ANAT 2020: Clinical Anatomy 4 - Muscles of the Head & Neck OP

platysma origin

inferior border of mandible, skin, and subcutaneous tissue of lower face

platysma insertion

fascia covering superior parts of pectoralis major and deltoid muscles

platysma action

draws corners of mouth inferiorly and widens it in expressions of sadness and fright; draws skin of neck superiorly when teeth and clenched

sternocleidomastoid origin

lateral surface of mastoid process of temporal bone and lateral half of superior nuchal line

sternocleidomastoid insertion

sternal head: anterior surface of manubrium of sternum

clavicular head: superior surface of medial third of clavicle

sternocleidomastoid actions

unilateral: ipsilateral lateral flexion & contralateral rotation of c-spine

bilateral: extends neck at AO joints; flexes neck to bring chin to manubrium; thrusts chin forward while keeping head level

longus colli origin

anterior tubercle of C1 (atlas); bodies of C1-C3; TVPs of C3-C6

longus colli insertion

bodies of C5-T3; TVPs of C3-C5

longus colli actions

unilateral: flexion & contralateral rotation (torsion) of c-spine

bilateral: cervical flexion

longus capitis origin

basilar part of occipital bone

longus capitis insertion

anterior tubercles of TVPs of C3-C6

longus capitis action

capital flexion

anterior scalene origin

TVPs of C3-C6

anterior scalene insertion

1st rib

anterior scalene actions

unilateral: ipsilateral side bend, contralateral rotation, and flexion of the neck

bilateral: flexes head

accessory: muscle of respiration

middle scalene origin

posterior tubercles of TVPs of C2-C7

middle scalene insertion

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

middle scalene actions

unilateral: ipsilateral flexion of neck

accessory: elevates 1st rib during forced inspiration

upper trapezius origin

medial third of superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7 / T1

upper trapezius insertion

lateral third of clavicle, spine of scapula, and acromion

upper trapezius actions

(with other fibers) elevate, retract, and rotate scapulae superiorly

ipsilateral sidebend, contralateral rotation, and extension of the neck

levator scapula origin

posterior tubercles of TVPs of C1-C4

levator scapula insertion

medial border of scapula superior to root of scapular spien

levator scapula actions

unilateral: ipsilateral lateral flexion, rotation, and extension of c-spine

elevates scapula and rotates its glenoid cavity inferiorly by rotating scapula

posterior scalene origin

posterior tubercles of TVPs of C4-C6

posterior scalene insertion

external border of 2nd rib

posterior scalene actions

unilateral: ipsilateral lateral flexion, rotation, and extension of neck

accessory: elevates 2nd rib during forced inspiration

splenius capitis origin

SPs of C3-T3

splenius capitis insertion

fibers run superolaterally to mastoid process of temporal bone and lateral third of superior nuchal line of occipital bone

splenius capitis actions

unilateral: ipsilateral lateral flexion and rotation of c-spine

bilateral: extension

splenius cervicis

SPs of T3-T6

splenius cervicis insertion

tubercles of TVPs of C1-C3 / C4

splenius cervicis actions

unilateral: ipsilateral lateral flexion & rotation of C-spine, primarily at capital region

bilateral: extends head & neck

rectus capitis posterior major origin

SPs of C2

rectus capitis posterior major insertion

lateral part of inferior nuchal line of occipital bone

rectus capitis posterior major actions

capital extension

rectus capitis posterior minor origin

posterior tubercle of posterior arch of C1

rectus capitis posterior minor insertion

medial part of inferior nuchal line of occipital bone

rectus capitis posterior minor actions

capital extension

obliquus capitis superior origin

TVPs of C1

obliquus capitis superior insertion

occipital bone between superior and inferior nuchal lines

obliquus capitis superior actions

capital extension & ipsilateral lateral flexion

obliquus capitis inferior origin

SPs of C2

obliquus capitis inferior insertion

TVPs of C1

obliquus capitis inferior actions

ipsilateral capital rotation & capital extension

digastric origin

anterior belly: digastric fossa of mandible

posterior belly: mastoid notch of temporal bone

digastric insertion

intermediate tendon to body and greater horn of hyoid

digastric actions

working with infrahyoid muscles, depresses mandible against resistance; elevates and steadies hyoid during swallowing and speaking

