Interclavicularis anticus digastricus muscle in a female body donor: a case report

Background and objectives Muscular variations of the ventral thoracic wall are generally common and of great clinical interest. Materials and methods An unusual muscular variation of the ventral thoracic wall was observed and dissected in a West-European female body donor. Results An interclavicularis anticus digastricus muscle was observed and studied. It originated from the manubrium sterni and inserted bilaterally to the clavicles. Both muscle bellies were interconnected by a tendon on the ventral surface of the manubrium sterni. The muscle was innervated by branches of the lateral pectoral nerve. Conclusions The interclavicularis anticus digastricus muscle is a muscular variation of the ventral thoracic wall of unknown prevalence. This variation might be of clinical interest in orthopaedics and thoracic surgery. It is also a vulnerable structure during infraclavicular insertion of a subclavian vein catheter or fractures of the clavicle.

Novel Variants of the Sternal Muscle in an Adult and an Anencephalic Infant: Embryological Insights and Clinical Implications

Background The sternal muscle is a supernumerary variant of the thoracic muscles found in 3–8% of the population. When present, it can be unilateral or bilateral, which can produce confusions during surgeries and imagenological examinations. Methods We report the finding of the sternalis muscle in two human cadavers, one adult and one anencephalic infant. The muscles were dissected from the fixed bodies and their morphometry analysed. Results In the case of the adult, we observed two sternal muscles connected in the superior portion by a central tendon. In the case of the anencephalic infant, we found a bilateral sternal muscle, in which the bellies came from the contralateral pectoralis major muscles. The two sternalis muscle variants found here were impossible to categorise according to the current classifications. Conclusions The sternalis muscle displays variants that are still not classified, as observed in the case of the adult and the infant, in which its presence was correlated with anencephaly. We discuss about this muscular variation in the clinical, imagenological and surgical context and propose a developmental link with the occurrence of neural tube closure defects.

Infraglenoid Muscle as an Anatomic Variation of the Anterior Rotator Cuff

Case. We report a patient with osteoarthritis of the shoulder joint who underwent reverse shoulder arthroplasty and showed anatomical variation in the subscapularis muscle (SM). A variation of the rotator cuff originating from the anteroinferior aspect of the glenoid was separated from the SM by a septum and was named infraglenoid muscle (IGM). Conclusion. We suggest that the IGM may serve as an additional dynamic stabilizer for external rotation. Studying this particular muscular variation would lead to better understanding of the anatomical structures around the glenoid cavity.