BONY SKELETON OF THE NECK

Like other regions of the body, the neck has a central bony skeletal core upon which other structures attach or are related. The bones of the neck consist of the base of the skull and the 7 cervical vertebrae.

If we take a look at the base of the skull, the major parts that are related to the upper neck are the:

  1. Foramen magnum
  2. Occipital condyle (articulates with the superior process of the atlas.
  3. External occipital protuberance
  4. Mastoid process

Below the base of the skull, you will find the vertebral column. The top vertebrae (7 cervical) provide support for the neck structures. You will also note that these vertebrae allow passage of an important arterial supply to the brain and brain stem, the vertebral artery. vertebral column
The first cervical vertebra is the atlas and is considered an atypical cervical vertebra because it has no body or spinous process. It articulates with the occipital condyles of the skull above it and with the superior articular processes of the axis below it. It also articulates with the dens of the axis below. If viewed from above, you can identify the following parts of the atlas:

  1. Anterior arch
  2. Anterior tubercle
  3. Superior articular process (articulate with the occipital condyle of the skull)
  4. Foramen transversarium
  5. Transverse process
  6. Posterior arch
  7. Posterior tubercle
  8. Vertebral canal (continuous with the foramen magnum at the base of the skull). The brain stem continues inferiorly as the spinal cord at the margin of the foramen magnum.
The axis is the second cervical vertebra. This vertebral is also called an atypical vertebra because it has an upward projection called the dens that articulates with the inner aspect of the anterior arch of the atlas just posterior to the anterior tubercle. Some of the identifiable parts are the:
  1. dens
  2. body
  3. superior articular process
  4. transverse process with its vertebral foramen
  5. pedicle
  6. lamina
  7. bifid spine
The 3rd, 4th, 5th, and 6th cervical vertebrae are known as the typical cervical vertebrae because they all have the same characteristics and except for the foramen for the vertebral artery similar to other typical vertebrae of the spinal cord. These characteristics are:
  1. body
  2. pedicle
  3. foramen for vertebral artery
  4. superior articular process
  5. lamina
  6. spinous process (bifid in case of cervical vertebrae)
  7. vertebral canal
  8. transverse process (consists of a groove that carries a cervical spinal nerve and, of course the foramen for the vertebral artery)
The 7th cervical vertebra starts to pick up characteristics of the upper thoracic vertebrae and may even produce a cervical rib, which can cause pathological problems related to the brachial plexus.

It has the same characterists as other typical cervical vertebra except that there is no foramen for the vertebral artery and it may not have a bifid spinous process. After the vertebral artery arises from the subclavian artery, it enters the transverse foramen of the 6th cervical vertebra bypassing the 7th.

The spinous process of the 7 cervical vertebra is longer than those of the other cervical vertebrae and is not buried under the ligamentum nuchae of the neck. Therefore, it is easy to see and to palpate and is called the vertebra prominens. This can serve as a surface landmark demarcating the neck (cervical) from the thoracic regions of the body.

Anterior Neck

As with all regions of the body, your study should start out with a look at the living region being studied. In the neck, the following diagram points out the major landmarks of the neck.
  • Common carotid artery (cc)
  • Internal carotid artery (ic)
  • External carotid artery (ec)
  • Carotid sinus (cs)
Superficial structures that you should know from the lateral view of the neck.
  • sternomastoid
  • trapezius
  • occipital lymph nodes (on)
  • retroauricular lymph nodes (ran)
  • superficial cervical lymph nodes (scn)
  • submental lymph nodes (smn)
  • buccal lymph nodes (bn)
  • parotid lymph nodes (pn)
  • submandibular lymph nodes (not labeled but uner angle of mandible)
It is very important to visually project deep structures onto the surface of a person or patient when making educated clinical diagnoses. The first thing you will usually do during a physical examination is to palpate any superficial structure that you can so that you can tell if abnormal changes have occurred. Swollen lymph nodes will tell you if there is an infection in an area that is drained by the nodes. The superficial group of nodes in the neck drain the skin of the face and nose, scalp and external ear. The submental nodes also drain the tip of the tongue. Deeper regions of the head and neck drain into a deep group of lymph nodes and are less palpable.
In the anterior neck, you can palpate the cartilages of the larynx and trachea. The thyroid gland is closely associated with the cricoid cartilage and the tracheal rings and should always be palpated in a general physical examination of the neck. Another very important structure that is palpable is the carotid artery. You should practice taking a carotid pulse since this is one site that is probably most often used to check to see if a person is still living.
The carotid artery pulse can be felt by pushing lateral to the upper border of the thyroid cartilage just under the anterior edge of the sternomastoid muscle.

