(19) Neck: Anterior Triangle 2 & Root

subclavian artery

Branches off brachiocephalic trunk (right) and aorta (left) to give rise to upper arm arteries. Passes between anterior and middle scalene, where it has 3 parts relative to the anterior scalene (medial, posterior, & lateral).

axillary artery

continuation of the subclavian artery after passing the inferior border of the first rib

medial part of the subclavian artery

first part of the subclavian artery that is medial to the anterior scalene muscle. Branches into the vertebral artery, thyrocervical trunk, & internal thoracic artery.

vertebral artery

branch of the medial part of the subclavian artery that enters the transverse foramen of C6 & passes between anterior scalene muscle and longus colli on its way to supply blood to the head

thyrocervical trunk

branch of the medial part of the subclavian artery that branches into the inferior thyroid artery, transverse cervical artery, & suprascapular artery to supply the thyroid gland & scapular muscles

inferior thyroid artery

branch of thyrocervical trunk that passes deep to the sympathetic trunk to supply the thyroid gland

transverse cervical artery

branch of the thyrocervical trunk that supplies trapezius & joins anastomoses around the scapula. Superior to suprascpular artery.

suprascapular artery

branch of the thyrocervical trunk that joins anastomoses around the scapula. Inferior to transverse cervical artery.

internal thoracic artery

branch of the medial part of the subclavian artery that supplies the anterior wall of the chest

posterior part of the subclavian artery

Second part of the subclavian artery that is posterior to the anterior scalene muscle. Branches into the costocervical trunk.

costocervical trunk

Branch of the posterior part of the subclavian artery that branches into the deep cervical artery & supreme intercostal artery to supply deep neck & upper intercostal muscles

lateral part of the subclavian artery

Third part of the subclavian artery that is lateral to the anterior scalene muscle. Branches into the dorsal scapular artery.

dorsal scapular artery

Branch of the lateral part of the subclavian artery that passes btetween superior & middle trunks of brachial plexus & supplies levator scapulae and rhomboids.

*in 30% of people it arises from the transverse cervical artery instead of the subclavian.

Carotid Bifurcation

The point of division at which the common carotid artery branches into the internal and external carotid arteries at the C4 vertebral level near the superior border of the thyroid cartilage

carotid branches in the neck

none from internal carotid, several from external carotid

visceral structures associated with Carotid Bifurcation

Carotid body & Carotid Sinus

carotid body

mass of tissue at carotid bifurcation containing chemoreceptors that monitor oxygen & CO2 levels in blood & send visceral afferent signals to CNS via fibers of the Glossopharyngeal & Vagus nerves.

carotid sinus

swelling in internal carotid artery just above carotid bifurcation containing pressure receptors that monitor blood pressure & send visceral afferent signals to CNS via fibers of the Glossopharyngeal & Vagus nerves.

8 branches of external carotid artery

1. Superior thyroid

2. Ascending pharyngeal

3. Lingual

4. Facial

5. Occipital

6. Maxillary

7. Posterior Auricular

8. Superficial temporal

superior thyroid artery

branch of the external carotid artery that supplies the thyroid gland and larynx

lingual artery

branch of the external carotid artery that supplies the supplies the tongue, sublingual glands, & submandibular glands. Closely associated with facial artery (but is more inferior)

facial artery

Branch of the external carotid artery that supplies the lower region of the face, mouth, and nose, & the muscles & glands in those areas. Closely associated with lingual artery (but is more superior)

occipital artery

Branch of the external carotid artery that supplies the scalp. Closely associated with posterior auricular artery (but is more inferior)

posterior auricular artery

Branch of the external carotid artery that runs behind the ear & supplies the scalp. Closely associated with occipital artery (but is more superior)

ascending pharyngeal artery

Branch of the external carotid artery that supplies the pharynx, soft palate, and auditory tube

maxillary artery

1 of the terminal branches of the external carotid artery that supplies the deep face & meninges

superficial temporal artery

1 of the terminal branches of the external carotid artery that supplies the external ear & anterior scalp

Lymph drainage in Neck

-thoracic duct drains into junction of left subclavian and left internal jugular veins at the venous angle

-right lymphatic duct drains into junction of right subclavian and right internal jugular veins at the venous angle

