ANATOMY AND PHYSIOLOGY
Emergency Medical Service
First Semester S.Y. 2012 – 2013
LESSON PLAN
LESSON 7 – SKELETAL SYSTEM

Bone Functions
o Support, Protection and Movement

Bones give shape to structures such as
the head, face, thorax and limbs.

They also provide support and
protection.

E.g. bones of the lower limbs,
pelvis and vertebral column
support the body weight.

E.g. bones of the skull protect the
eyes, ears and the brain.

E.g. bones of the rib cage and
shoulder girdle protect the heart
and the lungs.
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
Blood Cell formation

Hematopoiesis – process of blood cell
formation

Bone marrow – soft, netlike mass of
connective tissue within the medullary
cavities of long bones.

Red marrow – responsible for red
blood cell (erythrocytes) white
blood cells (leukocytes) and blood
platelets. It is red because of
oxygen-carrying pigment
hemoglobin.

Yellow marrow – responsible for
storage of fats and is inactive in
blood cell production.
Number of Bones

The number of bones in human
skeleton is often reported to be 206.
But the actual number varies from
person to person.
Bone Structures
o Bone Classification – bones are classified
according to their shapes – long, short, flat
or irregular.

Long bones – have long longitudinal
axes and expanded ends. (forearms
and thigh)

Short bones – are somewhat cubelike, with their lengths and widths
roughly equal. (wrist and ankles)


o
Flat bones – are plate-like structure
with broad surfaces. (ribs, scapula,
skull)
Irregular bones – have a variety of
shapes and are usually connected to
several other bones. (vertebra, facial
bones)
Division of the Skeleton

Axial Skeleton – consist of the bony
and cartilaginous parts that support
and protect the organs.

Skull – cranium and facial bone

Hyoid Bone – located in the neck
between the lower jaw and the
larynx. Does not articulate, but is
fixed in position.

Vertebral Column – or spinal
column consists of many vertebra
separated by cartilaginous
intervertebral discs. This column
forms the central axis of the
skeleton.

Thoracic Cage – protects the
organs of the thoracic cavity and
upper abdominal cavity. Composed
of 12 ribs including the sternum.

Appendicular Skeleton – consists of
the bones of the upper and lower limbs
and the bones that anchor the limbs to
the axial skeleton.

Pectoral Girdle – is formed by a
scapula or shoulder blade and
clavicle or collarbone on both sides
of the body. Aids in upper limb
movements.

Upper Limbs – consists of
humerus or arm bone, radius and
ulna or forearm bones, and hand. 8
carpals or wrist bones, 5
metacarpals, and 14 phalanges or
finger bones.

Pelvic Girdle – formed by two
coxae or hipbones which are
attached to each other anteriorly
and to the sacrum posteriorly.

Lower Limbs – each consists of a
femur or thigh bone, two leg bone;
tibia (shin bone) and fibula and a
foot. They articulate at the knee
joint where patella or kneecap
covers the anterior surface. There
are 7 tarsals, 5 metatarsals, and
14 phalanges or toes.
o
The Skull

The human skull usually consists of 22
bones that except for the lower jaw are
firmly interlocked along sutures.

The mandible or lower jawbone is a
moveable bone held to the cranium by
ligaments.

Cranium

Encloses and protects the brain,
and its surface provides
attachments for muscles that make
chewing and head movement.
o Frontal Bone – forms the
anterior portion of the skull
above the eyes.
o Parietal Bone – one parietal
bone is located on each side of
the skull just behind the frontal
bone. It is shaped like a curved
plate and has four borders.
They are fused at the midline
along sagittal suture and meet
the frontal bone along coronal
suture.
o Occipital Bone – bone joins
the parietal bones along the
lambdoid suture. It forms the
back of the skull and the base
of the cranium.
o Temporal Bones – bone on
each side of the skull joins the
parietal bone along a
squamous suture. It also house
the internal ear structures.
o Sphenoid bone – is wedged
between several other bones in
the anterior portion of the
cranium. This bone helps form
the base of the cranium, sides
of the skull and floors and side
of the orbits.
o Ethmoid Bone – located in
front of the sphenoid bone.
Consists of two masses, one on
each side of the nasal cavity.
These plates form part of the
roof of the nasal cavity, and
nerves associated with the
sense of smell pass through
tiny openings.


Facial Skeleton

Consists of 13 immovable bones
and movable lower jawbone. These
provides attachments for muscles
that move the jaw and control
facial expressions.
o Maxillary bones – form the
upper jaw. Together they form
the keystone of the face. It
comprises; hard palate
(mouth) side and floor of nasal
cavity. Also contains socket of
the upper teeth.
o Zygomatic Bones – are
responsible for the
prominences of the cheek
below and to the sides of the
eyes. Each bone has a
temporal process.
o Lacrimal Bones – is a thin,
scale-like structure located in
the medial wal of each orbit
between the Ethmoid bone and
maxilla.
o Nasal Bone – are long, thin
and nearly rectangular. They
form the bridge of the nose.
o Vomer Bone – thin, flat vomer
bone is located along the
midline within the nasal cavity.
o Mandible – or lower jawbone
is a horizontal, horseshoeshaped body with flat ramus
projecting upward at each end.
The Vertebral Column

Extends from the skull to the pelvis
and forms the vertical axis of the
skeleton.

It is composed of many bony parts
called vertebrae.

Separated by masses of fibro cartilage
called intervertebral discs.

