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Flashcards in 1a1-chapter 10 muscular system Deck (73):
1

myology

the study of the muscular system

2

number of muscles

about 600 human skeletal muscles
•constitute about half of our body weight

3

three kinds of muscle tissue

skeletal, cardiac, smooth

4

specialized for one major purpose

converting the chemical energy in ATP into the mechanical energy of motion

5

Functions of Muscles

Movement
Stability
Control of openings and passageways

6

Movement

–move from place to place, movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth
–role in communication –speech, writing, and nonverbal communications

7

Stability

–maintain posture by preventing unwanted movements
–antigravity muscles –resist the pull of gravity and prevent us from falling or slumping over
–stabilize joints

8

Control of openings and passageways

sphincters –internal muscular rings that control the movement of food, bile, blood, and other materials

9

Heat production by skeletal muscles

as much as 85% of our body heat

10

Connective Tissues of a Muscle

endomysium
perimysium
epimysium
Fascia

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endomysium

–thin sleeve of loose connective tissue surrounding each muscle fiber
–allows room for capillaries and nerve fibers to reach each muscle fiber

12

perimysium

–slightly thicker layer of connective tissue
–fascicles–bundles of muscle fibers wrapped in perimysium
–carry larger nerves and blood vessels, and stretch receptors

13

fascicles

bundles of muscle fibers wrapped in perimysium

14

epimysium

–fibrous sheath surrounding the entire muscle
–outer surface grades into the fascia
–inner surface sends projections between fascicles to form perimysium

15

Fascia

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

16

Fascicle Orientation of Muscles

strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles.

17

fusiform muscles

–thick in middle and tapered at ends
–biceps brachii , gastrocnemius

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parallel muscles

–have uniform width and parallel fascicles
–can span longer distances than other shapes
–rectus abdominis, zygomaticus major

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triangular (convergent) muscles

–fan-shaped, broad at origin and tapering to a narrower insertion
–pectoralis major, temporalis

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pennate muscles

–fascicles insert obliquely on a tendon (feather shaped)
–unipennate, bipennate or multipennate
–palmar interosseus, rectus femoris and deltoid

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circular muscles (sphincters)

–ring around body opening
–orbicularis oculi, urethral and anal sphincters

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indirect attachment to bone

tendons bridge the gap between muscle ends and bony attachment
•the collagen fibers of the endo-, peri-, and epimysium continue into the tendon
•from there into the periosteum and the matrix of bone
•very strong structural continuity from muscle to bone
•biceps brachii, Achilles tendon

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aponeurosis

tendon is a broad, flat sheet (palmar aponeurosis)

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retinaculum

connective tissue band that tendons from separate muscles pass under

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direct (fleshy) attachment to bone

–little separation between muscle and bone
–muscle seems to immerge directly from bone
–margins of brachialis, lateral head of triceps brachii

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dermis of the skin

some skeletal muscles do not insert on bone, but in dermis of the skin –muscles of facial expression

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Origin

bony attachment at stationary end of muscle

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Belly

thicker, middle region of muscle between origin and insertion

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Insertion

bony attachment to mobile end of muscle

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action

the effects produced by a muscle
–to produce or prevent movement

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prime mover (agonist

muscle that produces most of force during a joint action

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synergist

muscle that aids the prime mover
–stabilizes the nearby joint
–modifies the direction of movement

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antagonist

opposes the prime mover
–relaxes to give prime mover control over an action
–preventing excessive movement and injury

34

antagonistic pairs

muscles that act on opposite sides of a joint

35

fixator

muscle that prevents movement of bone

36

Muscle Actions Across Elbow

prime mover -brachialis
•synergist -biceps brachii
•antagonist -triceps brachii
•fixator -muscle that holds scapula firmly in place
–rhomboids

37

intrinsic muscles

entirely contained within a region, such as the hand
–both its origin and insertion there

38

extrinsic muscles –

act on a designated region, but has its origin elsewhere
–fingers –extrinsic muscles in the forearm

39

innervation of a muscle

refers to the identity of the nerve that stimulates it
–enables the diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function

