Pterygopalatine Fossa Flashcards
Pterygopalatine fossa
The pterygopalatine fossa is a small area deep in the skull between the maxilla and sphenoid bone
PTERYGOMAXILLARY FISSURE
It’s a narrow space that lies between the
tuberosity of the maxilla anteriorly and the pterygoid process of the sphenoid posteriorly. It is the entrance from the infratemporal fossa to the more medial located pterygopalatine fossa.
Pathways of Pterygopalatine fossa
- infratemporal fossa - pterygomaxillary fissure
- middle cranial fossa - foramen rotundum
- base of the skull - pterygoid canal
- orbit - inferior orbital fissure
- nasal cavity - sphenopalatine foramen
- oral cavity (palate) - greater palatine canal
- nasopharynx - lesser palatine canal and pharyngeal canal
Sphenopalatine foramen
Found on the medial wall of the pterygopalaitne fossa, it is formed by a small notch in the upper
part of the perpendicular plate of the palatine bone where it joins the sphenoid bone
Contents of Pterygopalatine fossa
Primary Structures in the pterygopalatine fossa are:
• Maxillary Artery
• Maxillary nerve
• Pterygopalatine ganglion
Maxillary Artery
In Pterygopalatine fossa
The maxillary artery leave the infratemporal fossa and enters the pterygopalatine fossa through the pterygopalatine fissure
Pterygopalatine part of the maxillary artery
- Alveolar artery branches
- Infraorbital artery
- Descending palatine artery
- Sphenopalatine artery
Alveolar artery branches
Supply upper teeth, maxillary sinus & gums
Infraorbital artery
Supplies mid portion of the face
Descending palatine artery
Divides into greater and lesser branch to supply the hard and soft palates
Sphenopalatine artery
Passes through the sphenopalatine foramen to
supply the posterior portions of the nasal cavity
Maxillary Nerve
Maxillary Nerve (V2) is entirely sensory. It enters the pterygopalatine fossa posteriorly through the foramen rotundum and gives off multiple branches that convey sensory neurons from the nasal cavity, palate, nasopharynx, maxillary teeth and skin of the mid-face.
Branches of Maxillary Nerve
- zygomatic nerve
- infraorbital nerve
- ganglionic branches
- greater and lesser palatine branches
- posterior superior nasal branches (medial & lateral) & nasopalatine
- pharyngeal branches
Zygomatic nerve
Supplies skin over the cheek
Infraorbital nerve
Supplies skin of the mid-face
Alveolar nerves
Supplies the maxillary teeth
Greater and lesser palatine nerves
Supplies the hard ans soft palates
Nasal nerves
Supplies the posteroinferior part of nasal covity
Pharyngeal nerves
Supplies the nasopharynx
Pterygopalatine Ganglion
It is the largest of four parasympathetic ganglia in the head. It lies within the pterygopalatine fossa
where it is attached to the maxillary nerve by the latter’s two ganglionic branches.
The nerve of the pterygoid canal
It brings preganglionic parasympathetic fibers
(from the greater petrosal nerve) and postganglionic sympathetic fibers (from the deep petrosal nerve) to the ganglion.
Sympathetic fibers
Located in Pterygopalatine Fossa
The sympathetic fibers pass through the ganglion without change and travel
with the branches of the maxillary nerve to their destinations
Parasympathetic fibers
Located in Pterygopalatine Fossa
The preganglionic parasympathetic fibers synapse in the pterygopalatine ganglion. The now postganglionic fibers attach themselves (as “hitch hikers”) to branches of the maxillary nerve that distribute them to the minor salivary glands of the hard and soft palate, the small glands of the nasal cavity and the upper pharynx.
Lacrimal Gland Innervation
After synapsing in the pterygopalatine ganglion, postganglionic neurons travel first in the Zygomatic nerve then join the Lacrimal nerve via a communicating branch that is located in the lateral side of the orbit.
Nose
It’s comprised of the external nose and the nasal cavities (paired)
Nasal septum
The nasal septum separates the nasal cavities from each other. The vomer (posterior) and the perpendicular plate of the ethmoid bone (superior) form the bony structure. The septal cartilage, part of the external nose, completes it anteriorly.
