Fatty infiltration and morphology of cervical muscles in patients with temporomandibular disorders: A case-control study.

BACKGROUND: Changes in the fatty infiltration and/or muscle volume of neck muscles can alter cervical spine alignment and cranial load distribution, which may cause pain in the orofacial region. OBJECTIVES: The aim of the study was to examine the muscle volume and fatty infiltration of neck muscles in patients with temporomandibular disorders (TMD). MATERIAL AND METHODS: This case-control study included 18 patients with TMD and 18 ageand sex-matched controls. The muscle volume and fatty infiltration of the neck muscles of the participants were measured using magnetic resonance imaging (MRI) and ITK-SNAP software. The 3D models of the sternocleidomastoid (SCM), splenius capitis (SPLC), semispinalis cervicis (SC)-semispinalis capitis (SCP), and multifidus (M) muscles within the C3-C7 range were created using ITK-SNAP, a semi-automatic segmentation software. The models were used to determine the volumes and fatty infiltration levels. The Neck Disability Index (NDI) was used to assess neck pain-related disability. The severity of TMD was determined using the Fonseca Anamnestic Index (FAI), while jaw-related disability was measured with the Jaw Functional Limitation Scale-20 (JFLS-20). Pain levels were recorded at rest and during chewing using the numeric rating scale (NRS). RESULTS: There were no statistically significant differences in total muscle volume, fatty infiltration volume and fatty infiltration percentage of the SCM, SPLC, SCP, SC, and M muscles between the 2 groups (p > 0.05). The patient group had higher NDI scores compared to the controls (p < 0.001). The NDI scores correlated positively with the JFLS-20 (r = 0.831, p < 0.001), FAI (r = 0.815, p < 0.001) and NRS scores at rest (r = 0.753, p < 0.001) and during chewing (r = 0.686, p < 0.001). CONCLUSIONS: The present study did not identify any significant differences in the neck muscle volume or fatty infiltration between the TMD patients and controls. However, the severity of neck disability was found to correlate with jaw function, pain and TMD levels.

Neck muscle function improves after neck exercises in individuals with whiplash-associated disorders: a case-control ultrasound study with speckle-tracking analyses.

A whiplash injury can alter neck muscle function, which remains years after the injury and may explain why symptoms such as persistent pain and disability occur. There is currently limited knowledge about dynamic neck muscle function in chronic whiplash-associated disorders (WAD), and about the extent to which altered muscle function can improve after rehabilitation. Ultrasound can detect mechanical neck muscle function by measuring real-time deformation and deformation rate in the muscles. This method was used for five dorsal neck muscles in participants with chronic WAD versus matched controls in resistant neck rotation. We obtained real-time, non-invasive ultrasound measurements using speckle tracking, multivariate analyses, and mixed-design ANOVA analyses. The results showed altered deformation in the three deepest neck muscle layers, with less deformation area in the WAD group compared to controls in rotation to the most painful side at baseline. Participants in the WAD group performed three months of neck-specific exercises, resulting in improved deformation in the deep neck muscles in WAD and with a similar deformation pattern to controls, and the significant group differences ceased. We reveal new and important insights into the capability of ultrasound to diagnose altered neck muscle function and evaluate an exercise intervention.

Muscle texture features on preoperative MRI for diagnosis and assessment of severity of congenital muscular torticollis.

OBJECTIVES: To develop an objective method based on texture analysis on MRI for diagnosis of congenital muscular torticollis (CMT). MATERIAL AND METHODS: The T1- and T2-weighted imaging, Q-dixon, and T1-mapping MRI data of 38 children with CMT were retrospectively analyzed. The region of interest (ROI) was manually drawn at the level of the largest cross-sectional area of the SCM on the affected side. MaZda software was used to obtain the texture features of the T2WI sequences of the ROI in healthy and affected SCM. A radiomics diagnostic model based on muscle texture features was constructed using logistic regression analysis. Fatty infiltration grade was calculated by hematoxylin and eosin staining, and fibrosis ratio by Masson staining. Correlation between the MRI parameters and pathological indicators was analyzed. RESULTS: There was positive correlation between fatty infiltration grade and mean value, standard deviation, and maximum value of the Q-dixon sequence of the affected SCM (correlation coefficients, 0.65, 0.59, and 0.58, respectively, P < 0.05).Three muscle texture features-S(2,2)SumAverg, S(3,3)SumVarnc, and T2WI extreme difference-were selected to construct the diagnostic model. The model showed significant diagnostic value for CMT (P < 0.05). The area under the curve of the multivariate conditional logistic regression model was 0.828 (95% confidence interval 0.735-0.922); the sensitivity was 0.684 and the specificity 0.868. CONCLUSION: The radiomics diagnostic model constructed using T2WI muscle texture features and MRI signal values appears to have good diagnostic efficiency. Q-dixon sequence can reflect the fatty infiltration grade of CMT.

