Pterygoid Muscle Research Articles

Tractography analysis results of the trigeminus nerve, which contains fibers responsible for proprioception sensation and motor control in Adolescent Idiopathic Scoliosis.

Cross-sectional Study. It is not yet clear whether the loss of proprioceptive sensation and muscle weakness seen in adolescent idiopathic scoliosis (AIS) is the result of central nervous system dysfunction or secondary to spinal deformity. In our study, in order to find an answer to this question, we examined the microarchitecture of the nervus trigeminus, which is least affected by spinal deformity and contains both proprioceptive sensory and motor fibers. In this single-center, cross-sectional cohort study, 40 Lenke Type 3 (27 female, 13 male) AIS patients and 40 (25 female, 15 male) healthy individuals between the ages of 10-18 years. Tractography of the nervus trigenimus was performed using the "DSI Studio" program. The volumes of the targeted musculus pterygoideus lateralis and musculus pterygoideus medialis were measured using the Insight Segmentation and Registration Tool Kit (ITK -SNAP) program. The data were evaluated using the Statistical Package for the Social Sciences 22.0 program for Windows. There was no significant difference between the two groups in terms of baseline characteristics (p˃0.05). Left nervus trigeminus fiber number and fiber ratio were significantly higher in the control group compared to the scoliosis group p < 0.05. Right and left lateral pterygoid muscle showed lower volume and volume percentage in the scoliosis group compared to the control group (p < 0.05). According to the study data, proprioceptive sensory and motor control dysfunction in AIS is predicted to develop independently of spinal deformity.

Ultrasonographic assessment of the lateral pterygoid muscle for BoNT-A injection.

The upper head of the lateral pterygoid muscle (LPM) is known to insert into the capsule of the temporomandibular joint and articular disc, and therefore its relationship with temporomandibular disorders (TMD) has been consistently suggested. The aim of the study was to determine the anatomical features of the LPM using ultrasonographic (US) imaging. Around 120 hemifaces from 60 healthy Korean volunteers were included in this study. US images were taken with the subject's mouth 2 cm open. The transducer was placed at a position where the infratemporal fossa could be observed through the mandibular notch, and its position was recorded. The locations of the coronoid process (CorP), lateral margin of the condylar process (ConP), and midpoint of CorP and ConP (MP) were measured with reference to the ala-tragus line. The thicknesses of the skin and subcutaneous tissue, the masseter muscle, the temporalis muscle, and the depth of the LPM were measured at the MP. The masseter muscle, temporalis muscle, and LPM were observed in all cases and located in order from superficial to deep. The MP was located 39.6 ± 3.3 mm anterior and 7.8 ± 1.6 mm inferior to the tragus. The thicknesses of the skin and subcutaneous tissue, the masseter muscle, the temporalis muscle, and the depth of the LPM at the MP were 9.7 ± 1.0, 10.3 ± 1.3, 10.9 ± 1.6, and 30.9 ± 1.9 mm, respectively. The information reported in this study may be useful for determining the location of the LPM and adjacent anatomical structures in TMD patients and provide accurate and safe injection guidelines.

Arthroscopic Anatomy of the anteromedial wall of the temporomandibular joint: Implications in articular disc displacement

Numerous anatomical and imaging studies have established a close relationship between disc displacement of the temporomandibular joint (TMJ) and the medial wall of the TMJ. These studies have revealed a direct association between disc displacement without reduction (DDWoR) and the occurrence of fatty degeneration within the superior fascicle of the lateral pterygoid muscle (SPLM). While the etiology of this phenomenon remains unclear, it has been suggested that it stems from the interaction between this muscle fascicle and the bony surface of the medial wall of the joint.

Effectiveness of Laser Therapy in Treatment of Temporomandibular Joint and Muscle Pain.

