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Anatomy > Muscular System > Flashcards

Muscular System Flashcards

1
Q

muscle tissue types

A

skeletal
cardiac
smooth

muscles = organs → have all four basic tissue types: muscle, nerve, connective, vasculature)

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2
Q

excitability

A

ability to respond to stimulation from NS

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3
Q

contractility

A

ability to shorten and pull (bone)

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4
Q

extensibility

A

ability to contract over different lengths
contraction at rest or while stretched

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5
Q

elasticity

A

ability to regain original length

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6
Q

characteristics of skeletal muscle

A

somatic structures = under voluntary control (sympathetic innervation)
innervated by spinal nerves + cranial nerves
contractile organs - attach directly or indirectly onto bones
contraction produces motion of the body

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7
Q

functions of skeletal muscle

A

produce movement at joints via tendons or muscle fibres
maintain posture + body position
support soft tissues
regulate orifices (sphincters)
maintain body temperature

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8
Q

structure of skeletal muscle

A

organ → fascicle → fibre → myofibril → sarcomere
(organ → fibre are covered with connective tissue sheath)

muscle covered by epimysium
fascicle covered by perimysium
fibre covered by endomysium

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9
Q

structure of muscle fibre

A

muscle cell
contains myofibrils, nuclei, mitochondria, sarcoplasm (cytoplasm)
membrane = sarcolemma

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10
Q

myofibrils

A

surrounded by sarcoplasmic reticulum + t-tubules
contain sarcomeres

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11
Q

sarcomere

A

basic contractile unit of muscle
intedigitation of thick and thin filaments
boundaries = Z lines (pair)
centre = M line

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12
Q

H band

A

middle of sarcomere
contains only thick filaments (myosin)

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13
Q

I bands

A

margin of sarcomere (near Z lines)
contains only thin filaments (actin)

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14
Q

A band

A

zone of overlap
contains both thin and thick filaments

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15
Q

muscle contraction

A

depolarization of sarcolemma → spreads through t-tubules
release of Ca2+ from SR = cross-bridging between thick and thin filaments → pivoting of myosin heads towards M line

width of I band + H band decreases
width of A band remains constant

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16
Q

nerve stimulation

A

each muscle fibre is innervated by a motor neuron
neuron fires → signals fibre to contract

contraction is all or none = fibre either contracts or doesn’t

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17
Q

motor unit

A

motor neuron + fibres it innervates
(all muscle cells controlled by single motor neuron)

amount of muscle tension depends on number of motor units stimulated

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18
Q

slow twitch fibres

A

red - lots of mitochondria + myoglobin
narrow diameter
resistant to fatigue = sustained contraction (less powerful)
aerobic metabolism produces ATP

ex. calf: soleus muscle has higher proportion of slow fibres = enlarged in marathon runner

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19
Q

fast twitch fibres

A

white - less myoglobin
large diameter
rapid contraction → powerful
fatigue easily
anaerobic glycolysis produces ATP

ex. calf: gastrocnemius muscle has higher proportion of fast fibres = enlarged in sprinter

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20
Q

parallel muscles

A

fascicles run parallel to long axis of muscle
most common muscle type
large force exerted because all fascicles pull in same direction = only one action

ex. rectus abdominus (flat band), biceps brachii (spindle-shaped)

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21
Q

spindle shaped muscle

A

parallel muscle with tendon at either end
central portion = belly
during contraction → belly widens and muscle shortens

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22
Q

convergent muscles

A

fan-shaped
fascicles originate over wide area but converge at common attachment site
direction of pull can change by varying which fascicles contract
less force exerted because not all fascicles pull in same direction

ex. pectoralis major, trapezius

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23
Q

circular muscles

A

fibers are arranged concentrically around opening → form sphincters
contraction reduces diameter of opening

ex. orbicularis oculi (eye) + oris (mouth)

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24
Q

pennate muscles

A

tendons run through body of muscle
fascicles form oblique angle relative to tendon
contain more muscle fibres than parallel muscle of same size = generate more force

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25
Q

unipennate

A

muscle fibers are on one side of tendon
single plane pennation

ex. extensor digitorum (forearm)

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26
Q

bipennate

A

muscle fibres are on both sides of tendon

ex. rectus femoris (thigh)

