a&p exam 3 full set

muscle function

movement- move from place to place, move body parts, move body contents in breathing, circulation, digestion, aid in communication;
stability- maintain posture, stabilize joints;
control openings and passageways- sphincters are internal muscle rings;
heat production by skeletal muscles;
glycemic control- muscle store glucose

endomysium

thin sleeve of loose connective tissue around each fiber (cell)- allows room for capillaries and nerve fibers, provides chemical environment for muscle fiber

perimysium

thicker layer of connective tissue that wraps fascicles; fascicles- bundles of muscle fibers wrapped together; carries nerves, blood vessels, and stretch receptors

epimysium

fibrous sheath surrounding entire muscle- outer surface grades into fascia, inner surface projections from perimysium

fascia

sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

what does the orientation of fascia determine

the strength of the muscle and the direction of its pull

fusiform muscle shape

thick in middle of muscle, tapered at ends of muscle, terminate in tendons; parallel= uniform width of muscle

triangular (convergent) muscle shape

broad at one end and narrow at the other

pennate- feather-shaped muscle shape

include unipennate, bipennate, multipennate

circular (sphincter) muscle shape

form rings around body openings

muscle compartments

a group of functionally related muscles enclosed by fascia; also contains nerves and blood vessels that supply the muscle group; muscles of upper limb divided into anterior and posterior compartments; muscles of lower limbs divided into anterior, posterior, medial, lateral compartments; intramuscular septa are very thick fascia that separate one compartment from another

compartment syndome

a muscle or blood vessel in compartment is injured → blood and tissue fluid accumulate in compartment → fascia prevent compartment from expanding with increasing pressure → mounting pressure on muscles, nerves, and blood vessels- blood flow to compartment is obstructed by pressure, if ischemia persists for more than 2-4 hours, nerves begin to die, after 6 hours, muscles begin to die; nerves can regenerate to some extend after pressure relieves, but muscle damage is permanent; treatment- immobilization of limb and fasciotomy (incision to relieve compartment pressure)

tendons- indirect attachment to bone

connect muscles to bone; collagen fibers of the endo-, peri-, and epimysium continue into the tendon and from there into the periosteum and matrix of bone

aponeurosis- indirect attachment to bone

tendon is a broad, flat sheet

retinaculum- indirect attachment to bone

connective tissue band that tendons from separate muscles pass under

direct fleshy attachment to bone

little separation between muscle and bone; muscle seems to emerge directly from bone; ex- margins of brachialis, lateral head of triceps brachii

origin

bony attachment at stationary end of muscle

belly

thicker, middle region of muscle between origin and insertion

insertion

bony attachment to mobile end of muscle

intrinsic muscle

entirely contained within a region, such as the hand

extrinsic muscle

acts of a designated region but has attachment elsewhere; finger movements- extrinsic muscles in the forearm

action of muscle

effects of muscle produce or prevent movement; 4 categories- prime mover (agonist), synergist, antagonist, fixator

prive mover (agonist)

muscle that produces most of force during a joint action

synergist

muscle that stabilizes the prime mover; stabilizes the nearby joint, modifies the direction of movement, may contribute additional force

antagonist

muscle that opposes the prime mover; relaxes to give prime mover control over an action; prevents excessive movement and injury; antagonist pairs- muscles that act on opposite sides of joint

fixator

prevents movement of bone

muscle categories in elbow flexion

prime mover- brachialis, synergist- biceps brachii, antagonist- triceps brachii, fixator- muscle that holds the scapula firmly in place (rhomboids)

spinal nerves

arise from the spinal cord, are named based on adjacent vertebrae (T6, L4, S2), emerge through intervertebral foramina, split into anterior and posterior ramus, innervate muscles below the neck; plexus- web-like network of spinal nerves adjacent to vertebral column

cranial nerves

arise from the base of the brain, emerge through skull foramina, innervate the muscles of the head and neck, numbered CN I to CN XII (12 pairs)

muscle nomenclature

latin names; describe distinctive aspects of the structure, location, or action of muscle; ex- depressor labii inferioris (pulls bottom lip down), flexor digiti minimi brevis (short muscle that flexes pinky finger)

muscles of facial expression

muscles that insert in the dermis and subcutaneous tissues; tense the skin and produce facial expressions; found in scalp, around the eyes, nose, mouth, and in neck

