IT Fossa Flashcards
What is the location of the IT fossa on dry skull?
Posterior to maxilla, inferior to zygomatic arch (a region of temporal bone), deep to ramus of mandible, and superficial to the lateral pterygoid plate of sphenoid bone
What is the clinical significant of the IT fossa? That is, what important structures run though?
Maxillary artery and its numerous branches, V3 of trigeminal nerve emergies, chorda tympani nerve (branch of CN7) passes through it, and masticatory muscles and TMJ are located within and nearby.q
What is located in the mandibular fossa and what is anterior to it?
The temporomandibular (TM joint) which includes the head and neck of the condylar process of the ramus of the mandible. It is bordered anteriorly by the articularly tubercule of the temporal bone.
What is the significance of the mandibular foramen?
Located on the deep side of the mandible, it is where the inferior alveolar nerve enters the jaw to supply your teeth. It is located right next to the mylohyoid groove
What is the mylohyoid groove?
Surface and line for the travelling of the nerve to the mylohyoid which carries motor fibers from V3 to the mylohyoid muscle + anterior belly of the digastric. It branches off from the inferior alveolar nerve before it enters the mandibular foramen
What comes from the petrotympanic fissue?
It’s the crack from which the chorda tympani rises, which carries motor fibers from CN7 and will join the lingual nerve to supply the anterior 2/3 of tongue
What is the maxillary artery and what is its course?
One of the terminal branches of the external carotid artery, along with the superficial temporal artery. It courses posterior to the neck of the mandible and anteriorly through IT fossa before dipping down into the PT fossa.
It is superficial to the lateral pterygoid muscle about 2/3 of the time, and deep about 1/3
What are the four important branches of the maxillary artery?
- Middle meningeal artery
- Inferior alveolar artery
- Deep temporal artery (2)
- Buccal artery
What is the middle meningeal artery? What is special about it?
Branch of maxillary artery, supplies dura of cranial cavity. It passes through the foramen spinosum, which is just posterior to the foramen ovale
It is encircled by the auriculotemporal nerve!! A sensory branch of V3
What is the inferior alveolar artery? What is its terminal name?
Branch of maxillary artery, supplies the jaw and teeth. Passes along with the inferior alveolar nerve through the mandibular foramen, and terminates as the mental artery through the mental foramen
What is the deep temporal artery?
Two arteries that branch upward from maxillary and supply the temporalis muscle
What is the buccal artery?
Branch of maxillary artery that supplies the buccinator muscle
How does the V3 enter the IT fossa?
Through the foramen ovale, which is anterior to the foramen spinosum
What is the lingual nerve?
A branch of V3 which is sensory to the anterior 2/3 of tongue, floor of mouth, and lower gums. It is parallel and anterior to inferior alveolar, enters mouth next to ramus of mandible before passing under mucosa below 3rd molar.
What is the inferior alveolar nerve?
A branch of V3 which is sensory to lower teeth, chin, and lower lip (via mental). It runs parallel and posterior to the lingual nerve until entering the mandibular foramen. Exits mental foramen as mental nerve in chin region.
What is the mental nerve?
It is the terminal branch of inferior alveolar nerve, which is sensory to lower lip and chin
What is the buccal nerve?
A branch of V3 which is sensory to cheek and lower gingiva. Emerges through lateral pterygoid muscle and heads superficially to cheek. Does NOT supply motor to buccinator
What is the auriculotemporal nerve?
A branch of V3 which is sensory to auricle (outer ear) and TM joint. It often encircles the middle meningeal artery
Where do the motor branches of the trigeminal nerve come from?
Only V3
What motor branches from from V3?
- Mastication muscles - temporalis, masseter, medial and lateral pterygoids
- Motor to mylohyoid and anterior digastric muscles (via mylohyoid nerve)
- Motor to Tensor Veli Palatini and Tensor Tympani muscles (ear)
What is the Chorda Tympani nerve?
A branch of facial nerve (CN 7) which travels with lingual nerve after passing through the middle ear cavity and entering the IT fossa. Gives taste sensation to anterior 2/3 of tongue
How does the chorda tympani nerve relate to the PANS?
Carries parasympathetic preganglionic fibers from CN7 to the submandibular ganlgion, before synapsing in the submandibular ganglion. The postganglionic fibers innervate the submandibular and sublingual glands
What is the function of the Lesser Petrosal nerve?
Carries preganglionic PANs fibers from CN9 to the otic ganglion
Where is the Otic ganglion and where does it send pans fibers too?
Located medial to V3 close to where it enters IT fossa at foramen ovale. The postganglionic fibers leave and travel with the auriculotemporal nerve