40

spinal nerves arise from the spinal cord

–emerge through intervertebral foramina
–immediately branch into a posterior and anterior ramus
–innervate muscles below the neck

41

plexus

weblike network of spinal nerves adjacent to the vertebral column

42

cranial nerves arise from the base of the brain

–emerge through skull foramina
–innervate the muscles of the head and neck
–numbered I to XII

43

Muscles of Facial Expression

muscles that insert in the dermis and subcutaneous tissues
•tense the skin and produce facial expressions
•innervated by facial nerve (CN VII)
•paralysis causes face to sag
•found in scalp, forehead, around the eyes, nose and mouth, and in the neck

44

Muscles of Chewing and Swallowing

extrinsic muscles of the tongue
–tongue is very agile organ
–pushes food between molars for chewing (mastication)
–forces food into the pharynx for swallowing (deglutition)
–crucial importance to speech
•intrinsic muscles of tongue
–vertical, transverse, and longitudinal fascicles

45

Muscles of Chewing

temporalis, masseter, medial pterygoid, lateral pterygoid

46

depression

to open mouth

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elevation

biting and grinding

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protraction

incisors can cut

49

retraction

make rear teeth meet

50

lateral and medial excursion

grind food

51

aponeurosis

aponeurosis–tendons of oblique and transverse muscles –broad, fibrous sheets

52

hernia

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

53

inguinal hernia

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

54

hiatal hernia

–stomach protrudes through diaphragm into thorax
–overweight people over 40

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umbilical hernia

–viscera protrude through the navel

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compartments

spaces in which muscles are organized and are separated by fibrous connective tissue sheets (fasciae)
–each compartment contains one or more functionally related muscles along with their nerve and blood supplies

57

intermuscular septa

(thick fascia) separates compartments

58

compartment syndrome

one of the muscles or blood vessels in a compartment is injured

59

Compartment Syndrome

mounting pressure on the muscles, nerves and blood vessel triggers a sequence of degenerative events
–blood flow to compartment is obstructed by pressure
–if ischemia(poor blood flow) persists for more than 2 –4 hours, nerves begin to die
–after 6 hours, muscles begin to die

60

treatment

immobilization of limb and fasciotomy–incision to relieve compartment pressure

61

fasciotomy

incision to relieve compartment pressure

62

Anterior Group of Muscles of Pectoral Girdle

pectoralis minor
serratus anterior

63

Posterior Group of Muscles of Pectoral Girdle

–trapezius-superficial
–levator scapulae, rhomboideus minor, and rhomboideus major -deep

64

Muscles Acting on Arm

•nine muscles cross the shoulder joint and insert on humerus
•two are axial muscles because they originate on axial skeleton

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axial muscles because they originate on axial skeleton

–pectoralis major –flexes, adducts, and medially rotates humerus
–latissimus dorsi –adducts and medially rotated humerus

66

seven scapular muscles

originate on scapula
–deltoid
•rotates and abducts arm
•intramuscular injection site
–teres major
•extension and medial rotation of humerus
–coracobrachialis
•flexes and medially rotates arm
–remaining four form the rotator cuff that reinforce the shoulder joint

67

Rotator Cuff Muscles

•tendons of the remaining four scapular muscles form the rotator cuff
•“SITS” muscles –for the first letter of their names
–supraspinatus
–infraspinatus
–teres minor
–subscapularis

68

Muscles Acting on Forearm

elbow and forearm capable of flexion, extension, pronation, and supination
–carried out by muscles in both brachium (arm) and antebrachium (forearm)

69

principalelbow flexors

anterior compartment
•brachialis and biceps brachii
–brachialis produces 50% more power than biceps brachii
–brachialisis prime mover of elbow flexion

70

principal elbow extensor

posterior compartment
•triceps brachii
–prime mover of elbow extension

71

Carpal Tunnel Syndrome

prolonged, repetitive motions of wrist and fingers can cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic
–puts pressure on the median nerve of the wrist that passes through the carpal tunnel along with the flexor tendons

72

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

73

flexor retinaculum

bracelet-like fibrous sheet that the flexor tendons of the extrinsic muscles that flex the wrist pass on their way to their insertions