Branches Of Mandibular Nerve Research Articles

An Anomalous Relationship of the Maxillary Artery with the Mandibular Nerve Branches: A Rare Case Report of Two Anatomical Variations

Abstract The maxillary artery (MA) and mandibular nerve are important structures in the infratemporal fossa (ITF) supplying large portions of the face. During a medical dissection course, two rare anatomical variations pertaining to the MA’s relationship to the mandibular nerve branches were found in three ITF. In these cases, the MA was seen to travel medial to the mandibular nerve branches. Case 1 had bilateral, asymmetric variations. On the left, the MA traveled medial to a trunk formed by the inferior alveolar and lingual nerves and lateral to the chorda tympani nerve (CTN). On the right, the MA passed lateral to the lingual and CTNs and medial to the inferior alveolar nerve. Case 2 had a unilateral variation on the left such as the variation seen on the right in Case 1. A clear understanding of MA variations has several clinical implications. This study provides a resource that may prevent complications such as bleeding, hematoma, and injury to the mandibular nerve or its branches during clinical procedures.

Branches of Trigeminal Nerve Causing Idiopathic Trigeminal Neuralgia and Effectiveness of Microvascular Decompression for Immediate Pain Relief

Objective: To determine the efficacy of microvascular decompression for immediate pain relief of idiopathic trigeminal, caused by different branches of trigeminal nerve. Study Design: Descriptive study. Place and Duration of Study: Department of Neurosurgery, Mardan Medical Complex, Mardan from 1st January 2020 to 30th June 2021. Methodology: One hundred and thirty nine patients were collected from Tertiary Care Hospitals of KPK. A consent form and detailed history was performed with clinical examination and relevant investigations like CT and MRI of the brain. Pre-operative preparation was done with following investigations like complete blood count and viral serology for hepatitis, coagulation profile was carried out. Patients was assessed and included in the study according to the inclusion and exclusion criteria. The patients were operated by the same neurosurgeon. Patients were assessed after 72 hours post-operatively for pain relief by Visual Analogue Scale (VAS- Scale). Results: The mean age was 63±12.24 years. The data was divided into two 37% male and 63% females were included in the study. The most common branch of trigeminal nerve causing pain is right infraorbital (V2), (45) 32.37% and 23.02% is right inferior alveolar nerve V3. The less common branch of mandibular nerve is right lingual nerve 0.719 %. The study showed that microvascular decompression was effective in 88% patients and was not effective in 12% patients. The trigeminal neuralgia is common in old age patients from 60 to 80 years that is 45%. Conclusion: The most common branch of the trigeminal nerve was right infraorbital nerve causing pain in old age individuals and it is concluded that microvascular decompression was 88% effective in idiopathic trigeminal neuralgia in terms of immediate pain relief. Key words: Efficacy, Microvascular decompression, Idiopathic trigeminal neuralgia, Immediate pain relief

Topographical Landmarks for the Identification of Branches of Mandibular Nerve and Its Surgical Implications: A Cadaveric Study.

IntroductionBasic knowledge of anatomy is crucial in providing predictable, safe, and efficacious mandibular anesthesia as the mandibular nerve is vulnerable to injury during dental procedures and other surgical manoeuvers. The lack of availability of the appropriate topographical bony landmarks for the location of the branches of this nerve often accounts for iatrogenic injuries and the failure to obtain adequate local anesthaesia. Hence we aimed to describe the topographical landmarks of the branches of the mandibular nerve and their variations in the infratemporal fossa.MethodologyIn 16 formalin-fixed cadavers, irrespective of the sex of the cadavers, bilateral dissection of the infratemporal fossa was done after identifying the necessary bony landmarks. The mandibular nerve and its branches were traced out and the required measurements were taken using the digital vernier caliper. The results were statistically analysed for mean, range, and standard deviation.ResultsThe masseteric nerve is 15.87+/-1.64 mm superior to the lowest point on the mandibular notch. The lingual nerve in the third molar area is at the depth of 24.75+/-2.38 mm from the angle of the mandible (gonion), making an angle of 50° with the base of the mandible. 20.13+/-3.1 mm inferior to the mandibular notch is the precise location of the mandibular foramen which allows access to the inferior alveolar nerve. The incidence of accessory mandibular foramen in the dissected samples is 9.37%.ConclusionThe topography of the masseteric nerve, lingual nerve, and inferior alveolar nerve was studied using constant and reliable bony landmarks in the cadaver which might aid effective dental and facio-maxillary surgical procedures. However, the outcome of this study could not be applied to paediatric patients as the subjects were restricted to adult cadavers.

