MYOLOGY1
Department of anatomy
Luzhou medical college
Made by professor Xiao
Introduction
The muscles of the
human body are
The skeletal muscle
The cardiac muscle
The smooth muscle
The skeletal
muscle
The cardiac muscle
Right pulmonary veins
Superior vena cava
Left pulmonary veins
Aortic valves
Valves of pulmonary artery
Right ventricle
Left atrium
Superficial layer
Left ventricle
Middle layer
Superficial layer
Middle layer
Deep layer
Cardiac apex
The smooth muscle
Introduction
The muscles
of the locomotor
appartus are the
skeletal muscles, all of
them are attached by at
least one end to some
part of the skeleton.
The skeletal muscles
are the voluntary
muscles. Each skeletal
muscle possesses a
definite shape,
structure, location, and
is supplied by
abundant blood vessels,
lymphatic system and
nerves so it can be
regarded an organ.
Morphology of the skeletal muscles.
Each muscle is composed of a collection of muscle
fibers that are bounded together and surrounded by
connective tissue.
Endomysium
Perimusyium
Epimysium
Belly
Tendon.
At each end of the skeletal muscle the connective
tissue blend with the strong collagen bundles to
form the tendon that anchor it to the structure of
bone, cartilage, articular capsule.
Structures
Belly
Tendon
(aponeurosis)
Muscular fibers
(endomysium)
Bundle of
the muscles
Bundle of muscles
(perimysium)
Muscle
(epimysium)
Muscle cells
The structures
Of the muscles
Origin.
The fixed attachment is called the origin.
Insertion. the moveable one is called insertion.
Fascia. Fascia can be divided into two types.
Superficial fascia and Deep fascia.
Superficial fascia.
It immediately beneath the cutis, covering almost the
entire body. it is a layer of loose connective containing fat
in varying quantity.
Deep fascia.
It is a dense, inelastic fibrous membrane, forming a strong
investment, which not only bind down collectively the
muscles In each region, but also give seperate sheath to
each as well as to the vessels and nerves.
Innervation
•Neuro-muscular
junction
•Motor unit
The Morphology of skeletal muscle
Muscle belly, Tendon, Aponeurosis
Long short Broad (External oblique m.) ,Bipennate m.
Unipennate m. Multipennate m. ,Digastric m. Orbicularis
•Origin and insertion
•Movable point
•Fixed point
•Prime mover
•Antagonist
•Fixator
•synergist
The Supplementary Structure of the
Skeletal Muscles
Superficial fascia and deep fascia
Tendon and Aponeurosis
Synovial sheath , Synovial
Bursa and Tendon Synovial
Sheath
Locomotor Biomechanics
Attachment
and Lever
Runing Effect:
• Trans-axis
Component of Forces
• Rotation Component
of Forces
Articular Surface
Reaction Effect:
• Pressure Reaction
Forces
• Tangent Component
of Forces
 Most movement is the result of several muscle
working at the same time
 Most muscles are arranged in opposing pairs
at joints
– prime mover or agonist contracts to cause the
desired action
– antagonist stretches and yields to prime mover
– synergists contract to stabilize nearby joints
– fixators stabilize the origin of the prime mover
• scapula held steady so deltoid can raise arm
Section 2
The muscles of the trunk
The muscles of the trunk can be divided into
the muscles of the
Back
Thorax
Diaphragm
Abdomen
perineum
The muscles of the back
The muscles of the back which are located
on the posterior aspect of the trunk and
can be divided into two groups , superficial
and deep.
Ⅰ. Superfacial muscles
Trapezius
Latissimus dorsi
Levator scapulae
Rhomboid
Ⅱ. Deep muscles
Erector spinae(sacrospinalis)
Trapezius
Situation the trapezius is large, triangular muscle that
extend over the back of the neck and thorax.
Origin superior nucheal line of occipital bone, and
spine of seventh cervical vertebrae and all thoracic
vertebrae.
Insertion clavicle and acromion and spine of scapula.
Action
The upper fibers elevates the scapula,
The middle fibers pull scapula medially
Lower fibers pull scapula downward.
Nerve supply
accessory nerve
cervical nerve C3, C4
Latissimus dorsi.
Situation
The latissimus dorsi is a large triangular muscle
that extend over the lumbar region and lower part of
the thorax.
Action
It extend, adduct, and medially rotate the arm.
Draw arm downward and back ward.
Nerve supply
Thoracodorsal nerve.
Levator scapulae
Origin from the transverse processes of upper four
cervical vertebrae.
Insertion superior vertebral border of the scapula.
Action elevate the scapula and rotate it downward.
Innervation
Dorsal scapular nerve and cervical nerve C3 and C5.
Rhomboid
major
and minor
Action
Adduct
scapula
and
slightly
rotate it
downward.