It supports the head, and the trunk of
the body yet is flexible enough to
permit movement such as bending
forward, backward or to the side.

It also protects the spinal cord.

Vertebral column has four curvatures

Cervical Curvature – primary curve

Thoracic Curvature - secondary

Lumbar Curvature - secondary

Sacral Curvature – primary curve
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
Cervical Vertebrae

Comprise the bony axis of the neck

7 cervical vertebrae

The first vertebra is the atlas which
supports the head. It appears bony
ring with two transverse process.

The 2nd vertebra is the axis, bears
a tooth-like dens (odontoid
process) on its body. As the head
is turned from side to side, the
atlas pivots around the dens.
Thoracic Vertebrae

12 thoracic vertebra

Larger than those in cervical
region.

Each has a long, pointed spinous
process which slopes downward
and facets on the sides of its body.
Lumbar Vertebrae

5 Lumbar Vertebra

Supports more weight that the
superior vertebrae and have larger
and stronger bodies.
Sacrum

A triangular structure at the base
of the vertebral column.

Composed of 5 vertebrae that
develop separately but gradually
fuse between age 18-30.

It forms the posterior wall of the
pelvic cavity.

During vaginal examination, a
physician can feel this projection
and use it as a guide in
determining the size of the pelvis.
Coccyx

The tail bone

The lowest part of the vertebral
column and is usually composed of
4 vertebrae that fuse.

Acts as shock absorber when
sitting

Slipping on floor or ice can fracture
or dislocate the coccyx.
Thoracic Cage
o Includes the ribs, thoracic vertebrae,
sternum and the costal cartilages that
attach the ribs to the sternum.
o These bones support the shoulder girdle
and upper limbs, protect the viscera in the
thoracic and upper abdominal cavities and
play a role in breathing.
o Ribs

Usual number of ribs is 24. One pair
attached to each of the 12 thoracic
vertebrae.
The first 7 ribs are called true ribs
(vertebrosternal ribs)

The remaining 5 pairs are called false
ribs. Their cartilages do not reach the
sternu.

The last 2 pairs are called floating ribs.

Characteristic of a rib

Long

Slender shaft

Curves around the chest

Slopes downward.
Sternum

Also called the breastbone.

Located along the midline in the
anterior portion of the thoracic cage.

Flat, elongated bone that develop in 3
parts.

Manubrium

Body

Xyphoid Process

o

Pectoral Girdle

Also called the shoulder girdle.

Composed of 4 parts

Two clavicles (collarbone)

Two scapulae (shoulder blades)
o Clavicles

Are slender, rod like bones with
elongated S-shapes located at the base
of the neck, run horizontally between
the sternum and the shoulder.
o Scapulae

Are broad, somewhat triangular bones
located on either side of the upper
back.

It has 3 boarders:

Superior boarder – on superior
edge.

Axillary or lateral border –
directed toward the upper limb.

Vertebral or medial border –
closest to the vertebral column.

The Upper Limb
o Bones of the upper limb form the
framework of the arm, forearm, and hand.
o They also provide attachments for muscles
and interact with muscles to move limb
parts.
o
The Humerus

A long bone that extends from the
scapula to the elbow.

Its upper end is a smooth rounded
head that fits into the glenoid cavity of
the scapula.
Just below the head are two processes
– a greater tubercle on the lateral side,
and lesser tubercle on the anterior
side.
Radius

Located on the thumb side of the
forearm, is somewhat shorter that its
companion, the ulna.

The radius extends from the elbow to
the wrist and crosses over the ulna
when the hand is turned so that the
palm faces backward.
Ulna

Longer than the radius and overlaps
the end of the humerus posteriorly.

At its proximal end, the ulna has a
wrench like opening, the trochlear
notch tat articulates with the trochlea
of the humerus.

The olecranon process, located above
the trochlear notch, provides an
attachment for the muscle that
straightens the upper limb at the
elbow.
Hand

Is made up of the wrist, palm, and
fingers.

It contains eight small carpal bones.
“carpus bone”

Five metacarpal bones, one in line with
each finger, form the framework of the
palm of metacarpus.

The phalanges are the finger bones.

There are three in each finger,
proximal, middle and distal phalanx.

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
Lower Limb
o Bones of the lower limb form the
frameworks of the thigh, leg and foot.
o They include femur, tibia, fibula, tarsal,
metatarsals, phalanges.
o Femur

Or thighbone, is the longest bone in
the body and extends from the hip to
the knee.

A large, rounded head at its proximal
and projects medially into the
acetabulum of the coxa.

A superior, lateral greater trochanter
and an inferior medial lesser
trochanter. These processes provide
attachments for muscles of the lower
limbs and buttocks.
o Patella

Or kneecap, is flat sesamooid bone
located in a tendon that passes
anteriorly over the knee.
It controls the angle at which this
tendon continues toward the tibia, so it
functions in lever actions associated
with lower limb movements.
Tibia

Or the shinbone, is the larger of the
two leg bones and is located on the
medial side.
Fibula

Is a long slender bone located on the
lateral side of the tibia.

It ends are slightly enlarged into a
proximal head and distal lateral
malleolus.
Foot

Is made up of the ankle, the instel and
the toes.

Ankle or tarsus is composed of seven
tarsal bones.

Calcaneus or heel bone is below the
talus where it projects backward to
form the base of the heel.

The instep or metatarsus consists of
five elongated metatarsal bones.

The phalanges of the toes are shorter,
but otherwise similar to those of the
finger and align and articulate with
metatarsal.

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