Anterior Triangle of the Neck In Detail

The neck is arbitrarily subdivided into two triangles by the sternocleidomastoid muscle:


Triangles of the Neck Anterior Triangle Posterior Triangle
  • submental (smen)
  • submandibular (sm)
  • muscular-visceral (mus)
  • carotid (car)
  • occipital
  • supraclavicular  (omoclavicular)
Starting above the hyoid bone in the anterior triangle, we have two small triangles: submental and submandibular (or digastric). We will start this study by looking at the submandibular triangle first then the submental.

The Submandibular Triangle
Once the skin over the mandible and upper neck is removed, you can identify the submandibular triangle and its boundaries.

Boundaries

  • mastoid & mandible above
  • anterior belly of digastric anteriorly (abd)
  • posterior belly of digastric (pbd) and stylohyoid posteriorly (sh)
The superficial (roof) structures of the submandibular region are:
 
  • platysma
  • facial vein (fv)
  • cervical branch of facial nerve (cbf)
Removal of the superficial structures displays the submandibular salivary gland itself.
The remaining contents of the submandibular triangle are structures passing through:
  • facial artery (fa)
  • lingual nerve and submandibular ganglion (ln)
  • submandibular duct (smd)
  • lingual artery (la)
  • hypoglossal nerve (XII)
Notice that the lingual nerve and submandibular duct pass through a gap between the hypoglossal (hg) and mylohyoid (mh) muscles and the lingual artery passes deep to the hyoglossus muscle.

The Submental Triangle

The submental triangle is located between the two anterior digastric muscles (abd). Structures found here are the submental lymph node(s) (ln) that drain the floor of the mouth. The mylohyoid muscle (mh) arise from the body of the hyoid bone and insert into the mylohyoid line of the inside of the mandible. This muscle aids in swallowing and in depressing the mandible.

The Carotid Triangle

The boundaries of the carotid triangle are:
  • posterior belly of digastric muscle (pbd)
  • superior belly of the omohyoid muscle (so)
  • anterior border of sternomastoid muscle (st)
Boundaries of Carotid Triangle
Starting from the most superficial aspects of the carotid triangle, we will point out the items that are related to it.
Roof of carotid trianglecarotid triangle roof


The first layer, under the skin and superficial fascia includes the platysma, which forms the roof of the carotid triangle. Note the location of the carotid triangle in purple.

 Vein of the carotid triangle With the roof removed, you can see the boundaries of the carotid triangle and the superficial veins related to it:
  • common facial vein (cf) (within carotid triangle)

  • Other structures near by:
  • retromandibular vein (rm)
  • posterior auricular vein (pav)
  • facial vein (fv)
  • external jugular vein (ej)
  • anterior jugular vein (aj)
The nerves that enter the carotid triangle and that lie superficial to the internal jugular vein, internal and external carotid arteries are:
  • hypoglossal (XII)
  • C1 root of ansa cervicalis (C1)
  • C1 fibers running with hypoglossal nerve (nerve to thyrohyoid muscle (nth)
  • C2-C3 root of ansa cervicalis
  • ansa cervicalis (ac)
Nerves within the carotid triangle
Reflection of sternomastoid and removal of common facial veincontents of carotid triangle cca-common carotid artery
eca-external carotid artery
  • sta-supterior thyroid artery
  • oa-occipital artery
  • la-lingual artery
  • fa-facial artery
  • ica-internal carotid artery
Finally, we reach the deepest aspect of the carotid triangle, frequently called the floor. The muscles, at this level, are the middle and lower pharyngeal constrictors (mpc and ipc). The structures seen passing through this level are:
 
  • superior laryngeal nerve, a branch of the vagus its 2 terminal branches
  • internal laryngeal (ilb--sensory to upper part of the larynx)
  • external laryngeal (elb--motor to the cricoid muscle)
Floor of the carotid triangle

Muscular or Visceral Triangle

The muscular triangle has the following boundaries:
  • mid line of neck (1)
  • superior belly of omohyoid (2)
  • sternomastoid (3)
The muscles forming and within the triangle are seen in image labeled Muscles (these muscles are often called the strap muscles, for obvious reasons:
  • superficial layer
    • sternohyoid (sh)
    • superior belly of omohyoid (oh)
  • deep layer
    • thyroid (th)
    • sternothyroid (st)
Boundaries Muscles
When the strap muscles are reflected, you are able to see the thyroid gland (tg) with its arteries (superior thyroid artery from the external carotid (sta) and the inferior thyroid artery from the thyrohyoid trunk from the subclavian (ita).

