Morphological investigation of sternocleidomastoid muscle in fetuses

Knowledge related to variations of the origin and insertion of sternocleidomastoid muscle (SCM) may be helpful in preventing complications during surgeries in the cervical region. This study aimed to examine variations and morphometric properties of SCM in fetuses in terms of infancy and early childhood surgeries. The neck regions of 27 (11 boys, 16 girls) fetuses with a mean age of 23.30±3.40 (19-30) weeks and fixed with 10% formalin present in the laboratory of Gaziantep University Faculty of Medicine, Department of Anatomy were dissected bilaterally. Photographs of the dissected fetuses were taken in the standard position. Morphometric measurements such as length, width and angle were performed on the photographs using the ImageJ program. In addition, the origo and insertio of SCM were detected. Taking into account the studies in the literature, a classification consisting of 10 types associated with the origin of SCM was carried out. No statistically significant difference was observed in the parameters in terms of side and gender (p>0.05), except from the linear distance between the clavicle and motor point where accessory nerve enters SCM (p=0.022). Two headed SCM (Type 1) was detected in 42 out of 54 sides. Two-headed pars clavicularis (Type 2a) was detected on nine sides and three-headed (Type 2b) on one side. A two-headed pars sternalis (Type 3) was detected on one side. A single-headed SCM (Type 5) was also detected on one side. Knowing the variations and sizes of SCM is thought to be important for the prevention of complications during infancy and early childhood surgeries. Therefore, the data obtained from our study may be useful to clinicians in terms of the treatment of pathologies such as congenital muscular torticollis.