
articulation with a vertebra.
• The last two have a head but no tubercle.
– Each of the 12 pairs (all) has a neck, angle and a
198
body
199
200
201
• The pelvis is divided into two:
– a pelvis major (false pelvis)
–and a pelvis minor (true pelvis or
obstetric pelvis) by the pelvic brim.
–the pelvic brim
• gives the anteroposterior (AP)
diameter of the superior pelvic
aperture or pelvic inlet.
202
203
• There are structural differences
between the pelvis of an adult
male and that of an adult female
which reflect the female’s role in
pregnancy and parturition.
204
• F. Thigh
• Femur (thigh bone):
– This is the only bone of the thigh.
– It’s the longest, heaviest, strongest bone in
the body.
– Parts
– The proximal end
• rounded head articulates with the acetabulum
• The neck
• greater trochanter,
• lesser trochanter.
– The shaft (body)
205
• Patella (kneecap)
–a triangular sesamoid bone.
–articulate with the medial and lateral
condyles of the femur
–The patella protects the knee joints
– strengthens the quadriceps tendon.
–It also increases the leverage of the
quadriceps femoris muscle as it extends
the knee joints.
206
Leg
• Tibia (Shinbone)
• articulates proximally with the femur at the knee
joint to bear the weight of the body & distally
with the talus of the ankle.
• parts
• Proximaly
– medial and lateral condyles
– intercondylar eminence.
– Between the condyles is the
– The tibial tuberosity.
– fibular notch.
– lateral and medial epicondyles.
• Distal end
– The medial malleolus
207
208
• Tarsus:
– consists of seven tarsal bones.
– The talus articulates with the tibia and fibula
to form the ankle joint.
– The calcaneus is the largest of the tarsal
bones and provides skeletal support for the
heel of the foot. .
– The navicular bone lies anterior to the talus.
– The remaining four tarsal bones form a distal
series that articulate with the metatarsal
bones.
– These are, from medial to lateral side, the
medial cuneiform, intermediate cuneiform,
and lateral cuneiform bones, and the cuboid
bone.
209
210
• 3.4 Articulations/Joints
The skeletal system is able to permit body movement a
The science concerned with the study of joints is called
arthrology.
• classified according to structure or function.
• Structurally 3 types (i.e., based on presence or
absence of joint cavity).
– Fibrous joint
– Cartilagenous joints
– Synovial joints
• Functionally 3 types of joints (i.e. based on the degree
of movement)
– Synarthroses –immovable joints
– Amphiarthroses – slightly movable
– Diarthroses – freely movable
211
• Fibrous Joints
– lacks a joint cavity
– articulating bones JOIN by a fibrous connective
tissue.
– are rigid and relatively immovable.
– 3 types: sutures, syndesmoses and gomphoses
• Sutures:
– Found only b/n the flat bones of the skull
– characterized by a thin layer of dense regular
connective tissue that binds the articulating bones.
– They form at 18months of age and replace the
pliable fontanels of an infant’s skull.
• Syndesmosis:
– Found only in forearm) and leg where adjacent
bones
– E.g., tibiofibular joint, and radioulnar joint
212
• Gomphosis:
• Cartilagenous joints
– lack a joint cavity
– articulating bones binds by cartilage.
– They allow limited movement in response to
twisting, compression or stress.
– The two types of cartilagenous joints are
symphyses and synchondroses.
– Symphyses:
• the adjoining bones are separated by a
pad of fibrocartilage.
• This pad cushions the joint and allows
limited movement. E.g., symphysis pubis
213
and intervetebral discs.
• Synchondroses:
– Have hyaline cartilage b/n the bone segments.
– articulations b/n the ribs and the sternum. Some
temporary joints of these sorts exist between the
epiphyses and diaphyses of long bones forming
epiphyseal plates (growth lines) in children.
• Synovial joints
– These joints are the most common and
– make up most of the joints of the skeletal
system.
– Hence, they provide free movement in most
parts of the body (diarthrotic).
214
49
215
• Based on the type of movements they permit
and the shapes of the articular surfaces, they
are classified as
– gliding
– hinge
– pivot
– condyloid
– saddle or
– ball-and socket joints
216
• Plane/ Gliding:
–Allows only side-to-side and back-andforth movements with some slight
rotation.
–The articulating surface can be nearly
flat or one may be slightly concave and
the other slightly convex.