Background/Objectives: Temporomandibular joint disorders (TMDs) express a condition derived from a broad spectrum of etiological factors and clinical manifestations. Many treatment options have been developed for TMDs; nevertheless, conservative and non-invasive approaches ought to be prioritized. Laser therapy is an effective treatment for pain management due to its non-invasive nature and capacity for tissue regeneration. This review aimed at bringing an overview of the present evidence regarding the efficiency of laser therapy on myofascial or temporomandibular joint disorders pain. Methods: The search was conducted in four electronic databases: PubMed, Web of Science, Embase, and Scopus, of studies published between January 1997 and January 2023. The following terms have been extensively searched: "laser treatment", pain management", "temporomandibular joint disorders", "masseter muscle pain", "pterygoid muscle pain", and "temporal muscle pain". The inclusion criteria were original papers, available in full text, and written in English. Cohen's Kappa coefficient was used to assess the inter-rater reliability for article selection. The methodological quality was assessed with the Cochrane Risk of Bias tool for randomized controlled trials and the National Heart, Lung, and Blood Institute's quality assessment tool for before-after studies with no control group. Results: Out of 846 identified records, 7 studies were included, of which 5 were randomized controlled trials. The inter-rater reliability for article selection showed an almost perfect agreement (Cohen's Kappa = 0.832, p < 0.001). The protocol of laser application was not standardized; the laser wavelength ranged from 633 to 940 nm, with a power output range from 25 to 1600 mW. The number of sessions varied from 3 to 12, with a frequency of application from 1 time per week to 3 times per week. All studies reported pain reduction after laser therapy. Conclusions: Laser therapy is an efficient method to treat TMDs related to muscle pain. To accomplish the desired results, a standard procedure must be followed; however, the protocol is still not fully designed.

Successfully Modified Dillman-Anderson Myectomy for Marcus Gunn Jaw Winking Ptosis Repair: A Case Report

Introduction: Marcus Gunn jaw winking ptosis (MGJWP) is a type of ptosis present from birth which is characterized by winking of the ptotic eyelid during jaw movement. Case illustration: A 6-years-old child came with a complaint of a right eyelid drooping since birth. The eyelid droop was not progressive. Patient had difficulty to read at a distance, since two years ago. The eyelids moved when the patient chews, sucks, or moving jaw from side to side. Examination did not demonstrate any apparent ptosis of either eyelid nor the movement of eyelids when chewing. On examination of ptosis status on right/left eye, MRD1:0/3, MLD:1/5,LA:4/12 and FIP:6/10.Modified Dillman and Anderson’s myectomi with removal of levator muscle above whitnall’s ligament followed by frontalis suspension using autogenous fascia lata was performed successfully on this patient. Discussion: MGJWP is ptosis in one eye since birth which causes the ptosis eyelid to wink due to provocation of the same side pterygoid muscle. The jaw winking movement is caused by mouth movements such as opening, moving the mouth to the right and left, chewing and sucking. Modified Dillman and Anderson's myectomi with removal of levator muscle followed by frontalis suspension was chosen because it has a better outcome. In the postoperative period, there were no more complaints of ptosis and the jaw winking was resolved. Serious postoperative complications of this surgical technique such as entropion, worsening jaw winking and exposure keratopathy were not found. Conclusion: For severe MJGWP , Modified Dillman and Anderson’s myectomy technique gives satisfactory results in both ptosis correction and jaw winking without serious complications.

A new and simplified extraoral approach for inferior alveolar nerve block: a cadaveric study and clinical case reports.

Inferior alveolar nerve (IAN) and lingual nerve (LN) blocks are commonly performed using the intraoral landmark techniques. However, these methods have a risk of unanticipated nerve and arterial injury or a higher failure rate. We developed a novel extraoral approach for the IAN and LN blocks, the "inferior alveolar nerve block mandibular angle approach (IANB-MA)," using ultrasound guidance. The mechanism of action of this nerve block was examined anatomically, and its clinical feasibility was reported. We performed the IANB-MA on four cadavers using different dye volumes (2, 4, 6 and 8mL). The ultrasound probe was placed on the lower edge of the mandibula of each cadaver, and the needle was advanced to the mandibular inner surface. Blue acrylic paint solution was injected, and its spread was evaluated by dissection. Our study showed that the medial pterygoid muscle fascia was stained in all cadavers. The dye reached the LN consistently, and the IAN was stained with higher volumes (6mL and 8mL). The pterygomandibular space was filled with 6mL and 8mL of the dye. The IANB-MA successfully reduced pain in three patients with trigeminal neuralgia, tongue or jaw pain. The IANB-MA is a novel ultrasound-guided approach to the IAN and the LN. The clinical feasibility and effectiveness of this technique were confirmed in our patients. It may be a good alternative analgesic approach to other conventional approaches.

