CASE 3. Ms. Sherry Goldsmith, daughter of a local dentist, was involved in a two-car collision yesterday on Highway 280. She suffered severe facial.

CASE 3

Ms. Sherry Goldsmith, daughter of a local dentist, was involved in a two-car collision yesterday on Highway 280. She suffered severe facial injuries. Upon observation and inspection at the UAB Hospital Emergency Room, she was found to have the following injuries and accompanying symptoms:

The entire ramus of the left mandible was shattered and displaced medially into the infratemporal fossa.

Both the condyloid and coronoid processes were broken off on the left side.

The impact drove the temporomandibular joint (TMJ) medially and broke off the spine of the sphenoid.

A large sliver of the front window pane passed deeply into the infratemporal fossa, reaching the level of the infratemporal crest of the temporal bone and beyond.

A large hematoma, the specific origin of which was unknown, was noted within the fossa shrouding the other “contents”.

After careful debridement of all the facial wounds, an MRI was performed to determine the total “anatomical” involvement of the injuries.

After a lengthy hospitalization and numerous surgical interventions, Ms. Goldsmith was noted to demonstrate the following neural and/or neuromuscular disorders.

Ipsilateral loss of taste sensations on the anterior part of the tongue.

Ipsilateral loss of general sensations on the anterior part of the tongue.

The intact mandible deviated toward the side of the impact.

There was a cutaneous anesthesia involving a strip of skin extending from the ipsilateral lower lip and chin and proceeding anterior to the ear and superior to the scalp.

There was anesthesia to the ipsilateral lingual gingiva (mandibular region),floor of the mouth and mandibular teeth

There was a reduction of the volume of saliva.

What are the bony boundaries of the infratemporal fossa?

Questions-Temporal and Infratemporal Fossae

Infratemporal fossa-separate from temporal fossa by the infratemporal crest of the greater wing of the sphenoid bone.

Bounded by: Roof – Inferior aspect of greater

wing of sphenoid Medial Wall – lateral surface of lateral

pterygoid plate Lateral Wall – ramus of mandible Anterior Wall – posterior surface of

maxilla Posterior Wall – anterior surface of

condylar process of mandibule and styloid process

Name the six, usually expected, contents of the infratemporal fossa.

Muscles of mastication (except masseter)

Pterygoid plexus of veins

First and second parts of maxillary artery (mandibular and pterygoid parts)

Mandibular division of trigeminal nerve

Otic ganglion

Chorda tympani nerve

Discuss the specific attachments and actions of the muscles of mastication.

TemporalisO: from temporal

fossa and temporalis fascia

I: muscle fibers converge to form a thick tendon which passes deep to zygomatic arch and inserts into coronoid

process and anterior border of ramus of mandible inferiorly to last molar

Temporalis

A: vertical fibers (anterior) – powerful closer of jaw (elevator of

mandible)

horizontal fibers (posterior)-retract jaw (chief one)

Masseter

O: superficial fibers-zygomatic

process of maxilla and lower border of

zygomatic archdeep fibers-lower border zygomatic

arch (posterior 1/3) and entire medial surface of zygomatic arch

Masseter

I: lateral surface of coronoid process, ramus and angle of mandible

A: elevates and protracts jaw

Lateral Pterygoid – 2 heads

Upper head(sphenomeniscus part)O: from

infratemporal surface of greater wing of sphenoidd

I: articular disc (meniscus) of TMJ and upper part of neck of mandible

Lower head (main part)

O: lateral surface of lateral pterygoid plate

I: Pterygoid fovea of neck of

mandible

A (of both heads): protract (chief one) and depresses jaw

Medial Pterygoid-2 heads

- occupies same position internal to angel of mandible as does masseter externally

Deep Head (main one)

O: medial surface of lateral pterygoid plate and

pyramidal process of palatine bone

Superficial Head

O: tuberosity of maxilla

I (of both heads):medial suface of angel and ramus of mandible (as high

as mandibular foramen)

A (of both heads):elevates and

protracts jaw

Explain the peculiar deviation of the intact mandible.

Contraction of the intact pterygoid muscles (mainly the lateral pterygoid) “pulls” mandible toward side of lesion when mouth is opened.

Name the foramen through which the mandibular division of the trigeminal nerve (V3) passes into the infratemporal fossa. In which boundary of the infratemporal fossa is this foramen located? Does V3 supply any muscles other than the muscles of mastication?

V3 enters infratemporal fossa through the foramen ovale which is located in the roof of the fossa. V3 supplies all the muscles derived from pharyngeal arch 1. These include not only the four muscles of mastication, but also the mylohyoid, anterior belly of digastric, tensor tympani and tensor palati muscles.

Explain the cutaneous loss demonstrated by the patient.

