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panel involving three staffs from the Anatomy, Physiology auriculotemporal nerve both proximal and distal to its
and Oral and Maxillofacial Departments. Content from the origin. In one of the specimens, a number of nerve fibers
relevant papers was tabulated for analysis. were observed entering the mandible via the retromolar
fossa. A second “plexus” was located between the
A total of six relevant papers (cadaveric studies on third mandibular canal and the roots of the mandibular teeth,
molar innervations) were selected, and findings from the and was composed of small fine filaments which arose
papers were recorded. The relevant information from each from the intramandibular plexus. These fine filaments
of these cadaveric studies is summarized below.
appeared to enter the roots of the teeth on their lateral
[1]
Carter and Keen noted a fine network of neurovascular surfaces as well as at the apices. The relationship of the
bundles in the area lateral to the roots of the mandibular inferior alveolar artery to the nerve plexus was notable.
molar teeth and extending up into the ramus. This Instead of the artery lying below the nerve in the main
network was traced backward to one or more foramina part of the bony canal, and then passing superior to the
in the areas of insertion of the muscles of mastication. nerve in the distal part of the channel as is most often
The most common connection occurred with bundles described, the nerve and artery formed an intertwined
leaving the lateral pterygoid and temporal muscles. The plexus throughout the canal. The NVP thus lay in a distinct
neurovascular bundles leaving the temporalis muscle bony canal which was observed as far as the mental
were traced to foramina in the retromolar fossa, where foramen, but which disappeared distal to this point. [5]
the lowest fibers of the temporalis gain their insertion. Blanton and Jeske found branches of the mandibular
[6]
This part of the network ramified through the cancellous division of the inferior alveolar nerve originating high
bone, and eventually established one or more obvious in the infratemporal fossa and travelling to the base
junctions with the main trunk of the inferior alveolar of the coronoid process (high and anterior to the
nerve, or with branches sent by the latter to the mandibular foramen) to enter the mandible. These
molar roots. Microscopically, several bundles of this branches carried sensory innervations to the second and
posterior plexus and nerve fibers and blood vessels were third molars. Branches of the mandibular division or of its
consistently demonstrated. The largest of supplementary inferior alveolar or buccal branches also noted to enter the
foramina (internal diameter 0-4 mm or greater) was mandible in the retromolar fossa area and to carry sensory
most commonly seen in the retromolar fossa (one-third fibers to the first and third molars. The better-documented
of the mandibles) and near the condyle (one-fifth of the of the accessory nerves includes the mylohyoid nerve, as
mandibles). The foramina were commonly in or near the well as branches of the mandibular division (V3) of the
areas of insertion of the muscles of mastication, and trigeminal nerve, all of which arise high in the cranium
probably transmitted the neurovascular bundles found on and enter the mandible each according to its own route.
dissection. These “accessory” nerves formed a plexus The incidence of mylohyoid innervation to the mandibular
[1]
in the cancellous bone of the ramus and the body of teeth is approximately 60%. The mylohyoid nerve can
the mandible lateral to the molar roots and the inferior arise from the inferior alveolar nerve anywhere from
alveolar nerve. Branches of this plexus seemed to join 5 mm to 23 mm proximal to the level of the mandibular
either the inferior alveolar nerve or its molar branches. foramen, and it enters the mandible at a point distal to
[1]
The links described are believed to offer an alternative the mandibular foramen. Therefore, deposition of local
escape route for pain impulses even after the effective anesthetic in the vicinity of the mandibular foramen
blockade of inferior alveolar nerve at its entry into during the administration of an inferior nerve block
mandible.
often does not block the mylohyoid nerve. The authors
[6]
Variations in the branching pattern or topographical recommended performing the mylohyoid nerve block in
relationships of the mandibular nerve often accounted the vicinity of the retromental foramina.
for failure to obtain adequate local anesthesia for Studies have reported the incidence of the retromolar
routine oral and dental procedures, and for unexpected foramen as 1.7%, [7,8] 7.7%, and 19.5% in the general
[9]
injury to branches of the nerve during operation. In population, 23% in native populations of North
[4]
[10]
2/20 dissections, Anil et al. noted the emergence of the America and 21.9% in the Indian population. However,
[4]
[11]
[12]
auriculotemporal nerve from the posterior root of the Bilecenoglu and Tuncer found an incidence of 25%
[12]
mandibular nerve. They also observed a nerve originating which is the second highest rate in the literature after
from the auriculotemporal nerve and joining the inferior Schejtman et al. study (72%). The histopathologic
[13]
alveolar nerve on both sides just posterior to the maxillary investigation found the contents of the neurovascular
artery. These two nerve branches and the mandibular bundle to be striated muscle fibers, thin myelinated nerve
nerve formed a loop reminiscent of the brachial plexus. [4]
fibers, numerous venules, and a muscular artery having a
In a study by Zoud and Doran, the main trunk of the lumen of 120-130 µm. This is similar to the results found in
[5]
[13]
inferior alveolar nerve exhibited a branching structure Schejtman’s studies. Compared to the nutrient foramina
reminiscent of the brachial plexus of the upper and canals, the retromolar foramen and canal were found
limb. This plexus-like structure was compounded by to have vascular and neural contents. The presence of
delicate interweaving of the inferior alveolar artery. this type of canal may explain anesthetic insufficiency
[7]
There were numerous communications between the and/or bleeding at this location during routine surgery.
individual components, including fine filaments to the The distal end of the retromolar canal advanced to the
108 Plast Aesthet Res || Vol 2 || Issue 3 || May 15, 2015