The anatomy of mastication in a toothless mammal: Morphological characteristics of the temporomandibular joint in the platypus (Ornithorhynchus anatinus)

AbstractThe temporomandibular joint (TMJ) is a distinguishing feature of mammals, and in most mammals includes an articular disc that buffers the loads placed on it by mastication. The disc is well developed in mammals with significant lateral masticatory jaw movements but is absent in toothless mammals, including extant monotremes, although histological studies of developing monotremes have shown rudimentary discs that fail to mature. Platypus (Ornithorhynchus anatinus) grind their food between keratinous pads in the maxillae and lower jaws and are the only edentulate mammals that masticate their food. In this study, we characterize the anatomy of the TMJ of the adult platypus to see if we can reconcile the anatomy, including the absence of the articular disc, with the mandibular movements observed in video recordings. We studied the gross anatomy of the maxillofacial region and the microstructure using microcomputed tomography (micro‐CT) and histological examination. Platypuses had well‐developed masticatory muscles but lacked an articular disc between the mandibular condyle and glenoid fossa. The surface of the glenoid fossa was slightly concave than that of the condylar head was correspondingly slightly convex. The pre‐ and postglenoid processes were not well developed. Micro‐CT showed dense trabecular bone in the anterior part of the condyle, where the lateral pterygoid muscle attached. Histological analysis showed that the surfaces of the condyle and glenoid fossa consisted of dense, avascular and thickened fibrous connective tissue. In addition, well‐developed synovial folds were present. These anatomical characteristics are consistent with both anterior and lateral movements of the mandible, while the thick layer of connective tissue substitutes for a disc by absorbing the mechanical stresses associated with mastication. The failure of the disc primordium to develop cannot be attributed to a lack of muscle development, but the distribution of stresses in the toothless platypus jaw is likely to be different from those in a masticating eutherian.

A head-to-head comparison of 18F-FDG PET/CT and 18F-FDG PET/MR in patients with nasopharyngeal carcinoma under different disease settings.

Positron emission tomography/computed tomography (PET/CT) and magnetic resonance imaging (MRI) are complementary in staging of nasopharyngeal carcinoma (NPC). The combination of MRI and functional imaging from PET in PET/MR is promising in NPC management. Diagnostic performance of PET/CT and PET/MR was compared in 46 patients with histologically confirmed NPC under different disease scenarios, including primary non-metastatic cases, primary metastatic cases, recurrence and/or metastasis after treatment, and post-treatment follow-up cases. Forty-six patients underwent both PET/CT and PET/MR in the same day. Primary tumor extension into risk-stratified anatomic structures, retropharyngeal and cervical lymph node metastasis, distant metastasis and post-treatment follow-up results, were compared. For high-risk structures, PET/MR detected two more sides of tensor/levator veli palatine muscle involvement, one more case of clivus involvement, and ruled out 12 false-positive sides of prevertebral muscle involvement by PET/CT. For medium-risk structures, PET/MR detected four more sides of medial pterygoid muscle involvement. For low-risk structures, abnormal signal on massa lateralis atlantis was detected by PET/MR. PET/MR detected 14 more positive retropharyngeal lymph nodes and more liver micrometastases than PET/CT. Overall, PET/MR changed two patients' T staging. Positron emission tomography/MR outperforms PET/CT in delineating muscle, skull-base bone, and nodal involvement, and identifying liver micrometastases, may serve as a single-step staging modality for NPC.