The injury damaged the three cutaneous branches of V3. These include: mental n.(branch of inf.

alveolar n.) supplies lower lip and chin

buccal n. supplies cheek

auriculotemporal n Supplies ear and temple

(scalp)

Explain the loss of taste on the anterior part of the tongue.

The ipsilateral chorda tympani nerve (a branch off VII) was lesioned.

Explain the decreased volume of saliva.

By severing the otic ganglion and/or its connections to the parotid gland by way of the auriculotemporal nerve, the ipsilateral saliva is decreased.

Additionally, the innervation of the ipsilateral sublingual and submandibular glands has been destroyed (damage to the chorda tympani n).

Identify the branch of the maxillary artery which enters the middle cranial fossa. From what part of the maxillary artery does it arise?

Middle meningeal a. It arises from the first (mandibular) part.

Discuss the pathway by which this artery enters the middle cranial fossa.

The middle meningeal a. passes superiorly (between the two roots of the auriculotemporal n.) and enters the middle cranial fossa through the foramen spinosum.

What does this artery supply?

It supplies most of the dura mater (but NOT the brain) and some of the skull bones.

Name the condition which results from tearing this artery within the cranial cavity. What will be the consequence if this injury is not repaired immediately?

Epidural hematoma (extradural hemorrhage). Compression of brain resulting in death.

Through what fissure does the maxillary artery extend medially out of the infratemporal fossa?

Pterygomaxillary fissure

What type of joint is the TMJ (joint)? Be specific.

TMJ- Questions

A modified hinge type of synovial joint

What structure lies inside the TMJ and what kinds of movement occur in each part of the joint?

An articular disc (an oval plate of avascular fibrous tissue) lies inside the joint and divides it into two compartments. Gliding (sliding) movements occur in the upper joint compartment; hinge(rotational) movements in the lower joint compartment.

Describe the movements of the head of the mandible when the mouth is opened widely.

When opening the mouth, two movements occur in this sequence:

The head rotates (tilts) on the inferior surface of the disc about a horizontal axis, and

in order to prevent impinging of the jaw on the parotid gland and sternocleidomastoid muscle, the head and disc glide forward onto the inferior suface of the articular tubercle. This movement is produced by contraction of the lateral pterygoid.

Note: When closing the mouth the sequence of movements is reversed.

Name the parts of the mandibular fossa and their boundaries.

Articular part of mandibular fossa

This is a concavity in the squamous part of the temporal bone and it is bounded anteriorly bh the articular tubercle and posteriorly by the postglenoid tubercle(also part of the squamous temporal bone.

Articular part of mandibular fossa

This part of the fossa lodges the head of the mandible and is composed of thin bone. A blow (upper cut) to the mandibleby, for example, one of those heavyweight boxers may drive the head of the mandible into the middle cranial fossa.

Nonarticular part of mandibular fossa

This part of the fossa is formed by the tympanic part of the temporal bone. It lodges a small part of the parotid gland(glenoid lobule). The nonarticular part of the fossa lies between the TMJ (anteriorly) and theexternal auditory meatus (posteriorly)

What bony structure offers resistance to medial displacement of the head of the mandible?

The spine of the sphenoid bone.

Discuss the intrinsic and extrinsic ligaments of the TMJ and the specific function of the lateral thickening of the fibrous capsule.

Intrinsic ligament: The fibrous capsule

is relatively loose and is thickened at only one site-laterally. Therefore, there is only one intrinsic ligament-the fan-shaped lateral ligament (temporomandibular ligament)- with its base attached to the zygomatic process of the temporal bone and its apex to the lateral side of the neck of the mandible.

Intrinsic ligament: This ligament limits

posterior movement of the mandible, thus protecting the external auditory meatus, parotid gland, superficial temporal vessels, and auriculotemporal nerve from damaging compression.

Extrinsic ligaments:These ligaments do not provide much support.

Stylomandibular ligament-from tip of styloid process to angle of mandible. It is thickening of the deep cervical fascia and separates the parotid from the submandibular gland.

Extrinsic ligaments:

Sphenomandibular ligament-from spine of sphenoid to lingula of mandible. It is a remnant of the first pharyngeal arch cartilage.

Name the arterial supply and nerve supply of the TMJ.

Arterial supply Superficial temporal

and maxillary arteries

Nerve supply Auriculotemporal

and masseteric nerves

Explain (a) the movement resulting in the most common displacement of the TMJ, and (b) the “clicking” sound produced by chronic dislocation of this joint.

Dislocation is common. It usually occurs with the jaw open and the condyle (head) precariously perched on the articular eminence (tubercle). A sudden contraction of the lateral pterygoid propels the condyle anteriorly over the tubercle and into the infratemporal fossa. Dislocation usually happens when someone yawns or laughs uproariously; then, as with all dislocation, neighboring muscles go into spasm to prevent painful movement.

This joint is notorious for repeat dislocations as the capsule and disc attachment becomes more loose with each dislocation; “clicking of the jaw” is the result.