Versatility of the Berger-Tenenhaus Approach for Mandibular Fractures.

Mandibular fractures between the angle and condyle can be difficult to access and treat. The authors sought to evaluate a small transcutaneous incision between the marginal mandibular and buccal nerve branches (Berger-Tenenhaus incision) to treat these fractures. Ten cadaveric hemi-faces were dissected. Surrounding facial nerve branches were identified and measured in relation to the discussed incision. Our clinical experience with the approach for mandibular angle, ramus, subcondylar, and condylar fractures was reviewed. Operative technique and postoperative outcomes were examined. The incision is located in a safe interval between neighboring facial nerve branches. Marginal mandibular nerve branches maintained a consistent distance beneath the incision along its length (median distances of 0.95-cm (SD ± 0.5), 1.05-cm (SD ± 0.5), and 1.00-cm (SD ± 0.8) posterior to anterior, respectively). Buccal nerve branches increased in distance and ascended away from the incision line (median distances of 0.75-cm (SD ± 0.9), 1.4-cm (SD ± 0.8), and 1.45-cm (SD ± 0.9) respectively posterior to anterior). No nerves were injured. In our clinical experience, all postoperative patients (n = 9) have had successful fracture reduction with restoration of occlusion, intact facial nerve function and an acceptable cosmetic result. The Berger-Tenenhaus incision can safely and efficiently be used to treat difficult to access mandible fractures between the angle and condyle. VI.

Reproductive outcomes in Criollo mares using semen biotechnologies

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

Endogenous plasma progesterone levels in normal mares and embryo recipient mares between days 11 and 16 of gestation in a commercial breeding program

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

Effect of cryoprotectant exposure on blastocyst development of vitrified immature equine oocytes

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

The presence of uterine edema on day fourteen post ovulation and its effects on embryo transfer rates

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

Gross Anatomical, Radiographic and Doppler Sonographic Approach to the Infra-auricular Parotid Region in Donkey (Equus asinus)

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

Linear measurement of the nucleus basalis of Meynert in Alzheimer's disease and mild cognitive impairment

The present study was performed on 12 heads of donkey’s cadavers of both sexes for different anatomic techniques and on 20 live adult donkeys for ultrasonographic approaches of local anesthetic techniques. The aim was to achieve safe desensitization of the ear canal and tympanic membrane in addition to measuring different parameters of the structures occupying the infra-auricular parotid region. The internal auricular nerve was divided into two fine branches and constituting, at its origin, a characteristic V-shape with the caudal auricular nerve. The styloid process of auricular cartilage was an adequate landmark for ultrasonographic needle-guided anesthesia for internal auricular and auriculopalpebral nerves, whereas the great auricular nerve was easily palpated subcutaneously that showed safety and success in all cases. The auricular branch of mandibular nerve joined the auriculopalpebral branch of facial nerve. The maxillary vein was descending, partially embedded within the texture of the parotid glandular tissue. The parotid gland divided into five segments was clearly demarcated by maxillary vein tributaries with three main collecting radicles pouring into the parotid duct. The mandibular duct received about 12–15 fine radicles and supplied with a separate branch from the external carotid artery. Using the Doppler sonographic technique in donkeys for diagnosis of ear affections, evaluation of retrograde sialography to salivary glands with their blood vasculature and their indices might be helpful for the detection of different critical abnormalities, such as stenosis, thrombosis, and other vasopathological affections through measuring their resistivity and pulsatility indices.

