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82 Cards in this Set
- Front
- Back
____ muscle tissue can contract rapidly and with great force, but tires quickly |
skeletal |
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organization of skeletal muscle fibers |
--each fiber is enclosed in a delicate connective tissue sheath called endomysium --several sheathed muscle fibers are then wrapped by a coarser fibrous membrane called a perimysium to form a bundle of fibers called a fascicle --fascicles are then bound together by a connective tissue overcoat called epimysium |
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tendons |
mostly tough collagen fibers anchor muscles provide durability conserve space |
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smooth muscle structure |
spindle-shaped single nucleus surrounded by scant endomysium arranged into layers (usually 2 layers total), one that runs circularly and one that runs longitudinally (these two layers relax and contract alternately) |
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______ muscle contraction is slow and sustained |
smooth |
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functions of skeletal muscle |
1. produces movement 2. maintains posture 3. stabilizes joints 4. generates heat |
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skeletal muscle accounts for _____% of body mass |
40% |
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Z disk |
interruption in light (I) band, darker area |
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H zone |
lighter central zone of the dark (A) band that has an M line at the center that contains tiny protein rods that hold adjacent thick filaments together bare zone |
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myofibrils |
organelles of skeletal muscle cells composed of chains of tiny contractile units called sarcomeres (made up of even smaller fibers called myofibrils) |
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thick filaments |
myosin contain ATPase enzymes extend entire length of dark A band midparts are smooth but the ends are studded with small projections (myosin heads aka crossbridges) |
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function of cross bridges |
to link thick and thin filaments together during muscle contraction |
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thin filaments |
actin regulatory proteins that dictate when myosin heads can bind to thin filaments anchored to the Z disk do not extend into the middle of a relaxed sarcomere |
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skeletal muscle contraction in the sarcomere |
actin-containing filaments slide toward each other into the center of sarcomere, causing light zones to disappear because actin and myosin are completely overlapped |
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sarcoplasmic reticulum |
stores calcium and releases it to facilitate muscle fiber contraction |
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special properties of muscle cells |
1. excitability 2. contractility 3. extensibility 4. elasticity |
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motor unit |
motor neuron and all of the skeletal muscle cells that it innervates |
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events at neuromuscular junction |
1. action potential reaches axon terminal of motor neuron 2. calcium channels open and Ca2+ enters the axon terminal 3. Ca2+ entry causes some synaptic vesicles to release the neurotransmitter ACh into the synaptic cleft 4. ACh diffuses across synaptic cleft and binds to receptors in sarcolemma 5. ACh binds to receptors, causing channels to open, and Na+ passes into muscle fiber while K+ simultaneously leaves the muscle fiber. More Na+ enter than K+ leave, resulting in depolarization of the cell and the production of an action potential. |
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events that return muscle cell to its resting state |
1. diffusion of K+ out of the cell 2. operation of sodium-potassium pump moves ions via active transport back to their starting positions |
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____ ions trigger the binding of actin to myosin |
Ca2+ |
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how are graded responses produced? |
1. changing frequency of muscular stimulation 2. changing the number of muscle cells being stimulated at one time |
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fused tetanus |
when the muscle is stimulated so rapidly that no evidence of relaxation can be seen and the contractions are completely smooth and sustained |
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direct phosphorylation of ADP by creatine phosphate |
very quick (takes a fraction of a second to produce more ATP) although extensive, each cell's store of creatine phosphate is exhausted in 15 seconds |
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aerobic respiration |
provides 95% of ATP for muscle activity slow provides 32 ATP per glucose molecule requires constant supply of nutrients and oxygen |
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anaerobic glycolysis and lactic acid formation |
used during intense muscle activity glycolysis yields 2 ATP per glucose molecule pyruvic acid is converted to lactic acid 2.5x faster than aerobic respiration can provide ATP to fuel 30-40 seconds of strenuous muscle activity |
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isotonic contraction |
myofibrils slide past one another muscle shortens movement occurs |
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isometric contraction |
contractions in which muscles do not shorten |
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five golden rules of skeletal muscle activity |
