Download Ppts/Gross Anatomy Case 3

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.
Questions-Temporal and
Infratemporal Fossae

What are the bony
boundaries of the
infratemporal fossa?

Infratemporal
fossa-separate
from temporal
fossa by the
infratemporal
crest of the
greater wing of
the sphenoid
bone.
Bounded by:
 Roof –
 Medial Wall –
 Lateral Wall –
 Anterior Wall –
 Posterior Wall –
Inferior aspect of greater
wing of sphenoid
lateral surface of lateral
pterygoid plate
ramus of mandible
posterior surface of maxilla
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.

Temporalis
O:
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

A:
Temporalis
vertical fibers
(anterior) –
powerful closer of
jaw (elevator of
mandible)
horizontal fibers
(posterior)-retract
jaw (chief one)

Masseter
O:
superficial fiberszygomatic process
of maxilla and
lower border of
zygomatic arch
deep 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.)


buccal n.


supplies lower lip and chin
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
TMJ- Questions

What type of joint is the TMJ
(joint)? Be specific.

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 ligamentthe 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 ligamentfrom 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.