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Muscular System Diana Ventura Per 2 (Muscles (Thorax (Pectoralis minor,…
Muscular System Diana Ventura Per 2
Major Functions of Muscular System
Posture- maintain body position
Stabilizing- joints, body posture, regulate
organ volume
Motion/Movement- change in body position; also movement of substances within the
body
Thermogenesis- heat production; contraction produces heat; helps with
homeostasis
Muscle Tissues
Cardiac Muscle- cells are long, cylindrical, branched, and has single central nucleus; striated- visible banding; forms the heart wall; involuntary- can’t consciously control it; joined to another cell at intercalated discs; interconnected nature of cardiac muscle cells allows heart to circulate blood
throughout body
Smooth Muscle- aka visceral muscles; 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, blood vessels, urinary and reproductive organs; involuntary; controls movement inside internal organs
Skeletal Muscle- cells are long, cylindrical, parallel, and multinucleated; attached by tendons to bones; striated- visible banding/stripes; voluntary- subject to conscious control; makes up about 40 – 50% of body weight
Muscle Contraction(sliding filament theory)
Step 3- Myosin head attaches to actin, forming actin/myosin crossbridges
Step 4- Myosin head moves toward M line of sarcomere, pulling actin filaments past myosin
Step 2- Ca++ binds to actin myofilament, exposing the myosin binding site
Step 5- This action is repeated many times powered by ATP (ATP needed to release myosin heads from actin)
Step 1- Nerve impulse or action potential travels down sarcolemma and into T-tubules, causing sarcoplasmic reticulum to release Ca++ into sarcoplasm
Step 6- Z lines get closer together as actin and myosin filaments slide past each other, and sarcomeres shorten (H zone disappears), shortening the entire myofibril
Muscles
Thorax
Pectoralis minor, pectoralis major, serratus anterior, & interoostals
Arm
Triceps brachii, biceps brachii, & brachialis
Shoulder
Trapezius & deltoid
Abdomen
Rectus abdominis, external oblique, internal oblique, & transversus abdominis
Neck
Platysma, stemohyoid, & sternocleidomastoid
Forearm
Pronator teres, brachioradialis, flexor carpi radialis, & palmaris longus
Facial
Epicranius, frontal belly, orbicularis oculi, zygomaticus, & orbicularis oris
Pelvis/Thigh
Iliopsoas, tensor fascia lata, sartorius, adductor longus, gracilis, rectus femorus, vastus lateralis, vastus medialis
Head
Temporalis & Masseter
Leg
fibularis longus, extensor digitorium longus, tibialis anterior, gastrocnemius, & soleus
Anterior
Posterior
Neck
Epicranius, occipital belly, sternocleidomastoid, trapezius, splenius capitis, splenius cervicis, levator scapulae, rhomboid minor, & rhomboid major
Shoulder
Deltoid, infraspinatus, teres mijor, rhomboid major, & latissimus dorsi
Arm
Triceps brachii & brachialis
Forearm
Brachioradialis, extensor carpi radialis longus, flexor carpi ulnaris, extensor carpi ulnaris, & extensor digitorum
Hip
Gluteus medias & gluteus maximus
Thigh
Adductor magnus, gracilis, biceps femoris, semitendinosus, semimembranosus, & iliotibial tract
Leg
Gastrocnemius, soleus, fibularis longus, & calcaneal (achilles) tendon
Structures of Skeletal Muscle
Ligaments- strong cords of fibrous connective tissue that attach bone to bone
Bursae- synovial-lined sacs containing synovial fluid; located between some tendons and underlying bones
Tendons- strong cords of fibrous connective tissue that attach muscles to bone
Body- main part of the muscle
Insertion- the end of a muscle attached to the bone that moves when a muscle
contracts
Origin- the end of a muscle that attaches to the bone that does not move when
contraction of the muscle occurs
Body Movement Terminology
Adduction- movement of limb toward the midline
Circumduction- proximal end of a limb is
stationary and the distal end moves in circle
Abduction- movement of limb away from midline
Dorsiflexion- lifting the superior surface of foot towards shin
Rotation- movement of a bone around a longitudinal axis
Plantar flexion- pointing toe
Hyperextension- extension beyond 180°
Inversion- turn sole of foot medially
Extension- movement that increases angle of join
Eversion- turn sole of foot laterally
Flexion- movement that decreases angle of join
Supination- forearm rotates laterally so palm faces anteriorly
Pronation- forearm rotates medially so palm faces posteriorly
Opposition- movement of thumb to touch tips of other fingers