extrinsic muscles of the tongue- muscles of chewing and swallowing

pushes food between molars for chewing (mastication); forces food into the pharynx for swallowing (deglutition); crucial importance to speech

intrinsic muscles of tongue- muscles of chewing and swallowing

vertical, transverse, and longitudinal fascicles

four pairs of muscles in biting and chewing muscles of mandible

temporalis, masseter, medial pterygoid, lateral pterygoid; function in depression to open mouth, elevation for biting and grinding, protraction so incisors can cut, retraction to make rear teeth meet, lateral and medial excursion to grind food

suprahyoid group- muscles of chewing and swallowing

digastric, geniohyoid, mylohyoid, stylohyoid- concerned with aspects of chewing, swallowing, and vocalizing

infrahyoid group- muscles of chewing and swallowing

omohyoid, sternohyoid, thyrohyoid, sternothyroid- fix hyoid bone from below, allowing suprahyoid muscles to open mouth

3 pairs of pharyngeal constrictors- muscles of chewing and swallowing

drive food into esophagus during chewing

muscles acting on the head

originate in the vertebral column, thoracic cage, and pectoral girdle; extrinsic muscles; insert on cranial bones; actions: flexion- tipping head forward, extension- holding head erect, lateral flexion- tipping head to side, rotation- turning the head to left and right; may cause contralateral movement- movement of head toward opposite side; may cause ipsilateral movement- movement of head toward same side

neck flexors- muscles acting on the head

sternocleidomastoid, scalenes

neck extensors- muscles acting on the head

trapezius, splenius capitis, semispinalis capitis

muscles of thr trunk

4 functional groups- muscles of respiration, muscles supporting the abdominal wall, muscles that support movement of the vertebral column, muscles that support the pelvic floor

breathing requires use of muscles enclosing thoracic cavity- muscles of respiration

diaphragm, external intercostals, internal intercostals, innermost intercostals

other muscles of chest and abdomen contribute to breathing- muscles of respiration

sternocleidomastoid and scalenes of neck, pectoralis major and serratus anterior of chest, latissimus dorsi of back; abdominal muscles- internal and external obliques and transverse abdominis; some anal muscles

diaphragm- muscles of respiration

muscular dome between thoracic and abdominal cavities; contraction flattens diaphragm- enlarges thoracic cavity (inspiration); in relaxation, diaphragm rises- shrinks in thoracic cavity (expiration)

external intercostals- muscles of respiration

elevate ribs, expands thoracic cavity

internal intercostals- muscles of respiration

depresses and retracts ribs, compresses thoracic cavity

muscles of abdominal wall

external abdominal oblique- unilateral contraction causes contralateral rotation of waist;
internal abdominal oblique- unilateral contraction causes ipsilateral rotation of waist;
transverse abdominal- compresses abdominal contents but does not contribute to movements of vertebral column;
rectus abdominus- flexes lumbar region and produces foreword bending at waist

superficial muscles- muscles of the back

extend, rotate, and laterally flex, vertebral column- latissimus dorse, trapezius

deep muscles act on vertebral column- muscles of back

erector spinae (iliocostalis, longissimus, spinalis)- from cranium to sacrum, extension and lateral flexion of vertebral column; semispinalis thoracis- extension and contralateral rotation of vertebral column; quadratus lumborum- aids respiration, ipsilateral flexion of lumbar vertebral column; multifidus- stabilizes adjacent vertebrae, maintains posture

muscles of the pelvic floor

3 layers (compartment) of muscles and fascia that span pelvic outlet- transversed by anal canal, urethra, and vagina

perineum- muscles of the pelvic floor

diamond shaped region between the thighs; bordered by 4 bony landmarks- pubic symphysis anteriorly, coccyx posteriorly, ischial tuberosities laterally; urogenital triangle- anterior half, anal triangle- posterior half;

superficial perineal space- muscles of the pelvic floor

ischiocavernosus- maintains erection, bulbospongiosus- aids in erection, expels remaining urine

deep perineal space- muscles of the pelvic floor

urigenital triangle contains urogenital diaphragm- deep transverse perineal muscle, external urethral sphincter, and compressor urethrae in females; anal triangle- external anal sphincter

