11.1.11+-+Nose,+Nasal+Cavities,+and+Paranasal+Sinuses

Nose, Nasal Cavities, and Paranasal Sinuses


 * 1. Describe three functions of the nose.**

olfaction, respiration, defense


 * 2. Describe the various parts of the external nose and its underlying bone, cartilage, muscles, vascular and nerve supply.**

External nose is made up of nasal bone and anterior nasal spine of maxillary bone with cartilage sheet as septum. There are three muscles involved: transverse part of nasalis (wrinkles nose skin), alar part of nasalis (flares nostrils), depressor septa nasi (depresses philtrum). Sensory innervation comes from infraorbital nerve (V2), external nasal nerve (V1), and infratrochlear nerve (V1). Vascularization comes from external nasal artery and angular artery. Motor innervation from muscular branches of CN VII


 * 3. Name the bones that contribute to boundaries of the nasal cavity (especially the septal and lateral walls).**

Septal wall: nasal, frontal, ethmoid, sphenoid, vomer, palatine, maxillary Lateral wall: all the same plus lacrimal and inferior conchae


 * 4. Identify the conchae, their contributing bones and the specific spaces (or meatus)**

Ethmoid makes up superior and middle conchae. Inferior conchae is the inferior conchae. The space between roof of nasal cavity is the sphenoethmoidal recess. Space below superior concha is superior meatus; below middle concha is middle meatus; below inferior concha is inferior meatus.


 * 5. Name the four pairs of paranasal sinuses. Describe how each sinus communicates with or drains into specific sites in the nasal cavity. Note the relationships of each paranasal sinuses with adjacent structures.**

Four paranasal sinuses: frontal, ethmoidal cavities, sphenoid, maxillary. Frontal drains through frontal canal into middle meatus. Anterior ethmoid also drains into middle meatus. Posterior drains into superior meatus. Sphenoid drains into sphenoethmoidal recess. Maxillary drains into middle meatus. Each paranasal sinus is within bone it shares a name with. Maxillary behind maxilla prominence. Frontal behind supraciliary arch. Sphenoid in sphenoid body. Ethmoid cavities in superior ethmoid.


 * 6. Describe the age-dependent changes in the size of paranasal sinuses.**

Paranasal sinuses grow with age.


 * 7. Identify the structures in roof and floor of the maxillary sinus. What are the functional implications?**

By old age the maxillary sinus has grown so that the roots of the superior teeth extend into the cavity. The effect is that infections of either the tooth or sinus can spread to the other.


 * 8. Describe the significance of the drainage of the nasolacrimal duct.**

The nasolacrimal duct from the eye drains into the anterior inferior meatus. This is why one's nose runs while crying.


 * 9. Describe the neural innervations of the posteroinferior and anterosuperior portions of the nasal cavity. Identify specific cranial nerves involved and the sensations carried by these nerves. Idenfity the autonomic innervation of the nasal cavity and paranasal sinuses.**

V1 sends branches called medial internal nasal and lateral internal nasal n. via anterior ethmoidal foramina to anterior portion of nasal cavity. V2 sends off several branches from the pterygopalatine ganglia. The nasopalatine nerve extends anteroinferiorly on the wall of the septum. The posterior superior lateral nasal branch and the posterior inferior lateral nasal branch innervate the posterior 2/3 of the nasal cavity on the superior, middle, and inferior conchae.

CN I sends many olfactory nerve fibers through the cribriform plate to the superior conchae.

Other branches from V1 innervate the superior 3 paranasal sinuses. Supraorbital n. innervates frontal sinuses. Nasociliary n. innervates ethmoidal cavities. Posterior ethmoidal n. innervates sphenoid sinuses. Other branches from V2 innervate the maxillary sinuses: superior alveolar nn.

Postganglionic parasympathetic nerve fibers branch from the facial nerve control secretion by mucosal cells. Sympathetic innervation modulates blood supply.


 * 10. Describe the pathway of arteries supplying the nasal cavity and identify the source of the penetrating branches and structures traversed by these nasal arteries.**

The sphenopalatine artery (a branch from the maxillary a.) is the principal blood supplier to the nasal cavity. The greater palatine a., another branch from maxillary a., also subserves the nasal canal.

The opthalmic a. puts off two branches that subserve the superior portion of the nasal cavity: anterior and posterior ethmoidal a.

The facial a. puts off one branch that subserves the inferior portion of the nasal cavity: septal branch of superior labial a.