1. almost all skeletal muscles cross at leas one joint 2. typically bulk of muscle lies proximal to joint crossed 3. all skeletal muscles have at least two attachments (origin and insertion) 4. skeletal muscles can only pull, they never push 5. during contraction, a muscle insertion moves toward the origin |
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origin |
muscle attachment at immovable or less moveable bone |
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insertion |
muscle attachment to moveable bone |
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a muscle that crosses on the anterior side of a joint produces _______ |
flexion |
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a muscle that crosses on the posterior side of a joint produces _______ |
extension |
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a muscle that crosses on the lateral side of a joint causes ____ |
abduction |
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a muscle that crosses on the medial side of a joint produces _____ |
adduction |
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circular arrangement of fascicles |
when fascicles are arranged in concentric rings typically found around external body openings "sphincters" |
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convergent arrangement of fascicles |
fascicles converge toward a single insertion tendon muscles are usually triangular or fan-shaped |
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parallel arrangement of fascicles |
length of fascicles run parallel to the long axis of the muscle straplike muscles |
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fusiform arrangement of fascicles |
variation of parallel spindle shaped muscle with an expanded belly |
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pennate arrangement of fascicles |
short fascicles attach obliquely to a central tendon |
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pectoralis major |
large, fan-shaped muscle covering upper part of chest that forms anterior wall of axilla origin: sternum, clavicle, and 1st-6th ribs insertion: proximal humerus function: adducts and flexes humerus |
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intercostal muscles |
deep muscles located between ribs external intercostals: used during inhalation internal intercostals: used in forced exhalation |
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rectus abdominus |
paired most superficial muscles of abdomen enclosed in apneurosis origin: pubis insertion: sternum and 5-7th ribs function: flexes vertebral column, also compresses abdominal contents during defecation and childbirth |
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external obliques |
make up lateral walls of abdomen paired superficial muscles origin: lower 8 ribs insertion: iliac crest function: flexes and rotates vertebral column |
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internal obliques |
deep to external obliques origin: iliac crest insertion: last three ribs function: flex vertebral column, rotate trunk and bend trunk laterally |
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transversus abdominus |
deepest muscle of abdominal wall fibers run horizontally across the abdomen origin: lower ribs and iliac crest insertion: pubis function: compresses abdominal contents |
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deltoid |
triangle-shaped origin: scapular spine and clavicle insertion: proximal humerus (deltoid tuberosity) function: abducts humerus |
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quadratus lumborum |
form part of posterior abdominal wall origin: iliac crest, lumbar fascia insertion: transverse processes of upper lumbar vertebrae function: flex spine laterally (when acting separately) or extends spine (when acting together) |
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erector spinae |
paired deep muscles of back that span entire length of vertebral column origin: iliac crests, ribs 3-12, and vertebrae insertion: ribs, thoracic and cervical vertebrae function: extends and laterally flexes spine longissimus, iliocostalis, spinalis |
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trapezius |
most superficial muscles of posterior neck and upper trunk diamond/kite-shaped antagonists of sternocleidomastoids origin: occipital bone and all cervical and thoracic vertebrae insertion: scapular spine and clavicle function: extend head; depress, elevate, adduct, and stabilize scapula |
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latissimus dorsi |
paired large flat muscles that cover lower back origin: lower spine and iliac crest insertion: proximal humerus function: extends and adducts humerus |
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gluteus maximus |
superficial muscle of hip makes up most of flesh in buttocks origin: sacrum and ilium insertion: proximal femur (gluteal tuberosity) function: extends hip when forceful extension is required; is not essential or particularly important in producing the movements needed for walking |
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gluteus medius |
beneath gluteus maximus for most of its length origin: ilium insertion: proximal femur function: abducts thigh, steadies pelvis during walking |
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iliopsoas |
fused muscle composed of iliacus and psoas major prime mover of hip flexion origin: ilium and lumbar insertion: femur (lesser trochanter) function: flexes hip |
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fibularis muscles (longus, brevis, tertius) |
lateral part of leg origin: fibular insertion: metatarsals of foot function: plantarflexion and eversion of foot |
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soleus |