deepest compartment- muscles of pelvic floor

pelvic diaphragm: levator ani- supports viscera and defecation, coccygeus- supports and elevates pelvic floor

hernias

viscera protrudes througha weak point in the muscular wall of the abdominopelvic cavity; inguinal, hiatal, umbilical

inguinal hernia

most common type of hernia (rare in women), viscera enter inguinal canal or even the scrotum

hiatal hernia

stomach protrudes through diaphragm into thorax, overweight people over 40

umbilical hernia

viscera protrude through the navel

muscles acting on shoulder and upper limb

upper limb is used for a broad range of powerful and subtle actions- climbing, grasping, writing, playing instruments, and manipulating small objects; functional groups- muscles that act on the scapula, muscles that act on the humerus and shoulder joint, muscles that act on the forearm and elbow joint, muscles that act on the wrist, hand, and fingers

muscles acting on the shoulder

originate on axial skeleton; insert on clavicle and scapula; scapula loosely attached to the thoracic cage- capable of great movement, rotation, elevation, depression, protraction, retraction; clavicle braces shoulder and moderates movements

anterior group of muscles of pectoral girdle

pectoralis minor- draws scapula laterally, ribs 3-5 to coracoid process of scapula; serratus anterior- draws scapula laterally and foreword, prime mover for reaching and pushing, all ribs to medial border of spine

posterior group of muscles of pectoral girdle

trapezius- stabilizes scapula and shoulder, elevates and depresses shoulder apex;
levator scapulae- elevates scapula and flexes neck laterally;
rhomboideus minor- retracts scapula and braces shoulder;
rhomboideus major- retracts scapula and braces shoulder

muscles acting on the arm

9 muscles across the shoulder joint and attach to the humerus- 2 are axial muscles acting on the axial skeleton- pectoralis major (flexes, adducts, and medially rotates humerus), latissimus dorsi (adducts and medially rotates humerus); 7 muscles originate on scapula- deltoid (rotates and abducts arm), teres major (extension and medial rotation of humerus), coracobrachialis (flexes and medially rotates arm); 4 form rotator cuff (reinforces shoulder joint)- supraspinatus, infraspinatus, teres minor, subscapularis

muscles with bellies in the brachium- muscles acting on the forearm

principal elbow flexors- anterior compartment- brachialis (prime mover) and biceps brachii, synergistic flexors- biceps brachii, brachioradialis;
principal elbow extensors- posterior compartment- triceps brachii (prime mover)

muscles with bellies in the antebrachium- muscles acting on the forearm

most act on the hand and wrist; brachioradialis- flexes elbow, anconeus- extends elbow, pronator quadratus- prime mover in forearm pronation, pronator teres- assists pronator quadratus in pronation, supinator- supinates the forearm

anterior group- muscles acting on the wrist and hand

extrinsic muscles of the forearm, intrinsic muscles in hand;
extrinsic muscle actions- flexion and extension of wrist and digits, radial and ulnar flexion, finger abduction and adduction, thumb opposition;
anterior (flexor) compartment- superficial layer: flexor carpi radialis, flexor carpi ulnaris, flexor digitorum superficialis, palmaris longus;
anterior (flexor) compartment- deep layer: flexor digitorum profundus, flexor pollicis longus

posterior group- muscles acting on the wrist and hand

extend wrist and fingers, adduct/abduct wrist, extend and abduct thumb (pollicis);
posterior (extensor) compartment- superficial layer: extensor carpi radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris;
posterior (extensor) compartment- deep later: abductor pollicis longus, extensor pollicis brevis, extensor pollicis longus, extensor indicis

thenar group- intrinsic muscles of the hand

fleshy mass at base of thumb; adductor pollicis, abductor pollicis brevis, flexor pollicis brevis, opponens pollicis

hypothenar group- intrinsic muscles of the hand

fleshy base of the little finger; abductor digiti minimi, flexor digiti minimi brevis, opponens digiti minimi

mid palmar group- intrinsic muscles of the hand

hollow of palm; dorsal interosseous muscles (4), palmar interosseous muscles (3), lumbricals (4)

flexor retinaculum- carpal tunnel syndrome

bracelet-like fibrous sheet, passed under by flexor tendons crossing the wrist

carpal tunnel

tight space between the flexor retinaculum and the carpal bones; flexor tendons passing through the tunnel are enclosed in tendon sheaths, enable tendons to slide back and forth quite easily

