Muscular System

By

Dr. Noura El Tahawy

Function:

1) movement

2) maintain posture

3) joint stability

4) generate heat

Muscles

Movements of Muscles

Movements of Muscles

• Extension: increasing angle between body parts

• Flexion: decreasing angle between body parts

– Dorsiflexion vs. Plantarflexion

– Inversion vs. Eversion

• Abduction: moving away from the median plane

• Adduction: moving towards the median plane

• Rotation: moving around the long axis

• Circumduction: moving around in circles

• Elevation: lifting body part superiorly

• Depression: moving body part inferiorly

• Supination: rotating forearm laterally

• Pronation: rotating forearm medially

• Protraction: Anterior movement

• Retraction: Posterior movement

Movements of

Muscles

Types of Muscles

Skeletal Muscle Tissue

• Cells

– Cylindrical, long,

Striations

• Attached to the

Skeleton

• Voluntary movements

• Attached to bones,

fascia, skin

• Origin & Insertion

• Somatic nerve supply

Cardiac Muscle

•Myocardium-heart

muscle

– Pumps blood

through vessels

• Cells

– Branching,

chains of cells

– Single or

Binucleated

– Striations

•Cardiac Muscle-

Involuntary

•Supplied by

Autonomic nervous

system

Smooth Muscle Tissue

Cells

Single cells, uninucleate

No striations

Smooth Muscle-Involuntary

2 layers-opposite orientation (peristalsis)

Lines hollow organs, blood vessels

Supplied by Autonomic nervous system

Skeletal muscles

•A skeletal muscle has two or more

attachments. The attachment that moves the

least is referred to as the origin, and the one

that moves the most, the insertion

•The fleshy part of the muscle is referred to

as its belly.

•The ends of a muscle are inserted into bones,

cartilage, or ligaments by cords of fibrous

tissue called tendons.

Skeletal Muscle

Muscles of the Upper Limb

Deltoid

The biceps is tri-articulate,

meaning that it works

across three joints. The

most important of these

functions are to supinatethe

forearm and flex the elbow.

Posterior Compartment of the Arm

Triceps

Muscles of the Lower Limb

Anterior Compartment Thigh

Quadriceps muscles

Posterior Compartment of the thigh

Functional Muscle Groups

(Muscle Actions)

• Agonist: one muscle or group of muscles actively

contract to produces particular movement of a joint

and is/are called a primary mover (eg) biceps brachii is

main flexor of forearm

• Antagonist: Any muscle that opposes the action of the

prime mover is an antagonist. Before a prime mover

can contract, the antagonist muscle must be equally

relaxed. (eg) triceps brachii is antagonist to biceps

brachii

Functional Muscle Groups(Skeletal Muscle action)

The biceps is tri-articulate,

meaning that it works

across three joints. The

most important of these

functions are to supinatethe

forearm and flex the elbow.

Example 2 for Agonist and AntagonistExample 2 for Agonist and Antagonist

Fixators: A fixator contracts isometrically (i.e., contraction increases the tone

but does not in itself produce movement) to stabilize the origin of the prime

mover so that it can act efficiently. For example, the muscles attaching the

shoulder girdle to the trunk contract as fixators to allow the deltoid to act on the

shoulder joint.

Functional

Muscle

Groups (Skeletal Muscle

Action)

• Synergists: : In many locations in the body the prime mover muscle crosses several joints before it reaches the joint at which its main action takes place. To prevent

unwanted movements in an intermediate joint, groups of muscles called synergists

contract and stabilize the intermediate joints. For example, the flexor and extensor

muscles of the carpus contract to fix the wrist joint, and this allows the long flexor and

extensor muscles of the fingers to work efficiently

Functional Muscle Groups (Skeletal Muscle Action)

Functional Muscle Groups

• Agonist = primary mover of a muscle, major

response produces particular movement

– (eg) biceps brachii is main flexor of forearm

• Antagonists = oppose/reverse particular

movement, prevent overshooting agonistic

motion

– (eg) triceps brachii is antagonist to biceps brachii

Functional Muscle Groups

• Synergists = muscles work together, adds extra force to

agonistic movement, reduce undesirable extra movement

– (eg) muscles crossing 2 joints

• Fixators = a synergist that holds bone in place to provide

stable base for movement

– (eg) joint stablilizers

Naming Muscles

• Location: (eg) brachialis = arm

• Shape: (eg) deltoid = triangle

• Relative Size: (eg) minimus, maximus, longus

• Direction of Fascicles: (eg) oblique, rectus

• Location of Attachment: (eg) brachioradialis

• Number of Origins: (eg) biceps, quadriceps

• Action: (eg) flexor, adductor, extensor

Muscle System: uses levers to move objects

• How it works: A rigid bar moves on fixed point when a

force is applied to it, to move object

• Lever = rigid bar = bone

• Fulcrum = fixed point = joint

• Effort = force applied = muscle contraction

• Load = object being moved = bone

Muscle Basics to Remember

• 3 Types: Skeletal, Cardiac, Smooth

• Origin vs. Insertion

• Direct vs. Indirect Attachments

– direct = right onto bone

– indirect = via tendon/aponeurosis

• more common

• leave bony markings = tubercle, crest, ridge, etc.

• Sometimes attach to skin

Thanks