Muscles

Dr. Sama ul Haque

Objectives

• Define a muscle.• Classify muscles according to their structure

and functions.• Differentiate the types of muscles, on the

basis of structural peculiarities and functions.• Understand terms related to muscles.• Know how the muscles are named.

Types of the muscle

• Skeletal: Striated and voluntary.

• Smooth: Non-striated and involuntary.

• Cardiac: Striated and involuntary.

Are effectors which enable movement to be carried out.

Muscles

Types of connective tissues wrappings of skeletal muscle

• Endomysium : a delicate connective tissue sheath surrounds muscle fiber.

• Perimysium : a coarser fibrous membrane surrounds several sheathed muscle fibers to form bundle of fibers called a fascicle.

• Epimysium : a tougher overcoat of connective tissue surrounds many fascicles.

• The Epimysium blend into the strong, cord- like tendons, or into sheet-like Aponeurosis.

• Function: attaching the muscle to bone…. Providing durability Conserving space

Muscles & the Skeleton

• Skeletal muscles cause the skeleton to move at joints

• They are attached to skeleton by tendons.• Tendons transmit muscle force to the bone.• Tendons are made of collagen fibres & are

very strong & stiff

Muscle function

• Providing movement• Maintaining posture• Stabilizing joint • Generating heat

Skeletal Muscle• Functions of Skeletal

Muscle– Produce Movement– Maintain posture– Stabilize joints– Generate Heat

• Sites of Muscle Attachment– Bones– Cartilage– Connective tissue

coverings

• Muscle Fibers blend into a connective tissue attachment– Tendon—cordlike

structure– Aponeurosis—sheet-like

structure• Properties of Muscle

– Irritability – ability to receive and respond to a stimulus

– Contractibility – ability to shorten when an adequate stimulus is received

– Extensibility – ability to lengthen when an adequate stimulus is received

– Elasticity – ability to return to normal shape

• Origin : is the point where the muscle is attached to immovable or less movable bone.

• Insertion : is the point where the muscle attached to movable bone.

• Prime mover : the muscle that has the major responsibility for causing a movement.

• Antagonist : the muscle that reverse a movement.

Antagonistic Muscle Action

• Muscles are either contracted or relaxed• When contracted the muscle exerts a pulling

force, causing it to shorten• Since muscles can only pull (not push), they

work in pairs called antagonistic muscles• The muscle that bends the joint is called the

flexor muscle• The muscle that straightens the joint is called

the extensor muscle

Elbow Joint• The best known example of antagonistic

muscles are the biceps & triceps musclesElbow joint flexed

Flexor m uscles contractedExtensor muscles re laxed

Elbow joint extendedExtensor muscles contracted

Flexor m uscles relaxed

biceps

triceps

Section through arm

Flexorm uscles

Extensor m uscles

Hum erusBone

Naming Skeletal muscles• Direction of the muscle fibers: Orbicularis

oris, Occuli • Relative size of the muscle: Gluteus

Maximus, Medius, Minimus• Location of the muscle: Obturator Internus• Number of the origin: Biceps, Triceps• Location of the muscle’s origin and insertion: Occipito-frontalis

• Shape of the muscle: Deltoid• Action of the muscle: Pronator Quadratus

Shape and Fiber Architecture of Skeletal muscle

• Terms related to Muscle:

– Belly (Fleshy part, Contractile)

– Tendon (C.T, Non-Contractile)

– Aponeurosis (Flattened tendon)

– Ligament

Thank you