carpal tunnel syndrome

repetitive motions of wrist and fingers cause tissues to become inflamed, swollen, or fibrotic; those motions put pressure on the median nerve and cause inflammation, symptoms include tingling and muscular weakness in the palm and medial side of the hand

muscles acting on the lower limb

largest muscles found in the lower limb; adapted more for strength needed to stand, maintain balance, walk, run; several cross and act on 2 or more joints: leg- the part of the limb between the knee and ankle, foot- includes tarsal region (ankle), metatarsal region, and toes

anterior muscles of the hip

iliopsoas (includes iliacus and psoas major)- flexes thigh at hip, share common tendon on femur

lateral/posterior muscles of the hip- muscles acting on hip and femur

tensor fascia latae- extends knee, laterally rotates knee;
gluteus maximus- forms mass of the buttock, prime hip extensor, provides most of lift when you climb stairs;
gluteus medius and minimus- abduct and medially rotate thigh

posterior group of muscles of the hip- muscles acting on hip and femur

lateral rotators- 6 muscles inferior to gluteus minimus: gemellus superior, gemellus inferior, obturator externus, obturator internus, piriformis, quadratus femoris

medial (adductor) compartment of thigh- muscles acting on hip and femur

5 muscles act as primary adductors of the thigh- adductor brevis, adductor longus, adductor magnus, gracilis, pectineus

anterior (extensor) compartment- muscles acting on knee and leg

quadriceps femoris- prime mover of knee extension, most powerful muscle in the body, has four head- rectus femoris, vastus lateralis, vastus medialis, vastus intermedius, all converge on single quadriceps (patellar) tendon, extends to patella then continues as patellar ligament, attaches to the tibial tuberosity;
sartorius- longest muscle in the body

posterior (flexor) compartment of the thigh- muscles acting on the knee and leg

hamstring muscles from lateral to medial- biceps femoris, semitendinosus, semimembranosus

anterior (extensor) compartment of the leg- muscles acting on the foot

dorsiflex the ankle, prevent toes from scuffing ground when walking; fibularis (peroneus) tertius, extensor digitorum longus, extensor hallucis longus, tibialis anterior

posterior compartment (superficial group)- muscles acting on the foot

three muscles of the superficial group: gastrocnemius- plantar flexes foot and flexes knee, soleus- plantar flexes foot, plantaris- weak synergist for triceps surae; triceps surae- collective name for gastrocnemius and soleus, attaches to the calcaneus via calcaneal tendon

posterior compartment (deep group)- mscuesl acting on the foot

flexor digitorum longus- flexes phalanges, flexor hallucis longus- flexes great toe, popliteus- acts on knee

lateral (fibular) compartment- muscles acting on the foot

fibularis longus, fibularis brevis

intrinsic muscles of the foot

4 ventral muscle layers- support arches, abduct and adduct toes, flex toes; 1 dorsal muscle- extensor digitorum brevis- extends toes

common athletic injuries

muscles and tendons are vulnerable to sudden, intense stresses; proper conditioning and warm up needed; injuries include- compartment syndrome, shin splints, pulled hamstrings, tennis elbow, pulled groin, rotator cuff injury

excitability (responsiveness)- characteristic of muscles

to chemical signals, stretch, and electrical changes across plasma membrane

conductivity- characteristic of muscles

local change triggers a wave of excitation that travels along the muscle fiber

contractility- characteristic of muscles

local change triggers a wave of excitation that travels along the muscle fiber

contractility- characteristic of muscle

shortens when stimulated

extensibility- characteristic of muscle

capable of being stretched between contractions

elasticity- characteristic of muscle

returns to original resting length after being stretched

skeletal muscle characteristics

voluntary- usually subject to conscious control; striated- alternating dark and light transverse bands

length of muscle cell

muscle fiber- as long as 30 cm

skeletal muscle organization

cells are long, packed with units called myofibrils; connective tissue wrappings around muscle cells- endomysium, perimysium, epimysium

endomysium

connective tissue around a single muscle fiber/cell

perimysium

connective tissue around muscle fascicle

epimysium

connective tissue between muscle and muscle

fasicle

bundle of cells within a perimysium

sarcolemma- skeletal muscle fibers (cells)

plasma membrane of a muscle fiber