– E.g., Intercarpal and intertarsal joints,
sternoclavicular joint and the joint
between the articular processes of
adjacent vertebrae.
217
Fig 3.4 A. Plane joint; B. Saddle
joint; C. Condyloid/ellipsoidal joint
Sliding joint
218
• Condyloid:
– An oval, convex articular surface fits
into an elliptical, concave depression
– This permits angular movement in two
directions (biaxial) such as up-and-down
and side-to-side motion.
–E.g., atlanto-ocipital and radiocarpal
joints.
219
220
• Saddle:
– A saddle-shaped joint whose articular process,
each of which, has a concave surface in one
direction and a convex surface in another
– It’s a modified condyloid joint that allows a wide
range of movement.
– E.g., joint at the thumb between the trapezium of
the carpus and the first metacarpal bone
221
• Hinge:
– Allows bending in only one plane like a hinge of a
door.
– The surface of one of the articulating bones is
always concave and the other, convex.
– E.g., knee, humeroulnar (elbow), interphalange
joints.
222
Hinge joint
223
• Pivot:
• Permits rotation about a central axis in
which a conical or rounded surface fits into
a depression.
• E.g., atlantoaxial and radioulnar joints.
224
225
• Ball-and-socket:
– Formed by the articulation of a rounded
convex surface with a cuplike cavity .
– This provides the greatest range of movement
of all synovial joints.
– E.g., hip and shoulder joints
226
Ball & Socket joint
227
Muscular
system(Myology )
• Composed of muscles and
tendons
• Muscles which make up 40–50%
of total adult body weight.
• Consists of over 600-700
individual skeletal muscles
• Produces body movement
• Heat production (maintain
Temp.)
• Maintains posture
• Control the openings
(sphincters)
•
•
•
•
Three type of muscle tissue
Skeletal muscle
Cardiac muscle
Smooth muscle
228
• 4.1 Types of muscles
• Muscle is classified into 3 categories according
to morphology and physiological function:
• Depends on the presence or absence of cross
striations, location and functions.
• 1) Skeletal (Striated) = striated (striped in
appearance under microscope), voluntary
(under conscious control)
• 2) Cardiac = striated, involuntary
• 3) Smooth = non-striated, involuntary
229
Skeletal Muscle Tissue
230
• Muscle shapes
• Flat muscles
– have parallel fibers
– e.g., external oblique.
• Pinnate muscles
– feather-like (L. pennatus, feather)
– may be unipennate, bipennate, or multipennat
– e.g., extensor digitorum longus (unipennate),
bellies of the gastrocnemius (bipennate), and
deltoid (multi-pennate).
231
232
 Fusiform muscles
 are spindle shaped with a round, thick belly
 e.g., biceps brachii.
 Quadrate muscles
 have four equal sides (L. quadratus, square),
 e.g., pronator quadratus.
 Circular or sphincteral muscles
 surround a body opening or orifice,
 e.g., orbicularis oris
biceps brachii
-two heads of attachment
e.g. gastrocnemius muscles have two bellies
triceps
-three heads; the digastric and
233
• 4.2.4 Naming of skeletal muscles.
– named on the basis of shape, location,
attachment orientation of fibers, relative
position, or function..
• 1. Shape:
– rhomboideus (like a rhombus),
– trapezius (like a trapezium);
• 2. based on number of heads of origin:
– triceps (three heads),
– biceps (two heads).
• 3. Location:
– pectoralis (in the chest, or pectus),
– intercostal (between ribs),
234
• 4. Attachment:
– (zygomaticus,
– temporialis,
– nasalis,
– femoris,
– tibialis,
– sternocleidomastoid (sternum, clavicle, and
mastoid process of the skull)
• 5. Size:
– maximus (large)
– minimus (smaller),
– longus (long),
– brevis (short)
235
• 6.Orientation of fibers:
– rectus (straight),
– transversus (across),
– obliquus (oblique),
– orbicularis (circular).
• 7. Relative position:
– lateral,
– medial,
– internal, and
– external.
236
• 8. Function
– adductor
– Flexor
– levator (lifter)
• Origin
- extensor
- pronator
– is usually the proximal end of the muscle, the
most stationary end, and a thick mid region of
a skeletal muscle is known as belly
• Insertion
– is usually the distal end of the muscle
attached to the bone undergoing the greatest
movement.