-there is more drainage on the left side than the right

body of hyoid bone

main portion of hyoid bone

lesser horn of hyoid bone

the smaller, superior projection from where the greater horn and the body of the hyoid bone meet

greater horn of hyoid bone

the larger, posterior projection from the body of the hyoid bone

cartilaginous skeleton of anterior neck

Epiglottis, Thyroid cartilage, Cricoid cartilage

thyroid cartilage

The wing-shaped plate of cartilage that sits anterior to the larynx

superior horn of thyroid cartilage

part of the thyroid cartilage that attaches to the greater horn of the hyoid bone via ligament

right lamina of thyroid cartilage

right half of thyroid cartilage

left lamina of thyroid cartilage

left half of thyroid cartilage

superior thyroid notch

deep notch in middle of superior border of thyroid cartilage

laryngeal prominence

Projection of thyroid cartilage, known as Adam's apple.

inferior horn of thyroid cartilage

part of the thyroid cartilage that articulates with cricoid cartilage

cricoid cartilage

the ring-shaped structure that forms the lower portion of the larynx

thyrohyoid membrane

connects thyroid cartilage to hyoid bone. Has a hole for internal branch of superior laryngeal nerve and superior

laryngeal artery

cricothyroid ligament

connects cricoid cartilage to thyroid cartilage. has a medial part & 2 lateral parts (one on each side)

Parts of the mandible

body, ramus, mandibular foramen, mylohyoid groove, mylohyoid line, digastric fossa

body of mandible

main horizontal portion of the mandible

ramus of mandible

main vertical portion of the mandible

mandibular foramen

Hole on the deep medial surface of the ramus that allows for passage of neurovasculature

mylohyoid groove

small groove that passes anteriorly to and inferiorly from the mandibular foramen where mylohyoid nerve travels

mylohyoid line

diagonal line on deep surface of mandible that enables attachment of mylohyoid muscle

digastric fossa

part of mandible where the anterior belly of digastric muscle inserts

suprahyoid muscles

mylohyoid, digastric, stylohyoid, geniohyoid

Mylohyoid

2 muscles that run from the mylohyoid line on the mandible to a shared midline raphe attached to the hyoid bone.

-Functions to elevate hyoid & contract to make floor of mouth rigid

-Innervated by the mylohyoid nerve (a CN V3 branch)

Stylohyoid

suprahyoid muscle that runs from styloid process of temporal bone to greater horn of hyoid, superior to the posterior belly of digastric

-Functions to elevate and retract hyoid

-Innervated by the facial nerve

Digastric

Suprahyoid muscle with anterior and posterior bellies connected to the body & greater horn of hyoid bone by an intermediate tendon. Perforates the stylohyoid muscle.

-Acts to elevate hyoid & depress mandible

anterior belly of digastric muscle

part of the digastric that attaches to the digastric fossa on inner surface of mandible.

-Innervated by the mylohyoid nerve (branch of V3)

posterior belly of digastric muscle

part of the digastric that attaches to the notch near the mastoid process of the temporal bone

-Innervated by the facial nerve

Geniohyoid

Suprahyoid muscle in the floor of the oral cavity

-Functions to pull hyoid anteriorly

-Innervated by the Hypoglossal Nerve

2 parts of the cervical plexus

1. Cutaneous part to skin (GLAST)

2. Somatic motor part to skeletal muscles

Motor portion of cervical plexus

Ansa Cervicalis, Nerve to Thyrohyoid, Phrenic nerve

ansa cervicalis

C1, C2, C3 ventral rami that provide somatic motor innervation to the omohyoid, sternothyroid, & sternohyoid, the loop of which rests on the carotid sheath. Has a superior & inferior root.

superior root of ansa cervicalis

C1 ventral ramus that contributes to ansa cervicalis after first traveling with CN XII

inferior root of ansa cervicalis

C2-C3 ventral rami that contribute to ansa cervicalis

nerve to thyrohyoid

C1 ventral ramus that runs along the hypoglossal nerve & provides somatic motor innervation to the thyrohyoid

phrenic nerve

C3-C5 ventral rami provide motor innervation to the diaphragm

vagus nerve branches in the neck

pharyngeal branch, superior laryngeal nerve, recurrent laryngeal nerve

Nodose ganglion/Inferior vasal ganglion

Sensory ganglion of the vagus nerve inferior to skull base that contains visceral sensory cell bodies

pharyngeal branch of vagus nerve

Branch of vagus nerve that supplies muscles of pharynx and soft palate

superior laryngeal nerve

Branch of the vagus nerve that branches into internal and external laryngeal nerves.