Assessing the oral and suprahyoid muscles in healthy adults using muscle ultrasound to inform the swallowing process: a proof-of-concept study.

The oral and suprahyoid muscles are responsible for movements of swallowing. Our study aimed to determine the reproducibility of static and dynamic measurements of these muscles using bedside ultrasound equipment. Forty healthy participants were recruited prospectively. Primary outcomes were evaluation of mass measurements of the anterior bellies of the digastric, mylohyoid, geniohyoid and tongue in B-mode ultrasound. Secondary outcomes were evaluation of geniohyoid muscle layer thickness and function using M-mode. Muscle mass measurements demonstrated little within-participant variability. Coefficient of Variance (CoV) across muscles were: anterior belly digastric (5.0%), mylohyoid (8.7%), geniohyoid (5.0%) and tongue (3.2%). A relationship between sex (r2 = 0.131 p = 0.022) was demonstrated for the geniohyoid muscle, with males having higher transverse Cross Sectional Area (CSA) (14.3 ± 3.6 mm vs. 11.9 ± 2.5 mm, p = 0.002). Tongue size was correlated with weight (r2 = 0.356, p = 0.001), height (r2 = 0.156, p = 0.012) and sex (r2 = 0.196, p = 0.004). Resting thickness of the geniohyoid muscle layer changed with increasing bolus sizes (f = 3.898, p = 0.026). Velocity increased with bolus size (p = < 0.001, F = 8.974). However swallow time and slope distance did not, potentially influenced by higher coefficients of variation. Oral and suprahyoid muscle mass are easily assessed using bedside ultrasound. Ultrasound may provide new information about muscle mass and function during swallowing.

MRI and frozen section evaluation of mylohyoid muscle in determining surgical approach for T2-T3 floor of the mouth cancer.

PURPOSE: The choice of surgical approach for floor of the mouth (FOM) cancer, particularly for intermediate-stage tumors (cT2-cT3), remains controversial. This study aims to evaluate a method considering mylohyoid muscle (MM) invasion as a determinant for surgical approach selection, utilizing magnetic resonance imaging (MRI) preoperatively and frozen section (FS) analysis intraoperatively. METHODS: This observational retrospective cohort study analyzed patients undergoing surgical resection of cT2 and cT3 FOM squamous cell carcinoma (SCC) between January 2013 and June 2023. MM infiltration assessed by preoperative MRI determined the surgical approach: clear infiltration led to compartmental surgery (CS), while doubtful or absent infiltration led to transoral surgery (TOS). Conversion from TOS to CS occurred intraoperatively based on macroscopic evidence or positive FS. Data collected included demographic, clinical, surgical, and pathological variables. Survival analysis was conducted using Kaplan-Meier method. RESULTS: Among 44 patients included, majority had cT2 tumors (59.1%). MM resection was necessary in 22.7% of cases. Overall survival (OS) and progression-free survival (PFS) did not significantly differ between TOS and CS groups. Radiological depth of invasion (rDOI) < 10 mm is correlated with MM preservation in 89% of cases, while rDOI > 10 mm is correlated with MM resection only in 23.8% of cases. Pathological depth of invasion (pDOI) discrepancies were observed in the two groups: in CS group is shown a higher pDOI (> 10 mm) confirmation (90%). Surgical complications and functional outcomes differed between TOS and CS groups. CONCLUSION: Considering MM invasion for surgical approach selection in cT2-cT3 FOM tumors appears oncologically safe, with better functional outcomes in muscle preservation. Preoperative MRI for MM assessment combined with intraoperative FS analysis provides reliable guidance for surgical decision-making.

Pyomyositis in the sternocleidomastoid muscle in a previously healthy 36-year-old woman.