Correlation between GLCM-based texture features of the lateral pterygoid muscle and cognitive function in patients with idiopathic normal pressure hydrocephalus: a preliminary report.

The potential relationship between mastication ability and cognitive function in idiopathic normal pressure hydrocephalus (iNPH) patients is unclear. This report investigated the association between mastication and cognitive function in iNPH patients using the gray level of the co-occurrence matrix on the lateral pterygoid muscle. We analyzed data from 96 unoperated iNPH patients who underwent magnetic resonance imaging (MRI) between December 2016 and February 2023. Radiomic features were extracted from T2 MRI scans of the lateral pterygoid muscle, and muscle texture parameters were correlated with the iNPH grading scale. Subgroup analysis compared the texture parameters of patients with normal cognitive function with those of patients with cognitive impairment. The mini-mental state examination score correlated positively with the angular second moment (P < 0.05) and negatively with entropy (P < 0.05). The dementia scale (Eide's classification) correlated negatively with gray values (P < 0.05). Gray values were higher in the cognitive impairment group (64.7 ± 16.6) when compared with the non-cognitive impairment group (57.4 ± 13.3) (P = 0.005). Entropy was higher in the cognitive impairment group (8.2 ± 0.3) than in the non-cognitive impairment group (8.0 ± 0.3) (P < 0.001). The area under the receiver operating characteristic curve was 0.681 (P = 0.003) and 0.701 (P < 0.001) for gray value and entropy, respectively. Our findings suggest an association between heterogeneity of mastication and impaired cognitive function in iNPH patients and highlight muscle texture analysis as a potential tool for predicting cognitive impairment in these patients.

Trismus as a Sign of Metastasis of Lung Cancer to Lateral Pterygoid Muscle: A Rare Case Report

Trismus as a Sign of Metastasis of Lung Cancer to Lateral Pterygoid Muscle: A Rare Case Report

Re-classifying cT4b buccal mucosa / Gingivo-buccal complex cancers: Do we need to change?

IntroductionT4b carcinoma are termed as very locally advanced carcinoma of oral cavity. These tumors are deemed borderline resectable or unresectable. Role of surgery for these group of patients is not very well defined. We aimed to relook role of surgery for cT4b carcinoma oral cavity. Material and methodsWe evaluated 596 patients of cT4 oral cancers. Two hundred eighteen patients were stagged as cT4b based on clinico- radiological findings. These patients underwent bite composite resection either upfront or post neoadjuvant chemotherapy. Additional compartmental infratemporal fossa clearance was done for patients with involvement of more than 2 of following structures: medial and lateral pterygoid muscles, pterygoid plates, temporalis at tip of coronoid process, high masseter involvement and retroantral fat pad involvement. Oncological outcomes and prognostic factors were estimated. ResultsPatients were treated between Aug 2013 to May 2021. Compartmental ITF clearance was done for 93 patients and rest had standard surgical clearance. One hundred and twelve patients had node positive disease. The median age of group was 50 years (Range= 24 to 84 years). On a median follow up of 54 months (IQR = 1-111 months), 136 (62.4%) were alive and 82 (37.6%) patients died. Five year Loco-regional control, disease free survival and overall survival was 54%, 52% and 59% respectively. On multivariate analysis, presence of nodal disease, perineural invasion and bone involvement were significant factors affecting overall survival. ConclusionSurgery for cT4b oral cancer is feasible and associated with acceptable oncological outcomes.

A New Method in Dealing With Children's Condylar Fracture by Botulinum Toxin A Injection in Lateral Pterygoid Muscle.

