Muscles - Head and Trunk Flashcards
epicranius - occipital belly
bipartite muscle consisting of frontal and occipital parts, covers dome of skull
origin - occipital and temporal lobes
insertion - epicranial aponeurosis
with aponeurosis fixed, fixes aponeurosis and pulls scalp posteriorly
Epicranius - frontal belly
bipartite muscle consisting of frontal and occipital parts, which covers dome of skull.
origin - epicanial aponeurosis
insertion - skin of eyebrows and root of nose
action - with aponeurosis fixed, frontal belly raises eybrows
orbicularis oculi
tripartite sphincter muscle of eyelids
origin - frontal and maxillary bones and ligaments around orbit
insertion - encircles orbit and inserts in tissue of eyelid
action - various parts can be activated individually: closes eyes, produces blinking, squinting, draws eyebrows inferiorly
corrugator supercilii
small muscle; activity associated with that of orbicularis oculi
origin - arch of frontal bone above nasal bone
insertion - skin of eyebrow
action - draws eyebrows inferiorly and medially, wrinkles forehead vertically
levator labii superioris
thin muscle between orbicularis oris and inferior eye mrgin
origin - zygomatic bone and infraorbital margin of maxilla
insertion - skin and muscle of upper lip and border of nostil
action - opens lips, raises and furrows upper lip
zygomaticus major and minor **
extends diagonally from corner of mouth to cheekbone
origin - zygomatic bone
insertion - skin and muscle at corner of mouth
action - raises lateral corners of mouh upward (smiling muscle)
risorius
slender muscle, runs inferior and lateral to zygomaticus
origin - fascia of masseter muscle
insertion - skin at angle of mouth
action - draws corner of lip laterally (tenses lip, zygomaticus synergist)
depressor labii inferioris
small muscle from lower lip to mandible
origin - body of mandible lateral to its midline
insertion - skin and muscle of lower lip
action - draws lower lip inferiorly
depressor anguli oris
small muscle lateral to depressor labii inferioris
origin - body of mandible below incisors
insertion - skin and muscle at angle of mouth below insertion of zygomaticus
action - draws corners of mouth downward and laterally; zygomaticus antagonist
orbicularis oris
multilayered muscle of lips with fibers that run in many different directions; most run circularly
origin - arises indirectly from maxilla and mandible; fibers blended with fibers of other muscles associated with lips
insertion - encircles mouth; inserts into muscle and skin at angles of mouth.
action - closes lips, purses and protrudes lips (kissing/whistling muscle)
mentalis
one of muscle pair forming v-shaped mass on chin
origin - mandible below incisors
insertion - skin of chin
action - wrinkles chin, protrudes lower lip
buccinator
principle muscle of cheek; runs horizontally, deep to masseter
origin - molar region of maxilla and mandible
insertion - orbicularis oris
action - compresses cheek (whistling), draws corner of mouth laterally, holds food between teeth when chewing
masseter
covers lateral aspect of mandibular rmus; can be palpated on forcible closure of jaws
origin - zygomatic arch and maxilla
insertion - angle and ramus of mandible
action - prime mover of jaw closure, elevates mandible
temporalis **
fan-shaped muscle lying over parts of frontal, parietal, and temporal bones
origin - temporal fossa
insertion - coronoid process of mandible
action - closes jaw, elevates and retracts mandible
platysma
unpaired muscle: thin, sheetlike superficial neck muscle, plays role in facial expression
origin - fascia of chest (over pectoral muscles) and deltoid
insertion - lower margin of mandible, skin, and muscle at corner of mouth
action - tenses skin of neck (depresses mandible, pulls lower lip back and down)
sternocleidomastoid **
two-headed muscle located deep to platysma on anterolateral surface of neck; fleshy parts on either side indicate limits of anterior and posterior triangles of neck
origin - manubrium of sternum and medial portion of clavicle
insertion - mastoid process of temporal bone and superior nuchal line of occipital bone
action - simultaneous contraction of pair causes flexion of neck forward (vs resistance); independently, rotate head twd opposite shoulder
digastric
consists of two bellies united by an intermediate tendon; assumes V shape under chin
origin - lower margin of mandible (anterior belly) and mastoid process (posterior belly)
insertion - by a connective tissue loop to hyoid bone
action - acting in concert, open mouth and depress manible. elevates hyoid bone
sternohyoid
runs most medially along neck; straplike
origin - manubrium and medial end of clavicle
insertion - lower margin of body of hyoid bone
action - depresses larynx and hyoid bone (mandible fixed). may also flex skull
mylohyoid **
just deep to digastric, forms floor of mouth
origin - medial surface of mandible
insertion - hyoid bone and median raphe
action - elevates hyoid bone and base of tongue during swallowing
pectoralis major
large fan-shaped muscle covering upper portion of chest
origin - clavicle, sternum, cartilages of ribs 1-6, aponeurosis of external oblique muscle
insertion - fibers converge to insert by short tendon into intertubercular sulcus of humerus
action - prime mover of arm flexion, adducts, medially rotates arm, with arm fixed, pulls chest upward (forced inspiration)
serratus anterior
fan-shaped muscle deep to scapula; beneath and inferior to pectoral muscles on lateral rib cage
origin - lateral aspect of ribs 1-8
insertion - vertebral border of anterior surface of scapula
action - prime mover to protract and hold scapula against chest wall; rotates scapula, causing inferior angle to move laterally and upward; essential to raising arm; fixes scapula for arm abduction
deltoid **
fleshy triangular muscle forming shoulder muscle mass
origin - lateral 1/3 of clavicle; acromion and spine of scapula
insertion - deltoid tuberosity of humerus
action - acting as a whole, prime mover of arm abduction; specific fibers aid in flexion, extension, rotation of humerus
pectoralis minor **
flat, thin muscle directly beneath and obscured by pec. major
origin - anterior surface of ribs 3-5, near costal cartilage
insertion - coracoid process of scapula
action - with ribs flexed, draws scapula forward and inferiorly; with scapula fixed, draws ribcage superiorly
external intercostals
11 pairs lie between ribs; fibers run obliquely downward and forward toward sternum
origin - inferior border of rib above it
insertion - superior border of rib below it
action - pulls ribs toward another to elevate rib cage, aid in inspiration (antagonistic to internal intercostals)
