Infratemporal Fossa
Background Information:
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This dissection will require the team to work in a very small
area of the face and the structures that must be found are equally small.
A delicate dissection will be necessary for the lab to be successful.
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This dissection deals with terminal branches of the external
carotid artery; a review of these branches will greatly aid in the speed
and accuracy of identifying structures.
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For removing the mandible, it is best to use the electric
saws that will be brought out for the dissection. Laboratory instructors
will aid and demonstrate in the use of the saws. As always, be sure
to have the proper protection (especially the eyes) as small pieces of
bone will become airborne A hammer and chisel can also be used for
removing the mandible but it often leads to destroying the structures beneath
it. As there are a limited number of electric saws, exercise patience
or opt for the hand method of removal.
Dissection:
1. Remove fat and fascia from the temporalis muscle
and the zygomatic arch.
2. Cut the zygomatic arch at its anterior and
posterior ends, preserving the TMJ and reflect it and the masseter muscle
superiorly. Be sure to preserve the artery and nerve which supply
the masseter; they will be traveling through the mandibular notch piercing
the deep surface of the muscle. Cut out the section of the muscle
with the artery and nerve. Strip the masseter from the surface of
the mandible down to the angle.
3. Cut the coronoid process from the mandible
and reflect it and temporalis superiorly. Preserve the long buccal
nerve and buccal artery found on the deep surface of the mandible or with
in the fibers of the temporalis tendon. Preserve the deep temporal
arteries and nerves located deep to the temporalis.
4. Cut the mandible from just in front of the
neck of the condyle down to just above the mandibular foramen and then
forward to the anterior edge. Remove the cut section of bone.
Slide a finger under the anterior edge of the mandible near the angle and
feel for the lingula to determine where the mandibular foramen is located.
Slide a blunt probe beneath the anterior edge of the mandible and gently
direct it in an inferior direction. When the probe can descend no
further down the mandible, it is resting on the lingula and a cut through
the mandible superior to the probe will protect the mandibular foramen
and the inferior alveolar nerve which is entering the foramen.
5. Remove the pterygoid venous plexus located
on top of the lateral pterygoid muscle.
6. Locate the inferior alveolar artery and nerve
which appears at the inferior edge of the lateral pterygoid and travels
down to the
mandibular foramen, crossing the medial pterygoid.
Identify the mylohyoid artery and nerve which branch off of the inferior
alveolar artery and nerve just before entering the mandibular foramen.
Locate the sphenomandibular ligament; it is attached to the lingula and
travels posteriorly deep to the Inferior Alveolar artery and nerve.
7. Locate the lingual nerve which travels just
medial to the inferior alveolar nerve curving anterior-medially across
the medial pterygoid toward the tongue.
8. Locate the maxillary artery. It will
be traveling medially above or below the lateral pterygoid.
9. Remove the lateral pterygoid piece by piece
doing so will expose the branches of the maxillary artery. Identify
and preserve all of the branches. Follow the inferior alveolar and lingual
nerves back to foramen ovale locating the other branches. Identify
and preserve all of these nerves.
Pictorial Atlas:
Maxillary Artery
Mandibular Nerve - V3
Other Nerve Contributions
Mandible
Muscles of Mastication
Pterion
Images
Infratemporal Fossa
Structures List