Pyomyositis is a bacterial infection of striated muscle, usually located to muscles in the extremities or pelvis. We present a microbiologically unique case report of pyomyositis in the sternocleidomastoid muscle (the first of its kind in Denmark) caused by Staphylococcus epidermidis, S. capitis and possibly Streptococcus pneumoniae. Pyomyositis is very rare but can lead to critical complications such as endocarditis and sepsis. It is therefore important to know the condition when evaluating an infected patient with muscle pain. Treatment consists of antibiotics and - if relevant - surgical abscess drainage.

FDG uptake in the cervical muscles after neck dissection: imaging features and postoperative natural course on 18F­FDG­PET/CT.

PURPOSE: This study aimed to assess the imaging features and postoperative natural course of 18F-fluorodeoxyglucose (FDG) uptake in the cervical muscles after neck dissection. MATERIALS AND METHODS: This study included 83 patients who underwent preoperative and postoperative 18F-FDG-PET/CT and were diagnosed with head and neck malignancy after neck dissection. Postoperative 18F-FDG-PET/CT was performed within 5 years after neck dissection. Preoperative and postoperative FDG uptake of the trapezius, sternocleidomastoid, scalene, pectoralis major, and deltoid muscles was visually assessed. Increased postoperative uptake was visually defined as higher postoperative FDG uptake than the preoperative one in the corresponding muscle. The maximum standardized uptake value (SUVmax) was measured in cases with increased postoperative uptakes. RESULTS: Increased postoperative uptakes were observed in 43 patients (52%). The trapezius (31/83, 37%), sternocleidomastoid (19/83, 23%), and scalene (12/83, 14%) muscles were involved, as opposed to the pectoralis major and deltoid muscles were not. Increased postoperative uptakes were observed on the dissected side in all 43 patients. Significant differences between SUVmax estimated from the mixed-effects model and postoperative months were observed in the trapezius muscle (Coefficient (ß) = -0.038; 95% confidence interval (CI): [-0.047, -0.028]; p < 0.001) and sternocleidomastoid muscle (ß = -0.015; 95% CI: [-0.029, -0.001]; p = 0.046). CONCLUSIONS: Increased postoperative uptakes in the cervical muscles were observed on the dissected side in approximately half of the patients after neck dissection. The SUVmax in the trapezius and sternocleidomastoid muscles decreased after surgery over time.

Longitudinal visibility of MRI findings in living victims of strangulation.

Initial experiences with magnetic resonance imaging (MRI) of living strangulation victims demonstrated additional findings of internal injuries compared to the standard clinical forensic examination. However, existing studies on the use of MRI for this purpose mostly focused on the first 48 h after the incident. The aims of this study were (a) to evaluate the longitudinal visibility of MRI findings after violence against the neck by performing two MRI examinations within 12 days and a minimum of four days between both MRI scans and (b) to assess which MRI sequences were most helpful for the detection of injuries. Twenty strangulation victims participated in this study and underwent one (n = 8) or two (n = 12) MRI scans. The first MRI examination was conducted during the first five days, the second five to 12 days after the incident. Two blinded radiologists assessed the MRI data and looked for lesions in the structures of the neck. In total, 140 findings were reported in the 32 MRI examinations. Most of the findings were detected in the thyroid and the muscles of the neck. T2-weighted SPACE with fat suppression, T1-weighted TSE and T1-weighted MPRAGE were rated as the most helpful MRI sequences. Subjects who showed findings in the initial scan also demonstrated comparable results in the second scan, which was performed on average 8.4 days after the incident. Our results show that even up to 12 days after the incident, the criminal proceeding of strangulation cases may greatly profit from the information provided by an MRI examination of the neck in addition to the standard clinical forensic examination.

Double Chin Concerns after En Bloc Mandibular U-Shaped Osteotomy: Submental-Cervical Soft Tissue Changes and Anterior Belly of Digastric Muscle Assessment.