237
Muscle Attachements
238
Nerves to muscles cont…
• Muscles of the head and neck innervated by
cranial nerves, that emerges from the base of
the skull foramina.
• Not all skeletal muscles are innervated by
cranial nerves.
• Others innervated by spinal nerves, which
originate from a spinal cord through
intervertebral foramina and branches to dorsal
and ventral ramus.
240
241
242
•Antagonistic & Synergistic
Muscles
• Muscles that perform opposite actions (one
contracts while other relax) are called
antagonistic muscules.
e.g: Biceps brachii & triceps
•
Synergistic Muscles- are muscles that
perform similar actions ( both contract as well
as relax at the same time)
243
Muscles of the Head & Neck
 Muscles of the facial expressions
 Frontalis
. Platsma
 Orbicularis oculi
.Temporalis
 Nasalis
. Occipitalis
 Lavator labii superioris . Bussinator
 Orbicularis oris
 Masseter
 Depressor labii inferioris
 Depressor anguli oris
244
Temporalis
Frontalis
Occipitalis
Orbicularis oculi
Sternocleidomastoid
Zygomaticus
Orbicularis oris
Masseter
245
246
Muscles of chewing &
Swallowing
 Function: Food manipulation, tongue mov`t
chewing and swallowing.
a) Extrinsic muscles of the tongue
o The tongue is a very agile organ; both intrinsic
and extrinsic muscles controls its complex
movements.
• Intrinsic muscles - consists of variable numbers
of vertical, transverse and longitudinal fascicles.
247
Muscles of chewing
Produce the biting and chewing
movements of mandible .
- temporalis
- masseter
- pterygoid ( 2 pairs)
The three muscles are innervated by
mandibular nerves.
248
Muscles of the trunk
 Muscles of respiration
- Diaphragm
- Internal / External intercoastal
muscles
 Muscles of anterior abdominal wall
- External abdominal oblique
- Internal abdominal oblique
- Transverse abdominal
- Rectus abdominis
249
Internal Intercostal
External Intercostal
Diaphragm
250
 Muscles of the Back
• These muscles primarily extend , rotate,
and laterally flex the vertebral column.
- latismus dorsi
- trapizius
- serratus muscles
- erector spine
- illiocostalis
- longismus and spinalis muscle
251
Latissmus Dorsi
Extend, Adduct & Rotate Arm Medially
252
Trapezius
Infraspinatus
Deltoid
Teres major
Teres minor
Latissimus dorsi
Gluteus medius
Gluteus maximum
Iliotibial tract
253
 Muscles of the pelvic floor
• The floor of the pelvic cavity is formed by
3 layers of muscles and fasciae that span
the pelvic outlet and supports the viscera.
• It is penetrated by the anal canal, urethra,
and vagina, which opens in to a diamond
shaped region called perineum.
• The perineum is bordered by four bony
land marks.
254
- Muscles of pelvic floor are divided in to 3
compartments:
. Superficial perineal space
- ischiocavernosus
- bulbospongiosus
- superficial transverse perineal
 are innervated by pudendal nerve.
. Middle compartments
- external urethral sphincter
- external anal sphincter
255
- deep transverse perineal muscle
 Pelvic diaphragm
• are the deepest compartments
• Muscles present in this region are:
- lavetor ani and
- coccygus
256
 Muscles of the shoulder & upper
limb
• These muscles are used for the rotation,
elevation, depression, protraction , flexion
extension, adduction and abduction of pectoral
girdle and upper limbs.