Extramandibular Presentation in the Course of the Inferior Alveolar Nerve: A Case Report and Review of the Literature

The inferior alveolar nerve (IAN) is a branch of the mandibular nerve, the third division of the trigeminal nerve (V cranial nerve). Its location and course into the mandible is very important because of its susceptibility to the injury during any surgical or prosthetic approaches. Cone beam computed tomography (CBCT) is a three-dimensional imaging modality, with less exposure than multi slice computed tomography (MSCT), being considered an ideal imaging tool for maxillofacial diagnosis. We present an unusual extramandibular submucosal course of IAN in relationship with a mandibular exostosis, and with no association with the sensory disorder. J Med Cases. 2018;9(12):403-405 doi: https://doi.org/10.14740/jmc3215

Masticatory Muscles and Branches of Mandibular Nerve: Positional Relationships Between Various Muscle Bundles and Their Innervating Branches.

The masticatory muscles, which are composed of four main muscles, are innervated by branches of only one of the cranial nerves, the mandibular nerve. This muscle group has a variety of very complex functions. We have investigated the origins and insertions of the masticatory muscles and the adjacent bundles of the main muscles, and closely examined the positional relationships between the muscle bundles and innervating branches. According to the findings of the nerve branching patterns, the masticatory muscles can be classified into two groups: the inner group consisting of the lateral pterygoid muscle, and the outer group consisting of the other muscles and adjacent muscle bundles. Further, the outer muscle group is sub-divided into the three other main muscles (the masseter, the temporalis, and the medial pterygoid muscle) and the adjacent various transitional muscle bundles. Anat Rec, 302:609-619, 2019. © 2018 Wiley Periodicals, Inc.

In Situ Hybridisation Study of Neuronal Neuropeptides Expression in Models of Mandibular Denervation with or without Inflammation: Injury Dependant Neuropeptide Plasticity

Neuronal expression of neuropeptides is altered following peripheral tissue injury associated with inflammation or nerve injury. This results in neuropathic pain with or without neurogenic inflammation which is a major health problem regularly seen in trigeminal neuralgia. Activation of the trigeminal system results in the release of vasoactive neuropeptides substance P and Calcitonin Gene-related Peptide (CGRP) which contribute to nociception, pain and neurogenic inflammation in injured tissues.AimTo study the alterations in the neuronal neuropeptides expressions in models of tissue injury associated with either nerve injury or with inflammation and to determine if denervation would alter the neuronal response to inflammation.Material and methodsExperiments were performed on rat mandibles to produce three models. Firstly, denervation model by sectioning one of the mandibular nerve branches (inferior alveolar nerve). Secondarily, inflammation model by intra-gingival injection of lipopolysaccharide (LPS). Thirdly, combined denervation and inflammation model by sectioning the nerve with subsequent LPS injection. The animals were sacrificed seven days postoperative. Trigeminal ganglia on the operated sides were processed for in situ hybridisation for neuropeptides; substance P and CGRP mRNAs. Images were analysed for morphological and morphometric analysis using Image J software.Resultssubstance P and CGRP mRNAs were expressed in small and medium-size primary afferent neurons in the mandibular division of the trigeminal ganglia. Both the denervation and the inflammation models showed alteration in neuropeptides expression in the sensory primary afferent neurons innervating the affected mandibular tissues. While, denervation resulted in a significant (substance P=P<0.04, CGRP=P<0.01) downregulation contrarily, inflammation resulted in a significant (P<0.001) upregulation of neuropeptides’ mRNAs. Interestingly, denervation prior to induction of inflammation resulted in insignificant changes in neuropeptides levels. There was a strong correlation (Pearson Correlation=0.8) between substance P and CGRP expression.ConclusionWe show that tissue damage associated with nerve injury or inflammation results in alteration of neuropeptides levels in the innervating primary afferent neurons. Tissue destruction associated with chronic inflammatory condition such as arthritis and periodontitis are believed to be due to the production of neuromodulators causing neurogenic inflammation. Here we show that denervation abolishes the neuronal response to inflammation. Therefore, tissues denervation could relieve neurogenic inflammation associated with chronic disorders through regulation of neuronal neuropeptide production. Moreover, the current model that combined denervation and inflammation provides a useful animal model to study the contribution of nerve-related mediators in the pathophysiology of tissue injury.

