Lab Manual - Nasal Cavity and Pharynx

Assignments:

Learning Objectives:

Upon completion of this session, the student will be able to:

  1. Describe the nasal cavity, its general morphology including walls, openings, nasal septum, conchae, meatuses, and its general neurovascular supply.
  2. List the paranasal sinuses and where each opens into the nasal cavity.
  3. Describe the hard and soft palate.
  4. Describe the pharynx and its subdivisions, its muscular and fascial components, its general neurovascular supply, and its anatomical relationships.
  5. Describe the location and neurovascular supply of the pharyngeal, palatine, and lingual tonsils.
  6. Describe the location of the deep cervical lymph nodes and the general pattern of their afferent and efferent channels.

Procedure:

1. Review the osteology of the nasal cavity. (Play movie; View images: N 2, 4A, 4B, 6A, 6B, 8, 9, 11, 48, 49, 55, 63, 64, 65, 67, 92, 94A, 94B, TG 7-03, 7-04, 7-06, 7-07, 7-08, 7-21, 7-22, 7-23, 7-24, 7-32, 7-41, 7-44, 7-65, 7-67B, 7-67C, 7-68A, 7-68B, 7-70)

Locate on a skull the pterygopalatine fossa, sphenopalatine foramen, nasal aperture, nasal bones, medial pterygoid plate, pterygoid hamulus, and maxilla. On a partial or sagittally-sectioned skull, identify the bony septum of vomer and ethmoid (perpendicular plate). Note sphenoid sinus, frontal sinus, maxillary sinus, conchae, ethmoidal air cells, and hard palate.

2. Examine the nasal cavity, its regions and internal structures. (Play movie; View images: N 1, 40, 41, 43, 46, 47, 125, TG 7-03, 7-41A, 7-41B, 7-43, 7-45, 7-77)

In the nasal cavity, examine the nasal septum. Observe that it consists of cartilaginous and bony parts. Note the short stumps of the olfactory nerve (CN I) in the superior third of the septum and lateral nasal walls. The arteries and nerves of the nasal mucosa are tiny and difficult to dissect. Observe in your text or atlas the complexity of their arrangement. Identify the nares (anterior nasal openings), vestibule and conchae. On the lateral nasal wall find: the superior, middle and inferior nasal conchae; the superior, middle and inferior meatuses; the sphenoethmoidal recess. Consider the structure and functions of conchae.

Surface anatomy of the nose
Surface anatomy of the paranasal sinuses
MRI of the nasal cavity

3. Remove the conchae on one side to expose the meatuses, the ethmoidal bulla and hiatus semilunaris and the openings of the sinuses. (Play movie; View images: N 41A, 41B, 41C, 42A, 42B, 44, 45, 46, 47, 52, 53, 73, 106, TG 7-19, 7-35, 7-43A, 7-43B, 7-44, 7-45AB, 7-45CD, 7-72)

With scissors, cut away the conchae from their points of attachment on one side of the skull. In the inferior meatus, locate the opening of the nasolacrimal duct. Remove the bony covering of the medial side of the duct and trace it to the lacrimal sac within the fossa of the lacrimal sac of the orbit. In the middle meatus, note the semilunar hiatus and, just above it, the ethmoidal bulla. With a probe explore the infundibulum (superior part of semilunar hiatus) and locate the frontonasal duct, which drains the frontal sinus. Explore the frontal sinus. Also note opening of anterior ethmoidal air cells in the semilunar hiatus. In the posteroinferior part of the semilunar hiatus locate the opening of the maxillary sinus. On the surface of the ethmoidal bulla probe the middle ethmoidal air cells. Now lift or remove the superior concha and, in the superior meatus, locate an opening to the posterior ethmoidal air cells. In the sphenoethmoidal recess probe an opening to the sphenoid sinus. Examine the sphenoid sinus. Note the mucoperiosteal lining and its continuity with the nasal cavity. The frontal and sphenoid sinuses may have septa (sagittal) that may make them appear shallow or nonexistent. Note the relation of the sphenoid sinus to the hypophysis and the internal carotid artery. Remove the lateral wall of the nasal cavity on one side of the head and explore the maxillary sinus and the ethmoidal air cells. Consider drainage of sinuses and air cells.

Skull structures

While removing the mucoperiosteum of the lateral wall, note its blood supply. Most comes through the sphenopalatine foramen from the sphenopalatine artery, a terminal branch of the maxillary artery, but some comes from the anterior and posterior ethmoidal arteries. Note again short stumps of the olfactory nerves (I) passing through the cribriform plate of the ethmoid.

4. Examine the nasopharynx and soft palate. (Play movie; View images: N 37A, 37B, 37C, 63, 64, 52, 63, 64A, 64B, 68, 69, TG 7-06, 7-22, 7-23, 7-24, 7-39, 7-67)

In the roof of the mouth identify the soft palate, uvula, hard palate; palpate the hamulus of the medial pterygoid plate.

In the nasopharynx identify: opening of auditory tube, torus tubarius, pharyngeal tonsil and pharyngeal recess.

Skull structures

5. Examine the subdivisions of the pharynx, noting their features. (Play movie; View images: N 41, 62, 64, 66, 67, 69, 70, TG 7-22, 7-23AB, 7-23C, 7-39, 7-41)

Define nasal, oral and laryngeal portions of pharynx. What boundaries separate these regions?

Nasopharynx: Identify the choanae, soft palate and uvula, torus tubarius, pharyngeal recess, and the pharyngeal tonsil.

Oropharynx: Identify the palatoglossal and palatopharyngeal folds, tonsillar fossa, and palatine tonsil (if present). Remove one tonsil from its bed or fossa. What structures lie immediately deep (lateral) to it? Identify the glossopharyngeal nerve as it passes to the base of the tongue, inferior to the palatine tonsil. Where is the lingual tonsil? Identify the glossoepiglottic folds.

Laryngopharynx: Identify the epiglottis, which divides the oropharynx from the laryngopharynx, laryngeal inlet, piriform recesses and entrance to the esophagus.

Retropharyngeal space: Identify the retropharyngeal space between the posterior wall of the pharynx and the vertebral column and associated muscles, covered by prevertebral fascia. Identify the buccopharyngeal fascia lining the pharynx posteriorly, and the pharyngobasilar fascia, the submucosal lining of the pharynx.

Structures of the pharynx and larynx

6. Palpate the deep cervical lymph nodes. (View images: N 75, TG 7-74)

On yourself or a partner, palpate the chain of deep cervical lymph nodes that lies along the internal juguglar vein. Locate the palpation point of the jugulodigastric node.