Ministry of Health of Ukraine

Ministry of Health of Ukraine

Bukovinian State Medical University

“APPROVED”

on methodical meeting of the Department of Anatomy, Topographical anatomy and Operative Surgery

“………”…………………….2008 р. (Protocol №……….)

The chief of department

professor ……………………….……Yu.T.Achtemiichuk

“………”…………………….2008 р.

METHODICAL GUIDELINES

for the 3d-year foreign students of English-spoken groups of the Medical Faculty

(speciality “General medicine”)

for independent work during the preparation to practical studies

the Theme of studies

“Topographical anatomy and operative surgery

of the organs of the neck”

MODULE I

Topographical Anatomy and Operative Surgery

of the Head, Neck, Thorax and Abdomen

Semantic module

Topographical Anatomy and Operative Surgery of the Head and Neck

Chernivtsi – 2008

1. Actuality of theme:

The topographical anatomy and operative surgery of the neck are very importance, because without the knowledge about peculiarities and variants of structure, form, location and mutual location of their anatomical structures, their age-specific it is impossible to diagnose in a proper time and correctly and to prescribe a necessary treatment to the patient. Surgeons usually pay much attention to the topographo-anatomic basis of surgical operations on the neck.

2. Duration of studies: 2 working hours.

3. Objectives (concrete purposes):

To know the definition of regions of the neck.

To know classification of surgical operations on the neck.

To know the topographical anatomy of the organs of the neck.

4. Basic knowledges, abilities, skills, that necessary for the study themes (interdisciplinary integration):

5. Advices to the student.

5.1. Table of contents of the theme:

The Pharynx

The pharynx is situated behind the nasal cavities, the mouth, and the larynx. It is somewhat funnel shaped, with its upper, wide end lying under the skull and its lower, narrow end becoming continuous with the esophagus opposite the sixth cervical vertebra. The pharynx has a musculomembranous wall that is deficient anteriorly. Here, it is replaced by the posterior nasal apertures, the oropharyngeal isthmus (opening into the mouth), and the inlet of the larynx. The wall of the pharynx has three layers: mucous, fibrous, and muscular.

Muscles of the pharynx

The muscles of the pharynx consist of the superior, middle, and inferior constrictor muscles, whose fibers run in a more or less circular direction, and the stylopharyngeus and salpingopharyngeus muscles, whose fibers run in a more or less longitudinal direction. The successive contraction of the constrictor muscles propels the bolus of food down into the esophagus. The lowest fibers of the inferior constrictor muscle, sometimes referred to as the cricopharyngeus muscle, are believed to exert a sphincteric effect on the lower end of the pharynx, preventing the entry of air into the esophagus between the acts of swallowing.

The longitudinal muscles elevate the pharynx and larynx during swallowing.

Interior of the pharynx

The pharynx is divided into three parts: nasal, oral, and laryngeal.

Nasal Part of the Pharynx

The nasal part of the pharynx lies behind the nasal cavities, above the soft palate. When the soft palate is raised and the posterior wall of the pharynx is drawn forward, as in swallowing, the nasal part of the pharynx is shut off from the oral part of the pharynx. It has a roof, a floor, an anterior wall, a posterior wall, and lateral walls.

The roof is supported by the body of the sphenoid and the basilar part of the occipital bone. A collection of lymphoid tissue, called the pharyngeal tonsil, is present in the submucosa of this region.

The floor is formed by the sloping upper surface of the soft palate. The pharyngeal isthmus is the opening in the floor between the free edges of the soft palate and the posterior pharyngeal wall. During swallowing, this communication between the nasal and oral parts of the pharynx is closed by the elevation of the soft palate and the pulling forward of the posterior wall of the pharynx.

The anterior wall is formed by the posterior nasal apertures, separated by the posterior edge of the nasal septum.

The posterior wall forms a continuous sloping surface with the roof. It is supported by the anterior arch of the atlas vertebra.

The lateral wall, on each side, has the pharyngeal opening of the auditory tube. The posterior margin of the tube forms an elevation called the tubal elevation.

The salpingopharyngeus muscle, which is attached to the lower margin of the tube, produces a vertical fold of mucous membrane called the salpingopharyngeal fold. The pharyngeal recess is a small depression in the lateral wall behind the tubal elevation. A collection of lymphoid tissue in the submucosa behind the opening of the auditory tube is called the tubal tonsil.

