Temporal/Infratemporal Fossa

Question 1

What is the temporomandibular joint formed by and where is it located?

Answer 1

TMJ is formed by:
Condyle of Mandible (Head)
Articular Tubercle of Temporal Bone

It is located just anterior to the external auditory meatus.

Question 2

What four ligaments passively support the TMJ and what are their attachments?

Answer 2

1. Sphenomandibular (spine of sphenoid - lingula of mandible)
2. Stylomandibular (styloid process of temporal - posterior margin of ramus/angle of mandible)
3. Lateral ligament (articular tubercle of temporal bone - posterior neck of mandibular condyle)
4. Capsule

Question 3

What is the structure of the TMJ synovial capsule?

Answer 3

The synovial capsule is divided into an upper (gliding portion) and lower (hinging portion) by the articular disc.

The gliding movement is responsible for wider jaw opening.

Question 4

What bones make up the pterion?

Answer 4

The pterion is composed of the temporal, frontal, sphenoid, and parietal bones.

It is a part of the temporal fossa

Question 5

What are the boundaries of the temporal fossa?

Answer 5

The floor is composed of the pterion and the bones contributing to it.

The roof is the temporals muscle & fascia.

The inferior boundary is the zygomatic arch (laterally) and the infratemporal crest of the greater wing of sphenoid bone (medially). The area between the inferior boundary limits is what communicates with the infratemporal fossa.

Question 6

What are the boundaries of the infratemporal fossa?

Answer 6

ANT - infratemporal surface of maxilla
POST - temporal bone (vertical plate & styloid process)
SUP - infratemporal crest & surface of GW of sphenoid
MED - lateral pterygoid plate of sphenoid
LAT - ramus of mandible
INF - muscles of infratemporal fossa

Question 7

Where is the pterygomaxillary fissure and what passes through it?

Answer 7

The PtMx fissure is an opening into the PP fossa at the medial boundary of the ITF; it conducts vasculature traveling to the PP fossa (mainly maxillary artery & branches).

Question 8

What opening allows the communication between the middle cranial cavity and the infratemporal fossa?

Answer 8

Foramen Ovale - CN V3, lesser petrosal n. (GVE of VII), accessory meningeal a.

Foramen Spinosum - CN V2, middle meningeal a., meningeal n. branch of V3

Question 9

What are the contents of the infratemporal fossa?

Answer 9

Muscles of MAST

V3 & Branches (AT, Ling, Inf Alv., Buccal, BE branches)

Maxillary A. & Branches (Part 1 & 2)

Maxillary V. & Pterygoid Plexus

Question 10

Muscle table for Temporalis M.

Answer 10

Origin - bone & fascia of temporal fossa
Insert - coronoid of mandible
Action [ANT/MID fibers] - elevate mandible
Action [POST fibers] - retract mandible

All MAST are innervated by BE fibers of V3

Question 11

Muscle table for Masseter M.

Answer 11

Origin - zygomatic arch & bone
Insert - angle of lateral mandible
Action - elevate mandible
Course - runs parallel with medial pterygoid m.

All MAST are innervated by BE fibers of V3

Question 12

Muscle table for Medial Pterygoid M.

Answer 12

Origin [DEEP] - medial surf of lateral pterygoid plate (sphenoid) & pyramidal process of (palatine)
Origin [SUPF] - tuberosity & pyramidal process (palatine)
Insert - angle of medial mandible
Action - elevate (& laterally move) mandible
Course - parallel with masseter m. & deep to lateral pterygoid m.

All MAST are innervated by BE fibers of V3

Question 13

Muscle table for Lateral Pterygoid M.

Answer 13

Origin [SUPER] - roof of ITF (sphenoid)
Origin [INFER] - lateral surf of lateral pterygoid plate (sphenoid)
Insert [SUPER] - TMJ disc
Insert [INFER] - fovea of condyle (mandible)
Action - protrude & laterally move mandible

All MAST are innervated by BE fibers of V3

Question 14

What passes between the two heads of the lateral pterygoid muscles?

Answer 14

Buccal N. comes out between the two heads

Maxillary A. dives between the two heads (usually)

Question 15

What courses on the lateral surface of the medial pterygoid muscle?

Answer 15

Lingual N. & related vessels

Inferior Alveolar N. & related vessels

Question 16

What are the three fascias of mastication muscles?

What muscles do they envelop and what does it derive from?

Answer 16

All three fascias are superior continuations of the investing fascia of the neck (surrounding SCM/trapezius).

Masseteric fascia envelops the masseter m, and is continuous with the parotid fascia posteriorly.

Pterygoid fascia is on the deep surface of the medial pterygoid muscle

Temporalis fascia attaches inferiorly to the medial/lateral zygomatic arch, travels superiorly as deep & superficial layers around the temporalis muscle, and attaches superiorly to the temporal line.

Question 17

What space is created by the massertic fascia & pterygoid fascia?

Answer 17

The mastication space is created by the two fascias, which is a conduit for the spread of infection in the ITF and into the pterygoid venous plexus.

Question 18

Explain the mandibular component of the Maxillary A. and its branches.

Answer 18

Coursing along the lower border of the lateral pterygoid muscle -
1. Deep Auricular - EAM, TMJ, external tympanic membrane
2. Anterior Tympanic - internal tympanic membrane
3. Middle Meningeal (Foramen Spinosum) - periosteum, dura cranial cavity, tympanic cavity, tensor tympani m.
4. Accessory Meningeal (Foramen Ovale)
5A. Inferior Alveolar (Mandibular Foramen) - inferior teeth, mandible
5B. Artery to Mylohoid m. & Anterior Digastric m.
5C. Mental (Mental Foramen) - chin & lower lips

Question 19

Explain the pterygoid component of the Maxillary A. and its branches.

Answer 19

Courses adjacent to lateral pterygoid muscle -
3 Muscular Branches
1. Masseteric A.
2. Posterior & Anterior Deep Temporal A.
3. Internal & External Pterygoid A.
and
Buccal A. - runs ANT & INF with Buccal N. (V3) to supply buccal fat, buccinator, buccal-oral mucosa

Question 20

Explain the location of and communication of the pterygoid venous plexus.

Answer 20

Location - between temporalis m. and pterygoid m.s (venous equivalent of maxillary a.)

Communication - anastomoses superiorly with cavernous sinus (via emissary veins); anastomoses anteriorly with facial vein (via deep vein) that drains into IJV

Question 21

What forms the retromandibular vein?

Answer 21

The short maxillary vein (communicates with pterygoid plexus) and superficial temporal vein combine to form the retromandibular vein.

Retromandiublar and posterior auricular veins combine to form the EJV.

Question 22

Explain the Mandibular N’s branching after it exits the foramen ovale.

Answer 22

See notes.