Nasal Cavity, Paranasal Sinuses, Pterygopalatine Fossa Mikel H. Snow, Ph.D. Dept. of Cell & Neurobiology Neuroscience System July 25, 2018

Nasal Cavity and Paranasal Sinuses Lecture part 1 Nasal Cavity and Paranasal Sinuses

Objectives for Nasal Cavity & Paranasal Sinuses: Sinusitis affects 10% - 30% of Americans each year, and the annual cost for treatment is greater than $11 billion. Objectives for Nasal Cavity & Paranasal Sinuses: Functions of the paranasal sinuses Locations, relationships & drainages of the nasal sinuses Anatomical rationale underlying sinusitis symptoms

There are 4 pairs of paranasal sinuses, each named according to the bone they lie in: Frontal Sphenoid Ethmoid Maxillary Mucosa lining sinuses produces nitric oxide which is antiviral and bacteriostatic. Thus, they assist the immune system.

Turbinates are delicate, scroll-like bones that project medially into the nasal cavity to increase surface area. They are covered by a thick mucous membrane. Head CT - Coronal Turbinates

A meatus is the space immediately lateral to the turbinate. The scroll-like turbinates that project from the lateral nasal wall have slit-like spaces (meatuses) lateral to each turbinate. Superior turbinate Middle turbinate Inferior turbinate Vestibule A meatus is the space immediately lateral to the turbinate.

Sphenoethmoidal recess: The four pairs of paranasal sinuses, plus the nasolacrimal duct, drain into the nasal cavity. Superior meatus: Ethmoids (post.) Sphenoethmoidal recess: Sphenoid sinus Middle meatus: Frontal sinus Maxillary sinus Semilunar hiatus Ethmoids (ant & mid) Inferior meatus: Nasolacrimal duct

Nasal Cavity CT ? Uncinate process 2 septum Middle 1 Maxillary sinus Middle turbinate Inferior turbinate

Right Maxillary Sinus Surgery

Objectives for Pterygopalatine Fossa: Location of pterygopalatine fossa within the skull. Bony openings/structures connecting to pterygopalatine fossa Parasympathetic pathways for innervating the: lacrimal gland nasal mucous glands palatine mucous glands Somatosensory innervation to nasal cavity & palates.

Pterygomaxillary fissure The pterygopalatine fossa is a small space located just medial to the pterygomaxillary fissure. Its primary structures are the pterygopalatine ganglion and branches of the maxillary artery. Pterygopalatine ganglion Pterygomaxillary fissure

Sphenoid bone – posterior view The pterygopalatine fossa is somewhat cone-shaped, located between the infratemporal fossa laterally and nasal cavity medially. It has six openings. Sphenoid bone – posterior view Infratemporal fossa Nasal cavity

Six openings in to or out of the pterygopalatine fossa: Infraorbital (V2) & artery 4. Inferior orbital fissure Nasal nerves Sphenopalatine artery 1. Foramen rotundum Right side Maxillary (V2) 6. Sphenopalatine foramen Nasal Cavity Infratemporal Fossa 2. Pterygoid canal Greater petrosal nerve 5. Pterygomaxillary fissure nerve of pterygoid canal (Vidian’s) Maxillary artery 3. Greater palatine foramen Greater & lesser palatine n.

Maxillary Artery entering pterygopalatine fossa ECA Maxillary artery arising from external carotid artery

The maxillary artery passes thru the pterygomaxillary fissure, giving off its 3 terminal branches. One is the sphenopalatine artery. Maxillary a. Spheno- palatine artery Sphenopalatine foramen Pterygomaxillary fissure

90% of nosebleeds are anterior bleeds, typically involving septal vessels. Epistaxis means nosebleed Ophthalmic artery Internal carotid artery Branches from ophthalmic a. Sphenopalatine artery coming thru sphenopalatine foramen Maxillary artery 10% are posterior nosebleeds. Anastomosis between external & internal carotid systems In the nasal cavity, the sphenopalatine artery ramifies over the posterior 2/3 of nasal cavity.

Another terminal branch of the maxillary artery is the infraorbital artery that passes thru the inferior orbital fissure. Inferior orbital fissure Infraorbital artery Sphenopalatine foramen Pterygomaxillary fissure

Inferior orbital fissure Maxillary artery Infraorbital artery

The 3rd terminal branch of the maxillary artery is the descending palatine artery. Inferior orbital fissure Infraorbital artery Palatine foramen Descending palatine artery

Descending palatine artery in palatine canal The descending palatine artery exits the pterygopalatine fossa via the palatine canal and courses vertically downward to supply blood to the hard and soft palates. Sphenopalatine a. Maxillary artery Descending palatine artery in palatine canal Descending palatine artery on inferior surface of hard palate

The maxillary nerve enters the pterygopalatine fossa by passing thru foramen rotundum.

Lateral view of V2 Infraorbital nerve Foramen rotundum Appears as continuation of V2. Maxillary nerve

Opening of pterygoid canal The nerve of pterygoid canal passes thru the pterygoid canal to enter the pterygopalatine fossa. The nerve ends at the pterygopalatine ganglion. Opening of pterygoid canal Greater petrosal n. passes into canal to become nerve of pterygoid canal (Vidian’s nerve)

Nerve of pterygoid canal from greater petrosal n. The nerve of the pterygoid canal conveys parasympathetic preganglionic axons that synapse in the pterygopalatine ganglion. Pterygopalatine ganglion V2 Nerve of pterygoid canal from greater petrosal n.

What is course of greater petrosal nerve? Posterior entrance to pterygoid canal Lesser petrosal nerve Greater petrosal nerve Crosses floor of middle cranial fossa Geniculate ganglion Facial n

Pterygopalatine ganglion Greater petrosal nerve VII Para/pre Para/post Geniculate ganglion Pterygopalatine ganglion Greater petrosal nerve VII Superior salivatory nucleus Nerve of pterygoid canal (Vidian’s nerve) Nasal branches (mucous glands) Palatine nerves (mucous glands) Greater palatine n. Lesser palatine n.

Maxillary nerve V2

Lacrimal nerve Somatosensory V2 Vidian’s nerve

Somatosensory from V1 Somatosensory from V2 Septum flipped up