Region 1: Anterior Triangle of the Neck and Submandibular Region
Infrahyoid Muscles (strap muscles): sternohyoid, sternothyroid, thyrohyoid, omohyoid
Sternohyoid
O posterior manubrium (sterno)
I Hyoid bone, medial to omohyoid (hyoid)
Inn. Ansa cervicalis (C1, C2, C3)
Sternothyroid
O Posterior manubrium below sternohyoid (sterno)
I Thyroid cartilage (thyroid)
Inn. Ansa cervicalis (C1, C2, C3)
Thyrohyoid
O Thyroid cartilage (thyro)
I Hyoid bone
Inn. Branches C1, C2 via hypoglossal nerve
Omohyoid
O Superior border of scapula (near SUPRASCAPULAR NOTCH)
I Hyoid bone lateral to sternohyoid
Inn. Ansa cervicalis (C1, C2, C3)
Not. Composed of INFERIOR and SUPERIOR BELLIES
Suprahyoid Muscles: digastric, stylohyoid, myohyoid, geniohyoid
Digastric
O Posterior Belly: mastoid bone
I Anterior Belly: internal surface of mandible
Posterior Belly: facial nerve (CN VII) Anterior Belly: nerve to mylohyoid (off of
Inn. inferior alveolar nerve  branch of trigeminal nerve)
Stylohyoid
O Styloid process (stylo)
I Body of hyoid bone
Inn. Facial nerve (CN VII)
Mylohyoid
O Mylohyoid line of mandible
I Body of hyoid bone
Inn. Nerve to the mylohyoid (CN V)
Not. Form the floor of the mouth
Geniohyoid
O Inferior mental spine (on inner surface of symphysis menti)
I Hyoid bone
Inn. 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
--Contents:
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