A typical Communicating Pattern between Branches of Mandibular Nerve: Clinical Significance &amp; Review

The posterior division of the mandibular nerve is known to have three branches in the infra temporal fossa namely lingual, inferior alveolar and auriculotemporal nerves. These branches mainly innervate oral and temporomandibular structures like tongue, lower gingiva, mandibular bone, teeth, and part of the lower lip, chin and salivary glands. We describe a case with unusual communications between these branches. The knowledge of any unusual communications among these branches is highly significant due to the various treatment procedures undertaken in the region.

Ossified Pterygospinous Ligament-An anomaly in the infratemporal region of human Skulls and its applied importance

Pterygospinous ligament stretches from pterygospinous process of lateral pterygoid plate to the spinous process of sphenoid bone. Ocassionally this ligament ossifies in elderly. We carried out a study in subharti medical college, Meerut on 50 adult dry skulls to observe ossification of pterygospinous ligament. In our study, bilateral completely ossified Pterygospinous ligament was found in only 2% of skulls and rest 98% showed no ossification of the ligament. This ligament lies in close relationship to foramen ovale thus may cause entrapment of various branches of mandibular nerve resulting in mandibular neuralgia. Knowledge of ossified pterygospinous ligament is of great importance to maxillofacial, dental surgeons and anesthetists.

Variations in the branching pattern of posterior division of mandibular nerve: a case report

Abnormal communications among the branches of mandibular nerve especially the posterior division are significant due to various procedures undertaken in this region. These variations are worth reporting as they pose serious implications in several interventions in this region, and may even lead to false diagnosis. During routine dissection, the mandibular nerve and its branches were dissected in the infratemporal fossa. The branches from the posterior division of the mandibular nerve namely the inferior alveolar and auriculotemporal nerves were carefully dissected, and their abnormal branching pattern was noted. There was a communicating branch between left inferior alveolar and auriculotemporal nerve. There was also a variant recurrent branch from the left inferior alveolar nerve that supplied the lateral pterygoid muscle. Such variant branches and communications between the branches of mandibular nerve as seen in this case have an embryological basis and are clinically important in this region especially for dental surgeries and anesthesia.

Pterygospinous Bar and Foramen in the Adult Human Skulls of North India: Its Incidence and Clinical Relevance

Study of skulls has attracted the attention of anatomists since ages and sporadic attempts have been made to study skulls from time to time. Talking about the pterygoid processes of sphenoid bone, the irregular posterior border of lateral pterygoid plate usually presents, towards its upper part, a pterygospinous process, from which the pterygospinous ligament extends backwards and laterally to the spine of sphenoid. This ligament sometimes gets ossified as pterygospinous bar and a foramen is then formed, named pterygospinous foramen, for the passage of muscular branches of mandibular nerve. The present study was undertaken to observe the incidence and status of pterygospinous bony bridge and foramen, its variations, and clinical relevance in the adult human skulls of North India. For this purpose, 500 skulls were observed, belonging to the Anthropology Museum of Department of Anatomy, GSVM Medical College, Kanpur. Pterygospinous bars were found to be present in 51 skulls (10.2%), out of which completely ossified pterygospinous bony bridges were present in 20 skulls (4%) while 31 skulls (6.2%) had incompletely ossified pterygospinous ligaments. Such variations are of clinical significance for radiologists, neurologists, maxillofacial and dental surgeons, and anaesthetists, too.