Nasal Cavity Boundaries
The nasal cavities are separated from the:
• oral cavity (inferior) by the hard palate
• cranial cavity (superior) by the cribriform plate of the ethmoid bone
Lateral Nasal Wall
The lateral walls of the nasal cavity exhibit three conchae (turbinates), that project into the nasal cavity.
• superior and middle conchae are part of the ethmoid bone.
• inferior concha is an independent bone.
Meatuses
Meatuses are air passageways underneath each of the concha.
Sphenoethmoidal recess lies superior and posterior to the superior concha.
The conchae and meatuses serve to increase surface area and prevent laminar flow thereby providing greater contact between the inspired air and mucosal surfaces in order to filter, warm and humidify the air.
Posteriorly, the nasal cavities open into the nasopharynx at the choanae (posterior nasal apertures).
Paranasal Sinuses
They are air-filled evaginations of the respiratory part of the nasal cavity named for the bones which they invade:
• frontal
• Ethmoid
• maxillary
• sphenoid
All sinuses are lined by respiratory epithelium. Their ostia open into the lateral walls of the nasal cavity allowing drainage of mucous and equilibration of air.
Frontal sinuses
They are located in the vertical portion of the frontal bone. They drain into the middle meatus via frontonasal ducts
Ethmoid sinuses
They are a honeycomb of small, separate air cells that lies between the medial wall of the orbit and the upper lateral wall of the nasal cavity.
The bone between the sinuses and the orbit is particularly thin (lamina papyracea), thus infections in the ethmoid sinus can easily spread to the orbit.
Groups of Ethmoid Air Cells
The Ethmoid air cells are divided into three groups based on their position:
• Anterior: opens into the middle meatus
• Middle: opens into the middle meatus
• Posterior: drains into the superior meatus
Maxillary sinuses
They are located in the body of the maxilla and are the largest paranasal air sinuses.
Drainage occurs into the middle meatus through an ostium located on the most superior part of the
medial wall of the sinus.
It is non-gravity dependent and,therefore, poor.
Occasionally, the roots of teeth may erupt into the maxillary sinuses
Sphenoid sinuses
They are located in the body of the sphenoid bone posterior to upper part of the nasal cavities.
They are related to the pituitary gland, optic chasm, cavernous sinus and carotid artery.
Drainage occurs into the sphenoethmoidal recess by ciliary action only.
Gravity drainage is poor since the ostium on the anterior wall of the sinus is well above the floor.
Sites of Drainage for the Paranasal sinuses
- Sphenoethmoidal recess
- Superior nasal meatus
- Middle nasal meatus – complicated and important
- Inferior nasal meatus
Sphenoethmoidal recess
sphenoid sinus drains here
Superior nasal meatus
posterior ethmoid cells drain here
Middle nasal meatus
- frontal recess: frontonasal duct and anterior ethmoid cells drain here
- ethmoid bulla: bulging middle ethmoidal air cells and their ostia
- uncinate process: a sharp ridge of bone below the ethmoid bulla
- semilunar hiatus: opening between the ethmoid bulla above and uncinate process below leading into a groove; maxillary sinus drains here
Inferior nasal meatus
Nasolacrimal duct drains into the anterior portion of
this meatus. This explains why our noses run when we cry
Nasal Cavity
The bones and cartilages of the nasal cavity are covered by mucus membrane.
The entrance to each nasal cavity is called the vestibule.
This area is lined by skin and has vibrissae. These coarse hairs trap and remove particles of dust.
The remainder of each nasal cavity is the nasal fosa.
Each nasal fossa has a large respiratory area and a smaller olfactory area.
Respiratory mucous membrane
The mucous membrane of the respiratory area is pseudostratified columnar ciliated epithelium that is highly vascular and contains abundant mucous and
serous glands. This humidifies and warms incoming air and creates a sticky surface that traps and filters particulate matter. The cilia sweep secretions and debris posteriorly into the nasopharynx
Olfactory mucous membrane
The olfactory mucous membrane is limited to the roof and the upper portion of both the medial and lateral nasal walls of the fossae. It is less well
vascularized and covered with noncilliated epithelium. Modified olfactory nerve cells form nerve fibers that traverse the cribriform plate of the ethmoid bone to synapse in the olfactory bulb.