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27
Q

multipennate

A

tendon branches with muscle

ex. deltoid

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28
Q

naming: structure/shape of muscle

A

deltoideus = triangular
maximus = large
brevis = short

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29
Q

naming: specific region

A

carpi = wrist
abdominis = abdomen

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30
Q

naming: attachment sites

A

sternocleidomastoideus = sternum, clavicle, mastoid process

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31
Q

naming: in relation to other muscles

A

profundus = deep
superficialis = superficial

32
Q

naming: action

A

flexor = flexion movement

33
Q

production of movement

A

muscles:
- attach on individual bones or soft tissue
- usually cross at least one joint
- pull a bone toward another so movement is produced at joint
- stabilize a joint so others can produce movement

34
Q

agonist

A

prime mover → major muscle to cause action
contraction produces particular movement

ex. biceps femoris flexes leg at knee joint

35
Q

synergist

A

assists prime mover in performing action

ex. semitendinosus (hamstring) also flexes leg at knee joint

36
Q

antagonist

A

opposes movement of agonist

ex. quadriceps femoris extends leg at knee joint

37
Q

lever

A

rigid structure
moves on fixed point (fulcrum = Fc)
requires force to move a weight

force generated by muscle contraction

38
Q

first class lever

A

W - Fc - F
increases range and speed of movement but requires larger force

ex. head: Fc = atlanto occipital joint
(not many examples)

39
Q

second class lever

A

Fc - W - F
increases force at expense of range and speed of movement

ex. raising ankles: Fc = foot; F = soleus muscle + achilles tendon
(not many examples)

40
Q

third class lever

A

Fc - F - W
increase range and speed of movement at expense of force

ex. flexion of forearm: Fc = elbow; F = biceps brachii (attached to radius)
most common in body

41
Q

action vs function

A

ex. gluteus medius and minimus

action = abduction of thigh at hip joint
function = keep pelvis straight during walking

42
Q

axial musculature

A

associated with axial skeleton: skull, vertebral column, ribs
innervated by cranial or spinal nerves
attachments on axial skeleton, associated organs, or soft tissue

43
Q

functions of axial musculature

A

vision, mastication, facial expression, swallowing
upright posture + movement of back
support of abdominal + pelvic viscera
respiration
urination, defecation, parturition

44
Q

groups of axial musculature

A

head + neck
back
thorax + abdominopelvic cavities
pelvis + perineum

45
Q

extraocular muscles

A

innervated by oculomotor, trochlear, and abducens nerves (CNs III, IV, VI)

levator palpebrae superioris
superior rectus
medial rectus
inferior rectus
inferior oblique
lateral rectus
superior oblique

46
Q

CN VI palsy

A

paralysis of right side lateral rectus = right eye can’t move to the right

47
Q

muscles of mastication

A

innervated by trigeminal nerve (CN V) - mandibular division (3)

temporalis
masseter
medial pterygoid
lateral pterygoid

48
Q

biomechanics of mastication

A

lateral pterygoid = depressor of mandible to open mouth
- pulls condyle of mandible anteriorly = move down + forward

temporalis (pull up + back), masseter, medial pterygoid (pull up + forward) = elevation of mandible when closing mouth

49
Q

muscles of facial expression

A

innervated by facial nerve (CN VII)

orbicularis oculi
orbicularis oris
platysma
occipitofrontalis
buccinator

50
Q

Bell’s palsy

A

damage to facial nerve (CN VII)
lesions typically at or beyond stylomastoid foramen = affect all ipsilateral motor branches
ipsilateral upper and lower facial asymmetry = facial paralysis

51
Q

pharyngeal muscles

A

innervated by vagus nerve (CN X)

tensor + levator veli palatini
superior constrictor
middle constrictor
inferior constrictor

52
Q

tongue muscles

A

innervated by hypoglossal nerve (CN XII)
control position of tongue

palatoglossus
styloglossus
hyoglossus
genioglossus

53
Q

neck muscles

A

innervated by cranial or cervical nerves

mylohyoid
digastric (2 bellies)
infrahyoids
sternocleidomastoid
longus capitis
longus colli
scalene muscles

54
Q

biometrics of swallowing

A
  1. contraction of mylohyoid and tongue muscles = floor of mouth tenses + elevation of hyoid bone
  2. contraction of tensor and levator veli palatini muscles = tense + elevate soft palate to close gap between nose + mouth
  3. elevation of larynx by many muscles = close airway
  4. sequential contraction from top of constrictor muscles = push bolus into esophagus
55
Q

back muscles

A

transversospinal group
- delicate adjustments at zygapophyseal joints of vertebrae

extensors: (maintain upright posture)
longissimus
spinalis
iliocostalis
erector spinae