OBJECTIVE: To assess submental-cervical soft tissue changes after en bloc mandibular U-shaped osteotomy and examine alterations in the anterior belly of digastric muscle (ABDM). METHODS: A retrospective study analyzed 20 patients who underwent en bloc mandibular U-shaped osteotomy from 2018 to 2023. Preoperative (Tp) and long-term follow-up (Tf) CT data were collected for analysis, measuring mandibular volume, soft tissue thickness at menton (Mes) and cervicale (C), and ABDM parameters (length, cross-sectional area (CSA), volume, distance from centroid point to the mandibular margin). Correlation analyses were performed to investigate the connection between soft tissue thickness changes, ABDM changes, and mandibular osteotomy volume. RESULTS: Long-term follow-up revealed a significant increase in soft tissue thickness at the Mes and C points after U-shaped mandibular osteotomy, especially at the C point. The adaptive length of ABDM decreased, CSA increased, and volume decreased, but the ABDM centroid point shifted downward relative to the mandibular margin, indicating drooping protrusion. The increment of soft tissue thickness was moderately positively correlated with the amount of osteotomy, and the decrement of ABDM length and volume were slightly positively correlated with the amount of osteotomy. CONCLUSION: The degree of soft tissue relaxation after U-shaped osteotomy is related to the extent of osteotomy. Notably, the protrusion of ABDM relative to the mandibular margin affects submental-cervical contour aesthetics. Prior to U-shaped osteotomy, it is crucial to assess the soft tissue condition of the patient's lower face, and the individualized design of the osteotomy volume should be carried out cautiously and safely. LEVEL OF EVIDENCE IV: This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Defining the Shape of the Mylohyoid Muscle: A Morphometric Imaging Study.

OBJECTIVES: Implantable hypoglossal nerve stimulation (HNS) therapy is an evolving therapeutic alternative for patients with refractory obstructive sleep apnea (OSA). The muscular anatomy of this region has implications for surgical access through this zone as well as positioning and anchoring of hardware in this area. The purpose of this study was to radiologically describe the topography of the mylohyoid muscle and adjacent structures across a wide age spectrum. METHODS: We retrospectively evaluated computed tomography scans of the neck in 102 patients who were imaged for reasons unrelated to the floor of mouth or submental space. Patients with prior surgery or pathology in the area of interest were excluded. Fourteen relevant muscle measurements were made on a midline sagittal image and a coronal image positioned at the midpoint between the hyoid bone and the mandible. RESULTS: We included 49 men and 53 women with an average age of 44 years (range 19-70). The average mylohyoid length was 42 mm; the average distance between the anterior digastric bellies was 17 mm. The average angle of the central mylohyoid was 174° in the sagittal plane and 164° in the coronal plane. Several measurements were significantly correlated with patient age, including the angle measurements and the distance between the digastric muscles. Aberrant digastric anatomy was common. CONCLUSIONS: The mylohyoid muscle has multiple radiologically distinct segments with predictable curvatures. An understanding of submental muscular anatomy, along with its variability between patients, may be beneficial to the development of bilateral implantable neurostimulation technology for the treatment of refractory OSA. LEVEL OF EVIDENCE: N/A Laryngoscope, 134:2970-2975, 2024.

Reliability of ultrasonography to measure cervical multifidus, semispinalis cervicis and longus colli muscles dimensions in patients with unilateral cervical disc herniation: An observational cross-sectional test-retest study.

BACKGROUND: Ultrasonography (US) has been suggested to assess the morphology and function of cervical muscles; but little is known about the reliability of the US measures in patients with cervical disc herniation (CDH). The purpose of this study was to evaluate within-day inter and intra-rater and between-day intra-rater reliability of US to measure dimensions of deep cervical muscles in patients with unilateral CDH. METHODS: Thirty patients with unilateral CDH participated. Anterior-posterior and lateral dimension of longus colli (LC), multifidus (MF) and semispinalis cervicis (SC) were measured using B-mode ultrasound. The measurements were repeated by rater A 1 h (for within-day reliability) and one week (for between-day reliability) later. For inter-rater reliability, rater B performed all muscles measurements like rater A. RESULTS: Within-day reliability measurement for all muscles was good to excellent with IntraClass Correlation Coefficients (ICC) ranging from 0.82 to 0.96, standard error of measurement (SEM) from 0.18 to 0.46 and minimal detectable changes (MDC) from 0.43 to 1.09. Between-day reliability was good for all muscle dimensions with ICC ranging from 0.75 to 0.89, SEM from 0.30 to 0.64 and MDC from 0.71 to 1.52. Inter-rater reliability was also good with ICC ranging from 0.75 to 0.89, SEM from 0.34 to 0.65 and MDC from 0.81 to 1.55. CONCLUSIONS: US was demonstrated to have high within-day inter and intra-rater and between-day intra-rater reliability to measure muscles dimensions in patients with unilateral CDH. It can be used to assess deep cervical muscles or to monitor the effects of interventions.

Isolated left sternocleidomastoid pyomyositis: a rare presentation of cervical sepsis.

