Core Curriculum Syllabus: Review of Anatomy - The Neck

The neck contains important communications between the head and the body, including air and food passages, major blood vessels and nerves, and the spinal cord. Many vital structures are compressed into a narrow area which is engineered for maximal mobility to permit variation in head position relative to body.

A. Skeleton - primarily composed of the vertebral column. Anteriorly, the hyoid bone, and laryngeal and tracheal cartilages support the aerodigestive spaces. These are suspended from the mandible and base of skull by a system of muscles and ligaments.

B. Muscles - anteriorly, strap muscles connect the respiratory skeleton and sternum. There are also muscular attachments from the hyoid to the tongue, mandible, and styloid. The digastric muscle passes forward from the mastoid, attaches to the hyoid, then ascends to the anterior mandible. The sternocleidomastoid (SCM) divides the neck into anterior and posterior triangles. The posterior triangle is largely muscular. The anterior triangle which contains most of the vital structures, can be divided into smaller triangles by muscles.

The anterior and posterior bellies of the digastric form the submandibular triangle. The submental triangle is in the midline, between the anterior bellies. The vascular or carotid triangle is inferior to the digastric and hyoid.

The omohyoid is a small muscle, running at roughly 90 degrees to the SCM, from the hyoid to the scapula.

C. Nerves - the neck contains major branches of cranial nerves, as well as cervical roots.

  • Cranial Nerves
    • VII - the marginal mandibular branch dips down into the neck in the fascia overlying the submandibular gland. In addition to the muscles of facial expression, branches of VII innervate the platysma, the stylohyoid and the posterior belly of the digastric.
    • X - the vagus nerve exits the jugular foramen and travels inferiorly in the carotid sheath. It carries the parasympathetic fibers of the thoracic cavity and much of the GI tract, as well as laryngeal and pharyngeal sensory and motor branches.
    • The Spinal Accessory Nerve (XI) - supplies the trapezius and sternocleidomastoid muscles. It exits the jugular foramen, then runs posteriorly.
    • The Hypoglossal Nerve (XII) - supplies the muscles of the tongue. The nerve exits the skull through its own canal, runs downward in the carotid sheath, then curves forward superficially to the carotid at the level of the occipital artery to reach the tongue.
  • Cervical Nerves
    • Cervical plexus - anterior roots of C1-4
      • Ansa cervicalis - to strap muscles (some travel with XII)
      • Branches to phrenic nerve
      • Sensory
    • Phrenic nerve - C3-5
    • Brachial Plexus C5-T1
    • Posterior rami - to posterior muscles and skin
    • Cervical sympathetic chain - travels in carotid sheath

D. Major Vascular Structures

  • Carotid Artery - bifurcates into:
    • Internal (intracranial) - no branches in the neck
    • External (extracranial) - branches:
      • Superior thyroid
      • Ascending pharyngeal
      • Lingual
      • Facial
      • Occipital
      • Post-auricular
      • Superficial temporal
      • Internal maxillary
    • Thyrocervical trunk
      • Suprascapular
      • Transverse cervical
      • Inferior thyroid
    • Vertebral artery
    • Internal jugular vein (within carotid sheath)
    • External jugular vein

E. Visceral Column - pharynx, larynx, trachea, and esophagus.

F. Thyroid Gland

  • Developmentally derived from pharyngeal floor
  • Located anterior and lateral to the trachea
  • Closely related to recurrent laryngeal nerve and parathyroid glands
  • Blood supply
    • Arterial
      • Superior thyroid artery (branch of external carotid)
      • Inferior thyroid artery (branch of thyrocervical trunk)
      • Thyroid "ima" artery (variable)
    • Venous
      • Superior thyroid vein
      • Middle thyroid vein
      • Inferior thyroid vein

G. Parathyroid Glands

  • Four glands: two on each side
  • Derived from branchial pouches III and IV: Superior parathyroid glands from pouch IV and inferior parathyroid gland from pouch III.
  • Glands usually related to posterior surface of thyroid gland, but may be found as inferior as mediastinum

H. Anatomic triangles (superimposed on superficial neck anatomy):

Anatomic triangles of the neck

The neck can be divided into two major triangles, with multiple smaller triangles:


A. Anterior triangle - bordered by the anterior border of the SCM, midline of the neck, and the mandible

  • muscular triangle--formed by the midline, superior belly of the omohyoid, and SCM
  • carotid triangle--formed by the superior belly of the omohyoid, SCM, and posterior belly of the digastric
  • submental triangle--formed by the anterior belly of the digastric, hyoid, and midline
  • submandibular triangle--formed by the mandible, posterior belly of the digastric, and anterior belly of the digastric

B. Posterior triangle - bordered by the posterior border of the SCM, trapezius, and clavicle

  • supraclavicular triangle--formed by the inferior belly of the omohyoid, clavicle, and SCM
  • occipital triangle--formed by inferior belly of the omohyoid, trapezius, and SCM


I. Lymphatic drainage: major head and neck lymph node groups.

The lymph nodes of the neck can be divided into six levels within the defined anatomic triangles. These groups and the areas that they drain are particularly important when locating and working up a "neck mass" or possible malignancy. The groups and drainage areas are as follows:
Lymphatic drainage of the neck

  • I--Submental and submandibular nodes
  • II--Upper jugulodigastric group
  • III--Middle jugular nodes draining the naso- and oropharynx, oral cavity, hypopharynx, larynx.
  • IV--Inferior jugular nodes draining the hypopharynx, subglottic larynx, thyroid, and esophagus.
  • V-- Posterior triangle group
  • VI--Anterior compartment group


Individual Lymph Nodes in the Head and Neck:

Lymph nodes of the head and neck

 

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Bobby R. Alford Department of Otolaryngology-Head and Neck Surgery
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Last modified: Jan. 23, 2006