Nerve
supply
Dorsal
scapular
nerve
Ⅱ. Deep muscles Erector spinae(sacrospinalis)
Ⅱ. Deep muscles
Erector spinae (sacrospinalis)
Situation
It is a collective name for a group of deep muscles of the
back. It fill up the vertebral groove on each side of vertebral
Spines.
Origin
The sacrum, the ilium, and associated ligaments.
Insertion
The erector spinae ascends alongside the lumbar spines. At
About the level of the last rib, it divided into three parts that
Ascend on the back of the chest, where they are inserted into
the ribs and vertebrae. From these bones it runs continuously
upward to insert into the mastoid process of the temporal bone
Action
Bends and rotates the spinal column
The muscle of the thorax
They are divided into two parts, extrinsic and
intrinsic
Ⅰ) The extrinsic muscles
All of this group arise from the outer surface
of the thorax and insert into shoulder girdle or
humerus.
1. The pectoralis major
2. The pectoralis minor
3. Serratus anterior
Ⅱ) The intrinsic muscles
1. The external intercostal muscles
2. The internal intercostal muscles
1.The pectoralis major
Situation
The large thick ,fan shaped muscle covers the upper
part of the chest.
Origin Clavicle, sternum cartilage of 2nd to 6th ribs.
Insertion Intertubercular sulcus of the humerus.
Action flexed, adducts, rotate arm medially.
Innervation pectoral nerve.
2. The pectoralis minor
Situation
The flat shaped triangular muscle lies deep to the
pectoralis major.
Action
Elevates 3rd to 5th ribs during inspiration.
Innervation
Pectoral nerve
3. The serratus anterior
Situation
The thin large powerful muscle overlies the lateral
portion of the thorax.
Origin
It arises by a series slips from upper 8--9 ribs and the
oblique externus abdominis.
Insertion
Vertebral border and inferior angle of scapula.
Action
Holds the scapula against the chest wall, pull the scapula
forward in throwing and pushing.
Innervation
Long thoracic nerve.
Ⅱ) The intrinsic muscles
1. External intercostal muscle.
 Situation
They are located in the each intercostal space
superfacially. They extend from the tubercle of
the ribs to the costal cartilage.
 Orgion
They arise from the lower border of each rib .
 Insertion
The upper border of the rib below.
2. Internal intercostal muscle
Situation
They are located in each intercostal space deep
to external intercostal muscle.
【Action】
The external intercostal muscle and internal
intercostal muscle are considered to be the
muscle of expiration. May be draw adjucent ribs
together during force of expiration.
【Innervation】
Intercostal nerve
The diaphragm
It is the dome-shaped septum dividing the
thoracic and abdominal cavities, hence, it form
the floor of the thorax and the roof of the
abdomen.
The diaphragm is composed of a central tendon
and a peripheral muscular portion.
The muscular portion is divided into three
parts.
According to the origin of its fibers.
The sternal part
The costal part
The lumbar (vertebral) part
There are three openings in the diaphragm :
①The aortic hiatus
②The esophageal hiatus
③ The vena cava foramen
Action
It is the principal muscle of inspiration.
Between the three original parts of the diaphragm,
there are usually triangular spaces without muscular
tissue, called the sternocostal triangle and the lumbocostal triangle.
These triangles are the common site for a
diaphragmatic hernia and an eventuation of the
diaphragm.
①The aortic
hiatus: aorta,
thoracic duct.
②The
esophageal
hiatus:
esophagus,
Vagal trunk
③ The vena
cava foramen
inferior vena
cava.
It is the
principal
muscle of
inspiration.
The muscles of the abdomen
Situation
They are located between the lower margin of the thorax and
The pelvis. Which can be divided into two groups, the anteroLateral and the posterior group.
The anterolateral group
1. External oblique muscle. (fig)
The external oblique muscle is the broad, largest, superficial
muscle of abdominal wall.
Origin
It arises from the outer surface of the lower 8 ribs and inserts
into the xiphoid process, the linea alba, the pubic crest, the
pubic tubercle, and the anterior half of the iliac crest.
Insertion
The majority of the fibers are inserted by the broad
aponeurosis.
Superficial inguinal ring.
A triangular shaped defect in the external oblique
aponeurosis lies immediatly above and medial to the pubic
tubercle. this is known as superficial inguinal ring.
Inguinal ligament.
Between the anterior superior iliac spine and the pubic
tubercle, the lower border of the aponeurosis is folded
back ward itself forming the inguinal ligament.
Action.
Support the abdominal contents
Compress the abdominal contents.
Flexion and rotation of the trunk.
Assists in the force of expiration and defection.
Innervation.
lower six thoracic, and iliohypogastric, ilioinguinal nerve.