- trapizius
- triceps
- serratus muscle - Biceps brachii
- pectoralis
- Brachialis
- levator scapulae
- rhomboidus
257
- deltoid …. etc
Deltoid
Abduct, Flex & Extend Arm
Posterior Brachium
Anterior Brachium
Trapezius
Deltoid
Deltoid
Brachialis
Biceps brachii
Triceps brachii
Latissimus dorsi
Flexor carpi ulnaris
Brachioradialis
258
Pectoralis major
Deltoid
Serratus anterior
Serratus anterior
External oblique
Rectus abdominis
External Oblique
Aponeurosis of external oblique
Transverse abdominis
Internal oblique
259
Pectoralis major
Deltoid
Serratus anterior
Serratus anterior
External oblique
Rectus abdominis
External Oblique
Aponeurosis of external oblique
Transverse abdominis
Internal oblique
260
Muscles of wrist Hand
• Fore arm ( anterior compartment)
.superficial muscles:
- Flexor Carpi radialis
- Flexor Carpi ulnaris
- Flexor digitorium superficialis
- Palmaris longus
. Deep muscles
- Flexor digitorium profondus
- Flexor pollicis longus
261
Brachioradialis
Brachialis
Brachioradialis
Biceps brachii
Pronator teres
Palmaris longus
Flexor carpi radialis
Flexor carpi
ulnaris
Flexor
carpi
ulnaris
Extensor
carpi
ulnaris
Extensor
carpi
radialis
Extensor
digitorum
Abductor
policis
longus
262
Fore arm ( posterior compartment)
.Superficial
- Extensor digitorium
- Extensor Carpi radialis
- Extensor Carpi ulnaris
- Extensor Carpi radialis Brevis
- Extensor digiti minimi
.Deep
- Adductor pollici longus
- Extensor pollici brevis
263
Cont…
• Flexor carpi—Flexes wrist
• Extensor carpi—Extends wrist
• Flexor digitorum—Flexes fingers
• Extensor digitorum—Extends fingers
• Pronator—Pronates
• Supinator—Supinates
264
Cont…
- Extensor pollici longus
- Extensor Indicis
 Muscles Acting on Hip and Lower Limb
. The largest muscles are found in the
lower limb
- Hip and Femur muscles
- Illiocus
- psoas
- obtrator externus
 are some anterior muscles of the Hip
265
266
- Gluteus maximus/ medius/minimus
- Tensor facia latae
- Biceps femoris
- Rectus muscle …etc
 Muscles acting on the Thigh & Foot
- Biceps femoris – most lateral muscle of
the group
- Semitendinosus – medial to biceps
femoris.
- Semimembranosus – deep to
semitendinosus.
267
Cont…
- Sartorius
- Gracilis
- Pectineus – on proximal thigh
- Adductor longus – large muscle mass forming
medial aspect of thigh.
- Quadriceps femoris (3)
. Rectus femoris
. Vastus medialis
. Vastus lateralis
268
Gastrocnemius
Soleus
Calcaneal tendon
8 of 11
269
Tibialis anterior
Peroneus
longus
Extensor
digitorum longus
Gastrocnemius
Soleus
270
The Nervous System
• is divided into
• the Central Nervous System (CNS),
– the brain
– spinal cord
• the Peripheral Nervous System (PNS),
– the cranial nerves
– the spinal nerves
– The Autonomic Nervous System (ANS).
• sympathetic
271
• parasympathetic divisions
Nervous Tissue: Neurons
 Neurons = nerve cells
Cells specialized to transmit messages
Major regions of neurons
Cell body – nucleus and metabolic center of
the cell
Processes – fibers that extend from the cell
body (dendrites and axons
272
Neuron Anatomy
 Cell body
 Nucleus
 Large nucleolus
273
Neuron Anatomy
 Extensions outside the cell body
Dendrites – conduct impulses toward the
cell body
Axons – conduct impulses away from the
cell body (only 1!)
274
Axons and Nerve Impulses
 Axons end in axonal terminals
 Axonal terminals contain vesicles
with neurotransmitters
 Axonal terminals are separated
from the next neuron by a gap
Synaptic cleft – gap between adjacent
neurons
Synapse – junction between nerves 275
Neuron Classification
276
Structural Classification of
Neurons
• Multipolar neurons – many extensions from the
cell body
277
Structural Classification of
Neurons
• Bipolar neurons – one axon and one dendrite
278
Structural Classification of Neurons
• Unipolar neurons – have a short single
process leaving the cell body
279
Support and protection of NS
• The entire delicate CNS is protected by:
–a bony
–the meanings,
–the cerebrospinal fluid (CSF
280
281
 CNS
• The Brain
-lies within the cranial vault
- Its hemispheric surface is convoluted and
has gyri and sulci.
- It consists of:
. Cerebrum
. Cerebellum
. Brain stem
. Diencephalons
282
283
284
• The cerebrum consists of two layers.
• white matter
– Beneath the cerebral cortex
– constitutes the second layer.
• cerebral cortex
– The surface layer
– is composed of gray matter( nerve cell bodies.)
– has numerous folds and grooves called
convolutions.
– The elevated folds of the convolutions are the
cerebral gyri (singular, gyrus)
– the grooves are the cerebral sulci (singular,
285
sulcus).