An elderly gentleman self-presented to A+E with a 7-day history of significant and progressive left-sided neck pain, swelling and fevers, despite oral antibiotics from his general practitioner. Examination revealed a large left-sided neck mass involving levels 2-5 of the neck that was firm to palpate, with erythematous overlying skin.An urgent CT scan demonstrated a large collection throughout the length of the left sternocleidomastoid muscle (SCM), measuring 13×5.5×4 cm, with extensive adjacent inflammatory change. He was subsequently taken to theatre for washout and debridement, during which the collection was found to be loculated and isolated to the SCM, with surrounding structures spared.Postoperatively, he was managed with intravenous fluids and a total of 2 weeks of intravenous antibiotics. The wound partially dehisced during healing and the cavity was packed with flaminal and regularly dressed with input from the tissue viability team. This was then left to heal by secondary intention and the patient was followed up in clinic over the following weeks to ensure resolution.

Diagnostic value of high-frequency ultrasound in omohyoid muscle syndrome.

PURPOSE: To investigate the diagnostic value of high-frequency ultrasound in omohyoid muscle syndrome. MATERIAL AND METHODS: A retrospective analysis of 11 patients diagnosed with omohyoid muscle syndrome was carried out, and the characteristics of high-frequency ultrasound images were summarized. RESULTS: Ultrasonography of the omohyoid muscle showed a narrow band of hypoechoic muscle bundle. The ultrasonographic manifestation of omohyoid muscle syndrome showed a thickening of the omohyoid muscle on the affected side. The omohyoid muscle on the affected side bulged forward during swallowing and lifted the overlying sternocleidomastoid muscle. The difference between the thickness of the omohyoid muscle intermediate tendon on the affected side and the healthy side at rest was statistically significant (t = 58.23, P < 0.001). The difference between the thickness of the affected omohyoid muscle intermediate tendon at rest and during swallowing was statistically significant (t = 14.57, P < 0.001). There was no statistically significant difference between the thickness of the omohyoid muscle intermediate tendon on the healthy side at rest and during swallowing (t = 0.56, P > 0.05). CONCLUSION: High-frequency ultrasound is the preferred imaging method in the diagnosis of omohyoid muscle syndrome.

Morphological and functional changes of the geniohyoid muscle in elderly patients after hip fracture surgery: Comparison of ultrasound images with a focus on swallowing function.

OBJECTIVE: The purpose of this study was to clarify, using ultrasound imaging, (1) whether the area and contraction of GH change in elderly patients after hip fracture surgery and (2) whether the changes in the area and contraction of GH are related to decline in swallowing function. METHODS: The participants were 21 female patients over 65 years of age who underwent hip fracture surgery. The patients were divided into two groups based on the results of swallowing assessment by water drinking: One with normal swallowing function (NSF) and the other with suspected decline in swallowing function (DSF). Sagittal cross-sectional area (SA) of GH at rest and the shortening rate (SR) of GH upon contraction during swallowing were compared at two time points: immediately and 2 weeks after surgery. Wilcoxon signed-rank test was used for intra-group comparisons, and Mann-Whitney U-test was used for between-group comparisons. RESULT: SA of GH decreased significantly at 2 weeks after surgery in both groups, regardless of their swallowing function. In the intra-group comparison, SR significantly decreased (worsened) only in DSF group. SR at 2 weeks after surgery was significantly higher in NSF than in the DSF. In the inter-group comparison, DSF showed a significantly smaller (worse) change of SR than NSF in 2 weeks after surgery. CONCLUSION: Decrease in muscle mass, or atrophy, of GH observed in both NSF and DSF, did not coincide with the post-operative change in GH contraction of the two groups. The results suggest the importance of continuous swallowing assessment in the elderly individuals during their perioperative period.

Contrast-enhanced Magnetic Resonance Imaging in Patients With Dropped Head Syndrome.

