Morphology of the mandibulo-stylohyoid ligament in human adults

The mandibulo-stylohyoid ligament is a consistently occurring connective tissue band or sheet that courses between the angle of the mandible and the stylohyoid ligament. Previously, in a few instances it has been variously named and described as a thickening of deep cervical fascia. Recently, Shimada et al. (1986) described the connective tissue thickening and named it the mandibulo-stylohyoid ligament because of its arrangement and attachments. In the present study the ligament was dissected in 99 adult cadavers (both white and black, 98 right sides, 95 left sides). It was present in all of the specimens examined and has been classified into three types according to refinements in its morphology. Type 1: The ligament was a thick, separate band that coursed from the region of the angle of the mandible to the stylohyoid ligament. Type 2: The ligament had the same attachments as Type 1 but was more extensive, being continuous with the stylomandibular ligament. Type 3: The ligament had the same attachments as Type 1 but was thin and less well developed. The Type 1 arrangement occurred 41% of the time, Type 2, 37% of the time, and Type 3, 22% of the time. The consistency and arrangement of the ligament suggests an important role of additional structural support in the region of the angle of the mandible and hyoid bone.