stylohyoid origin

styloid process of temporal bone

stylohyoid insertion

body of hyoid

stylohyoid actions

elevates & retracts hyoid, elongating the floor of the mouth

mylohyoid origin

mylohyoid line of mandible

mylohyoid insertion

mylohyoid raphe and body of hyoid

mylohyoid actions

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

geniohyoid origin

inferior mental spine of mandible

geniohyoid insertion

body of hyoid

geniohyoid actions

pulls hyoid anterosuperior; shortens floor of mouth; widens pharynx

omohyoid origin

superior border of scapula near suprascapular notch

omohyoid insertion

inferior border of hyoid

omoyhyoid actions

depresses, retracts, and steadies hyoid

sternohyoid origin

manubrium of sternum and medial end of clavicle

sternohyoid insertion

body of hyoid

sternohyoid actions

depresses hyoid after elevation during swallowing

sternothyroid origin

posterior surface of manubrium of sternum

sternothyroid insertion

oblique line of thyroid cartilage

sternothyroid actions

depresses hyoid and larynx

thyrohyoid origin

oblique line of thyriod cartilage

thyrohyoid insertion

inferior border of body and greater horn of hyoid

thyrohyoid actions

depresses hyoid and elevates larynx

temporalis origin

triangular muscle with broad attachment to floor of temporal fossa & deep surface of temporal fascia

temporalis insertion

narrow attachment to tip and medial surface of coronoid process and anterior border of ramus of mandible

temporalis actions

elevates mandible, closing jaws; posterior horizontal fibers are 1 degree retractors of the mandible

masseter origin

quadrate muscle, attaches to inferior border and medial surface of maxillary process of zygomatic bone and zygomatic arch

masseter insertion

angle and lateral surface of ramus of mandible

masseter actions

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

lateral pterygoid origin

triangular two-headed muscle attaching from infratemporal surface and crest of greater wing of sphenoid and lateral surface of lateral pterygoid plate

lateral pterygoid insertion

superior head: joint capsule and articular disc of TMJ

inferior head: pterygoid fovea on anteromedial aspect of neck of condyloid process of mandible

lateral pterygoid actions

bilateral: protracts mandible and depresses chin

unilateral: swings jaw toward contralateral side; alternate unilateral contraction produces larger lateral chewing movements

occipitofrontalis origin

front belly: epicranial aponeurosis

occipital belly: lateral two thirds of superior nuchal line

occipitofrontalis insertion

front belly: skin and subcutaneous tissue of eyebrows and forehead

occipital belly: epicranial aponeurosis

occipitofrontalis actions

front belly: elevates eyebrows and wrinkles forehead skin and protracts scalp in expressions of surprise and curiosity

occipital belly: retracts scalp, increasing effectiveness of frontal belly

corrugator supercilii origin

medial end of superciliary arch

corrugator supercilii insertion

skin superior to middle of supraorbital margin and superciliary arch

corrugator supercilii actions

draws eyebrow medially & inferiorly, creating wrinkles above the nose in expressions of concern or worry

orbicularis oris (oral sphincter) origin

medial maxilla and mandible; deep surface of peri-oral skin; angle of mouth (modiolus)

orbicularis oris insertion

mucous membrane of lips

orbicularis oris actions

tonus closes oral fissure; phasic contraction compresses and protrudes lips to kiss and resists distension when blowing

mentalis origin

body of mandible, anterior to roots of inferior incisors

mentalis insertion

skin of chin (mentolabial sulcus)

mentalis actions

elevates and protrudes lower lip; elevates skin of chin in expressions of doubt

buccinator origin

mandible, alveolar process of maxilla and alveolar part of mandible, and pterygomandibular raphe

buccinator insertion

angle of mouth (modiolus); orbicularis oris

buccinator actions

presses cheek against molars; works with tongue to keep food between occlusal surfaces and out of oral vestibule; resists distension whenblowing; makes the cheek taut to stop it from being compressed during chewing