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Anatomy Unit 2 > IT Fossa > Flashcards

IT Fossa Flashcards

1
Q

What is the location of the IT fossa on dry skull?

A

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

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2
Q

What is the clinical significant of the IT fossa? That is, what important structures run though?

A

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

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3
Q

What is located in the mandibular fossa and what is anterior to it?

A

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.

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4
Q

What is the significance of the mandibular foramen?

A

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

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5
Q

What is the mylohyoid groove?

A

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

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6
Q

What comes from the petrotympanic fissue?

A

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

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7
Q

What is the maxillary artery and what is its course?

A

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

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8
Q

What are the four important branches of the maxillary artery?

A
  1. Middle meningeal artery
  2. Inferior alveolar artery
  3. Deep temporal artery (2)
  4. Buccal artery
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9
Q

What is the middle meningeal artery? What is special about it?

A

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

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10
Q

What is the inferior alveolar artery? What is its terminal name?

A

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

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11
Q

What is the deep temporal artery?

A

Two arteries that branch upward from maxillary and supply the temporalis muscle

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12
Q

What is the buccal artery?

A

Branch of maxillary artery that supplies the buccinator muscle

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13
Q

How does the V3 enter the IT fossa?

A

Through the foramen ovale, which is anterior to the foramen spinosum

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14
Q

What is the lingual nerve?

A

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.

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15
Q

What is the inferior alveolar nerve?

A

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.

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16
Q

What is the mental nerve?

A

It is the terminal branch of inferior alveolar nerve, which is sensory to lower lip and chin

17
Q

What is the buccal nerve?

A

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

18
Q

What is the auriculotemporal nerve?

A

A branch of V3 which is sensory to auricle (outer ear) and TM joint. It often encircles the middle meningeal artery

19
Q

Where do the motor branches of the trigeminal nerve come from?

A

Only V3

20
Q

What motor branches from from V3?

A
  1. Mastication muscles - temporalis, masseter, medial and lateral pterygoids
  2. Motor to mylohyoid and anterior digastric muscles (via mylohyoid nerve)
  3. Motor to Tensor Veli Palatini and Tensor Tympani muscles (ear)
21
Q

What is the Chorda Tympani nerve?

A

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

22
Q

How does the chorda tympani nerve relate to the PANS?

A

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

23
Q

What is the function of the Lesser Petrosal nerve?

A

Carries preganglionic PANs fibers from CN9 to the otic ganglion

24
Q

Where is the Otic ganglion and where does it send pans fibers too?

A

Located medial to V3 close to where it enters IT fossa at foramen ovale. The postganglionic fibers leave and travel with the auriculotemporal nerve

25
Q

What PANS fibers travel with the auriculotemporal nerve?

A

Postganglionic fibers from the otic ganglion, which innervate the parotid gland

26
Q

What is the pterygoid venous plexus?

A

A vein network which lies between medial and lateral pterygoid muscles, as well as between temporalis and lateral pterygoid muscles.

27
Q

What is the clinical significance of the pterygoid venous plexus?

A

It is connected to the cavernous sinus via the emissary veins. Infections from the face, orbit, and nasal and oral cavities can spread to cranial cavity via this plexus.

28
Q

What are the two masticatory muscles in the IT fossa?

A

Lateral pterygoid and medial pterygoid

29
Q

What are the attachments and actions of the lateral pterygoid?

A

Origin: Lateral pterygoid plate, on lateral surface. +Infratemporal crest
Insertion: Neck of mandible
Action: Main protruder. Helps pull mandible forward and also some side to side movements for grinding and chewing.

30
Q

What are the attachments and actions of the medial pterygoid?

A

Origin: Maxilla and medial side of lateral pterygoid plate
Insertion: Angle of mandible (between ramus and inferior border)
Action: Elevates mandible and helps protrude somewhat (lateral is better). Does some side to side for grinding and chewing

31
Q

What are the attachments and actions of the temporalis muscle?

A

Origin: Temporal fossa
Insertion: Coronoid process of ramus of mandible (beneath zygomatic arch)
Action: Elevates mandible, some retraction via posterior fibers

32
Q

What are the primary retractors of the mandible?

A

digastric and stylohyoid

33
Q

What are the attachments and actions of the masseter muscle?

A

Origin: Zygomatic arch
Insertion: Ramus of mandible
Action: Elevates mandible, also helps protrude

34
Q

What does the head of the mandible articulate with in the TMJ?

A

Mandibular fossa and articular tubercule.

35
Q

What are the two movements at the TMJ? What are the significances of the articular disc and two joint compartments?

A

Hinge-like rotation, and forward gliding.

When opening the mouth, the mandibular head slides forward and the articular disc glides forward (upper compartment of joint cavity). Rotation of mandibular head occurs within the lower compartment of the joint cavity.

36
Q

How does the mandibular head sit in relation to the articular tubercule normally vs dislocated:

A

Normal: When fully opened, the mandibular head and articular tubercule are vertically aligned (head of bone moves anteriorly and inferiorly)
Dislocated: Mandibular heads of jaw move anterior to articular tubercule, generally caused by yawning or downward blow to open mouth

37
Q

Why can’t a mouth close completely when it’s dislocated, and what provides the pain?

A

Contact between upper and lower molars, when mandibular head is anterior to the articular tubercule.

Pain is provided by auriculotemporal nerve

38
Q

What ligaments stabilize the temporomandibular joint?

A

TM ligament (lateral ligament). - Around joint capsule.

  1. Stylomandibular ligament - from styloid process
  2. Sphenomandibular ligament - attached to spine of sphenoid bone, often confused with the inferior alveolar nerve
39
Q

What primarily stabilizes the temporomandibular joint?

A

The muscles of mastication

Anatomy Unit 2 (13 decks)

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