TBL25 - Temporal and Infratemporal Fossae

Question 1

Where is the temporal fossa in relation to the zygomatic arch? What bones make up the temporal fossa? What is the H-shaped pterion created by?

Answer 1

1) The temporal fossa is superior to the zygomatic arch
2) The fossa is formed by the frontal, parietal, sphenoid (greater wing), and temporal bones
3) The H-shaped pterion is created by the sutures that unite the bones

Question 2

What muscle fully occupies the temporal fossa? Where does this muscle attach to distally?

Answer 2

1) The temporal fossa is fully occupied by the fan-shaped temporalis muscle
2) The muscle attaches distally to the coronoid process of the mandible

Question 3

What is the infratemporal fossa inferior to and what is it bounded to laterally? What two things form the medial and anterior walls of the infratemporal fossa, respectively?

Answer 3

1) The infratemporal fossa is inferior to the zygomatic arch and bounded laterally by the ramus of the mandible
2) The lateral pterygoid plate of the sphenoid bone and posterior portion of the maxilla form the medial and anterior walls of the infratemporal fossa, respectively

Question 4

Observe the ramus and coronoid process of the mandible and observe the body and angle of the mandible. What two parts constitute the condylar process? Where does the mandibular notch sit between?

Answer 4

1) The head and neck constitute the condylar process

2) The mandibular notch is between the coronoid and condylar processes

Question 5

Which two parts make up the Temporomandibular

joint (TMJ)? Where is this joint located in relation to the external acoustic meatus?

Answer 5

1) The mandibular fossa of the temporal bone receives the head of the condylar process to form the TMJ
2) The joint is immediately anterior to the external acoustic meatus

Question 6

What does the masseter muscle attach to proximally and distally? What rests on the masseter muscle?

Answer 6

1) The masseter muscle attaches proximally to the zygomatic arch and distally to the lateral surface of the ramus of the mandible
2) The parotid gland rests on the masseter muscle

Question 7

Where do the medial and lateral pterygoid muscles reside? What muscles constitute the muscles of mastication and what joint do these muscles act on?

Answer 7

1) The medial and lateral pterygoid muscles reside in the infratemporal fossa
2) These two muscles along with the temporalis and masseter muscles constitute the muscles of mastication that act on the TMJ

Question 8

Where does the medial pterygoid muscle attach to proximally and distally? Where does the lateral pterygoid muscle attach to proximally and distally?

Answer 8

1) The medial pterygoid attaches proximally to the medial side of the lateral pterygoid plate and distally to the medial surface of the angle and ramus of the mandible
2) The lateral pterygoid attaches proximally to the lateral surface of the lateral pterygoid plate and distally to the medial surface of the mandibular neck

Question 9

Cite the three muscles of mastication that elevate the mandible, the prime depressor of the mandible, the principal muscle that protrudes the mandible, and the two muscles that retrude (retract) the mandible.

Answer 9

1) Elevation (close mouth): Temporalis, masseter, and medial pterygoid
2) Depression (open mouth): Gravity, Lateral pterygoid, suprahyoid, and infrahyoid muscles
3) Protrusion (protrude chin): Lateral pterygoid, masseter, and medial pterygoid
4) Retrusion (retrude chin): Temporalis (posterior oblique and near horizontal fibers) and masseter

Question 10

What is required to open the mouth widely?

Answer 10

Opening the mouth widely requires protrusion of the mandible and simultaneous contraction of the infrahyoid and suprahyoid muscles

Question 11

Why does TMJ dislocation typically occur anteriorly rather than posteriorly and which nerves are most susceptible to injury?

Answer 11

1) Posterior dislocation is uncommon, being resisted by the presence of the postglenoid tubercle and the strong intrinsic lateral ligament
2) Because of the close relationship of the facial and auriculotemporal nerves to the TMJ, care must be taken during surgical procedures to preserve both the branches of the facial nerve overlying it and the articular branches of the auriculotemporal nerve that enter the posterior part of the joint

Question 12

Why does the mouth fall open when sleeping?

Answer 12

1) When the mouth is closed and at rest, the heads of the mandible are held in the retracted position in the mandibular fossae, and the chin is elevated by the tonus of the retractors and elevators of the mandible
2) When sleeping in the supine or sitting position (head upright), as one enters a state of deep sleep, the tonic contraction relaxes and gravity causes depression of the mandible (the mouth falls open)

Question 13

What forms the superior boundary of the infratemporal fossa and contains the foramen ovale? Where is the foramen ovale located?

Answer 13

1) The inferior surface of the greater wing of the sphenoid bone forms the superior boundary of the infratemporal fossa and contains the foramen ovale
2) The foramen ovale is on the external surface of the cranial base

Question 14

CN V3 traverses the foramen ovale to enter what structure? Upon entering this structure, CN V3 generates which two nerves? What are the sensory distributions of these two nerves? What does the auriculotemporal nerve innervate?