internal laryngeal nerve

somatic sensory & parasympathetic branch of superior laryngeal nerve that passes through a hole in the thyrohyoid membrane & innervates the larynx

external laryngeal nerve

somatic motor branch of superior laryngeal nerve that runs along the cricothyroid muscle & innervates cricothyroid muscle of larynx & inferior constrictor muscle

recurrent laryngeal nerve

Branch of the vagus nerve that ultimately runs in tracheoesophageal grooves near the posterior part of the thyroid & innervates the larynx.

-right initially passes under subclavian artery

-left initially passes under arch of aorta posterior to ligamentum arteriosum

thyroid gland

Endocrine gland located in the visceral column of the neck (C5-T1) that secretes hormones directly into the blood (no duct) to regulate metabolism & calcium balance. Touches carotid sheath laterally. Composed of a right & left lobe connected by an isthmus.

parathyroid glands

Four small endocrine glands on the posterior of the thyroid gland that function in calcium metabolism

2 Sources of Thyroid Blood Supply

1. Superior thyroid artery (from the external carotid artery)

2. Inferior thyroid artery (from the thyrocervical trunk)

thyroid ima artery

a 3rd source of blood supply to the thyroid gland that is only present in some people. Comes off of the brachiocephalic trunk on the right side & runs up the front of the trachea.

3 veins that drain the thyroid

1. Superior thyroid vein

2. Middle Thyroid vein

3. Inferior thyroid vein

superior thyroid vein

drains upper part of thyroid into internal jugular vein

middle thyroid vein

drains middle part of thyroid into internal jugular vein

inferior thyroid vein

drains bottom part of thyroid into brachiocephalic vein (usually)

Subtriangles of Anterior Triangle

1. Muscular

2. Carotid

3. Submandibular

4. Submental

carotid triangle

Subdivision of the anterior triangle bordered by the posterior belly of the digastric superiorly, SCM laterally, and superior belly of the omohyoid inferiorly.

-Contains CCA, ICA, ECA (6 lower branches), IJV, CN X, CN ZII & ansa cervicalis

place to take a carotid pulse

carotid triangle, where there is access to the common carotid artery (medial to internal jugular vein)

location of hypoglossal nerve in anterior triangle

superior to tip of greater horn of hyoid, deep to posterior belly of gastric & mylohyoid

submandibular triangle

Subdivision of the anterior triangle bordered by the anterior belly of the digastric medially, posterior belly of the digastric laterally, & mandible inferiorly

-Contains submandibular gland, facial artery and vein, stylohyoid m., CN XII, lymph nodes

Roof of submandibular triangle

investing layer of deep cervical fascia

Floor of submandibular triangle

mylohyoid & hyoglossus muscles

submandibular gland

a salivary gland inside the lower jaw, part of which lies deep to the mylohyoid where the facial artery & vein run across it

submental triangle

unpaired subdivision of the anterior triangle that contains submental lymph nodes

Roof of submental triangle

investing layer of deep cervical fascia

floor of submental triangle

mylohyoid muscle; supports floor of oral cavity

root of neck

Junction between neck and superior thoracic aperture.

-External boundaries are the manubrium, clavicle, and T1 vertebra (approximately).

-Contains the interscalene triangle & the structures that pass anteriorly across the anterior scalene muscle.

interscalene triangle

Space between anterior and middle scalene muscles that contains the Brachial plexus & Subclavian artery (which runs posterior to anterior scalene muscle)

structures that pass anteriorly across anterior scalene

1. Subclavian vein (runs across the anterior part of the anterior scalene muscle)

2. Transverse cervical artery (runs superiorly on the anterior of the anterior scalene muscle)

3. Suprascapular artery (runs inferiorly on the anterior part of the anterior scalene muscle)

4. Phrenic nerve - runs inferiorly on the anterior part of the anterior scalene muscle)

Sympathetic trunk location in neck

extends to skull base, with cervical ganglia along it.

-Inferior thyroid artery passes posterior to it

vertebral vein

drains the posterior part of the head into the brachiocephalic vein (at the junction of the subclavian & internal jugular veins) in the root of the neck