Unique variation in the course of maxillary artery in infratemporal fossa: a case report

Maxillary artery is one of the key contents of the infratemporal fossa. Mandibular nerve and its branches form a clinically important relation of maxillary artery in this region. A comprehensive knowledge of variations of maxillary artery in the fossa is of special relevance in oral maxillofacial surgeries, management of epistaxis, intractable neuralgias or headaches. We found a unique variation of maxillary artery, presenting bilaterally, in relation to branches of mandibular nerve. During routine dissection in a 55-year-old male cadaver, maxillary artery was seen passing deep to lateral pterygoid muscle and crossed through the nerve loop formed between two roots of auriculotemporal nerve and posterior division of mandibular nerve. Further course of maxillary artery was medial to the posterior division of mandibular nerve. Maxillary artery gave its middle meningeal artery branch as it traversed through the nerve loop. A tortuous course taken by maxillary artery can lead to its entrapment causing headaches or nerve irritation presenting with neuralgia.

Foramen of civinini: a new anatomical guide for maxillofacial surgeons.

Study on Morphometric and radiological aspect on existence of foramen of civinini. Sphenoid bone comprises of some rare ossified ligaments, may encounter difficulty in surgical procedures. Incidence of Pterygospinous bars various with different racial groups and they are genetically controlled. Complete ossification of pterygospinous ligament form foramen of civinini. Entrapments of vessels or nerves may occur due to existence of pterygospinous bar. The bar may locate medially or inferiorly to formen ovale as seen in Hawaiian and lemurs. Co - existence of bar with the wide lateral pterygoid plate exhibits development of the bar from herbivore, carnivore and old world monkeys. Comparatively absence or small spine of civinini noted in new world monkeys, rodents and platyrrhines. Pterygospinousbar represents the phylogenetic remnant of Human beings. By using digital vernier caliper, the measurements of length, width of the pterygospinous bar and area of foramen of civinini including the length and breadth of lateral pterygoid plate were measured. Using X rays the radiological view was determined. In this study from 160 cases of skull and sphenoid bones revealed that complete and incomplete foramen of civinini in 1.25% and 7.5% of cases respectively. Peculiarly accessory foramen of civinini noticed in 1.25% of cases. Maximum area of foramen of civinini was 94.2mm(2). The maximum width of lateral pterygoid was noted as 19.6mm respectively. Mentocoronal view of skiagram clearly shows the bar. During Anaesthesia for trigeminal neuralgia may encounter difficult to pass the needle. The bar compress the mandibular nerve branches can cause lingual numbness, pain and speech impairment. Conductive anaesthesia on the mandibular nerve through the lateral subzygomatic route may be difficult to approach. Exploring the anatomical and clinical updates of pterygospinous bar may guide the surgeons and radiologists to overcome any difficulties in infratemporal and para or retropharyngeal regions.

Fetal developmental change in topographical relationship between the human lateral pterygoid muscle and buccal nerve

In adults, the lateral pterygoid muscle (LPM) is usually divided into the upper and lower heads, between which the buccal nerve passes. Using sagittal or horizontal sections of 14 fetuses and seven embryos (five specimens at approximately 20-25 weeks; five at 14-16 weeks; four at 8 weeks; seven at 6-7 weeks), we examined the topographical relationship between the LPM and the buccal nerve. In large fetuses later than 15 weeks, the upper head of the LPM was clearly discriminated from the lower head. However, the upper head was much smaller than the lower head in the smaller fetuses. Thus, in the latter, the upper head was better described as an 'anterior slip' extending from the lower head or the major muscle mass to the anterior side of the buccal nerve. The postero-anterior nerve course seemed to be determined by a branch to the temporalis muscle (i.e. the anterior deep temporal nerve). At 8 weeks, the buccal nerve passed through the roof of the small, fan-like LPM. At 6-7 weeks, the LPM anlage was embedded between the temporobuccal nerve trunk and the inferior alveolar nerve. Therefore, parts of the LPM were likely to 'leak' out of slits between the origins of the mandibular nerve branches at 7-8 weeks, and seemed to grow in size during weeks 14-20 and extend anterosuperiorly along the infratemporal surface of the prominently developing greater wing of the sphenoid bone. Consequently, the topographical relationship between the LPM and the buccal nerve appeared to 'change' during fetal development due to delayed development of the upper head.