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Leslie Ayala Muscular System (Body Movement terminology (Dorsiflexion-…
Leslie Ayala Muscular System
Name of the muscles
Shoulder
deltoid
infraspinatus
teres major
latissimus dorsi
Neck
trapezius
Sternocleidomastoid
Thorax
pectoralis major
serratus anterior
iliopsoas
Abdomen
rectus abdominis
external oblique
Thigh
Gracilis
Sartorius
Leg
Soleus
gastrocnemius
fibularis longus
extensor digitorum
longus
Forearm
flexor carpi ulnaris
Brachioradialis
Arm
Triceps brachii
Body Movement terminology
Dorsiflexion- lifting the superior surface of foot towards shin
Plantar Flexion- pointing toe
Circumduction- proximal end of a limb is
stationary and the distal end moves in circle
Inversion- turn sole of foot medially
Adduction- movement of limb toward the midline
Eversion- turn sole of foot laterally
Abduction-movement of limb away from midline
Supination-forearm rotates laterally so palm faces anteriorly
Rotation- movement of a bone around a longitudinal axis
Pronation- forearm rotates medially so palm faces posteriorly
Hyperextension- extension beyond 180°
Opposition-movement of thumb to touch tips of other fingers
Extension- movement that increases angle of joint
Flexion- movement that decreases angle of joint
Major Functions of the Muscular System
Movement of body (Voluntary muscles): contract and relax, interacts with tendons , functions in pairs
Movement of organs (Involuntary Muscles) : Maintain body temperature, maintain posture
3 Types of muscle tissue and their major functions/ characteristics
Cardiac Muscle
Cells are long, cylindrical, branched and has single central nucleus; which forms the heart wall; Which is joined to another cell at intercalated discs
Smooth Muscle
Also known as visceral muscles; the cells are spindle-shaped with single central nucleus and has no striations, appears smooth; found mainly in hollow walls of organs, such as the digestive tract
Skeletal Muscle
Cells are long, cylindrical, parallel, and multi nucleated; which are attached to the bones; Striated- Visible banding
Physiology of muscle contraction
Motor neuron
Nerve that never stimulates skeletal muscle, muscles must be stimulated by a nerve in order to contract
Motor unit
Made of one motor neuron and all muscle fibers it innervates, these cells all contract together
Small- control precise movements
Large- control large movements
Neuromuscular junction: connection of nerves and skeletal muscle
Synapse- connection between nerve with muscles and other organs
Axon - long portion of nerve; releases a chemical called a neurotransmitter
Neurotransmitter- chemical messenger stored and released by synaptic vesicles into synaptic cleft
Synaptic cleft- gap between neuron and sarcolemma
Muscle Contraction
1.Nerve impulse- reaches synaptic end bulbs and causes synaptic vesicles to fuse with presynaptic membrane and release ach
Ach diffuses across synaptic cleft, and binds with receptor on motor end plate
3.This causes receptor to change shape, and opens Na+ channels in sarcolemma
4.Electrical current is generated and is carried along sarcolemma, causes action potential (muscle contraction)
Sliding filament theory
1.
Nerve impulse or action potential travels down sarcolemma and into T-tubules, causing sarcoplasmic reticulum to release Ca++ into sarcoplasm
2.
Ca++ binds to actin myofilament, exposing the myosin binding site
3.
Myosin head attaches to actin, forming actin/myosin crossbridges
4.
Myosin head moves toward M line of sarcomere, pulling
actin filaments past myosin
5.
This action is repeated many times powered by ATP (ATP
needed to release myosin heads from actin)
Muscle Relaxation-
1.
ACh is broken down by an enzyme called acetylcholinesterase. (no longer stimulates muscle contraction)
2.
Action potentials are no longer generated, so the Ca++
release channels in S.R. close
3.
ATP breaks cross-bridge links between actin and myosin
4
Breakdown of ATP resets myosin, muscles now relaxed
5.
Resting potential is reacged when Na+ returns to its initial position