• Lobes of cerebrum
• Each cerebral hemisphere is
subdivided into 5 lobes by deep
sulci called fissures;
–The central sulcus (fissure of Rolando)
• b/n the frontal lobe and the parietal lobe.
– The lateral sulcus (fissure of Sylvius)
• b/n the frontal and parietal lobes.
286
287
288
289
290
Functions of Cerebrum
• Lobes
•
Frontal
– voluntary motor functions
– planning, mood, smell and social
judgement
• Parietal
– receives and integrates sensory
information
• Occipital
– visual center of brain
291
2. Diencephalon
–isis the second subdivision of the
forebrain and
– almost completely surrounded
by the cerebral hemispheres
–is located b/n the telencephalon
and mesencephalen
292
• Divide in to:
– thalamus
– hypothalamus
– the epithalamus
–the third ventricle and associated
structures,
• The 3rd ventricle forms a cavity on the
median plane within thediencephalon
293
294
• a. Thalamus:
–a paired, large, avoid mass of gray
matter, constituting nearly 4/5th of
the diencephalon.
–Each portion is located immediately
below the respective lateral
ventricle.
– Its principal function is to act as a
relay center for all sensory
impulses, except smell, to the
cerebral cortex.
295
• . Hypothalamus:
– a small portion of the diencephalon which
forms the floor and part of the lateral walls of
the third ventricle.
– The hypothalamus performs numerous vital
functions, .
– hormone secretion (pituitary)
– autonomic NS control
– thermoregulation (thermostat
– food & water intake (hunger & satiety)
– sleep & circadian rhythms
296
– memory (mammillary bodies
• emotional behavior
–anger, aggression, fear,
–pleasure, sex drive, orgasm
c. Epithalamus:
– the dorsal portion of the diencephalon that
includes a thin roof over the third ventricle.
– The inside lining of the roof consists of a
vascular choroids plexus where CSF is
produced.
– The pineal gland extends outward from the
posterior end of the epithalamus.
297
d. Pituitary gland (hypophysis):
–is supported by the sella turcica of the
sphenoid bone
–positioned on the inferior aspect of the
diencephalon and is attached to the
hypothalamus by a stalk-like structure
called the infundibulum.
– The pituitary gland is divided into:
• anterior portion(adenohypophysis)
and
• posterior portion( the
neurohypophysis).
298
3. The brain stem
–The brain stem contains nuclei for
autonomic functions of the body
and their connecting tracts.
– It is the portion of the brain that
attaches to the spinal cord and
–includes
• the midbrain
• pons
• medulla oblongata
299
300
301
Medulla oblongata
• is a bulbous structure B/N pons anteriorly and
the spinal cord posteriorly, at the level of the
foramen magnum .
• is connected to the cerebellum by the inferior
cerbellar peduncle.
• It consists of
– the pyramids- elevated structures on the
inferior side
• the pyramidal region is the deccussation
site cranial tracts
– the olive -an oval enlargement, on each
302
lateral surface
303
• 4. Cerebellum
– is the second lager structure in the brain.
– occupies the inferior and posterior aspect of
the cranial cavity.
– attached to the brain stem by three paired
bundles of nerve fibers called cerebellar
peduncles
• Superior -to MID BRAIN
• middle-PONES
• inferior. –to MO
– is separated from the overlying cerebrum by
a transverse fissure.
– The tentorium cerebelli
• separates it from the occipital and temporal
304
lobes.
• The cerebellum consists of
– two hemispheres
– the vermis- a central constricted area
• function
– Balance
• coordinating skeletal muscle contractions
by recruiting precise motor units within
muscles.
• Impulses for voluntary muscular movement
originate in the cerebral cortex and are
coordinated by the cerebellum.
305
306
. Meninges
–membranous coverings 0f CNS
–Are three layers from outside to
inside
• the dura mater
• the arachnoid mater
• the pia mater.
307
• The dura mater
– is in contact with bone
– is composed primarily of dense connective
tissue.
– The cranial dura mater is a double-layered
structure.
• The thicker outer periosteal layer adheres
tightly to the cranium.
• The thinner, inner meningeal layer follows
the general contour of the brain.
308
• The spinal dura mater is single layered and is
similar to the menigeal layer of the cranial
dura mater.
The arachnoid mater
 is the middle of the three meninges.
 The subarachnoid space is located
between the arachnoid mater and the
pia mater.
