OBSERVATION OF THE NECK

Clinical Problem

The family physician was consulted concerning a young girl whose head constantly tilted to the left. She was unable to straighten her head when asked. The physician determined that the left sternocleidomastoid was shorter than the right and had a fibrous consistency. A history revealed that the girl was delivered with difficulty by a breech presentation. Identify this condition.

Osteology

Review the base of the skull and cervical vertebrae. Note distinguishing features of each vertebrae.

Surface anatomy

Identify on the cadaver and a laboratory partner:

A. External occipital protuberance

B. Transverse process of atlas

C. Mastoid process

D. Vertebrae prominens

E. Hyoid bone - What is its vertebral level? It is used as a surgical landmark to locate what vessel?

F. Laryngeal prominence - What is its vertebral level?

G. Cricoid cartilage - What is its vertebral level?

H. Sternocleidomastoid

I. Platysma - What is the function of this muscle during breathing?

J. Trapezius

K. Supraclavicular fossa - The pulse of which blood vessel may be felt there?

L. External jugular vein - What conditions are indicated when this vein is prominent throughout its course in the neck?

M. Anterior jugular vein - Why is this vessel observed during blood transfusions?

Dissection: (Grant's Dissector, pp. 251-263)

I. Overview

The anatomy of the neck is most easily learned in relationship to triangles. This starts with the identification of the sternocleidomastoid. Students should also appreciate which muscles, glands and other structures are found in each fascial compartment.

II. Questions & Problems

A. What is the function of the sternocleidomastoid? What structures are related to it? How will the patient present when it has become fibrosis and shorten on one side because of injury? What is the clinical term for the condition? How is the injury produced during birth and is the resulting condition correctable? If the condition is not corrected, how will this effect the development of the head?

B. Define the boundaries of the posterior and anterior triangles of the neck. Demonstrate subdivisions of the triangles. What are the floors, roof and contents of each triangle? Where are the nerve point and carefree areas of the neck and what are their clinical significance?

C. Where are cervical plexus and brachial plexus nerve blocks performed. Practice this procedure on the cadaver using a syringe and needle.

D. Demonstrate the major structures found in relationship to the sclaneous anterior. Hypertrophy of this muscle may produce what neurological and circulatory symptoms? How would you correct the problem?

E. What is the surgical approach for isolating the phrenic nerve? When might a surgeon elect to anesthetize, crush or avulse the phrenic nerve?

F. Besides profuse bleeding, what is the danger of lacerating the external jugular vein where it pierces the roof of the posterior triangle along the posterior border of the sternocleidomastoid?

G. What is carotid endarterectomy? What structures are vulnerable during this procedure and what symptoms will be produced if they are damaged? Cut open the carotid arteries on one side of the cadaver and examine their insides. Keep notes!

H. What is the route by which lymph is drained from the head and neck back into the circulatory system? Which lymph nodes should a surgeon removed if there is a metastasis of a malignant tumor from the head? Which structures are most exposed during this surgery?

I. Locate the cervical sympathetic chain. At what vertebral level are the ganglia found? Why are there only three ganglion found instead of 8? Where do the preganglionic sympathetic fibers originate? How many gray and/or white communicating rami are associated with each ganglion? What and where is the ansa subclavius? Name the syndrome and list the symptoms if the cervical sympathetic chain is damaged.

J. Where does the thyroid gland develop? Why is it sometimes located in the tongue and what symptoms might result? What is the embryonic basis for forming a thyroglossal duct cyst? Why are stridor, dyspnea, dysphagia and/or hoarseness sometimes produced by thyroid hypertrophy or thyroidectomy?

K. Between what fascial layers does a retropharyngeal abscess form? What is the mechanism by which a retropharyngeal abscess causes mediastinitis and/or difficulty in swallowing, breathing, and speaking? How does such an abscess form in the first place?

L. Where are the carotid sinus and carotid body found? What are their functions? What symptoms might be produced if they are diseased?