Answer 14

1) CN V3 traverses the foramen ovale into the infratemporal fossa
2) It immediately generates the auriculotemporal and long buccal nerves
3) Auriculotemporal gives sensory innervation to the scalp superior to the ear while the buccal nerve gives sensory innervation to the lateral cheek
4) The auriculotemporal nerve also innervates the TMJ and external ear

Question 15

Where does the motor root of CN V emanate from? Where do these efferent fibers pass through and what do they join? What do these somatic motor fibers supply and what are these muscles derived from?

Answer 15

1) The motor root of CN V emanates from somatic motor neurons in the brain
2) The efferent fibers pass through the trigeminal ganglion and join CN V3 (CN V1 and V2 are sensory only)
3) The somatic motor fibers supply the muscles of mastication, which are derived from myoblasts of the 1st pharyngeal arch

Question 16

Where is the mandibular foramen located in relation to the mandible? What is the inferior alveolar nerve a branch of and when it enters the mandibular foramen, what does it supply? What does the inferior alveolar nerve terminate as and after exiting the mental foramen in the body of the mandible, what does it innervate?

Answer 16

1) The mandibular foramen is on the medial surface of the ramus of the mandible
2) The inferior alveolar nerve, another sensory branch of CN V3, enters the foramen to supply the teeth of the mandible
3) The inferior alveolar nerve terminates as the mental nerve that, after exiting the mental foramen in the body of the mandible, innervates the lower lip and chin

Question 17

Where is the injection site for a mandibular nerve block and what regions are anesthetized?

Answer 17

1) To produce a mandibular nerve block, an anesthetic agent is injected near the mandibular nerve where it enters the infratemporal fossa
2) The injection usually anesthetizes the auriculotemporal (scalp superior to ear), inferior alveolar (lower teeth), lingual (anterior two-thirds of tongue), and buccal branches of CN V3 (lateral cheek)

Question 18

Which cranial nerves contain presynaptic parasympathetic fibers in addition to their somatic fibers? Recall the parasympathetic distribution of CN X in the thorax and abdomen.

Answer 18

1) In addition to their somatic fibers, CNs III, VII, IX, and X contain presynaptic parasympathetic fibers
2) Vagus nerve = CN X

Question 19

What nerve is the lesser petrosal nerve a branch of and what type of nerve fibers is it composed of? What does this nerve traverse adjacent to CN V3 and where does it synapse?

Answer 19

1) The lesser petrosal nerve is the branch of CN IX (glossopharyngeal nerve) composed of parasympathetic fibers
2) It traverses the foramen ovale adjacent to CN V3 and synapses in the otic ganglion residing in the infratemporal fossa

Question 20

Where is the otic ganglion located near? What are postsynaptic fibers from the otic ganglion transported by and to where? What type of nerve fibers does the auriculotemporal nerve provide to the parotid gland?

Answer 20

1) The ganglion is located near the origin of the auriculotemporal nerve
2) Postsynaptic fibers from the otic ganglion are transported by the auriculotemporal nerve to the parotid gland
3) Thus, the auriculotemporal nerve provides somatic sensory fibers to the gland and visceral motor fibers to stimulate parotid gland secretion

Question 21

Why can pain from parotiditis extend to the TMJ, ear, and scalp superior to the ear?

Answer 21

Parotid gland disease often causes pain in the auricle and external acoustic meatus of the external ear, the temporal region, and TMJ because the auriculotemporal and great auricular nerves, from which the parotid gland and sheath receives sensory fibers, also supplies sensory fibers to the skin over the temporal fossa and auricle

Question 22

What is the maxillary artery a terminal branch of? What does the maxillary artery enter?

Answer 22

1) The maxillary artery is a terminal branch of the external carotid artery
2) The maxillary artery enters the infratemporal fossa

Question 23

Where is the foramen spinosum located in relation to the foramen ovale? What is the middle meningeal artery a branch of, what does it traverse, and what does it supply?

Answer 23

1) The foramen spinosum is posterior to the foramen ovale
2) The middle meningeal artery, a small branch of the maxillary artery, traverses the foramen spinosum to supply the meninges of the brain (to be studied later)

Question 24

Where does the inferior alveolar artery descend from and what does it follow the course of? What is the superficial temporal artery a terminal branch of and what does it supply?

Answer 24

1) The inferior alveolar artery descends from the maxillary artery to follow the course of the inferior alveolar nerve
2) The superficial temporal artery is the other terminal branch of the external carotid and supplies the scalp superior to the ear

Question 25

Where does the pterygoid venous plexus reside? Where do veins accompanying branches of the maxillary artery empty into? What vein does the plexus drain into? Where does this vein drain into?

Answer 25

1) The pterygoid venous plexus resides in the infra-temporal fossa
2) Veins accompanying branches of the maxillary artery empty into the plexus
3) The plexus drains into the deep facial vein, a tributary of the facial vein
4) The facial vein empties into the IJV