Muscular system

Muscle tissue

Skeletal

Cells are long, cylindrical, parallel, multinucleated. They are attached by tendons to bones. The striations are visible and it is voluntary.

Cardiac

Cells are long, cylindrical, branched, has single central nucleus. This has striations and it forms the heart wall. This type of tissue is involuntary. The cardiac is also joined to another cell at intercalated disc.

Smooth

Spindle-shaped cells with a single nucleus. No striations and it is found mainly in the hollow walls of the organs and eyes. It is also a involuntary.

Sliding filament theory

Skeletal muscles

Arms/shoulder muscles

  1. The nerve impulse or action potential travels down sarcolemma and into t-tubules causing sarcoplasmic reticulum to release Ca++ into sarcoplasm.
  1. Ca++ binds to actin myofilament exposing the myosin binding site.
  1. Myosin attaches to actin which forms actin/myosin cross bridges.
  1. Myosin head moves towards the M line of sarcomere which pulls actin filaments past myosin.
  1. This action is repeated many times powered by the ATP.

The Z line gets closer together as actin and myosin filaments slide past each other and sarcomeres shorten the entire myofibril.

Body movement

Flexion

Movement that decreases, angle of joint

Extension

Movement that increases angle of joint

Hyperextension

Extension beyond 180 degrees

Rotation

Movement of a bone around a longitudinal axis

Abduction

Movement of limb away from midline

Adduction

Movement of limb towards the midline.

Circumduction

Proximal end of a limb that is stationary and distal end moves in circle.

Dorsiflexion

Lifting the superior surface of foot towards the skin.

Plantar flexion

Pointing the toes.

Inversion

Turns the sole of foot medially.

Eversion

Turns the sole of foot laterally.

Supination

Forearm rotates laterally so palm faces anteriorly.

Pronation

Forearm rotates medially so the palm faces posteriorly.

Opposition

Movement of thumb to touch the tips of other things.

Physiology of muscle contraction

The skeletal muscles are composed of fibers which are made of sarcomeres. Each sarcomere contain a thick and think myosin filament and when the muscles slide past each other, the muscle contracts. Which results in a shortening in of sarcomere and the muscle.

For example strengthening the hip and elbow.

For example bending the elbow and hip.

For example back to 180 degrees: extension.

Example is shaking the head no.

An example raising hand up 90 degrees.

Bicep brachii

Deltoid

Located on the front part of the upper arm between the shoulder.It supinates forearm and flexes elbow.

Located on uppermost part of arm and shoulder. It abducts the arm.

Arm/forearm

Tricep brachii

Flexor carpi radialis

Flexor carpi ulnaris

Flexor digitorum superficialis

Extensor carpi radialis

Extensor digitorum

One of five main muscles that control the movements of the wrist. It starts on the lateral side of the humerus and attaching itself to the second metacarpal bone.

Located on the ulna side of the forearm.It flexes and adducts the hand.

It runs on the humerus between the shoulder and elbow.The movement is the extension and retraction of the forearm.

It is located on the anterior part of the forearm. It is visible when you flex.

Located in between the middle of the phalanges. Its main role is to flex fingers in the proximal interphalangeal joint and to flex metacarpophalangeal joints.

Located on posterior forearm. This helps movements of wrists and elbows.

Trunk

Pectoralis major

Rectus abdiminis

External oblique

Located on outermost surface of abdomen on each side of rectus abdominis. It flexes and rotates vertebral column.

Located on the upper chest and creates the bulk of the chest. It adducts and flexes humerus.

Located on the front of the body. It starts at the beginning of pubic bone and ends in the sternum. This flexes vertebral column.

Neck/head

Frontalis

Located at the front of forehead. This raises eyebrows.

masseter

It is anterior and it pulls mandible upwards.

Temporalis

This closes the jaw and it is anterior.

sternocleidomastoid

This is anterior and it flexes necks as well as it rotates the head.

orbicularis oculi

This is anterior and it blinks/closes eyes

zygomaticus

Anterior and it raises the corner of the mouth.

buccinator

Anterior and it compresses the cheek like when you whistle.

Platysma

Anterior and pulls corners of mouth inferiorly.

Hip/leg/thigh

gluteus maximus

soleus

posterior and extends hip.

posterior and flexes foot

gastrocnemius

posterior and flexes plantar foot and knee.

hamstring

posterior and it flexes knee/hip

Fibularis

Anterior and everts foot.

Sartorius

Anterior and flexes thigh on hip

Extensor

Anterior and extends toes

iliopsoas

Anterior and flexes hip

Tibialis anterior

Anterior and inverts foot

Adductor anterior

Anterior and adducts thighs

Tricep brachii

Posterior and extends elbow

Extensor digtorum

Posterior and extends both fingers and wrist.

extensor carpi radialis

Posterior and extends wrist and abducts hand.

flexor carpi ulnaris

Posterior and adducts hand/flexes fingers.