Posterior Belly Of Digastric Research Articles

Usefulness of simultaneous use of anatomical landmarks in identification of facial nerve in parotid gland dissection

Introduction: Identification of Facial nerve trunk is important in parotid surgery to avoid an iatrogenic injury. The objective of our study was to assess consistent and reliable landmarks for identification of the main trunk of facial nerve during parotid surgery.Methods: This prospective study was carried out in the department of Anatomy, faculty of Medicine, Ragama from 2022 to 2023. Our study included 35 fresh cadavers (70 parotid regions). The anatomical landmarks of tragal pointer (TP), tympanomastoid suture (TMS), and superior border of posterior belly of digastric (PBD) muscle to the facial nerve trunk was measured. The shortest distances were taken from the facial trunk by using a slide calliper.Results: The age of subjects of the cadavers ranged from 42 to 64 years with a mean of 54.4 years. The mean distance between the TP and the facial nerve trunk was 9.15 mm (8.1–11.7 mm). The mean distance between PBD and the facial nerve trunk was 8.6 mm (7.2–9.8 mm). The mean distance between the TMS and the facial nerve trunk was 6.5 mm (5.2–7.5 mm).Conclusion: Our study showed that the tympanomastoid suture line is the closest to the facial nerve trunk, followed by the posterior belly of digastric muscle and the tragal pointer respectively. Further clinical studies are needed to assess these landmarks through various parameters to determine their usefulness in surgical practice.

Targeted chemodenervation of the posterior belly of the digastric muscle for the management of jaw discomfort in facial synkinesis

Botulinum toxin (BT-A) chemodenervation has been proved to significantly improve the physical and psychological well-being of patients suffering from facial synkinesis. Despite this, a cohort of patients has persistent tightness and discomfort around the angle of the jaw, which may be caused by synkinesis within the posterior belly of digastric (PBD) muscle. This study was designed to evaluate the benefits of ultrasound-guided BT-A injections into the PBD. Thirty-three patients with recalcitrant tightness and discomfort around the angle of the jaw, despite maximal facial therapy and platysmal chemodenervation were selected for inclusion. Patients underwent ultrasound-guided BT-A injection into the ipsilateral PBD muscle (skin puncture site 1 cm inferior and posterior to the angle of mandible). Outcomes consisted of the Facial Disability Index (FDI), Synkinesis Assessment Questionnaire (SAQ), and a visual analogue scale (VAS) designed to assess tightness and pain around the PBD when moving the jaw, swallowing, and masticating. Questionnaires were completed two weeks before and postinjection. Statistical analysis was performed using a paired t-test. Nineteen patients completed the post-treatment outcome questionnaire. A statistically significant improvement was noted in the physical and social function aspects of the FDI and all aspects of the patient-reported VAS scores apart from tightness and pain on jaw retrusion and swallowing. There was no significant difference in the SAQ. This study has demonstrated the patient-perceived benefit of ultrasound-targeted BT-A chemodenervation of PBD. This represents a low-risk treatment option that can be easily added to the repertoire of treatments offered to patients with post paralysis facial synkinesis.

Reconstruction using sternocleidomastoid muscle flap versus posterior belly of digastric muscle flap compared with no reconstruction following superficial parotidectomy.

The most common complications following superficial parotidectomy are formation of contour deformity and development of Frey's syndrome. Multiple modalities are being used to prevent these complications. We hereby intend to compare the reconstruction modalities (sternocleidomastoid (SCM) muscle flap, posterior belly of digastric (PBD) muscle flap) with) No reconstruction (NR)following superficial parotidectomy. A comparative study was designed which included 15 patients requiring parotidectomy. These patients were divided into three groups viz. SCM, PBD, and NR. The functional outcome (facial nerve involvement, Frey syndrome, ear lobule sensation, neck movements) and the esthetic results were evaluated subjectively and objectively. The outcomes were statistically evaluated using chi-square test and ANOVA test. Facial nerve palsy occurred in 2 cases in each group, and all of them recovered completely within 6 months. The Minor starch iodine test was positive in 1 patient in the SCM group, in 2 patients in the PBD group, and in 4 patients in the NR group; only 1 patient of PBD group and 3 patients of NR group complained of gustatory sweating. Neck movements were unaffected in the PBD and NR groups; however, 1 patient complained of mild discomfort and pain during neck movements in the SCM group. Primary closure showed the worst results regarding cosmetic deformity. Hence, it is recommended to mandatorily reconstruct the defect. However, the sternocleidomastoid muscle flap is a better cosmetic option compared with posterior belly of digastric muscle flap. In cases with larger defects, a combination of both the flaps can be used. SCM flap also lowers the incidence of Frey syndrome objectively and subjectively with no reported hazard of the spinal accessory nerve and mildly affected neck movements.

Posterior belly of the digastric muscle: An important landmark for various head and neck surgeries

Objectives: The digastric muscle is an important landmark in head and neck surgeries. Important neurovascular structures such as the spinal accessory and hypoglossal nerves (HNs), internal jugular vein (IJV) and internal carotid artery lie deep to the posterior belly of digastric (PBD); the study relating to it deserves special mention in anatomical literature. Therefore, the present study aims to describe the PBD in relation to the essential anatomical landmarks. Materials and Methods: This study was carried out using 10 cadavers preserved in 10% formalin. The midpoint of IJV in the neck was identified as the point between the angle of the mandible and midclavicular point. The anatomical landmarks considered for measuring the parameters were tip of the mastoid process (TMP), loop of HN, midpoint of IJV, bifurcation of common carotid artery (CCA) and the midpoint of PBD. Various parameters were measured using the digital calipers. Results: The length of PBD was 3.77 ± 1.08 cm on right and 3.15 ± 0.05 cm on left side indicating slightly longer belly on the right. The extended length did not vary much on both the sides, which were 6.7 ± 1.23 cm on right and 6.7 ± 0.75 cm. The HN crossed PBD 2.72 ± 0.8 cm anterior to the TMP on right side, while on left side it was situated 2.1 ± 0.57 cm anterior to TMP. The distance between the midpoint of PBD and of IJV was 6.58 ± 0.99 cm on right side, whereas it was 6.1 ± 0.96 cm on left side. The distance between the midpoint PBD and bifurcation of CCA was 3.04 ± 0.61 cm on right and 2.78 ± 0.74 cm on left side. Conclusion: As the PBD muscle is an important surgical landmark, the present study adds to the existing knowledge about it. The present study has also included few newer landmarks, which were not given importance in the previous studies.

Anatomic Variation of the Anterior Belly of Digastric Muscle and Positional Relationship between the Posterior Belly of Digastric and Stylohyoid Muscle

Anatomic Variation of the Anterior Belly of Digastric Muscle and Positional Relationship between the Posterior Belly of Digastric and Stylohyoid Muscle