Topographic anatomy of the deep temporal nerves, with references to the superior head of lateral pterygoid

Anatomical Bases of the Temporal Muscle Trigger Points

Method

Temporal muscles of 14 adult cadavers were studied. The muscle bellies were divided into six areas, three superior (1.2 and 3) and three inferior areas (4, 5, and 6) lower, according to a Cartesian plane to analyze and describe the entry points of the branches of the deep temporal nerves into the muscle. The branching distribution was analyzed using Poisson log-linear tests with Bonferroni post hoc tests for comparison between groups (sextants) (p < 0.05).

Results

Deep temporal nerve entry points were found in the temporal muscle in all areas. Most of the branches were observed in areas 2 and 5, which coincide with the muscle fibers responsible for mandible elevation and related to the previously described MTPs. Fewer branches were found in areas 1 and 6, where contraction produces mandible retraction.

Conclusion

There is an anatomical correlation between the branching pattern of the deep temporal nerve and temporal muscle trigger points. Adequate knowledge of the innervation of the temporal muscle may help elucidate the pathophysiology of myofascial syndromes and provide a rational basis for interventional or conservative approaches and help surgeons avoid iatrogenic lesions to the deep temporal nerve lesion.

The surgical anatomy of the deep temporal nerve: A cadaveric study

BACKGROUND

The aims of this study were to investigate the surgical anatomy of the deep temporal nerve (DTN) and find (fixed/static) anatomical landmarks that could be used during surgery to localise the DTN branches.

METHODS

Ten hemifaces of Dutch cadavers were dissected at the Department of Anatomy of the Radboudumc. Landmarks and measurements of interest were number of branches of the DTN, distance from the tragus to the DTN, and distance from the cranial and caudal parts of the posterior root of the zygomatic bone until the DTN.

RESULTS

In this cadaveric study, 10 hemifaces were dissected (male, n = 6 [60%]; female, n = 4 [40%]) with an equal left/right side division. The number of deep temporal branches varied from 2 (30%) to 3 (70%) per side. The mean distance to the tragus varied from 40 to 53 mm, with a mean distance of 44.3 ± 4.4 mm. The mean distance from the cranial part of the posterior root of the zygomatic bone to the DTN varied from 29 to 35 mm, with a mean distance of 31.3 ± 2.1 mm. The distance from the caudal part of the posterior root of the zygomatic bone to the DTN varied from 8 to 17 mm, with a mean distance of 13.4 ± 3.4 mm.

CONCLUSION

This study investigated the surgical anatomy and landmarks used for identification of the DTN and its branches. It suggested using firm landmarks for nerve identification, such as the posterior root of the cranial and/or the caudal zygomatic bone.

Transfer of the deep temporal nerve for eyelid reconstruction in Mobius syndrome - an anatomic feasibility study and proposed surgical approach

Facial paralysis may result in significant functional, esthetic, and psychological morbidity. Mobius syndrome is a form of bilateral congenital facial paralysis that is particularly difficult to treat owing to the lack of readily available donor nerves, particularly in the upper face. In this study, we evaluate the feasibility of using the deep temporal nerves as donors for the innervation of free muscle grafts in the periorbital region. Preserved and fresh cadaver facial halves are dissected, and the course of the deep temporal nerves delineated. We find the middle branch of the deep temporal nerve to be located consistently 4.6 cm from the posterior edge of the tragus along the zygomatic arch, giving an easily identifiable surface landmark for our donor. Finally, we outline a proposed surgical approach for using the middle deep temporal nerve to innervate a free muscle graft to the eyelids through an interpositional nerve graft.

The Deep Temporal Nerve Transfer: An Anatomical Feasibility Study and Implications for Upper Facial Reanimation

BACKGROUND

Facial paralysis has a profound impact on the brow, and currently static procedures are the mainstay of treatment. The deep temporal branches of the trigeminal nerve, given their proximity to the brow, may serve as possible donor nerves for both potential innervation of a free muscle transfer in patients with prolonged facial palsy or nerve transfers in acute or subacute palsy. As such, the authors present the detailed surgical anatomy of the deep temporal nerve, assessing feasibility for both functional muscle and nerve transfers, including a proposed surgical technique.

METHODS

Thirty cadaver hemifaces were dissected to establish deep temporal nerve anatomy and perform axonal analysis.

