LSUE BIO1160 Hamlin Chapter 10 Exam 2/3 (Muscles)

Muscle functions include

movement, stability, control of body openings and passages, and heat production

Hormone secretion

•exercised muscles release hormones that stimulate glucose synthesis by liver and breakdown of visceral fat

Glycemic control

skeletal muscles absorb, store, and use a large share of body's glucose, so play a significant role in stabilizing its blood concentration

Myology

the study of the muscular system

Endomysium

•thin sleeve of loose connective tissue around each fiber

Perimysium

•thicker layer of connective tissue that wraps fascicles

Epimysium

•fibrous sheath surrounding entire muscle; blends with fascia and deeper connective tissues

Fascicles

•are bundles of muscle fibers wrapped together

•Carries nerves, blood vessels, and stretch receptors

Fascia

sheet of connective tissue between muscles or muscle groups

Fusiform muscles

thick in the middle with fascicles converging on each tapered end

Parallel muscles

uniform width and parallel fascicles

Triangular (convergent) muscles

broad at one end with fascicles converging on the other, narrower end

Pennate muscles

•feather-shaped; fascicles attach obliquely on a tendon that runs full length of muscle

Circular muscles (sphincters)

fascicles form rings around body openings and passages

muscle compartments

Fasciae package groups of functionally related muscles into

fasciae between compartments that are extra thick

intermuscular septa

Aponeurosis

tendon is a broad, flat sheet

Retinaculum

connective tissue band that tendons from separate muscles pass under

origin

the stationary end of a muscle that does not move

insertion

the moving end of a muscle

Intrinsic muscle

entirely contained within a region

Extrinsic muscle

•acts on a designated region but arises from another region

action

effect produced by a muscle to produce or prevent movement

Prime mover

muscle that produces most of the force of a movement; example: brachialis flexes elbow

Synergist

•muscle that aids the prime mover; example: biceps brachii assists brachialis

Antagonist

•muscle that opposes the prime mover; example: triceps brachii extends elbow

Fixator

muscle that prevents a bone from moving; example: rhomboid muscles fix scapula when biceps contracts

Innervation of a muscle

refers to the identity of the nerve that stimulates it

Orbicularis oculi

•sphincter of the eyelid; encircles and closes the eye

Levator palpebrae superioris

opens the eye; deep to orbicularis oculi; elevates upper eyelid

Orbicularis oris

complex of muscles in lips encircling mouth; four interlacing muscle quadrants; puckers lips

Mentalis muscles

•extend from upper margin of mandible to skin of chin; some people have mental cleft (dimple) between them; elevates and protrudes lower lip

Buccinator

muscle of the cheek; compresses cheek

Intrinsic muscles of the tongue

entirely within tongue; vertical, transverse, and longitudinal fascicles

extrinsic muscles of the tongue

arise from outside the tongue

Sternocleidomastoid

Contraction of one side: laterally flexes neck, rotates head to opposite side; Contraction of both sides together: flexes neck

Stylohyoid

elevates and retracts hyoid bone

Levator scapulate

elevates scapula

pharyngeal constrictors

make up the pharynx

Sternocleidomastoid

prime mover of neck flexion; extends from upper chest (sternum, clavicle) to mastoid process behind ear

Trapezius

extends from nuchal region over the shoulders and halfway down the back; large, superficial muscle

Diaphragm

muscular dome between thoracic and abdominal cavities; its fibers converge toward a central tendon

External intercostal muscles

most superficial layer; elevate ribs

Internal intercostal muscles

•deep to external intercostals; each is divided into intercartilaginous and interosseous parts; depress ribs

Innermost intercostal muscles

vary in number; same function as internal intercostals

External oblique muscle

most superficial layer; fibers pass downward and anteriorly; rotation (twisting) of waist

Internal oblique muscle

next deeper layer; fibers pass upward and anteriorly; rotation (twisting) of waist

Transverse abdominal muscle (transversus abdominis)

deepest layer; fibers pass horizontally

Rectus abdominis muscles

Paired muscles extending vertically from sternum to pubis; flexes waist

-Divided into segments by three tendinous intersections, giving them “six pack” appearance

linea alba

Enclose rectus abdominis as a vertical sleeve called the rectus sheath; meet at median line called

Trapezius

Elevates, depresses, retracts, and rotates the scapula; rotates the arm

Deltoid

curve of shoulder formed by large muscle

latissimus dorsi

Extends, adducts, and medially rotates the arm; draws the shoulder downward and backward

levatator scapulae

elevates and adducts scapula

lateral rotators

six muscles inferior to gluteus minimus; which allow for leg movement

Perineum

diamond-shaped region between the thighs

Anal triangle

posterior half of perineum

Urogenital triangle

anterior half of perineum

hernia

is any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity

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

Pectoralis minor

arises from ribs 3 to 5 and converges on coracoid process of scapula; protracts scapula

Levator scapulae

elevates scapula along with superior fibers of trapezius

rotator cuff

Tendons of four scapular muscles form the

Deltoid

triangular muscle capping shoulder; common site of intramuscular drug injections

Pectoralis major

large superficial muscle of chest; flexes, adducts, and medially rotates arm

Latissimus dorsi

large superficial muscle of mid and lower back; extends, adducts, and medially rotates arm

biceps brachii

flexes elbow and supinates forearm

Braciallis (prime)

Prime mover of flexing of the upper arm

bracioradialis action

flexes forearm, helps with supination and pronation.

triceps brachii

extends elbow

Pronator quadratus

prime mover in forearm pronation

Flexor carpi radialis

flexion and radial flexion of wrist

Flexor pollicis longus

flexion of phalanges of thumb

Extensor digiti minimi

•extension of wrist and joints of little finger

Carpal tunnel

tight space between the flexor retinaculum and the carpal bones

Carpal tunnel syndrome

prolonged, repetitive motions of wrist and fingers cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic

Thenar group

fleshy mass at base of thumb

Hypothenar group

fleshy base of the little finger

Midpalmar group

occupies hollow of palm; 11 small muscles divided into three groups:

Iliopsoas

flexes thigh at hip; collective term for two muscles that share a common tendon to the femur

Gluteus maximus

extends thigh at hip as in stair climbing; abducts thigh; forms mass of the buttock

Gluteus medius and gluteus minimus

abduct and medially rotate thigh; shift weight of trunk to load-bearing limb during walking

Lateral rotators

named for their action on the femur; six muscles inferior to gluteus minimus and deep to the two other gluteal muscles

Quadriceps femoris

prime mover of knee extension and most powerful muscle of body; has four heads

Quadriceps femoris Has four heads

rectus femoris, vastus lateralis, vastus medialis, vastus intermedius

Sartorius

straplike muscle that flexes hip and knee joints; laterally rotates thigh, longest muscle

Hamstring muscles

group of three muscles that flex the knee and extend the hip

Tibialis anterior

dorsiflexes and inverts foot

Extensor digitorum longus

•extends toes; dorsiflexes foot

Gastrocnemius

plantar flexes foot; flexes knee

calcaneal (Achilles) tendon

Attach to the calcaneus

Flexor digitorum longus

flexes phalanges of digits 2-5

Flexor hallucis longus

flexes great toe