ANAT 5010 - unit 10

- superior: inferior border of mandible

- posterior: anterior border of SCM

- anterior: median line of neck

what makes up the borders of the anterior triangle?

- muscular triangle

- carotid triangle

- submental triangle

- submandibular triangle

what are the subdivisions of the anterior triangle?

hyoid bone

only bone that does not articulate with any other bone; suspended by muscles and ligaments at the level of CV3-4

- tasting (tongue)

- opening jaw (floor of mouth)

- swallowing (floor of mouth)

- vocalization (larynx)

what does the hyoid act as an anchor for?

infrahyoid muscles

inferior to hyoid bone; straplike; act on hyoid and larynx; names refer to attachment points

origin: upper border of scapula (medial to scapular notch)

insertion: hyoid bone

what is the origin and insertion of the omohyoid?

action: depress and retract hyoid

innervation: ansa cervicalis

what is the action and innervation of the omohyoid?

origin: manubrium of sternum, sternoclavicular joint

insertion: hyoid bone

what is the origin and insertion of the sternohyoid?

action: depress hyoid

innervation: ansa cervicalis

what is the action and innervation of the sternohyoid?

origin: posterior manubrium

insertion: thyroid cartilage

what is the origin and insertion of the sternothyroid?

action: depress larynx

innervation: ansa cervicalis

what is the action and innervation of the sternothyroid?

origin: thyroid cartilage (opposite side of the sternothyroid insertion)

insertion: hyoid

what is the origin and insertion of the thyrohyoid?

action: depress hyoid and elevate larynx

innervation: C1 VPR fibers that are bound together with the hypoglossal nerve (CN X||)

what is the action and innervation of the thyrohyoid?

borders: anterior border of SCM, superior belly of omohyoid, median line

contents: infrahyoid muscles

what are the borders and contents of the muscular triangle?

suprahyoid muscles

superior to hyoid; act on hyoid, mandible, and mouth

origin: digastric fossa of mandible (anterior belly), mastoid process of temporal bone (posterior belly)

insertion: hyoid bone (via intermediate tendon)

what is the origin and insertion of the digastric muscle?

action: elevate hyoid, depress mandible

innervation: nerve to mylohyoid (branch of CN V3)(anterior belly), facial nerve (CN V||)(posterior belly)

what is the action and innervation of the digastric muscle?

origin: styloid process of temporal bone

insertion: hyoid bone

what is the origin and insertion of the stylohyoid muscle?

action: elevate hyoid

innervation: facial nerve (CN V||)

what is the action and innervation of the stylohyoid muscle?

origin: mylohyoid line of mandible

insertion: hyoid bone, median raphe between left and right mylohyoid

what is the origin and insertion of the mylohyoid?

action: elevate hyoid, elevate floor of mouth

innervation: nerve to mylohyoid (branch of CN V3)

what is the action and innervation of the mylohyoid?

raphe

seam where two halves fused

origin: inferior genial tubercle of mandible

insertion: hyoid bone

what is the origin and insertion of the geniohyoid?

action: elevate and protract hyoid (when mandible is fixed), depress and retract mandible (when hyoid fixed)

innervation: C1 VPR fibers (that are bound together with hypoglossal n)

what is the action and innervation of the geniohyoid?

borders: anterior belly of digastric, posterior belly of digastric, inferior margin of mandible

contents: submandibular gland, facial artery and vein

what are the borders and contents of the submandibular triangle?

borders: left anterior belly of digastric, right anterior belly of digastric, hyoid bone

contents: mylohyoid and geniohyoid

what are the borders and contents of the submental triangle?

borders: posterior belly of digastric, superior belly of omohyoid, anterior border of SCM

contents: common carotid artery, internal jugular vein, vagus nerve, hypoglossal nerve, ansa cervicalis

what are the borders and contents of the carotid triangle?

parents:

- right: brachiocephalic trunk

- left: aortic arch

terminal branches:

- internal carotid: no branches in neck

- external carotid: many branches in neck

what are the parent branches and terminal branches of the common carotid artery?