deep to gastrocnemius origin: proximal tibia and fibula (does not affect knee movement) insertion: calcaneus function: plantarflexion of foot |
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gastrocnemius |
forms curved calf of posterior leg has 2 heads origin: each head attaches on either side of distal femur insertion: calcaneus (heel via calcaneal tendon) function: prime mover of plantarflexion of foot; flexes knee |
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extensor digitorum longus |
lateral to tibialis anterior origin: proximal tibia (lateral tibial condyle) and proximal 3/4 of fibula insertion: phalanges of distal toes 2-5 function: prime mover of toe extension |
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tibialis anterior |
superficial muscle on anterior leg origin: upper proximal tibia insertion: first cuneiform (tarsal) and first metatarsal of foot function: dorsiflexion and inversion of foot |
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what muscles make up the quadriceps |
vastus medialis vastus intermedius vastus lateralus rectus femoris |
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quadriceps group |
origin: femur (vasti) and pelvis (rectus femoris) insertion: tibial tuberosity via patellar ligament function: all extend knee; rectus femoris also flexes hip because it crosses two joints |
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sartorius |
most superficial muscle of thigh origin: ilium insertion: medial proximal tibia function: flexes thigh on hip (weakly) |
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what muscles make up the hamstring |
semitendinosus semimembranosus biceps femoris |
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hamstring group |
origin: ischial tuberosity insertion: both sides of the proximal tibia and head of fibula in the case of biceps femoris function: extend hip and thigh, flex knee |
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adductor muscles |
medial side of each thigh origin: pelvis insertion: proximal aspect of femur function: adduct and medially rotate thigh |
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frontalis |
origin: cranial aponeurosis insertion: skin of eyebrows function: raises eyebrows, wrinkles forehead |
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occipitalis |
at posterior end of cranial aponeurosis covers posterior aspect of skull pulls scalp posteriorly |
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orbicularis oculi |
fibers run in circles around the eyes origin: frontal bone and maxilla insertion: tissue around eyes function: blinking, closing eye, winking, squinting |
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orbicularis oris |
kissing muscle origin: mandible and maxilla insertion: skin and muscle around mouth function: closes and protrudes lips |
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buccinator |
runs horizontally across cheek origin: maxilla and mandible near molars insertion: orbicularis oris function: compresses cheek (as in sucking), holds food between teeth when chewing |
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zygomaticus |
smiling muscle origin: zygomatic bone insertion: skin and muscle at corners of lips function: raises corners of mouth |
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temporalis |
fan-shaped, overlying temporal bone origin: temporal bone insertion: mandible function: closes jaw, works as synergist with masster |
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masseter |
covers angle of lower jaw origin: zygomatic process of temporal bone insertion: angle of mandible function: closes jaw by elevating mandible |
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platysma |
single sheet-like muscle that covers anterolateral neck frowning muscle origin: connective tissue covering superior chest muscles insertion: tissue around mouth function: tenses skin around neck |
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sternocleidomastoid |
2 headed muscle origin: one head at sternum and one head at clavicle (heads fuse before insertion) insertion: mastoid process of temporal bone function: flexes neck (when working together) and rotates head (when working alone) |
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biceps brachii |
2 heads powerful prime mover of elbow flexion origin: scapula of the shoulder girdle insertion: radial tuberosity of proximal radius function: flexes elbow and suppinates forearm |
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brachialis |
lifts ulna as biceps lifts the radius deep to biceps origin: distal humerus insertion: proximal ulna function: flexes elbow |
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triceps brachii |
antagonist to biceps brachii only muscle fleshing out posterior humerus origin: shoulder girdle and proximal humerus insertion: olecranon process of ulna in distal forearm function: extends elbow |
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extensor digitorum |
origin: distal humerus insertion: distal phalanges of 2nd to 5th fingers function: extends fingers |
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extensor carpi radialis |
origin: humerus insertion: base of 2nd and 3rd metacarpals function: extends wrist and abducts hand |
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flexor carpi ulnaris |
origin: distal humerus and posterior ulna insertion: carpals of wrist and fifth metacarpal function: flexes wrist and adducts hand |
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flexor carpi radialis: |
origin: distal humerus insertion: 2nd and 3rd metacarpals primary actions: flexes wrist and abducts hand |
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flexor digitorum superficialis |
origin: distal humerus, ulna, and radius insertion: middle phalanges of 2nd to 5th fingers function: flexes wrist and fingers |