Oral Part of the Pharynx

The oral part of the pharynx lies behind the mouth cavity and extends from the soft palate to the upper border of the epiglottis. It has a roof, a floor, an anterior wall, a posterior wall, and lateral walls.

The roof is formed by the undersurface of the soft palate and the pharyngeal isthmus. Small collections of lymphoid tissue are present in the submucosa on the undersurface of the soft palate.

The floor is formed by the posterior one-third of the tongue (which is almost vertical) and the interval between the tongue and the anterior surface of the epiglottis. The mucous membrane covering the posterior third of the tongue is irregular in appearance because of the presence of the underlying lymphoid tissue, the lingual tonsil.

The mucous membrane is reflected from the tongue onto the epiglottis. In the midline is an elevation, called the median glossoepiglottic fold, and two lateral glossoepiglottic folds. The depression on each side of the median glossoepiglottic fold is called the vallecula.

The anterior wall opens into the mouth through the oropharyngeal isthmus. Below this opening is the pharyngeal part of the tongue.

The posterior wall is supported by the body of the second cervical vertebra and the upper part of the body of the third cervical vertebra.

The lateral walls on each side have the palatoglossal and the palatopharyngeal arches or folds and the palatine tonsils between them.

The palatoglossal arch is a fold of mucous membrane covering the underlying palatoglossus muscle.

The interval between the two palatoglossal arches marks the boundary between the mouth and the oral pharynx and is called the oropharyngeal isthmus.

The palatopharyngeal arch is a fold of mucous membrane on the lateral wall of the oral part of the pharynx behind the palatoglossal arch. It covers the underlying palatopharyngeus muscle.

The tonsillar sinus is a triangular recess on the lateral wall of the oral pharynx between the palatoglossal arch in front and the palatopharyngeal arch behind. It is occupied by the palatine tonsil.

Palatine Tonsils

The palatine tonsils are two masses of lymphoid tissue located in the lateral walls of the oral part of the pharynx in the tonsillar sinuses. Each tonsil is covered by mucous membrane, and its free medial surface projects into the cavity of the pharynx. The surface is pitted by numerous small openings, which lead into the tonsillar crypts. The tonsil is covered on its lateral surface by a layer of fibrous tissue called the capsule.

The tonsil reaches its maximum size during early childhood, but after puberty it diminishes considerably in size.

Relations of the Palatine Tonsil

- Anteriorly: The palatoglossal arch.

- Posteriorly: The palatopharyngeal arch.

- Superiorly: The soft palate. Here, the tonsil becomes

continuous with the lymphoid tissue on the undersurface of the soft palate.

- Inferiorly: The posterior third of the tongue. Here, the palatine tonsil becomes continuous with the lingual tonsil.

- Medially: The cavity of the oral part of the pharynx.

- Laterally: The capsule is separated from the superior constrictor muscle by loose areolar tissue.

The external palatine vein descends from the soft palate in this loose connective tissue to join the pharyngeal venous plexus. Lateral to the superior constrictor muscle lies the loop of the facial artery. The internal carotid artery lies 2.5 cm behind and lateral to the tonsil.

Blood Supply The arterial supply to the tonsil is the tonsillar artery, a branch of the facial artery.

The veins pierce the superior constrictor muscle and join the external palatine, the pharyngeal, or the facial veins.

Lymph Drainage The lymph vessels join the upper deep cervical lymph nodes. The most important node of this group is the jugulodigastric node, which lies below and behind the angle of the mandible.

Laryngeal Part of the Pharynx

The laryngeal part of the pharynx lies behind the opening into the larynx and the posterior surface of the larynx. It extends between the upper border of the epiglottis and the lower border of the cricoid cartilage. It has an anterior wall, a posterior wall, and lateral walls.

The anterior wall is formed by the inlet of the larynx and by the mucous membrane covering the posterior surface of the larynx.

The posterior wall is supported by the bodies of the third, fourth, fifth, and sixth cervical vertebrae.

The lateral wall is supported by the thyroid cartilage and the thyrohyoid membrane. A small but important groove in the mucous membrane, called the piriform fossa, is situated on each side of the laryngeal inlet. It leads obliquely downward and backward from the region of the back of the tongue to the esophagus. The piriform fossa is bounded medially by the aryepiglottic fold and laterally by the lamina of the thyroid cartilage and the thyrohyoid membrane.

