Muscle system pt 2 Flashcards
Facial expression muscles
MM of facial expression
- zygomaticus: smile
- risorius: grin
- orbicular oculi: closes eyelid
- orbicularis oris: puckers lips
- platysma: pulls corners of mouth down
MM for chewing
- temporalis
- masseter
- buccinator
Muscles of tongue movement
3 muscles anchor + move tongue
- geniglossus
- hyoglossus
- styloglossus
muscles of neck and vertebral
- sternocleidomastoid: major head flexor and rotator
- sternocleidomastoid and scalenes: lateral head movements
- splenius capitis and cervicis portions: head extension, rotation, and lateral bending
- semispinalis capitis: synergist w/ sternocleidomastoid
Muscles of the vertebral column: trunk extension
deep intrinsic back muscles
1. erector spinae (sacrospinalis) group: prime movers of back extension and lateral bending
- lliocostalis (most lateral)
- longissimus
- spinalis (most medial)
2. semispinalis and quadratus lumborum: synergists in extension and rotation
Deep muscles of thorax: breathing
- muscle of respiration
- external intercostals: more superficial muscles; elevate ribs for inspiration (breathe in)
- internal intercostals: deeper muscles; aid forced expiration (breathe out)
diaphragm:
- partition between thoracic and abdominal cavities
- most important muscle in inspiration
- innervated by phrenic nerves
- upper cervical innervation (C3, C4, C5 keep the diaphragm alive)
Abdominal wall muscles
- rectus abdominis
- external obliques (most superficial)
- internal obliques
- transversus abdominis (deepest)
- valsalva maneuver: increased intra abdominal pressure used during coughing, vomiting, sneezing, defecation, and childbirth
Pelvic floor muscles
pelvic floor (pelvic diaphragm) composed of 2 paired muscles
- levator ani
- coccygeus
- floor of core muscles/supports pelvic organs
urogenital diaphragm
- contains external urethral sphincter (voluntary control of urination)
Superficial muscles of thorax
most extrinsic shoulder muscles
- act in combination to fix shoulder girdle (mostly scapula); move it to increase range of arm movements
- scapula actions: elevation, depression, rotation, protraction, and retraction
2 groups of muscles: anterior and posterior
- muscles of anterior thorax
- pectoralis minor: protraction + downward rotation of scapula
- serratus anterior (saw tooth): protraction
- boxing muscle
- subclavius: stabilizes pectoral girdle
Superficial muscles of the posterior thorax
posterior extrinsic shoulder muscles
1. trapezius:
- upper: elevation of scap (shrug)
- middle: retraction of scap
- lower: depression of scap
2. levator scapulae
3. rhomboids (major and minor): retraction + downward rotation
Muscles crossing shoulder joint
3 prime movers of arm
1. pectoralis major: adduction + flexion
2. latissimus dorsi: adduction + extension
3. deltoid:
- anterior fibers - flexion
- middle fibers - abduction
- posterior fibers - extension
Rotator cuff muscles act as synergists and fixators; originate on scapula; reinforce shoulder capsule; prevent dislocation
- supraspinatus: assist deltoid in abd
- infraspinatus: shoulder external rot
- teres minor: shoulder external rotation
- subscapularis: shoulder internal rotation
muscles crossing elbow joint
anterior flexor muscles
- brachialis and biceps brachii (2 heads) - chief forearm flexors
- brachioradialis - synergist and stabilizer
posterior extensor muscles
- triceps brachii - (3 heads) prime mover of elbow extension
- anconeus - weak synergist
Forearm muscles
- pronator teres and pronator quadratus pronate forearm
- supinator: synergist with biceps brachii in forearm supination
anterior compartments
1. flexor
- flexor carpi radialis (wrist flexion)
- palmaris longus
- flexor carpi ulnaris (wrist flexion)
- flexor digitorum superficialis and flexor digitorum profundus (finger flexion)
- flexor pollicis longus (thumb flexion)
posterior compartments
2. Extensors
- extensor carpi radialis longus and brevis (wrist extension)
- extensor digitorum (finger extension)
- extensor carpi ulnaris (wrist)
- extensor pollicis brevis and longus (thumb extension)
- extensor indicis (index finger)
- abductor pollicis longus (thumb abduction)