2.The internal oblique muscle. (fig)
The internal oblique muscle is also a broad and thin
muscular sheet that lies deep to the external oblique.
Origin
It arises from the thoracolumbar fascia, anterior
Two-thirds of iliac crest, and lateral two-thirds of the
Inguinal ligament. The muscles fibers radiate pass
upward and forward.
Insertion
Its posterior fibers ascend almost vertically and inserted
Into the cartilages of 7th to 10th ribs. The remaining
fibers end in a broad aponeurosis. The lower fibers of its
Aponeurosis arch over the spermatic cord in the inguinal
canal. These fibers with the aponeurosis fibers of
transversus abdominis form the inguinal falx (conjoined
tendon)-insert into the pubic crest and the pecten pubis.
The upper portion of its aponeurosis splits up to take part in
the formation of the rectus sheath. In the male, the lower
fibers extend downward and enclose the spermatic cord and
testis, called the cremaster.
Action. the action is same like external oblique muscle.
3. The transversus abdominis (fig)
It is the deepest one of three flat abdominal muscles.
Origin
It arises from the inner surface of costal cartilages of the lower
Six ribs, thoracolumbar fascia, iliac crest and lateral one-third
Of the inguinal ligament.
Insertion
Most of it fibers end in the aponeurosis that contributes to the
Sheath of rectus abdominis and the inguinal falx with the
Aponeurosis of the oblique internus abdominis.
4. The rectus abdominis
4Situation
4
.It. lies on each side of the linea alba and is largely enclosed in
Tthe sheath of the rectus abdominis.
hOrigin
eIt arises from the front of pubic symphysis and pubic crest.
Insertion
Anterior surface of the xiphoid process and the costal cartilage
Of 5th to 7th ribs.
There are three or four tendinous intersections
Actions
The anterolateral group of the abdominal muscles support and
Protect the viscera. Acting together, the abdominal muscles
Compress the abdomen to maintain and to increase the intraabdominal pressure. The muscles are therefore important in
Respiration, defecation, micturition, parturation, cough and
Vomiting. And also move the vertebral column in flextion,
rotation, and help to maintain posture.
5. The sheath of rectus abdominis
It is the strong, incomplete fibrous compartment of the rectus
Abdominalis. It is formed by aponeurosis of three layers flat
muscles anterolateral groups, in which the aponeurosis of
obliquus internus abdominis splits into two layers, one passing
anterior to the muscle and one passing posterior to it.
Anterior layer
join with the aponeurosis of obliquus externus abdominis to
form anterior sheath.
Posterior layer
join with the aponeurosis transversus abdominis to form the
posterior sheath.
Arcuate line: All the aponeurosis of the three flat muscles pass
Anterior to the rectus abdominis to form the anterior layer of the
Sheath of rectus abdominis. The lower limit of posterior layer of
the sheath is marked by a crescentic border called arcuate line.
6. Linea alba
It is placed on the anterior median line of the abdomen,
Extending from the xiphoid process to the pubic symphysis.
It is formed by the blending of the fibers of the sheath of
rectus abdominis of two sides.
Ⅱ posterior group
It consist of the psoas major and the quadratus lumbroum.
1. The psoas major mill be described in the muscles of the
lower limb.
2. The quadratus lumbroum is a roughly quadralateral thick
muscular sheet attached below to the iliac crest, above to the
last rib, and medially to the tip of transverses processes of the
1st to 4th lumbar vertebrae. The muscles is contact posterior
with the erector spinae.
Ⅲ the fasciae of abdomen
Ⅲ the fasciae of abdomen
 1. the superficial fascia
 Over the greater part of the anterolateral abdominal
wall, the superficial fascia consists of layer containing a
variable amount of fat. Of the lower part of the
abdominal wall, it may be divided into a fatty
superficial layer( Camper’s fascia) and a membranous
deep layer( Scarpa’s fascia) which contains elastic
fibers.
 2. the deep fascia
 It is unremarkable and blends with the epimysium of
each muscle.
 3. the inner investing fascia of the abdominal wall
 It covers all the inner surface of the abdominal cavity.
4. The inguinal canal
It is an oblique passage, 4-5cm long, through the
abdominal wall. It passes downwards and medially
from deep to superficial inguinal rings and lines
paralled to, and immediately above , the ligament.
The inguinal canal is occupied in male by the permatic
cord and in female by the round ligament of uterus.
Four walls: superior wall is the lower borders of the
internal oblique muscle and the transversus abdominis
muscle; inferior wall is the inguinal ligament; anterior
wall is formed by aponeurosis of external oblique
muscle and the partial fibers of internal oblique muscle
and the posterior wall is formed by the transverse
fascia and is strengthened in its medial one-third by the
inguinal falx (conjoined tendon).