56
Q

trunk muscles

A

intercostal muscles (3 layers)
abdominal muscles: → can increase intra-abdominal pressure
- rectus abdominis
- external + internal obliques
- transversus abdominis

57
Q

respiration

A

contraction of intercostal muscles produces elevation of ribs
increases volume of thoracic cavity
synovial joint in front and back = allows movement of ribs

contraction of diaphragm during inhalation → brings central tendon down to increase vol

58
Q

diaphragm

A

separates thoracic + abdominal cavities
chief muscle of respiration
holes for inferior vena cava, esophagus, and aorta

central tendon, muscle fibers, crura

59
Q

pelvic muscles

A

coccygeus
levator ani

form the pelvic diaphragm
provide support to pelvic viscera

60
Q

perineal muscles

A

innervated by pudendal nerve

external urethral sphincter
external anal sphincter
ischiocavernous
bulbospongiosus

61
Q

appendicular musculature

A

associated with appendicular skeleton (limb bones, shoulder + pelvic girdles)

attachment on axial + appendicular skeleton

62
Q

appendicular musculature - innervation

A

spinal nerves - form plexuses → branches of nerves leave plexus to innervate muscle compartments

limb muscles are organized into compartments - each is innervated by specific nerve branch of a plexus

63
Q

upper limb musculature

A

innervated by branches of brachial plexus (levels C5 to T1)
(exception: trapezius - CN XI)

major muscle groups: shoulder (pectoral girdle), arm, forearm, hand

joints are designed for mobility rather than stability
- positioning pectoral girdle
- moving arm, forearm + hand, hand + digits

64
Q

muscles moving pectoral girdle

A

trapezius
levator scapulae
rhomboids
serratus anterior

65
Q

force couple

A

muscles work together to complete a task not possible individually
ex. scapular rotation requires trapezius (pulling up near acromion + pulling down near vertebral border) and serratus anterior (protraction)

66
Q

muscles moving arm at shoulder joint

A

pectoralis major
deltoideus
latissimus dorsi
rotator cuff muscles:
- subscapularis
- supraspinatus
- infraspinatus
- teres minor
teres major

67
Q

muscles moving forearm at elbow joint

A

biceps brachii
brachialis
brachioradialis
triceps brachii

68
Q

muscles moving hand at wrist joint

A

flexor carpi radialis
plamaris longus
flexor carpi ulnaris
flexor retinaculum
extensor carpi radialis longus + brevis
extensor carpi ulnaris

69
Q

muscles moving digits

A

flexor digitorum superficialis
flexor pollicis longus
flexor digitorum profundus
extensor digitorum + extensor digiti minimi
extensors + abductor for thumb

3 palmar interossei
4 lumbricals
4 dorsal interossei

thenar muscles:
adductor pollicis
flexor pollicis brevis
opponens pollicis
abductor pollicis brevis

70
Q

Carpal Tunnel Syndrome

A

carpal tunnel = 9 flexor muscle tendons, surrounded by carpal bones and flexor retinaculum + median nerve

repetitive motion of flexor tendons can irritate their sheath coverings, leading to swelling and compression of median nerve in carpal tunnel

71
Q

power vs precision grip

A

power grip = active contraction of digital flexor muscles in forearm ex. flexor digitorum profundus
more force

precision grip = active contraction of some short muscles found in hand ex. thenar muscles
less force

72
Q

lower limb musculature

A

innervated by branches of lumbosacral plexus (levels L2-S3)

major muscle groups: hip (pelvic girdle), thigh, leg, foot

joints are designed for stability (various degrees of mobility)
locomotion, posture, balance
- moving thigh, leg, foot + toes

73
Q

muscles moving thigh at hip joint

A

gluteus maximus
lesser gluteals: (stabilization of pelvis)
- gluteus medius
- gluteus minimus

iliopsoas
adductor muscle group

74
Q

muscles moving leg at knee joint

A

quadriceps femoris:
- 3 vasti
- rectus femoris

sartorius
hamstring:
- semitendinosus
- semimebranosus
- biceps femoris (long + short heads)

75
Q

muscles moving foot at ankle joint

A

gatrocnemius
soleus
calcaneal tendon (Achilles)
2 peroneus (fibularis) muscles
tibialis anterior

76
Q

muscles moving toes

A

extensor digitorum longus
extensor hallucis longus
flexor digitorum longus
flexor hallucis longus
flexor digitorum brevis

77
Q
A

Anatomy (14 decks)

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