STUDY DESIGN: This is a retrospective study of a consecutive case series of dropped head syndrome (DHS). OBJECTIVE: To identify the characteristic features of contrast-enhanced magnetic resonance imaging (MRI) in DHS patients. SUMMARY OF BACKGROUND DATA: Isolated neck extensor myopathy DHS is thought to be caused by severe cervical extensor muscle weakness from age-related loss of elasticity. However, the MRI findings of the cervical extensor muscles in DHS patients have not yet been characterized. MATERIALS AND METHODS: The subjects were 34 patients with isolated neck extensor myopathy DHS who underwent contrast-enhanced MRI within seven months after onset and 32 patients with age-matched cervical spondylosis or cervical soft-tissue tumor as controls. The presence of enhanced findings in the cervical extensor muscles, the involved cervical levels, and the characteristically enhanced shape of those muscles were evaluated using contrast-enhanced MRI. RESULTS: In the DHS group, the contrast-enhanced MRI showed pronounced enhancement at splenius capitis in 34 cases, rhomboid in 23 cases, semispinalis cervicis in seven cases, and levator scapulae in three cases. In the non-DHS group, none of those extensor muscles were enhanced. The enhanced pattern was butterfly shaped in 29 cases (85.3%) and linear in five cases (14.7%). All were located at the spinous process attachment at C6 or C7 in the DHS group. In the non-DHS group, seven cases presented an enhanced image of the spinous process, with C5-6 in one case, C6 in five cases, and C7 in one case. CONCLUSIONS: In DHS, contrast-enhanced MRI showed intramuscular enhancement of the cervical extensor muscles, which was not present in non-DHS cases. The enhanced muscles included the splenius capitis muscle in all cases. These findings may be useful for developing a strategy for DHS treatment.

Real time ultrasound imaging shows changes in deep neck flexor activation during exercise in individuals with mechanical neck pain.

BACKGROUND: Deep neck flexor muscle atrophy and increased superficial neck muscle activation are associated with disability and pain intensity in individuals with neck pain. There is a lack of evidence to support direct assessment of deep neck flexor muscles in a non-invasive way during exercise performance to help determine the effectiveness of different neck strengthening exercises. OBJECTIVE: Compare longus colli (LC) and sternocleidomastoid (SCM) activation between individuals with and without neck pain using real time ultrasound (RTUS) during a series of craniocervical exercises. METHODS: This cross-sectional cohort study recruited 10 control and 10 neck pain participants to complete four deep neck flexor activation activities involving varying levels of craniocervical flexion. Dimensions of the LC and SCM were measured using RTUS at rest and during exercise. Independent t-tests assessed baseline differences and analysis of variance examined activation changes. RESULTS: At rest, the neck pain group had significantly smaller cross-sectional area and thickness of the LC compared to the control group (p< 0.05). During exercise, the neck pain group showed significantly larger increases in LC thickness and cross-sectional area across exercise compared to the control group, with no differences in SCM activation between groups. CONCLUSIONS: Despite atrophy, individuals with neck pain can activate their deep neck flexor muscles appropriately without activating their superficial neck flexor muscles in a supine series of craniocervical flexion exercise as measured by non-invasive ultrasound imaging.

Mylohyoid Muscle: Current Understanding for Clinical Management Part II: Clinical Anatomy, Radiology, and Surgical/Clinical Relevance.

The mylohyoid is one of the suprahyoid muscles along with the geniohyoid, digastric, and stylohyoid muscles that lies between the anterior belly of the digastric muscle inferiorly and the geniohyoid superiorly. In Part II, the radiology and clinical/surgical importance of the mylohyoid muscle will be discussed.

Variations and thicknesses of anterior belly of the digastric muscle: an ultrasonographic study.

PURPOSE: This study aims to evaluate the anatomy and anatomical variations of the anterior belly of the digastric muscle. METHODS: Hundred and fifty one ultrasonographic images of the digastric muscle pairs were evaluated in Near East University Faculty of Dentistry Department of Dentomaxillofacial Radiology. Morphological variations were recorded using the classification of the digastric muscle into 12 types by Kim et al. For the analysis, the Mann-Whitney U test and Chi-square test were used, and for the correlational analysis, Spearman's rho test was applied. P < 0.05 was considered statistically significant in all tests. RESULTS: Seventy female and 81 male patients aged 19-60 years were evaluated. Type 1 digastric muscle was observed in 145 of 151 patients, Type 2 in 3 patients, and Type 7 in 3 patients. The thicknesses of the right and left digastric muscles were measured, and a statistically significant difference was observed between the groups when the genders were compared. It was observed that both right and left digastric muscle thicknesses were higher in males than females. There was a statistically significant positive high correlation between right and left digastric muscle thicknesses (p = 0.000; r = 0.736). No statistically significant difference was found between genders (p = 0.596) in terms of anatomical variations. CONCLUSION: Considering that the variations of the digastric muscle may have a clinical significance role, the normal anatomy and variations of this muscle should be well known by maxillofacial surgeons and radiologists.