 The subarachnoid space contains the
CSF
309
• The pia mater
– is the deepest meninx attached to the
surfaces of the CNS
– It is composed of modified loose fibrous
connective tissue.
– It is highly vascular and .
– The ligamentum denticulatum is the lateral
extensions of the pia mater which attaches
the spinal cord to the dura mater.
– Both the pia mater and the arachnoid mater
specialize over the roofs of the ventricles to
310
form the choroid plexuses.
• Cerebrospinal fluid
• is secreted by choroidal epithelial cells
(ependymal cells) of the choroid plexuses in the
lateral, 3rd, and 4th ventricles
– Fills the space between
• the arachnoid and pia mater
• ventricles
• spinal cord.
• Functions:
– Shock absorption
– Support
311
– Nourishment
• About 500mL of CSF is produced per day.
• The total volume of CSF at any given
moment is 150mL
• CSF circulates from the choroid plexus
through the ventricles and the central
canal of the spinal cord.
• As it circulates, there is unrestricted
diffusion between it and the CSF of the
CNS.
312
• Spinal cord
• extends through the vertebral canal
• is surrounded by three meninges
• provides a means of neural
communication to and from the brain
through tracts of white matter.
• These are:
– Ascending tracts
– Descending tracts
• serves as a center for spinal reflexes.
313
• External Morphology
• Location
–, in adults, from the foramen magnum
to the lower border of the first lumbar
vertebra
– in newborns, it extends to the third
lumbar vertebra.
–is continuous with the medulla
oblongata at the spinomedullary
junction
314
• Attachments
• 1. Denticulate ligaments
– are two pial tissue that attach to the spinal
dura with about 21 teeth.
• 2. Filum terminale
– islower extetion of a pial filament from the
conus medullaris.
• 3. Spinal nerve roots
– provide the strongest anchorage and fixation
of the spinal cord to the vertebral canal
315
Shape
–is nearly cylindrical structure,
–is approximately 1 cm in diameter.
–has cervical (C5-T1) lumbar (L1-S2)
enlargements for the nerve supply of the
upper and lower extremities (the
brachial and lumbosacral plexuses,
respectively)
–terminates caudally as the conus
medullaris.
–averages in length 45 cm in males and
42 cm in females
316
• Surface structures and sulci
– underlie the pia mater and include.
• 1. Ventral/ anterior median fissure
– is a deep ventral midline groove
underlying the ventral spinal artery
• 2. Dorsal/ posterior median sulcus
– is a shallow dorsal midline groove that
is continuous with the dorsal median
septum
• 3. Ventral lateral sulcus
– is a shallow groove from which the
ventral rootlets emerge.
317
3. Ventral lateral sulcus
is a shallow groove from which
the ventral rootlets emerge
• 4. Dorsal lateral sulcus
– is a shallow groove into which the
dorsal rootlets enter
318
• . Internal Morphology
– in transverse sections, the spinal cord
consists of central gray matter and
peripheral white matter.
• A. Gray matter
– is located centrally within the spinal cord
– is butterfly- or H- shaped in a configuration
that varies according to spinal cord level.
– contains a central canal.
– is divided into three horns or cell columns on
each side
319
320
• 1. Dorsal/ posterior horn
– receives and processes sensory input
• 2. Lateral horn
– receives viscerosensory input.
– is found between the dorsal and ventral
horns.
– extends from (C8) T1 to L3
– is found at all levels.
• 3. Ventral/anterior horn
– contains predominately motor nuclei.
– is found at all levels.
321
322
• the white matter
–Tracts of the spinal cord
• are divided into ascending and
descending pathways.
–Ascending spinal Tracts
• Represent functional pathways that
convey sensory information from
soma or viscera to higher levels of the
neural axis.
• Usually decussate before reaching
their final destination
323
- Usually decussate before reaching
their final destination
–Descending spinal Tracts
• are concerned with somatic and
visceral motor activities.
• Have their cells of origin in the
cerebral cortex or in the brainstem
cord
324
• The peripheral nervous system
–is that portion of the nervous system
outside the CNS.
–The PNS functions to convey impulses
to and from the brain or spinal cord.