Condylar is one of the most vulnerable sites to be traumatized in pediatric mandible fracture, while temporomandibular joint ankylosis might be the most severe complication of condylar fracture in children. There exists a long-time controversy on the treatment of condylar fractures in children. Considering the risk of facial nerve injury and a certain probability of absorption or even ankylosis after open reduction and internal fixation (ORIF) of condylar fractures, a series of nonsurgical approaches are preferred in cases without severe malocclusion or shortening of the ramus. Our treatment plan was carried out through combining procedures of Botulinum toxin A injection in lateral pterygoid muscle with ORIF of para symphyseal fracture; subsequently, a conservative way of the occlusal splint with elastic traction was performed. Three patients of bilateral or unilateral condylar fractures, aged between 2y and 6y, were involved in this treatment. After more than 1 year's follow-up, the occlusion was satisfactory in all patients. Condylar remodeling was approximately complete in 3 months, and no unwanted complications were observed. We may expect this method to offer a new idea when dealing with children's condylar fracture.

Decreased Rates of Radiation-induced Trismus and Lowered Mastication Structure Doses in Patients Treated for Head and Neck Cancer During the Last Two Decades

AimsTo investigate how absorbed doses to mastication structures in modern radiotherapy (RT) technique for head and neck cancer (HNC) compared with earlier RT techniques and with published trismus tolerance doses. To compare the incidence of radiation-induced trismus by earlier and newer RT techniques. Materials and methodsThis study investigated two HNC patient cohorts treated with RT in 2007–2012 (three-dimensional conformal radiotherapy [3DCRT] and/or intensity-modulated radiotherapy [IMRT]; n =121 [Cohort 1]) and 2017–2020 (volumetric-modulated arc therapy [VMAT]; n =124 [Cohort 2]). All patients underwent RT without mastication structure–sparing intent, had normal mouth-opening ability before RT, and were prospectively assessed. Trismus was defined as the maximal interincisal opening ≤35 mm at any follow-up (3-, 6-, and 12-months post-RT). The temporomandibular joints (TMJs), masseter, and medial/lateral pterygoid muscles were delineated on the planning CT:s. Mean doses were compared between cohorts, and evaluated with respect to published trismus tolerance doses. P values ≤ 0.05 indicated statistical significance. ResultsWithin 12 months post RT, 74/121 (61%) of patients in Cohort 1 had experienced trismus compared to 11/124 (9%) in Cohort 2. Averaged mean doses (±S.D.) for the masseter muscles were 35.2±8.3 Gy in Cohort 1 and 20.2±8.7 Gy in Cohort 2 (P <0.001). Corresponding numbers were 19.1±16.2 and 4.3±4.3 Gy for the TMJs, 53.7±10.1 and 40.2±16.8 Gy for the medial pterygoid muscles, and 29.2±18.7 and 9.2±8.4 Gy for the lateral pterygoid muscles (all P <0.001). Masseter muscle doses were below tolerance doses in 23% of patients in Cohort 1 compared with 90% in Cohort 2. The corresponding numbers were 52% and 96% for the TMJs, 8% and 36% for the medial pterygoid muscles and 72% and 100% for the lateral pterygoid muscles. ConclusionMastication structure mean doses by more recent RT techniques were generally below proposed tolerance doses, with dose reductions of 10–20 Gy compared with earlier techniques. Modern RT without mastication-structure-sparing intent resulted in below 10% of HNC patients experiencing trismus compared with 60% treated with earlier techniques.

Multicriteria optimization of radiation therapy: Towards empowerment and standardization of reverse planning for head and neck squamous cell carcinoma

