Reading

Body Surface

The primary surface landmarks of the nasal cavity and paranasal sinuses are associated with the nose (nostril, septum and nasion) and eye (infraorbital margin). Branches of the ophthalmic (external nasal) and maxillary (infraorbital) divisions of the trigeminal nerve innervate the skin overlying the nasal cavity and paranasal sinuses.

Skeleton and Joints

The bones associated with the nasal cavity and paranasal sinuses are the maxilla, ethmoid, inferior concha, palatine, sphenoid, vomer and frontal. There are sutures (fibrous joints) between the adjacent bones.

Organization

The nasal region includes the nasal cavity, paranasal sinuses and pterygopalatine fossa. The nasal cavity is the first section of the upper respiratory tract positioned between the cranial base and the roof of the oral cavity. It consists of paired cavities extending from the nares of the external nose to the nasal pharynx separated by the nasal septum, and subdivided into three regions. The nasal vestibule is the most anterior region and is continuous with the respiratory region posteriorly and the olfactory region superiorly. The lateral walls of the nasal cavity have three turbinates or conchae. Three spaces, the meatuses, are positioned between the lateral wall and the inferior and lateral aspect of each concha.

The paranasal sinuses are air filled, mucosa lined expansions of the nasal cavity that extend into the adjacent sphenoid, ethmoid, frontal and maxillary bones. The ethmoid sinuses are comprised of a series of air cells. The anterior and middle air cells open into the middle meatus, and the posterior air cells open into the superior meatus. The frontal and maxillary sinuses open into the middle meatus and the sphenoidal sinus opens into the sphenoethmoidal recess posterior to the superior concha.

The pterygopalatine fossa is an inverted pyramid shaped space inferior to the orbit between the pterygoid process and the infratemporal surface of the maxilla. It communicates with the middle cranial fossa, orbit, nasal cavity, nasal pharynx, oral cavity and infratemporal fossa. Branches of the maxillary nerve and artery traverse the fossa and it houses the pterygopalatine ganglion.

Innervation

Branches of the nasociliary (ophthalmic division of the trigeminal nerve, cranial nerve V) and maxillary nerve (trigeminal nerve, cranial nerve V) innervate (sensory, postganglionic sympathetic and postganglionic parasympathetic) the mucosa lining the nasal cavity and paranasal sinuses. The postganglionic parasympathetic neurons arise from the pterygopalatine ganglion.

Blood Supply

Branches of the ophthalmic, maxillary and facial arteries supply the nasal cavity. The corresponding tributaries drain into the facial vein or the pterygoid venous plexus.