–The nerves of the PNS are classified as
• cranial nerves or
• spinal nerve
325
• Cranial nerves
–There are 12 pairs of cranial nerves
– The cranial nerves are designated by
roman numerals
–Their names indicate the structures
innervated or the principal functions of
the nerves
326
Olfactory Nerve
.Sense of smell
.Damage causes impaired sense of smell
327
Optic Nerve
-Provides vision
-Damage causes blindness in visual
field
328
Oculomotor Nerve
Eye movement, opening of eyelid, constriction of
pupil, focusing
Damage causes drooping eyelid, dilated pupil,
double vision, difficulty focusing and inability to329
move eye in certain directions
Trochlear Nerve
-Eye movement (superior oblique muscle)
-Damage causes double vision and
inability to rotate eye inferolaterally
330
Trigeminal Nerve
..Sensory to
face (touch,
pain and
temperature)
and muscles of
mastication
..Damage
produces loss
of sensation
and impaired
chewing
331
Abducens Nerve
-Provides eye movement (lateral rectus m.)
-Damage results in inability to rotate eye
laterally and at rest eye rotates medially
332
Facial Nerve
333
• Motor - facial expressions; salivary glands and
tear, nasal and palatine glands
• Sensory - taste on anterior 2/3’s of tongue
• Damage produces sagging facial muscles and
disturbed sense of taste (no sweet and salty)
334
Vestibulocochlear Nerve
-Provides hearing and sense of balance
-Damage produces deafness, dizziness,
nausea, loss of balance and nystagmus
335
Glossopharyngeal Nerve
336
• Swallowing, salivation, gagging and
respiration
• Sensations from posterior 1/3 of
tongue
• Damage results in loss of bitter and
sour taste and impaired swallowing
337
Vagus Nerve
338
• Swallowing, speech, regulation of viscera
• Damage causes hoarseness or loss of voice,
impaired swallowing and fatal if both are cut
Accessory Nerve
339
• Swallowing, head, neck and shoulder
movement
–damage causes impaired head,
neck, shoulder movement; head
turns towards injured side
340
Hypoglossal Nerve
Tongue movements for speech, food
manipulation and swallowing
if both are damaged – can’t protrude tongue
if one side is damaged – tongue deviates
341
towards injured side; see ipsilateral atrophy
Spinal nerves
–31 pairs of spinal nerves
• grouped as
–8 cervical
–12 thoracic
–5 lumbar
–5 sacral
–1 coccygeal
342
343
• Nerve plexuses
–Except in the thoracic nerves T2-T12,
the anterior rami of the spinal nerves
combine and then split again as
networks of nerves referred to as
plexuses.
–There are four plexuses:
• the cervical
• the brachial
• the lumbar
• sacra
344
• Cervical plexus
– formed by the anterior rami of the
nerves C1 - C4 and a portion of C5.
– Branches of this innervate the skin and
muscles of the neck, and portions of the
head and shoulders.
–E.g. Fibers from C3, C4, and C5 unite to
form the phrenic nerve, which
innervates the diaphragm thereby
causing it to contract during inspiration
345
• Brachial plexus
–It’s formed by the anterior rami of the
nerves C5 - T1 with contributions from
C4 and T2.
–Five major nerves
• the axillary
• radial
• musculocutaneus
• ulnar
• median nerves
–arise from this to supply sensory and
motor innervation to the upper limb
346
• Lumbar plexus
– It’s formed by the anterior rami of spinal
nerves L1 and L4 and some fibers from T12.
– Branches from this innervate structures of
• the lower part of abdomen
• anterior and medial potions of the lower
limb.
– E.g. femoral nerve innervates the anterior
muscles of the thigh
– obturator nerve innervates the medial
adductor muscles of the thigh
347
• Lumbar plexus
– It’s formed by the anterior rami of spinal
nerves L1 and L4 and some fibers from T12.
– Branches from this innervate structures of
• the lower part of abdomen
• anterior and medial potions of the lower
limb.
– E.g. femoral nerve innervates the anterior
muscles of the thigh
– obturator nerve innervates the medial
adductor muscles of the thigh
348
• The sciatic nerve
– is the largest branch of the sacral
plexus and is the largest nerve in the
body.
– It’s composed of two nerves• the tibial
• common fibular nerves.
• Tibial nerve
– innervates most of the posterior
thigh and leg muscles and many of
the plantar muscles.
349
Eyeball
• spherical in shape with anterior and posterior poles
• suspended in anterior half of orbital cavity
• The wall is composed of three concentric coats
(tunics) – fibrous, vascular, and sensory
• The internal cavity is fluid filled with humors –
aqueous and vitreous
• The lens separates the internal cavity into anterior
and posterior segments
350
Layers of the eyeball
• Three layers :
• Fibrous layer (outer coat), consisting of
the sclera and cornea.
