MUSCULAR SYSTEM
anatomical terminology
? Assume the anatomical position, what do these words mean?• Inferior; superior• Proximal; distal• Medial; lateral• Posterior; anterior
TYPES OF MUSCLES1. SKELETAL: • voluntary control• striated appearance
(alternating dark & light bands)
• Tendons attach mostly to bone
• Main function is movement
TYPES OF MUSCLE2. CARDIAC:• Heart muscle,
also striated• Involuntary
control (contracts without thought)
TYPES OF MUSCLE3. SMOOTH MUSCLE:• Lines the walls of blood vessels and
hollow organs• eg. Stomach and intestines
• Involuntary movement
MUSCLE FUNCTION• Interaction of bones, skeletal
muscles & joints = MOVEMENT• Muscles move substances within the
bodyeg. Smooth muscles move food through the intestines; cardiac muscle moves blood; skeletal muscle helps venous blood return to the heart
MUSCLE FUNCTION• Postural muscles contract to stabilize
and maintain body positions• Muscles can be active even when
there is no movement at a joint
MUSCLE FUNCTION• When muscles
contract voluntarily or involuntarily (as in shivering) they can generate up to 85% of body heat
MUSCLE PROPERTIES
• CONTRACTILITY: – Ability of muscle to
contract and generate force when stimulated by a nerve
– Only muscle tissue can do this
– Muscles are usually in pairs: when one contracts the other is stretched.
MUSCLE PROPERTIES
• EXTENSIBILITY:– The ability of a muscle to be stretched
beyond its normal resting length
MUSCLE PROPERTIES
• ELASTICITY:– The muscles’ ability to return to its
original resting length after the stretch is removed
? Give an example
Using contractility,extensibility & elasticity together…
SKELTAL MUSCLE STRUCTURE
• FASCIA: – Connective tissue surrounding tissues
(as in bones & muscles)–Made of fibrous tissue, adipose tissue
(fat) & fluid– Superficial or deep– Skeletal muscles mostly work in groups– Each group (compartment) is
surrounded by fascia
SKELTAL MUSCLE STRUCTURE
• 3 layers of Fascia in each individual muscle.
• EPIMYSIUM: the outer layer covering the entire muscle
• PERIMYSIUM: surrounds bundles of muscle fibres or fascicles
• ENDOMYSIUM: surrounds the individual muscle fibres
SKELTAL MUSCLE STRUCTURE
TENDONS• Layers of Fascia continue beyond
muscle to form TENDONS.– Strong, flexible bands of fibrous connective
tissue connecting muscle to bone– Various forms: rounded cord or flat sheet– Tendons can be grouped together in a
tendon sheath. These contain synovial fluid ?Why?
– They play an important role in muscle contraction & joint movement
TENDONS
MUSCLE FIBRE• Muscles contain thousands of long,
cylindrical fibres lying parallel to each other
• Inside are small structures called myofibrils – light & dark bands
• They are arranged into units called Sarcomeres.
• Sarcomeres contain contractile proteins called Actin & Myosin
MYOFIBRIL/SARCOMERE
MUSCLE FIBRE• Muscles have a good nerve & blood
supply.• Motor neurons send messages from
CNS to the muscle• Neurons release neurostransmitters
into the blood which stimulate the muscle to contract & produce force
• Muscles have a rich network of capillaries = good damage repair
DEFINE THESE TERMS
• Define and give an example for each of the following:
• ATROPHY• HYPERTROPHY• ORIGIN• INSERTION