ALH 3205: Anatomy of the Head and Neck
Professor Cohen
8/19/09
NECK CONTINUED
Triangles of the neck
 Each side of the neck is divided into anterior and posterior triangle based of
location of the SCM
 Posterior triangle (2):
o Anterior border (front) is formed by the posterior border (back) of
the SCM.
o The posterior border (back) is formed by the anterior border (front)
of the trapezius.
o The inferior border is formed by the middle ⅓ of the clavicle.
o The apex is where the SCM and the trapezius meet.
o The roof is formed by the deep cervical fascia and
o The floor is covered by fascia.
o Fascia covers 4 muscles:
o Spenius capitus
o Lavata scapula
o Middle and posterior scalenes
o The posterior triangle is further divided into by the inferior belly of
the omohyoid muscle:
o Supraclavicular triangle contains:
o Subclavian artery
o Suprascapular artery
o Supraclavicular artery
o Occipital triangle contains:
o Cranial X1 (spinal accessory)
o Posterior branches of the cervical plexus
o Including phrenic nerve (motor nerve of the diaphragm)
o Trucks of the brachial plexus
o Part of the EJV (external jugular vein)
o Lymph nodes
 Anterior triangle (2): * remember borders*
 The median line of the neck forms anterior border.
 The anterior border of the SCM forms the posterior border.
 The superior boundary is formed by the inferior border of the
mandible.
 The apex is the jugular notch on the manubrium.
 The roof is the subcutaneous tissue containing the platysma.
 Further divisions:
o Singular submental triangle
 Bw the two submandibulars
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Bordered anteriorly by the mandibular symphysis and
posteriorly by the hyoid bone
 Laterally bordered by the anterior bellies of the
digastric muscle
 Contents: a bunch of small lymph nodes
o R/L submandibular
 Glandular area bw the inferior border of the mandible
and the posterior border of the digastric muscle
 Primarily filled by the submandibular salivary gland
 In addition, you will find cranial nerve XII [hypoglossal]
 Also finds parts of the facial artery and facial vein
o R/L carotid
 Vascular area
 Bounded by the omohyoid muscle, the posterior belly of
the digastric muscle and the anterior border of the SCM
 The common carotid artery ascends to this triangle
 At the superior border of the thyroid cartilage [adams
apple] [cartilage of larynx at about C4] the CCA
bifurcates into the ECA and ICA [external and internal
carotid artery]
o At the point of bifurcation, the carotid sinus is
located
 Baroreceptor [pressure receptor] that
responds to changes in arterial blood
pressure
o Also at point of bifurcation is the carotid body
which is a peripheral chemo receptor associated
with the respiratory system
 Sensitive to PCO2, pH, and PO2 [last
thing that’s monitored]
o R/L muscle
 Median plane of the neck
 Bounded by the omohyoid muscle of the SCM
 Thyroid and parathyroid glands located in this region
 As a general statement, the major arteries in the anterior triangle
include the CCA, ECA, and ICA [ascend in the carotid sheath] ECA
leaves the sheath and ICA remains in
 Major vein is the internal jugular vein
 Major nerves include:
o the transverse cervical nerves which are from C2 and C3 and
are associated with the skin of the neck
o Cranial nerve XII and branches of cranial nerve IX and X
o Deep structures of the neck include the brachial plexus, the IJV, the
SCV (subclavian vein)
Root of the neck is at the superior thoracic aperture
Lymphatics:
 The superficial tissues of the neck are drained by the superficial lymph nodes
which run along the EJV
 In addition, they are drained by deep lymph nodes along the IJV
 They drain their lymph into the right lymphatic duct and the thoracic duct
{left} which are located bilaterally at the intersection of the subclavian vein
and the IJV
 Pump-less system and flows only one way [back toward the heart]
 Difference bw lymph and interstitial fluid is location
o That the interstitial fluid is formed when it leaves the capillary
network and is in the interstitial spaces
 When it moves into the lymph vessels it is called lymph
o By definition blood pressure is the force against the wall of the vessel
[greater in arteries than veins] so materials are pushed out of the
blood vessels making up the interstitial fluid
o The osmotic pressure is the same in arteries and veins
o 75% of lymph from the entire body returns to the vascular system by
the thoracic duct which enters the vascular system at the point where
the L subclavian vein and the L IJV meet
 All lymph from areas below the diaphragm as well as lymph
from the L half of the thoracic cavity, head neck and arm
returns via the thoracic duct
o Only 25 % enters from R lymphatic vein at the R subclavian and R IJV
 Above diaphragm, right half of the body [thorax, neck, head
and upper limb on right side] returns via the right lymphatic
duct
Viscera of the neck
 Thyroid gland-C4 superior edge/C5 to T1
o Two lobes [R/L] connected by the isthmus
o Hormones are deposited directly into the vascular system [endocrine]
o Endocrine glands usually have a very right blood supply
o Arteries associated with thyroid:
 Superior thyroid artery from external carotid artery [2]
 Inferior thyroids artery from the subclavian artery [2]
o Parathyroid embedded in sides of the thyroid glands
 Two superior and two inferior
 Supplied by inferior thyroid arteries
 Respiratory layer of the neck
o Include trachea, larynx, and pharynx
o Main function of these viscera is to provide a route for food and air
into the esophagus and respirator tract respectively
o Phonation [sound] is also a function of the larynx
o Larynx:
 Anterior neck C3 to C6 is the phonating mechanism
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It bridges the inferior part of the pharynx with the trachea
Protects the airway during swallowing
Composed of 9 pieces of cartilage: [plate 77]
Cartilage in this layer is C shaped to make room for esophagus
3 of the 9 are singular and the other are paired
 Thyroid- largest [Adams apple]
 Top of the thyroid is the thyroid notch where the two
haves come together
 Cricoid- only cartilage that goes all the way around
 Most inferior layer of the larynx
 Used as a landmark when tracheotomy [below will save
life and will not hurt the voice box]
 Epiglottic
 Arytenoid [2]
 Cuneiform [2]
 Corniculate [2]
Muscles of the larynx:
 Extrinsic- move the larynx superiorly and inferiorly
[suprahyoid and infrahyoid]
 Intrinsic- move the laryngeal parts within the larynx
which changes the length and tension of the vocal
chords producing different pitches
 Rima- glottidus refers to the space bw the vocal chords
which is altered by the intrinsic laryngeal muscles
 All but one of the laryngeal muscles are supplied by the
recurrent laryngeal nerves which is a branch of the
vagus nerve
Vessels:
 There are superior and inferior laryngeal arteries which
come off the superior and inferior thyroid arteries
 Veins that drain the larynx are the superior and inferior
laryngeal veins
 Lymph drainage of the larynx is into the superior and
inferior deep cervical lymph nodes
Trachea
o Runs from the inferior end of the larynx to about C5 or C6
o Ends at the sternal angle [angle of Lewis]
o Lateral to the trachea are the CCAs,
Pharynx
o Divided into 3 parts: naso, oro [contain palatine tonsils], and laryngo
o Nerves to the pharynx are parts of cranial nerve IX and X
Esophagus
o Starts in the neck and runs into the diaphragm
o Left side- behind the SCA and behind the thoracic duct
o Right side- the esophagus is in contact with the cervical pleura