• Vascular layer (middle coat), consisting
of the choroid, ciliary body, and iris.
• Inner layer (inner coat), consisting of the
retina, which has both optic and non-visual
parts.
351
352
Fibrous Tunic
• Forms the outermost coat of the eye and is
composed of
– Opaque sclera (posterior)
– Clear cornea (anterior)
• Sclera
– protects the eye and anchors extrinsic muscles
– form posterior 5/6 of eye ball
– posteriorly perforated for passage of optic nerve
– continues anteriorly with cornea at sclerocorneal junction
(limbus)
– inner part of limbus contains circular canal called sinus
venosus sclerae (canal of Schlemm)
– posteriorly fused with dura of optic nerve
– it provides insertion to extrinsic muscles
– pierced by optic nerve, ciliary ganglion, anterior ciliary
arteries, choroids veins
353
– it is avascular
• Cornea
– transparent and avascular
– lets light enter the eye
– forms anterior 1/6
– more convex than sclera
– made up of special connective tissue
354
Vascular Tunic (Uvea)
• Has three regions: choroid, ciliary body and iris
• Choroid region
– Supplies blood to all eye tunics
– Anteriorly ends at oraserrata by merging with ciliary
body
– Posteriorly pierced by optic nerve
– Attached to sclera loosely and retina firmly
– Contain venous plexus and capillaries
• Ciliary Body
– A thickened ring of tissue surrounding the lens
– Connects choroids with iris
– Composed of smooth muscle bundles (ciliary
muscles) and ciliary processes
– Anchors the suspensory ligament that holds the
lens in place
355
• Iris
– The colored anterior part of the eye
– Posses pigment cells; determine eye color
– Form circular curtain with opening at center called
pupil
– Regulates the amount of light entering the eye by 2
muscles
• Sphincter pupillae (ring muscle)
• Dilator pupillae (radial muscle)
– Close vision and bright light – pupils constrict
– Distant vision and dim light – pupils dilate
356
Sensory Tunic: Retina
• A delicate membrane between choroids and vitreous
body
• Composed of two layers:
– Pigmented layer – the outer layer that absorbs
light and prevents its scattering
– Neural layer – inner layer which contains:
• Photoreceptors that transduce light energy
• Bipolar cells and ganglion cells
– Ganglion cell axons: run along the inner surface
of the retina and leave the eye as the optic nerve
– The optic disc:
• A circular depression at the site where the optic
nerve leaves the eye
• Lacks photoreceptors; it is insensitive to light
thus called the blind spot
357
• The optic disc is the blind
spot of the eye because it
lacks rods and cones.
• Lateral to optic disc at
posterior pole is a small
oval yellowish area
called macula lutea; at
center is depressed
area called fovea
centralis (site of
maximum acuity of
vision)
358
The Ear
• The ear is the organ of hearing & balance
• divided into three parts:
• External ear:
– auricle
– external auditory meatus
• Middle ear (or tympanum, tympanic cavity):
– tympanic membrane
– tympanic cavity & antrum
– pharyngotympanic tube (or auditory tube, or
Eustachian tube)
• Internal (inner) ear:
– osseous (bony) labyrinth
– membranous labyrinth
359
The Ear
• External ear: is the part attached to lateral aspect
of the head & the canal leading inward; it captures
sound.
• Middle ear (or tympanum, tympanic cavity):
• is a cavity in the petrous part of the temporal bone
• bounded laterally, by a membrane & connected
internally to the pharynx by a narrow tube
• Internal (inner) ear:
• consists of a series of cavities within the petrous
part of the temporal bone: b/n middle ear laterally &
internal acoustic meatus medially.
• it converts mechanical signals from middle ear into
electrical signals  transferred to the brain.
• internal ear also contains receptors that detect 360
motion and position
The Ear
361
The Internal Ear
Membranous labyrinth:
• is a continuous system of
ducts & sacs within the bony
labyrinth.
• It is filled with endolymph &
separated from periosteum of
bony labyrinth by perilymph.
• Consisting of two sacs (utricle
& saccule) & four ducts (three
semicircular ducts & cochlear
duct)
• has unique functions related to
balance & hearing: utricle,
saccule, & three semicircular
ducts are part of vestibular
apparatus (i.e. organs of
balance);
362
363