PurposeThe purpose of this study was to assess if multicriteria optimization could limit interoperator variability in radiation therapy planning and assess if this method could contribute to target volume coverage and sparing of organ at risk for intensity-modulated curative radiation therapy of head and neck cancers. Material and methodsWe performed a retrospective analysis on 20 patients treated for an oropharyngeal or oral cavity squamous cell carcinoma. We carried out a comparative dosimetric study of manual plans produced with Precision® software, compared with the plans proposed using the multicriteria optimization method (RayStation®). We assessed interoperator reproducibility on the first six patients, and dosimetric contribution in sparing organs at risk using the multicriteria optimization method. ResultsMedian age was 69 years, most lesions were oropharyngeal carcinoma (65%), and 35% lesions were stage T3. First, we obtained a high degree of similarity between the four operator measurements for each patient at the level of each organ. Intraclass correlation coefficients were greater than 0.85. Second, we observed a significant dosimetric benefit for contralateral parotid gland, homolateral and contralateral masseter muscles, homolateral and contralateral pterygoid muscles and for the larynx (P<0.05). For the contralateral parotid gland, the mean dose difference between the multicriteria optimization and manual plans was −2.0Gy (P=0.01). Regarding the larynx, the mean dose difference between the two plans was −4.6Gy (P<0.001). ConclusionMulticriteria optimization is a reproducible technique and faster than manual optimization. It allows dosimetric advantages on organs at risk, especially for those not usually taken into consideration in manual dosimetry. This may lead to improved quality of life.

Dysphagia and Trismus After Tooth Extraction : Clinical Conondrum.

Clinicians should consider disorders of masticatory muscle including lateral pterygoid muscle as a differential diagnosis in patients presenting with dysphagia and trismus after tooth extraction.

The Maxillary Nerve Block in Cleft Palate Care: A Review of the Literature and Expert's Opinion on the Preferred Technique of Administration.

Although the maxillary nerve block (MNB) provides adequate pain relief in cleft palate surgery, it is not routinely used globally, and reported techniques are heterogeneous. This study aims to describe relevant anatomy and to present the preferred technique of MNB administration based on the current literature and the expert opinion of the authors. First, a survey was sent to 432 registrants of the International Cleft Palate Master Course Amsterdam 2023. Second, MEDLINE (PubMed interface) was searched for relevant literature on maxillary artery (MA) anatomy and MNB administration in pediatric patients. Survey response rate was 18% (n=78). Thirty-five respondents (44.9%) used MNB for cleft palate surgery before the course. A suprazygomatic approach with needle reorientation towards the ipsilateral commissure before incision was most frequently reported, mostly without the use of ultrasound. Ten and 20 articles were included on, respectively, MA anatomy and MNB administration. A 47.5% to 69.4% of the MA's run superficial to the lateral pterygoid muscle and 32% to 52.5% medially. The most frequently described technique for MNB administration is the suprazygomatic approach. Reorientation of the needle towards the anterior aspect of the contralateral tragus appears optimal. Needle reorientation angles do not have to be adjusted for age, unlike needle depth. The preferred anesthetics are either ropivacaine or (levo)bupivacaine, with dexmedetomidine as an adjuvant. Described MNB techniques are heterogeneous throughout the literature and among survey respondents and not routinely used. Further research is required comparing different techniques regarding efficacy and safety.

Temporomandibular Joint Histology

Background: The temporomandibular joint plays a crucial role in daily oral functions like mastication. A comprehensive understanding of the histological components of these joints proves valuable in deciphering their intricate anatomical structures. Purpose of the study: This study aimed to compare the histochemical stains of hematoxylin-eosin and Goldner's trichrome applied to a temporomandibular joint sample using the Wistar Rat as a biomodel. Results: Complete sagittal slices of murine biomodel hemicranium were evaluated and the comprehensive histological technique involved various steps, including perfusion, post-fixation, decalcification, dehydration, clarification, inclusion, cutting, staining, and assembly. The temporomandibular joint specimens were stained using H&amp;E and Goldner's trichrome. The histological description included structures such as the external auditory canal, mandibular fossa and condyle, pterygoid muscles, joint capsule, synovial membrane, articular disc, and articular surface. Special cell types like chondrocytes and synovial cells were also identified. Conclusion: Goldner's trichrome, an underutilized technique, exhibited superior chromatic richness in differentiating the cellular and tissue components of the temporomandibular joint. KEYWORDS: histology, joint capsule, synovial membrane, temporomandibular joint, temporomandibular joint disc, trichrome stain, Wistar rats.

Anatomical factors influencing temporomandibular joint clicking in young adults: temporomandibular joint structure disorder or lateral pterygoid muscle dysfunction?

