Muscles of Anterior Neck and Face

Question 0

sternothyroid

Answer 0

Origin: posterior surface of manubrium
Insertion: oblique line of thyroid cartilage
Innervation: C2 and C3 by a branch of ansa cervicalis
Action: depress hyoid and larynx

Question 1

sternohyoid

Answer 1

Origin: manubrium of sternum and medial end of clavicle
Insertion: body of hyoid
Innervation: C1-C3 by a branch of ansa cervicalis
Action: depresses hyoid after elevation during swallowing

Question 2

omohyoid

Answer 2

Origin: superior border of scapula near suprascapular notch
Insertion: inferior border of hyoid
Innervation: C1-C3 by a branch of ansa cervicalis
Action: depresses, retracts, and steadies hyoid

Question 3

thyrohyoid

Answer 3

Origin: oblique line of thyroid cartilage
Insertion: inferior border of body and greater horn of hyoid
Innervation: C1 via hypoglossal nerve
Action: depresses hyoid and elevates larynx

Question 4

digastric

Answer 4

Origin: anterior belly: digastric fossa of mandible
posterior belly: mastoid notch of temporal bone
Insertion: intermediate tendon to body and greater horn of hyoid
Innervation: anterior belly: nerve to mylohoid, a branch of inferior alveolar nerve
posterior belly: digastric branch of facial nerve (CN VII)
Action: working with infrahyoid muscles, depresses mandible against resistance; elevates and steadies hyoid during swallowing and speaking

Question 5

stylohyoid

Answer 5

Origin: styloid process of temporal bone
Insertion: body of hyoid
Innervation: stylohyoid branch of facial nerve
Action: elevates and retracts the hyoid, thus elongating floor of mouth

Question 6

mylohyoid

Answer 6

Origin: mylohyoid line of mandible
Insertion: mylohyoid raphe and body of hyoid
Innervation: nerve to mylohyoid, a branch of inferior alveolar nerve (from mandibular nerve, CN V3)
Action: elevates hyoid, floor of mouth, and tongue during swallowing and speaking

Question 7

geniohyoid

Answer 7

Origin: inferior mental spine
Insertion: body of hyoid
Innervation: C1 via hypoglossal nerve XII
Action: pulls hyoid anterosuperiorly; shortens floor of mouth; widens pharynx

Question 8

buccinator

Answer 8

Origin: mandible, alveolar processes of maxilla and mandible, pterygomandibular raphe
Insertion: angle of mouth (modiolus); orbicularis oris
Innervation: facial nerve (buccal branch)
Action: presses cheek against molar teeth; works with tongue to keep food between occlusal surfaces and out of oral vestibule; resist distension (when blowing)

Question 9

(Occipito)frontalis

Answer 9

Origin: epicranial aponeurosis
Insertion: skin and subcutaneous tissue of eyebrows and forehead
Innervation: facial nerve…temporal branch?
Action: elevates eyebrows and wrinkles skin of forehead; protracts scalp

Question 10

orbicularis oculi

Answer 10

Origin: medial orbital margin; medial palpebral ligament; lacrimal bone
Insertion: skin around margin of orbit; superior and inferior tarsi (tarsal plates)
Innervation: facial nerve
Action: closes eyelides: palpebral part does so gently; orbital part tightly (winking)

Question 11

orbicularis oris

Answer 11

Origin: medial maxilla and mandible; deep surface of peri-oral skin; angle of mouth
Insertion: mucous membrane of lips
Innervation: facial nerve
Action: tonus closes mouth; phasic contraction compresses or protudes lips (kissing) or resists distension (when blowing)

Question 12

masseter

Answer 12

Origin: quadrate muscle attaching to inferior border of medial surface of maxillary process of zygomatic bone and the zygomatic arch
Insertion: anterior and lateral surface of ramus of mandible
Innervation: anterior trunk of mandibular nerve (CN V3) via masseteric nerve
Action: elevates mandible; superficial fibers make limited contribution to protrusion of mandible

Question 13

temporalis

Answer 13

Origin: triangular muscle with broad attachment to floor of temporal fossa and deep surface of temporalis fascia
Insertion: narrow attachment to tip and medial surface of coronoid process and anterior border of ramus of mandible
Innervation: anterior trunk of mandibular nerve (CN V3) via deep temporal nerves
Action: elevates mandible, closing jaws; posterior, more horizontal fibers are retractors of mandible

Question 14

medial pteryoid

Answer 14

Origin: quadrangular two-headed muscle from (1) medial surface of lateral pterygoid plate and pyramidal process of palatine bone (2) tuberosity of maxilla
Insertion: medial surfaces of ramus of mandible, inferior to mandibular foramen
Innervation: anterior trunk of mandibular nerve (CN V3) via nerve to medial pterygoid
Action: acts synergistically with masseter to elevate mandible; contributes to protrusion; alternate unilateral activity produces smaller grinding movements

Question 15

lateral pterygoid

Answer 15

Origin: two-headed triangular muscle from (1) infratemporal surface and crest of greater wing of sphenoid (2) lateral surface of lateral pterygoid
Insertion: superior head attaches primarily to joint capsule and articular disc of TMJ; inferior head attaches primarily to pterygoid fovea on anteromedial aspect of neck of condyloid process of mandible
Innervation: anterior trunk of mandibular nerve (CN V3) via nerves to lateral pterygoid
Action: acting bilaterally, protracts mandible and depresses chin; acting unilaterally swings jaw toward contralateral side; alternate unilateral contraction produces larger lateral chewing movements