Region 1: Anterior Triangle of the Neck and Submandibular Region

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Region 1: Anterior Triangle of the Neck and Submandibular Region

Infrahyoid Muscles (strap muscles): sternohyoid, sternothyroid, thyrohyoid, omohyoid



posterior manubrium (sterno)


Hyoid bone, medial to omohyoid (hyoid)


Ansa cervicalis (C1, C2, C3)



Posterior manubrium below sternohyoid (sterno)


Thyroid cartilage (thyroid)


Ansa cervicalis (C1, C2, C3)



Thyroid cartilage (thyro)


Hyoid bone


Branches C1, C2 via hypoglossal nerve



Superior border of scapula (near SUPRASCAPULAR NOTCH)


Hyoid bone lateral to sternohyoid


Ansa cervicalis (C1, C2, C3)



Suprahyoid Muscles: digastric, stylohyoid, myohyoid, geniohyoid



Posterior Belly: mastoid bone


Anterior Belly: internal surface of mandible


Posterior Belly: facial nerve (CN VII)

Anterior Belly: nerve to mylohyoid (off of inferior alveolar nerve  branch of trigeminal nerve)



Styloid process (stylo)


Body of hyoid bone


Facial nerve (CN VII)



Mylohyoid line of mandible


Body of hyoid bone


Nerve to the mylohyoid (CN V)


Form the floor of the mouth



Inferior mental spine (on inner surface of symphysis menti)


Hyoid bone


Branch of C1 via hypoglossal nerve

Anterior Triangle

--Boundaries: base  lower margin of mandible

anterior  midline of neck

posterior  SCM muscle

--Subdivisions: 4 smaller triangles

*Digastric/submandibular triangle

a. Boundaries: two bellies of digastric (anterior and posterior)

lower border mandible

*Carotid triangle

a. Boundaries: posterior belly of digastric

superior belly of omohyoid

anterior margin of SCM muscle

*Muscular triangle

*Submental triangle

Submandibular Triangle

--Floor: mylohyoid and hyoglossus muscles


a. submandibular gland: major salivary gland

*lays below and in front of angle of the mandible

*Divided into large superficial part and smaller deep part

--superficial part: lays on inferior surface of mylohyoid muscle

--deep part: lays b/w mylohyoid and hyoglossus mm.

*submandibular duct (Wharton’s duct): opens under the tongue through an opening of a small papilla (SUBLINGUAL CARUNCLE)

b. submandibular lymph nodes

c. facial artery: branch of external carotid artery

*arises in carotid triangle  winds under border of mandible at ANTERIOR edge of masseter muscle  enters face

*terminal branch: submental artery

d. facial vein

*accompanies and runs posterior to facial artery

*To: internal jugular vein

e. mylohyoid nerve: sending branches to mylohyoid and anterior belly of digastric

f. intermediate tendon of the digastric muscle

g. hypoglossal nerve (CN XII): passes b/w mylohyoid and hyoglossus mm.

h. lingual nerve (from CN V): passes b/w mylohyoid and hyoglossus mm.

i. lingual artery (from external carotid artery): passes deep to hyoglossus m.

Blood Supply: Arterial

--Common Carotid Artery

*In carotid sheath with internal jugular vein and vagus nerve (CN X)

*at level of upper border of thyroid cartilage divides into internal and external carotid arteries

--at bifurcation: carotid body (chemoreceptors for O2 levels in blood)

carotid sinus (sense blood pressure)

--Internal Carotid Artery: no branches in the neck

--External Carotid Artery: branches in the neck

*superior thyroid artery: 4 branches

--superior laryngeal artery (accompanies internal branch of superior laryngeal nerve through thyrohyoid membrane)

*ascending pharyngeal artery: 1st artery to come off posterior surface of external carotid artery

* lingual artery: passes deep to hyoglossus muscle to supply tongue

*facial artery: passes to/throught submandibular gland to supply face

*occipital artery: comes off oppositie of facial artery, grooves medial surface of the mastoid process

--terminates in posterior scalp lateral to greater occipital nerve (C2)

*Posterior auricular artery

Blood Supply: Venous

--Venous Drainage of Superficial Structures of Head and Neck

*posterior auricular vein

*retromandibular vein

*facial vein

*external jugular vein

--From: posterior auricular vein and retromandibular vein

--Venous Drainage of Deep Structures of the Neck

*internal jugular vein

--Lies in carotid sheath with carotid artery and vagus nerve

--Descends from jugular foramen  moves from posterior to lateral in relation to carotid artery

Lymphatic Drainage of Head and Neck

--Facial nodes

--At junction of Head and Neck: submental, submandibular, occipital nodes

Nervous Supply

--Cranial Nerves in Anterior Triangle of Neck

*Trigeminal Nerve (CN V)

a. n. to mylohyoid: supplies mylohyoid and anterior belly of digastric

*Facial Nerve (CN VII)

a. cervical branch: supplies platysma

b. main trunk: supplies stylohyoid and posterior belly of digastric

*Glossopharyngeal Nerve (CN IX)

a. Supplies carotid sinus

*Vagus Nerve (CN X): passes inside carotid sheath  Lat to Med VNA

a. superior laryngeal nerve

--external branch: supplies cricothyroid m.

--internal branch: passes through thyrohyoid membrane and is sensory to laryngeal mucosa above true vocal folds

b. pharyngeal branch: forms pharyngeal plexus that contains motor fibers to pharyngeal muscles (except tensor veli palatine  CN V) and sensory to pharyngeal mucous membrane

c. recurrent (inferior) laryngeal branch: supplies vocal muscles and mucous membrane below true vocal folds

*Accessory Nerve (CN XI)

a. spinal part: enters deep surface of SCM to supply trapezius m.

*Hypoglossal Nerve (CN XII): carries brances from C1, C2 to ansa cervicalis in cervical plexus

--Ansa Cervicalis

*Innervates: infrahyoid muscles (strap muscles)

*forms a loop on anterior surface of internal jugular vein by connecting branches of hypoglossal and cervical nerves

~descendens hypoglossi/superior root: fibers from C1, C2 run with hypoglossal nerve

~descendens cervicalis/inferior root: fibers from C2, C3

--Cervical Portion of Sympathetic System

*superior cervical ganglion: branches to internal and external carotid aa.

*Middle cervical ganglions

*Inferior cervical ganglion: may fuse with 1st thoracic ganglion to form stellate ganglion

Thyroid Gland

--Shaped like the later H, endocrine gland

*2 lateral lobes: extending form oblique line of thyroid cartilage down to level of 5th or 6th tracheal ring

*Isthmus: connects lower thirds of lateral lobes, covers the 2nd and 3rd tracheal rings

--Blood Supply

*superior thyroid artery

*inferior thyroid artery

--Parathyroid Glands

*two superior and inferior on dorsal side of thyroid gland

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