Biology 122 Spring, 2008

Laboratory 24

Pharynx, Larynx & Neck

OBJECTIVES

At the end of this laboratory you should know:

1. Know the arrangement, innervation and the names of the major muscles associated with the posterior aspect of the neck.

2. Know the platysma muscle and infrahyoid strap muscles, their approximate origins and insertions, their innervation and their role in stabilizing and moving the laryngeal skeleton.

3. Understand the position and attachments of the anterior and middle scalene muscles and know the relationships of these muscles to the major neurovascular structures in the neck. The important relationships include:

Roots of brachial plexus - between the two scalene muscles

Subclavian artery - between the two scalene muscles at first rib

Subclavian vein - anterior to anterior scalene at level of first rib

Thyrocervical trunk - arises just medial to anterior scalene

Phrenic nerve - on the anterior surface of the anterior scalene

Transverse cervical and suprascapular arteries - cross over phrenic nerve where it lies on anterior surface of anterior scalene.

4. Be able to diagram the position and projections of the sympathetic chain in the neck including the input of preganglionic sympathetic fibers into the chain, the synaptic areas and the distribution of the postganglionic fibers.

5. Know the course and distribution of the glossopharyngeal and vagus nerves and their branches, specifically associated with the pharynx and larynx

6. Know the names and positions of the thyroid and cricoid cartilages and appreciate the position and parts of the thyroid gland in the neck with respect to the cartilages. Know the normal blood supply of the thyroid gland.

7. The important landmarks related to the pharynx and the internal landmarks of the larynx.

8. The organization and attachments of the muscles of the cheek (buccinator), intrinsic and extrinsic muscles of the tongue, the muscular walls of the pharynx (superior, middle and inferior constrictors) and the major muscles of the larynx (cricothyroid, posterior and lateral cricoarytenoids, thyroarytenoids and oblique and transverse arytenoid muscles).

9. The names, functions and relationships of structures leaving the skull through the jugular foramen (IX, X, XI, jugular vein) and hypoglossal canal (XII).

10. The basic skeletal components of the laryngeal skeleton and the major membranes and ligaments which link these parts.

PRELAB PREPARATION

1. Read the sections in your textbook that deal with the muscles and fascia of the neck (pp. 1046-1083). A detailed knowledge of the fascial layers is not required.

2. Read the sections of the textbook on the thyroid and parathyroid glands (pp. 1083-1089). Study the blood supply of the thyroid gland.

3. Review the origin, course and distribution of the brachial plexus and the phrenic nerve. Review the basic concepts and features of the sympathetic portion of the autonomic nervous system (synopsis of the autonomic nervous system, on website).

4. Read the portions of the textbook on the pharynx and larynx (pp. 1038-1109). Study the origin, course and distribution of all of the functional components associated with the glossopharyngeal, vagus and hypoglossal nerves (pp. 1147-1151) and review the buccal and lingual branches of the mandibular division of the trigeminal nerve.

5. Study descriptions of the act of swallowing.