If the thyroid gland is reflected laterally, the structures making up the larynx and trachea are seen:

  • thyrohyoid membrane (thm)
  • thyroid cartilage (Adam's apple)(tc)
  • cricothyroid membrane and ligament (ctm)
  • cricoid cartilage (cc)
  • tracheal rings (tr)
Thyroid gland and it arterial supply Cartilages and membranes
The thyroid gland is hidden under the sternohyoid and sternothyroid muscles and consists of two lobes and an isthmus. An occasional pyramidal lobe extends upward near the mid line.
The thyroid is supplied by superior (sta) and inferior (ita) thyroid arteries derived from the external carotid and thyrocervical trunk respectively. The inferior thyroid artery is closely associated with the recurrent laryngeal nerve (rln).		 Anterior View of Thyroid Gland Deep Surface of Thyroid Gland

Four small reddish-brown pea-sized glands may be seen on the deep surface of the thyroid gland. These are the superior and inferior parathyroid glands (ptg). Also note the close relationship of the recurrent laryngeal nerves to the thyroid gland and inferior thyroid artery (rln, ita).

Clinical Considerations
The cricothyroid ligament and membrane are frequently pierced in emergency situations to open the airway. You should be able to palpate this space on yourself or a friend, just to appreciate where it is. It has been known that an empty ball-point pen or a hollow stem has been used in the field to save lives, where an air passage has been closed above this region.

Structures Found AT the Root of the Neck

You will now disarticulate the sternoclavicular joint and identify the structures located at the root of the neck. The root of the neck is bounded by the manubrium of the sternum anteriorly, the first rib laterally and the first thoracic vertebra posteriorly. All structures passing from the head through the neck to lower regions pass through this area as well as structures arising in the thoracic cavity and passing out through this region. The following description of the root of the neck starts with the most anteriorly placed structures and proceeds to the most posteriorly placed ones.
Most anterior structures:
  1. brachiocephalic vein
  2. vertebral vein
  3. internal jugular vein
  4. subclavian vein
  5. thoracic duct
  6. thymus gland
The next layer can be considered the artery-nerve layer:
 
  1. lung
  2. vagus nerve
  3. common carotid artery
  4. subclavian artery
  5. ansa subclavius
  6. thyrocervical trunk
  7. vertebral artery
  8. internal thoracic artery
  9. trachea
  10. esophagus
The upper lobe of the lung (1) extends into the neck region. This is clinically important for anyone entering this region surgically since the lung can be punctured if the surgeon isn't careful.
The posterior part of the root of the neck is made up of the anterior surface of the body of the 1st thoracic vertebra with its anterior longitudinal ligament (in gray). When observing this area, you can see the nerves:
 
  1. ventral ramus of C8
  2. ventral ramus of T1
  3. lower trunk of brachial plexus
  4. stellate ganglion (inferior cervical + 1st thoracic ganglia)

List of Items Studied in this Section

Bones
mastoid process of temporal bone
body and angle of mandible

hyoid bone
body
greater horn
lesser horn
manubrium of sternum
1st thoracic vertebra
1st rib

Cartilages

thyroid
superior horn
inferior horn
cricoid
tracheal rings

Muscles

sternomastoid
anterior belly of digastric
posterior belly of digastric
stylohyoid
mylohyoid
sternohyoid
omohyoid (superior belly)
sternothyroid
thyrohyoid

Nerves

hypoglossal
superior laryngeal
internal laryngeal branch
external laryngeal branch
vagus
recurrent laryngeal
sympathetic chain
stellate ganglion
inferior cervical ganglion
1st thoracic ganglion

 Arteries

common carotid
internal carotid
external carotid
superior thyroid
lingual
facial
occipital
ascending pharyngeal
subclavian
thyrocervical trunk 
inferior thyroid
suprascapular
transverse cervical
vertebral
internal thoracic (mammary)

Veins

facial
common facial
internal jugular
vertebral

Lymphatics

thoracic duct on left
right lymphatic duct on right

 Viscera

submandibular gland
thyroid gland
parathyroid gland (maybe)
thymus
larynx
trachea
esophagus
Parotid & Infratemporal Regions   Posterior Cervical Triangle


Home
Table of Contents for Head & Neck
Practice Practical Exam
Practice Written Exam