Myology ppt

Myology
By
Dr. Luay Obed Hamza

Definition
Is the study of the structure,
arrangement, and action of muscles, it
is division of systematic anatomy deals
with the description of muscles and
accessory structures which function to
put the bones and joints in useful
motion.
Myology

It important to study the muscle that essential to understand those
structures involved during surgical procedure, those muscles
commonly considered in meat inspection and the common muscles
used for intramuscular injections.
help to understand the physiology of different types of muscle
tissues in:
 locomotion
 pumping blood
 other function of the visceral organs
Skeletal muscle is a butcher's meat
 Accounts for about half the weight of an animal; the percent
varies with species, breed, age and sex
Importance:

 Body weight may increase by deposition of fat within &
between muscle fibers
Most muscles are supplied by single nerve but some may
have multiple innervations.
Active muscles are richly supplied with blood vessels,
while atrophied muscles are poorly supplied with blood
so they look pale in color.
 There are three types of muscle: voluntary Skeletal
(striped) muscle, involuntary smooth muscle, and Cardiac
(branched or heart) muscle.
Cont’…

Morphologically
∗ 1. Striated : Skeletal and cardiac muscle
∗ 2. Non striated: Smooth muscle
 Functionally
∗ 1. Voluntary (under control): Skeletal muscle (are allow
movement from one place to another (location), movement
of one part of the body in relation to another , and the
maintenance of body posture)
∗ 2. Involuntary ( not under control): Smooth and cardiac muscle
(are responsible for breathing, heart beat, peristaltic
movements of the intestine, constriction of blood vessels and
many other vital functions)
Classification of the muscle
tissues:

Striated
Voluntary
Multinucleated located peripherally
Action: carry out movements of the
body, support the body and maintain the
posture of the body.
Location: skeletal muscle fibers occur in
muscles which are attached to the
skeleton.
Skeletal muscle

Non striated
Involuntary in action
i.e. its contraction is controlled by autonomic nervous
system.
Spindle shape muscle
Mono nucleus located centrally
Action: It is responsible for the contractility of hollow
organs, such as blood vessels, the gastrointestinal tract
and the urinary bladder.
Location: lines the excretory duct of glands, in the wall
of blood and lymphatic vessel and the vicseral organ
Smooth muscle

Striated: have cross striation and arranged in irregular
masses
Involuntary
Characterized by present of intercalated disc, branched
fiber
Central nucleus
Action: plays the most important role in the contraction of
the atria and ventricles of the heart. It causes the
rhythmical beating of the heart, circulating the blood and
its contents throughout the body.
Location: found in the walls of the heart, specifically the
myocardium.
Cardiac muscle

1.Muscle belly
2.Tendon (Aponeurosis)
Morphology of skeletal muscle

∗ The attachment of a muscle, usually to
bones:
Origin:
∗ the less movable of the two
attachments. In the limbs this is usually
the more proximal attachment.
Insertion:
∗ the more movable of the two
attachments. In the limbs this is usually
the more distal attachment.
Origin and insertion

Fleshy attachment: if the muscle appears to
come directly from the bone, it is said to be fleshy
attachment.
 Ex. Muscles attaching to the scapula.
Tendinous attachment: attachment is mediated
by connective tissue- tendons at the end of the
muscle to periosteum -may even penetrate the
surface of the bone for short distance.
Aponeurotic attachments: the flat, tendinous
sheets associated with flat muscles such as those
of the abdominal wall.
Attachment of muscles

∗ Depend on how they cross a joint, number of joints
crossed and the shape of the joints. The resulting
movements (muscle actions) are extension, flexion,
rotation, abduction, adduction and circumduction.
1. Flexor:
if the muscle is located on the side of the limb
toward which the joint bend in decreasing the angle
between the segments; it will be a flexor of that
joint.
Ex. biceps brachii is flexor of the elbow joint.
Action of muscle in the limb

2. Extensor:
if the muscle is located on the opposite side of
flexor.
Ex. triceps brachii is extensor of elbow joint.
3. Adductor:
muscles which tend to pull limb towards a median
plane.
4. Abductor:
those muscles that tend to move the limb away
from the median plane.
Action of muscle in the limb

∗ The muscle fibers (cells) are grouped
together into fascicles (bundles) that in
turn are grouped together to form the
muscle.
1. Parallel muscle: the muscle bundles
(fascicles) run parallel to each other the
entire length of the muscle (e.g.,
Sartorius and abdominal muscles). This
allows greatest shortening of the
muscle, but less strength of contraction.
Muscular arrangements

2. Pennate muscle: the muscle bundles converge on
a tendon at an angle. This arrangement allows more
bundles, thus, stronger contractions, but less
shortening because of the shorter length of the muscle
bundles (e.g., gastrocnemius muscle).
1.Unipennate muscle: a pennate muscle whose tendon
runs along one side.
2.Bipennate muscle: a pennate muscle whose muscle
bundles converge on a tendon from two directions.
3.Multipennate muscle: a pennate muscle whose
tendons branch inside the muscle.

3. Sphincter: a muscle whose fibers encircle an opening.
Contraction of its fibers closes the opening. This type of muscle is
found at the entrance and exit of a passageway (e.g., urinary
system, the anus and the openings of the stomach, pyloric sphincter
is smooth muscle, while Orbucularis oculi muscle of the eyelid is
skeletal muscle).
4. Constrictors: muscle arranged around the wall of tubes or
cavities, it is a muscle whose contraction narrows a vessel or
passage.
Muscular arrangements

Endomysium:
small amount of loose connective tissue
surrounding individual muscle fibers.
Perimysium:
is greater connective tissue around each fiber
Epimysium:
external sheath of connective tissue around the
entire muscle
Muscle associated fascia

1. Fascia: connective tissue membrane separating muscles from
each other and binding them into its position.Fascia divided into:
a.Deep fascia
b.Superficial fascia
2. Ligament: a short band of tough, flexible fibrous connective
tissue which connects two bones or cartilages or holds together a
joint.
Accessory structures

Tendon: a flexible but inelastic cord of strong fibrous
collagen tissue attaching a muscle to a bone. The tendon
may be:
∗ a. Short tendon
∗ b. Long tendon
Accessory structures

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