Head, Neck, and Thorax Muscles

temporalis

N: V3 nerve

A: elevates mandible, closing jaws; posterior, more horizontal fibers are primary retractors of mandible

masseter

N: V3 nerve

A: elevates mandible, closing jaws; superficial fibers make limited contribution to protrusion of mandible

lateral pterygoid

N: V3 nerve

A: bilateral: protracts and depresses mandible; unilateral: swings jaw towards contralateral side

medial pterygoid

N: V3 nerve

A: acts with masseter to elevate mandible; contributes to protrusion; alternate unilateral activity produces smaller grinding movements

sternocleidomastoid

SA: lateral surface of mastoid process of temporal bone and lateral 1/2 of superior nuchal line

IA: clavicular head attaches to superior surface of medial 1/3 of clavicle, sternal head attaches to anterior surface of manubrium of sternum

N: spinal accessory nerve (CN XI)

A: unilateral: laterally flexes and contralaterally rotates the neck; bilateral: extends the neck at the atlanto-occipital joints, flexes neck so chin approaches manubrium, protrudes head when cervical vertebrae are fixed, elevates manubrium and medial ends of clavicles to assist with deep respiration

anterior scalene

SA: transverse processes of C3-C6 vertebrae

IA: 1st rib

N: cervical spinal nerves C4-C6

A: flex head

middle scalene

SA: posterior tubercles of transverse processes of C5-C7 vertebrae

IA: superior surface of 1st rib; posterior to groove for subclavian artery

N: anterior rami of cervical spinal nerves

A: flexes neck laterally; elevates 1st rib during forced inspiration

posterior scalene

SA: posterior tubercles of transverse processes of C5-C7 vertebrae

IA: external border of 2nd rib

N: anterior rami of cervical spinal nerves C7 and C8

A: flexes neck laterally; elevates 2nd rib during forced inspiration

occipitofrontalis

A: front belly elevates eyebrows, and wrinkles skin of forehead, protracts scalp (indicating surprise or curiosity); occipital belly retracts scalp, increasing effectiveness of front belly

orbicularis oculi

A: closes eyelids, palpebral part does so gently, orbital part tightly (winking)

corrugator supercilii

A: draws eyebrows medially and inferiorly, creating vertical wrinkles above nose (demonstrating concern, worry)

nasalis

A: transverse part depresses medial end of eyebrow, wrinkles skin over dorsum of nose (conveying disdain/dislike), alar part flares nostrils

orbicularis oris

A: closes mouth when chewing and compresses/puckers lips

levator labii superioris

A: part of dilators of the mouth; elevate and/or evert upper lip; deepen nasolabial sulcus (sadness)

levator labii superioris alaeque nasi

A: flares nostrils

procerus

A: depresses medial end of eyebrow; wrinkles skin over dorsum of nose (disdain, dislike)

zygomaticus major

A: part of dilators of the mouth; elevate labial commissure, bilateral to smile (happiness), unilateral to sneer (disdain)

zygomaticus minor

A: part of dilators of the mouth; elevate and/or evert upper lip; deepen nasolabial sulcus (sadness)

buccinator

A: presses cheek against molar teeth; works with tongue to keep food between occlusal surfaces and out of oral vestibule; resists distension (when blowing)

levator anguli oris

A: part of dilators of the mouth; widens oral fissure as when grinning/grimacing

risorius

A: part of dilators of the mouth; depresses labial commissure bilaterally to frown (sadness)

depressor anguli oris

A: part of dilators of the mouth; depresses labial commissure bilaterally to frown (sadness)

depressor labii inferioris

A: part of dilators of the mouth; depresses and/or everts lower lip (pouting/sadness)

mentalis

A: elevates and protrudes lower lip; elevates skin of chin (doubt)

platysma

A: depresses mandible against resistance; tenses skin of inferior face/neck (tension/stress)

levator palpebrae superioris (LPS)

N: oculomotor nerve (CN III); deep layer is supplied by sympathetic fibers

A: elevates superior eyelid

superior oblique

N: trochlear nerve (CN IV)

A: abducts, medially rotates, and depresses medially rotated eye

inferior oblique

N: oculomotor nerve (CN III)

A: abducts, laterally rotates, and elevates laterally rotated eye

superior rectus

N: oculomotor nerve (CN III)

A: elevates, adducts, and medially rotates eye

inferior rectus

N: oculomotor nerve (CN III)

A: depresses, adducts, laterally rotates eye

medial rectus

N: oculomotor nerve (CN III)

A: adducts eye

lateral rectus

N: abducens nerve (CN VI)

A: abducts eye

genioglossus

N: hypoglossal nerve (CN XII)

A: depresses and protrudes tongue

hyoglossus

N: hypoglossal nerve (CN XII)

A: depresses and retracts tongue

styloglossus

N: hypoglossal nerve (CN XII)

A: retracts tongue

palatoglossus

N: vagus nerve (CN X)

A: elevates posterior portion of the tongue

longus capitis

N: anterior rami of C1-C3 spinal nerves

A: flex head

longus colli

N: anterior rami of C2-C6 spinal nerves

A: flexes neck with rotation (torsion) to opposite side if acting unilaterally

rectus capitis lateralis

N: branches from loop between C1 and C2 spinal nerves

A: flex head

rectus capitis anterior

N: branches from loop between C1 and C2 spinal nerves

A: flex head

digastric

N: anterior innervated by V3 nerve, posterior innervated by CN VII

A: working with infrahyoids, depresses mandible against resistance, elevates and steadies hyoid during swallowing and speaking

stylohyoid

N: facial nerve (CN VII)

A: elevates and retracts hyoid, thus elongating floor of mouth

mylohyoid

N: V3 nerve

A: elevates hyoid, floor of mouth, and tongue during swallowing and speaking

geniohyoid

N: hypoglossal n. (CN XII)

A: pulls hyoid anterosuperiorly, shortens floor of mouth, widens pharynx

omohyoid

N: ansa cervicalis (C1-C3)

A: depresses, retracts, and steadies hyoid

sternohyoid

N: ansa cervicalis (C1-C3)

A: depresses hyoid after elevating during swallowing

sternothyroid

N: ansa cervicalis (C1-C3)

A: depresses hyoid and larynx

thyrohyoid

N: hypoglossal n. (CN XII)

A: depresses hyoid and elevates larynx

external intercostal

N: intercostal nerve

A: elevates ribs during forced inspiration

internal/innermost intercostal

N: intercostal nerve

A: interosseous part: depresses ribs; interchondral part: elevates ribs; both during forced respiration

transversus thoracis

N: intercostal nerve

A: weakly depresses ribs; proprioception?