Core Curriculum Syllabus: Review of Anatomy - Nose and Paranasal Sinuses

The Nose

The nose is the air conditioner of the body, responsible for warming and saturating inspired air, removing bacteria and particulate debris, as well as conserving heat and moisture from expired air. Nasal breathing is important for optimal pulmonary function. It is also a prominent cosmetic feature of the face.

A. External Nose - the anterior, caudal portion of the nose is cartilaginous, while posteriorly and superiorly it is bony.

 

  • Framework
    • Cartilages: greater alar (lower lateral), septal, lateral nasal (upper lateral), lesser alar, sesamoid.
    • b. Bones: Nasal, maxillary, frontal
    Musculature: Nasalis, depressor septi, procerus, dilator naris. Blood supply
    • External carotid
      • External maxillary: lateral nasal, angular, alar, septal, external nasal.
    • Internal carotid: Ophthalmic, which gives rise to anterior ethmoid, posterior ethmoid, and dorsal nasal vessels.
    Lymphatics: facial artery, submandibular, parotid nodal drainage.
  • Nerve supply
    • Sensory trigeminal
      • Ophthalmic division: Nasociliary, external nasal, infratrochlear.
      • Maxillary division: infraorbital
    • Motor facial: Buccal, zygomatic branches

B. Internal Nose:

  • Floor - the floor of the nose is formed by the hard palate. The nasal cavity extends as far back as the soft palate, where the posterior choanae opens into the nasopharynx. Roof - the roof of the nose is adjacent to the anterior cranial fossa. The cribriform plate contains numerous tiny perforations which transmit sensory fibers to the olfactory bulbs. The sensation of smell is limited in man to a very small area of mucosa in the superior recesses of the nose. Posteriorly, the roof slants downward as the anterior wall of the sphenoid sinus. Lateral Walls - the turbinates, three or sometimes four bony shelves covered by erectile mucosa, project from the lateral wall of the nose. These processes serve to increase the interior surface area of the nose to facilitate heat and water exchange. They constantly engorge or shrink to accommodate changing physiologic requirements. They are also the chief structures involved in pathologic obstruction. A series of spaces are created by the overhanging edge of these turbinates.
    • Inferior Meatus - inferior to the inferior turbinate. Contains orifice of nasolacrimal duct. Middle Meatus - inferior to the middle turbinate. Contains semilunar hiatus, with openings of the maxillary, frontal, and anterior ethmoidal sinuses. Superior Meatus - drains posterior ethmoid cells.
    • Spheno-ethmoid recess - orifice of sphenoid sinus.

    Blood Supply
    • Anterior ethmoid - to roof and anterior superior portion of septum and lateral wall. Sphenopalatine - to lateral wall of nose Nasopalatine - supplies roof, septum, and floor Lateral nasal - supplies lateral nasal wall anteriorly. Descending palatine - supplies the lateral nasal wall posteriorly. Pharyngeal - supplies roof posteriorly Posterior ethmoid - supplies septum and lateral nasal wall superiorly
    • Septal - supplies septum inferiorly and floor
    Nerve supply
    • Medial internal nasal - to septum, anterosuperiorly Lateral internal nasal - to lateral wall, anterosuperiorly External nasal - to skin of back of nose Posterior superior nasal - supplies septum and lateral wall posteroinferiorly, to middle turbinate Posterior inferior nasal - to floor and inferior turbinate Pharyngeal - to choana Anterior superior alveolar - to inferior meatus
    • Infraorbital - to vestibule
  • Lymphatics: drained by
    • Facial venous drainage Retropharyngeal Superior deep cervical
    • Submandibular

Paranasal SinusesThese are air-filled, mucosal-lined cavities which develop in facial and cranial bones. The spaces communicate with the nasal airway. Their function is unknown but has been subject to a great deal of speculation. They could serve to decrease the weight of the skull or to function as resonators for the voice. In lower animals with a more acute sense of smell, the sinuses are largely lined by olfactory epithelium. Sinuses may have originally developed to increase the available surface area for the sense of smell. Therefore, in humans, with olfaction limited to a much smaller area, sinuses may be vestigial anachronisms.Though their function is obscure, their medical significance is not. Sinuses frequently become infected due to obstruction of normal drainage, and negative pressure in a sinus can cause headache. Neoplasms which arise in the sinuses can be occult for quite a long time, so that they are usually very advanced at the time of diagnosis. There are four groups of sinuses:

A. Frontal - Paired, in frontal bone. Posterior wall is adjacent to anterior cranial fossa. Usually asymmetrical, occasionally absent.

B. Maxillary - Paired, in maxilla. Superior wall - floor of orbit. Medial wall - lateral wall of nose. Inferiorly related to tooth-bearing area of maxilla.

C. Ethmoid - Numerous cells in superior and lateral walls of nose, and in medial walls of orbits.

D. Sphenoid - Paired, in sphenoid bone. Sella turcica projects into this space.

 

 

 

 

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Last modified: May 21, 2006