Quiet Respiration
During quiet respiration, air circulates primarily around the mucosa lining the inferior and middle conchae of the lateral nasal walls. Sniffing creates eddies that send inspired air toward the roof and permits the olfactory mucosa to recognize odors.
Arterial blood supply to Nasal cavity
External carotid system • Maxillary artery • Facial artery Internal carotid system • Ophthalmic artery
Ophthalmic artery
The anterior portion of the nasal cavity receives its blood supply from the Ethmoid branches of the Ophthalmic artery
Maxillary artery
The posterior portion of the nasal cavity receives its blood supply from branches of the Maxillary artery (primarily the Sphenopalatine artery)
Facial Artery
The facial artery supplies blood to a small area inside the vestibule via its septal branch
Little’s area / Kiesselbach’s plexus
It’s a region in the anteroinferior part of the
nasal septum where 4 arteries anastomose to form a vascular plexus.It’s common site for epistaxis (nose bleed)
Arteries of Little’s area / Kiesselbach’s plexus
- Anterior ethmoidal (from the ophthalmic artery)
- Spenopalatine artery (from the maxillary artery)
- Greater palatine artery (from the maxillary artery)
- Septal branch of the superior labial artery (from the facial artery)
Venous drainage
Extensive submucosal cavernous plexuses (erectile type tissue) are especially dense over the inferior and middle concha and the posterior nasal septum. In order to warm and humidify inspired air, approximately every 6 hours there is a cyclical fluctuation of venous engorgement.
The veins of one nasal cavity become engorged and the other side becomes decongested.
Venous drainage of Nasal cavity
- Ethmoidal veins
- Sphenopalatine vein
- Facial vein
Ethmoidal veins
Ethmoidal veins drain via the ophthalmic vein and then into the cavernous sinus
Sphenopalatine vein
The remainder of the venous drainage is via the sphenopalatine vein to the pterygoid plexus in the infratemporal fossa (mandibular vein - retromandibular vein)
Facial vein
Drains into the internal jugular vein
Lymphatics
- Submandibular lymph nodes
* Deep cervical lymph nodes
Submandibular lymph nodes
Submandibular lymph nodes drain the anterior region of the nose plus the frontal, anterior ethmoidal & maxillary sinuses
Deep cervical lymph nodes
Deep cervical lymph nodes receive lymph directly or via retropharyngeal nodes from the posterior region of the nasal cavity including the posterior ethmoidal cells, sphenoid sinuses and nasopharynx
Nerves to the Nasal Cavity
• Olfactory nerve (CN I) Ordinary Sensation • Ophthalmic nerve (V1) • Maxillary nerve (V2) Autonomic Nerves • Sympathetic nerves • Parasympathetic nerves
Olfaction
The olfactory nerve (CN I) provides the perception of smell. Rather than forming one discrete nerve, it consists of a collection of neurons in the roof of the nasal cavity. The cell bodies of the neurons are located in the olfactory mucosa and the axons pass through small holes in the cribiform plate to enter the cranial cavity.
These axons terminate by synapsing with neurons in the olfactory bulbs which are attached tot he brain via the olfactory tract.
Ordinary Sensation
Ophthalmic nerve (V1
The Ophthalmic nerve (V1) supplies the anterior 1/3 of the nasal cavity via its Anterior ethmoid nerve (a branch of the nasociliary)
Ordinary Sensation
Maxillaryc nerve (V2
The posterior 2/3 of the nasal cavity receives sensory innervation from the maxillary nerve via the shenopalatine foramen.
Collectively, the branches that supply this area are called the “Posterior nasal nerves”. One specific branch, the nasopalatine nerve travels on the nasal septum and communicated with the oral cavity via the incisive foramen.
Autonomic Nerves
- Parasympathetic nerves synapse in the pterygopalatine ganglion. Post ganglionic neurons supply mucous glands in the nasal cavity
- Sympathetic neurons innervate vessel in the nasal cavity