Nerve supply of the pharynx

The nerve supply of the pharynx is from the pharyngeal plexus; the latter is formed from branches of the glossopharyngeal, vagus, and sympathetic nerves.

The motor nerve supply is derived from the cranial part of the accessory nerve, which, via the branch of the vagus to the pharyngeal plexus, supplies all the muscles of the pharynx except the stylopharyngeus, which is supplied by the glossopharyngeal nerve.

The sensory nerve supply of the mucous membrane of the nasal part of the pharynx is mainly from the maxillary nerve. The mucous membrane of the oral pharynx is mainly supplied by the glossopharyngeal nerve. The mucous membrane around the entrance into the larynx is supplied by the internal laryngeal branch of the vagus nerve.

Blood supply of the pharynx

The arterial supply of the pharynx is derived from branches of the ascending pharyngeal, the ascending palatine, the facial, the maxillary, and the lingual arteries.

The veins drain into the pharyngeal venous plexus, which in turn drains into the internal jugular vein.

Lymph drainage of the pharynx

The lymph vessels from the pharynx drain either directly into the deep cervical lymph nodes or indirectly via the retropharyngeal or paratracheal nodes.

Deglutition (Swallowing)

Although we swallow without thinking, deglutition is a complex process whereby food is transferred from the mouth through the pharynx and esophagus into the stomach. The term bolus (L. bolos, lump or choice morsel) is used to describe the mass of food or quantity of liquid that is swallowed at one time. Solid food is masticated (chewed) and mixed with saliva to form a soft bolus during chewing. Deglutition is described in three stages: in the (1) mouth, (2) pharynx, and (3) esophagus.

The first stage of swallowing is voluntary, during which the bolus is pushed from the mouth into the oropharynx, mainly by movements of the tongue. The tongue is raised and pressed against the hard palate by the intrinsic muscles of the tongue.

The second stage of swallowing is involuntary and is usually rapid. It involves contraction of the walls of the pharynx. Breathing and chewing stop, and successive contractions of the three constrictor muscles move the food through the oral and laryngeal parts of the pharynx. The bolus of food is prevented from entering the nasopharynx by elevation of the soft palate. The tensor veli palatini and levator veli palatini muscles tense and elevate the soft palate against the posterior wall of the pharynx. These actions close the pharyngeal isthmus, thereby preventing food from entering the nasopharynx. Should a person happen to laugh during this stage, the muscles of the soft palate relax and may allow some food to enter the nasopharynx. In these cases the food, especially if it is liquid, is expelled through the nose.

As the bolus of food passes through the oropharynx, the walls of the pharynx are raised. The contraction of the pharyngeal muscles elevate the pharynx and larynx. Watch someone swallow, particularly a thin man, and observe that the laryngeal prominence rises. The palatopharyngeus and stylopharyngeus muscles elevate the larynx and pharynx in swallowing. Palpate your hyoid bone with your thumb and second digit as you swallow and verify that it also rises. The hyoid bone is raised and fixed during swallowing by contraction of the geniohyoid, mylohyoid, digastric, and stylohyoid muscles. Verify that elevation and anterior movement of the hyoid bone precedes elevation of the larynx.

During deglutition the vestibule of the larynx is closed, the epiglottis is bent posteriorly over the inlet of the larynx, and the aryepiglottic folds are approximated. These folds provide lateral food channels that guide the bolus of food from the sides of the epiglottis.

The food now passes over the oral surface of the epiglottis and the closed inlet of the larynx. All these actions are designed to prevent food from entering the larynx.

The third stage of swallowing squeezes the bolus from the laryngopharynx into the esophagus. This is produced by the inferior constrictor muscle of the pharynx.

Injury to the recurrent laryngeal nerves (e.g., during a thyroidectomy) results in paralysis of the muscles in the aryepiglottic folds. As a result, the inlet of the larynx does not close completely during swallowing and food may enter the larynx. Choking on food is a common cause of laryngeal obstruction, particularly in persons who have consumed excessive amounts of alcohol, or who have bulbar palsy (degeneration of motor neurons in the brain stem nuclei of CN IX and CN X that supply the muscles of deglutition).