Objective: This study aimed to investigate the selected anatomical factors that can potentially influence temporomandibular joint (TMJ) clicking in young adults by assessing TMJ structures and lateral pterygoid muscle (LPM) function using magnetic resonance imaging (MRI). Methods: The patients were divided into four groups: the healthy control group; the clicking on mouth opening group; the clicking on mouth closing group; and the clicking on mouth opening and closing group. Additionally, we used clinical palpation to evaluate the masticatory muscles' functional state and employed MRI using the OCOR-T1WI-FSE-CLOSED, OSAG-PDW-FSE-CLOSED, and OSAG-PDW-FSE-OPEN sequences to analyze the texture of the lateral pterygoid muscle (LPM). Results: The proportion of any articular disc or condylar morphology class did not differ significantly between the TMJ clicking and HC groups. The articular disc position did not differ significantly between the TMJ clicking and HC groups. In the TMJ clicking group, the presence of masticatory muscle dysfunction differed significantly between the clicking and non-clicking sides. Moreover, the LPM accounted for the highest proportion among masticatory muscles with tenderness in all TMJ clicking subgroups (77.78%-100%). Therefore, in the TMJ clicking group, the LPM texture was less defined, more uniform in gray scale, and more similar to local texture (p < 0.0001). Conclusion: The occurrence of TMJ clicking in young adults is unrelated to the TMJ structure but related to the function of masticatory muscles, particularly the LPM.

Trismus caused by migration of orthodontic archwire into the infratemporal fossa: a case report.

Soft tissue injuries are known complications of orthodontic treatment. Most of the injuries are mild, but severe complications can arise from deeper penetration or dislodgement of brackets and other foreign bodies into the surrounding tissues of the oropharynx and infratemporal fossa. The patient, accompanied by his parents, presented to the Children's Emergency Department with the concern of gradual limitation of mouth opening and eventual trismus, which occurred over a span of 2 weeks. The patient presented with trismus and slight discomfort at the left cheek region. He reported a history of gradual limitation to his mouth opening 2 weeks prior. He was wearing upper and lower fixed orthodontic appliances and the left distal end of the maxillary archwire was found to have migrated into the left infratemporal fossa. Left medial pterygoid muscle inflammation, or bleeding and haematoma formation, or infection within the infratemporal region. The maxillary archwire was removed in the Children's Emergency Department and a computed tomography (CT) scan performed subsequently confirmed the diagnosis of left medial pterygoid muscle inflammation. The patient was started on an intravenous (IV) antibiotic and a 2-day course of IV dexamethasone to reduce the muscle inflammation. By the second day, the patient was able to achieve a mouth opening of 6 mm, and by the second week, the mouth opening had returned to normal. The potential risk of soft tissue injury and complications from orthodontic treatment is generally mild and limited. Soft tissue injuries can be avoided with careful management by the operator with the proper precautions taken. Clinicians should be familiar with the surrounding soft tissue anatomy and be aware of the potential for more severe complications and provide management or referral to the appropriate specialty accordingly.

Pterygoideus proprius muscle: stuck between the greater wing and lateral pterygoid plate.

The muscles of mastication derive from a common embryological source, and the presence of accessory muscles in the infratemporal fossa (ITF) is uncommon. Here, we present findings from postmortem dissection of the ITF revealing a unilaterally present muscle extending from the greater wing of the sphenoid to blend inferiorly with the medial and lateral pterygoid muscles before attaching to the lateral pterygoid plate. This muscle is most consistent with the pterygoideus proprius muscle initially described in 1858. Though the exact embryological origin and function of this muscle remain speculative, these topics are nonetheless worth investigating as it may provide insight regarding the ontogeny of muscles descending from the first pharyngeal arch. Additionally, presence of the pterygoideus proprius muscle may have clinical implications and impact surrounding structures such as the mandibular division of the trigeminal nerve, maxillary artery, pterygoid venous plexus, masticatory muscles, and temporomandibular joint (TMJ).