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56 terms

Actions of Head/Neck/Trunk/Shoulder

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epicranius frontalis
Raises eyebrows
buccinators
Draws corner of mouth laterally; compresses cheeks, holds food between teeth
mentalis
Protrudes lower lips; wrinkles chin
epicranius occipitalis
Fixes aponeurosis and pulls scalp posteriorly
depressor labii inferioris
Draws lower lip inferiorly
masseter
Prime mover of jaw closure, elevate mandible
orbicularis oculi
Verious parts can be activated individually; closes eyes, produces blinking, squinting, draws eyebrows inferiorly
levator anguli oris
Elevates corners of the mouth
temporalis
Closes jaw; elevates and retracts mandible
levator palpebrae superioris
Raises upper eyelid or voluntarily opens the eye
depressor anguli oris
Zygomaticus antagonist; draws corners of mouth downward and laterally
medial pterygoid
Synergist of temporalis and masseter; elevates mandible; in conjunction with lateral pterygoid, aids in grinding
corrugator supercilii
Draws eyebrows medially and inferiorly; wrinkles skin of forehead vertically
depressor labii inferioris
Draws lower lip inferiorly
lateral pterygoid
Protracts jaw; in conjunction with medial pterygoid, aids in grinding teeth
levator labii superioris
Raises and furrows upper lip; opens lips
orbicularis oris
Closes lips; purses and protrudes lips (kissing and whistling muscle)
zygomaticus major/minor
Raises lateral corners of mouth upward (smile)
risorius
Draws corner of lip laterally; tenses lip; zygomaticus syngergist
platysma
Tenses skin of neck; depresses mandible; pulls lower lip back and down
digastric
Acting in concert, elevate hyoid bone; open mouth and depress mandible
geniohyoid
Pulls hyoid bone superiorly and anteriorly shortening the floor of the mouth, it draws the tongue forward
mylohyoid
Elevates hyoid bone and base of tongue during swallowing
thyrohyoid
Depresses hyoid bone; elevates larynz if hyoid is fixed
scalenes
Flex and slightly rotate neck; elevate ribs 1-2 (aid in inspiration)
sternocleidomastoid
Contraction of both muscles of pair causes flexion of neck forward, generally against resistance, acting independently, rotate head toward shoulder on opposite side
stylohyoid
Elevates and retracts hyoid bone
sternohyoid
Acting with sternothyoid and omohyoid depressed larynx and hyoid bone if madible is fixed, may also flex skull
sternothyroid
Lateral and deep to sternohyoid, same action
omohyoid
Straplike with two bellies, lateral to sternohyoid with same actions
pectoralis major
Prime mover of arm flexions; adducts, medially rotates arm; with arm fixed, pulls chest upwards (forced inspiration)
rectus abdominis
Flexes and rotates vertebral column; increase abdominal pressure; fixes and depresses ribs; stabilizes pelvis during walking; used in sit-ups
infraspinatus
Lateral rotations of humerus; helps hold head of humerus in glenoid cavity; stablizes shoulder
rhomboideus minor
Retracts and stabilizes the scapula, elevates the vertebral border, and rotates the scapula to depress inferior angle
serratus anterior
Prime mover to protract and hold scapula against chest wall; rotates scapula, causing inferior angle to move laterally and upward; essential to raising arm; fixed scapula for arm abduction
external oblique
Most superficial lateral muscle, compresses abdominal wall; also aids muscle of back in trunk rotation and lateral flexions; used in oblique curls
teres minor
Small muscle inferior to infraspinatus (same actions); a rotator cuff muscle
semispinalis
Actin together, extend head and vertebral column; acting independently (right vs. left) causes rotation towards opposite side
deltoid
Acting as a whole, prime mover of arm adduction; when only specific fibers are active, can aid in flexion, extension, and rotation of humerus
internal oblique
Most superficial lateral muscles, same as external oblique
teres major
Extends, medially rotates, and adducts humerus; synergist of lattisimus dorsi
erector spinae
Extend and bend the vertebral column laterally; fibers of the longissimus also extend head
pectoralis minor
With ribs fixed, draws scapula forward and inferiorly; with scapula fixed, draws rib cage superiorly
transversus abdominis
Compresses abdominal contents
supraspinatus
Initiates abduction of humerus; stabilizes shoulder joints
splenius
As a group extend of hyperextend head; when only one side is active, head is rotated and bent towards same side
external intercostals
Pull ribs toward one another to elevate rib cage; aid in inspiration
trapezius
Extends head; raises, rotates, and retracts scapula and stabilizes it; superior fibers elevate scapular (shrugging shoulders); inferior fibers depress it
levator scapulae
Elevates and adducts scapula; with fixed scapula, laterally flexes neck to the same side
quadratus lumborum
Each flexes vertebral column laterally; together extend the lumbar spine and fix rib 12; maintains upright posture
internal intercostals
Draw ribs together to depress rib cage; aid in forced expiration
latissimus dorsi
Prime mover of arm extensions; adducts and medially rotates arm; brings arm down in power stroke, as in striking a blow
rhomboideus major
Adducts, retracts, elevates, and rotates the scapula so that the glenoid cavity faces downward and stablizes the scapula
diaphragm
Prime mover of inspiration flattens on contractions
subclavius
Depresses clavicle and draws shoulder forward and downward
subscapularis
Medially rotates and stablizes the head of the humerus in the glenoid cavity