superior thyroid artery

most inferior branch of external carotid artery; serves thyroid gland; travels with external laryngeal nerve

superior laryngeal artery

branch of superior thyroid artery; travels with the internal laryngeal nerve through the thyrohyoid membrane

lingual artery

branches anteriorly off external carotid artery; passes deep to hyoglossus muscle to enter mouth to supply tongue

facial artery

branches anteriorly off external carotid artery; passes deep to submandibular gland, then curls superficially over mandible to supply face

ascending pharyngeal artery

branches medially/posteriorly off external carotid artery; serves walls of pharynx

occipital artery

branches posteriorly off external carotid artery; hooks over hypoglossal nerve superficially; travels with greater occipital nerve on posterior scalp

posterior auricular artery

branches posteriorly off external carotid artery; small; travels between external auditory meatus and mastoid process

superficial temporal artery

travels with auriculotemporal nerve anterior to external auditory meatus; terminal branch of external carotid artery

maxillary artery

passes deep to mandible to enter deep face region; terminal branch of external carotid artery

external jugular vein

superficial; descends superficial to SCM; drains directly into subclavian vein; formed from union of posterior branch of retromandibular vein and posterior auricular vein

internal jugular vein

deep; descends with carotid sheath; merges with subclavian vein to form brachiocephalic vein

retromandibular vein

formed from union of superficial temporal vein and maxillary vein; deep vein; posterior to ramus of mandible; has two terminal branches (anterior branch and posterior branch)

facial vein

continuous with angular vein

common facial vein

formed from union of anterior branch of retromandibular vein and facial vein; drains into internal jugular vein

ansa cervicalis

somatic motor innervation to infrahyoid muscles; formed from C1-C3 VPRs; loop shape; superficial to internal jugular vein; has a descendens hypoglossi and a descendens cervicalis

descendens hypoglossi

superior root of ansa cervicalis; formed from C1 VPR fibers running with hypoglossal nerve; supplies superior belly of omohyoid, upper parts of sternohyoid and sternothyroid

descendens cervicalis

inferior root of ansa cervicalis; formed from C2 and C3 VPR fibers; supplies inferior belly of omohyoid, lower parts of sternohyoid and sternothyroid

trigeminal, facial, glossopharyngeal, vagus, accessory, hypoglossal

what cranial nerves are in the anterior triangle?

trigeminal nerve (CN V)

branches into V1, V2, and V3; CN V3 gives off inferior alveolar nerve branch; inferior alveolar nerve gives off nerve to mylohyoid; N. to mylohyoid innervates mylohyoid and anterior belly of digastric muscle

facial nerve (CN V||)

trunk innervates stylohyoid and posterior belly of digastric muscle

glossopharyngeal nerve (CN IX)

conveys visceral sensory innervation from carotid sinus and carotid body, which are both located at bifurcation of common carotid artery

vagus nerve (CN X)

travels within carotid sheath; gives off superior laryngeal nerve branch; gives off recurrent laryngeal nerve branch that ascends between trachea and esophagus

internal laryngeal nerve

branch of superior laryngeal nerve that travels with superior laryngeal artery

external laryngeal nerve

branch of superior laryngeal nerve that travels with superior thyroid artery

accessory nerve (CN XI)

innervates SCM and trapezius

hypoglossal nerve

crosses superficial to carotid arteries; helps deliver C1 VPR fibers to ansa cervicalis, thyrohyoid, and geniohyoid muscles; passes deep to mylohyoid to innervate tongue muscles

superior cervical ganglion

source of internal and external carotid nerves

inferior cervical ganglion

may fuse with first thoracic ganglion to form stellate ganglion

sympathetic trunk of ANS

receives preganglionic sympathetic axons that originate at T1-L2 spinal cord levels, enter trunk via white rami in thorax, ascend to cervical region

source of postganglionic sympathetic axons that exit via gray rami (VPRs) into cervical spinal nerves, supply thoracic viscera via cardiac nerves, travel to head and neck via periarterial plexuses

glands

tissues that produce and release substances that perform bodily functions

endocrine glands

secrete products into bloodstream

exocrine glands

secrete products via ducts

submandibular gland

major salivary gland; fills submandibular triangle; facial artery passes deep and through; facial vein travels superficially

thyroid gland

anterior to trachea; endocrine gland producing thyroid hormone; butterfly shaped (lateral lobes and median isthmus connecting lobes); supplied by the superior thyroid artery (branch of external carotid) and inferior thyroid artery (branch of thyrocervical trunk)

parathyroid glands

four nodules on posterior surface of thyroid gland; endocrine glands producing parathyroid hormone