Muscular System, Victoria Gomez, Period 2 (physiology of muscle…
Muscular System, Victoria Gomez, Period 2
Major functions of the
Produce movement. Skeletal muscles are responsible of all movement and locomotion of the body.
Maintain body position and body posture. Skeletal muscles unknowingly and continuously maintain body posture.
Stabilize joints. Even as they pull on bones to cause movement, they strengthen and stabilize the joints of the skeleton.
Generate heat. Muscles generate heat as they contract, which plays a role in maintaining normal body temperature.
names of all the muscles
Facial: Frontalis(epicranius), temporalis, masseter, zygomaticus, orbicularis oculi, orbicularis oris
Neck: Platysma, Sternohyoid, Sternocleidomastoid
Shoulder: Trapezius, Deltoid
Arm: Triceps brachii, biceps brachii, brachialis
Thorax: Pectoralis major, pectoralis minor, serratus major, intercostals
Forearm: Pronator teres, brachioradialis, flexor carpi radialis, palmaros longus
Abdomen: Rectus abdominis, external oblique, internal oblique, transverse abdominis
Pelvis: lliopsoas, pectineus
Thigh: tensor fascia lata, sartorius, adductor longus, gracilis, rectus femoris, vastus lateralis, vastus medialis
Leg: fibularis longus, extensor digitorum longus, tibialis anterior, gastrocnemius, soleus
Neck: Epicranius(occipital belly), sternocleidomastoid, trapezius, splenius capitis, splenius cervicis, levator scapulae, rhomboid minor, rhomboid major
Shoulder: Deltoid, infraspinatus, teres major, latissimus dorsi
Arm: Triceps brachii, brachialis
Forearm: Brachiordialis, extensor carpi radialis longus, extensor carpi ulnaris, flexor carpi ulnaris, extensor digitorum
Hip: gluteus medius, gluteus maximus
Thigh: Adductor magnus, gracilis, biceps femoris, semitendinosus, semimembranosus, lliotibial tract
Leg: Gastrocnemius, soleus, fibularis longus, calcaneal(achiles) tendon
3 types of muscle tissues
Cardiac muscle tissue is only found in the heart.
Cardiac muscle- cardiac, striated, involuntary
Smooth muscle tissue is found in the visceral organs.
Smooth muscle- stomach, urinary bladder, respiratory passages, non-striated, involuntary
Skeletal muscle tissue is packaged into the skeletal muscles, organs that attach to and cover the skeleton.
Skeletal muscle- skeletal, striated, voluntary
body movement terminology
Angular movements: increase or decrease angle between 2 bones; movement along sagittal plane
Elevation, Protraction, flexion, extension, hyperextension, abduction, adduction, circumduction, rotation, supination, pronation, dorsiflexion, plantar flexion, inversion, eversion, retraction, depression, opposition
Gliding movements: one flat bone surface glides or slips over another similar surface
physiology of muscle contraction
Step 1: A contraction is triggered when an action potential in a motor neuron reaches the neuromuscular junction.
Step 2: Acetylcholine is the neurotransmitter that is released at a neuromuscular junction.
Step 3: The electrical signal travels along the muscle fibers plasma membrane and in the T tubules.
Step 4: Calcium is released from the sarcoplasmic reticulum as the action potential passes through the T tubules.
Step 5: The calcium travels and bonds to the molecules of the troponin.
Step 6: Troponin and tropomyosin are the two proteins found on actin filaments. ADP+Pi are bound to the myosin heads.
Step 7: When calcium binds to troponin it shifts position and pulls tropomyosin aside.
Step 8: The myosin head binds to the myosin binding site on the actin, and it forms a cross bridge.
Step 9: When myosin binds to actin ADP+Pi are released.
Step 10: A power stroke is when Pi is released causing the myosin heads to pivot forcing the actin and myosin to slide past each other and ADP is released.
Step 11: When ATP binds to the myosin heads, they release the actin filament, and the ATP turns into ADP+Pi.
Step 12: When the action potential ceases the sarcoplasmic reticulum pumps the calcium it released back into its interior, and after calcium leaves the troponin molecules, the tropomyosin molecules hide the myosin binding sites, and the actin and myosin filaments slide back into place.
structure and organizational levels of the skeletal muscle
A muscle consists of hundreds to thousands of muscle cells plus connective tissue wrappings, blood vessels, and nerve fibers.
Fascicle(portion of the muscle)
A fascicle is a discrete bundle of muscle cells, segregated from the rest of the muscle by a connective tissue sheath.
A muscle fiber is an elongated multinucleate cell; it has a striated appearance.
Myofibril(organelle filled with myofilaments)
Myofibrils are rod-like contractile elements that occupy most of the muscle cell volume. Composed of sarcomeres arranged end to end, they appear banded, and the bands of adjacent myofibrils are aligned.
Sarcomere(part of myofibril)
A sarcomere is the contractile unit, composed of myofilaments made up of contractile proteins.
Contractile myofilaments are thick and thin. Thick filaments contain bundled myosin molecules, thin filaments contain actin molecules. The sliding of the thin filaments produces muscle shortening. Elastic filaments provide elastic recoil when tension is released and help maintain myofilament organization.
disorders associated with the
Fibromyalgia: A disorder characterized by widespread musculoskeletal pain accompanied by fatigue, sleep, memory and mood issues.
Hernia: A hernia occurs when an organ pushes through an opening in the muscle or tissue that holds it in place. Hernias are most common in the abdomen, but they can also appear in the upper thigh, belly button, and groin areas.
Myalgia: Muscle pain resulting from any muscle disorder.
Myofascial pain syndrome: pain caused by a tightened band of muscle fibers, which twitch when the skin over them is touched. Mostly associated with overused or strained postural muscles.
Myotinic Dystrophy: Form of muscular dystrophy that affects muscles and many other organs in the body. The word myotonic is the adjective for the word myotonia, which is an inability to relax muscles at will.
Spasm: A sudden involuntary muscular contraction or convulsive movement.
Strain: A strain is a stretching or tearing of muscle or tendon.
Tetanus: A serious bacterial infection that causes painful muscle spasms and can lead to death.
Charleyhorse: Another name for a muscle spasm. Charley horses can occur in any muscle, but they're most common in the legs. These spasms are marked by uncomfortable muscle contractions.
Shin Splints: Pain caused by overuse along the shinbone.
Tennis Elbow: Irritation of the tissue connecting the forearm muscle to the elbow.
Torticollis: A rare condition in which the neck muscles contract, causing the head to twist to one side.