RESULTS

Two (53 percent) or three (47 percent) divisions of the deep temporal nerve were noted, with the most consistent division being the middle division (30 of 30 specimens). This division was consistently found approximately 4.1 cm (range, 3.7 to 4.5 cm) anterior to the tragus at the level of the zygomatic arch. For each 1 cm cranial to the arch, the nerve courses approximately 1 mm posteriorly. The number of axons in the proposed temporal branch is 1469 as it emerges from behind the zygomatic arch, 889 at 1 cm, 682 at 2 cm, 534 at 3 cm, 355 at 4 cm, 377 at 5 cm, and 256 at 6 cm.

CONCLUSION

Given its anatomical consistency, and expendability, the middle division of the deep temporal nerve is a viable donor nerve for dynamic upper facial reanimation with either nerve transfer or functional muscle transfer, depending on the length of facial palsy.

CLINICAL QUESTION/LEVEL OF EVIDENCE

Therapeutic, V.

Anatomy of the infratemporal crest: implications for cross-facial nerve grafting in temporal myoplasty

Temporalis transfers for reanimation in facial palsy have been criticised for the lack of neural input from a functioning facial nerve. Cross-facial nerve grafting to the deep temporal nerves may provide a solution. An anatomical study was performed to further elucidate the deep temporal nerves (DTN) and arteries, examining anatomical variation and infratemporal distribution. Seventeen temporalis muscles were dissected from 13 cadavers as part of a BSc project. The number, branching pattern, length and diameter of DTN were recorded. Arteries supplying the deep surface of temporalis and their relation to DTN were noted. Six specimens were processed using Sihler's staining technique. Arteries were injected with Iodixanol X-ray contrast medium and radiographs taken. All specimens displayed a single DTN originating from the anterior branch of V(3). A mean of 3 branches was observed. The nerve length was 14.22±3.95 mm. The point of entry of DTN into temporalis showed great consistency. Upon exiting the infratemporal fossa, the posterior deep temporal artery was deep and posterior to DTN in 65% of specimens. The branching pattern of DTN can be classified into three types. The deep arterial supply to temporalis was constant in all specimens. This study provides an anatomical basis for the planning and execution of cross-facial nerve grafting to temporalis, and for protection of vital structures. Furthermore, it helps to clarify inconsistencies in the literature regarding nomenclature of the nerve branching pattern of the deep temporal nerves.

The musculus pterygoïdeus proprius: an in-vivo approach with magnetic resonance imaging

There is a limited understanding of the normal function of the pterygoïdeus proprius muscle and the role that this muscle may have in temporomandibular disorders. Despite a well-described anatomical in-vitro approach to this muscle, there are still difficulties in investigating the fossa pterygopalatina. This study reveals an alternative in-vivo approach by magnetic resonance imaging to visualise the muscle in the fossa pterygopalatina on 78 head halves, describe the connections with the musculus temporalis and pterygoïdeus lateralis as well as report the incidence without dealing with the known inconveniences of the dissection approach. The results show an incidence of 12.82% for the musculus pterygoïdeus proprius equally divided between both genders. Two different types of bridging between the musculus temporalis and musculus pterygoïdeus lateralis were also found: (i) 'O' shape (6.41%) and (ii) 'Y' shape (6.41%). This study suggests the use of magnetic resonance imaging to investigate the different connections between vascular and muscular structures in the fossa pterygopalatina. Further research with this approach to link the appearance of the muscle with neurovascular entrapment syndromes is warranted.

Activity of superior head of human lateral pterygoid increases with increases in contralateral and protrusive jaw displacement

The hypothesis was that the superior head of human lateral pterygoid muscle (SHLP) plays a similar role in jaw movement as the inferior head of human lateral pterygoid muscle (IHLP). The aims were to determine the functional properties of SHLP single motor units (SMUs) and root mean square activity (RMS) of the SHLP during contralateral and protrusive jaw movement tasks and to compare these features with those identified previously for the IHLP. In 22 human subjects, SMUs were recorded intramuscularly from computer tomography-verified sites within the SHLP during standardized contralateral and protrusive jaw movement tasks recorded by a jaw-tracking device. Of the 50 SMUs discriminated, 39 were active during contralateral and 29 during protrusive jaw movements. The firing rates and RMS of the SHLP motor units increased with an increase in jaw displacement. The RMS activity across the entire trial during contralateral jaw movement was significantly greater than that during protrusion. Similarly to conclusions previously identified for the IHLP, the data are consistent with an important role for the SHLP in the control of contralateral and protrusive jaw movements. The similarities in SHLP and IHLP functional properties support the proposal that both heads should be regarded as a system of fibers acting as one muscle.