The development of the human lateral pterygoid muscle and the temporomandibular joint and related structures: a three-dimensional approach.

The development of the human fetal temporomandibular joint and surrounding structures was investigated in 11 specimens on the basis of histologic examination and three-dimensional reconstructions. Until the 10th week, there were no signs of the disc, joint spaces and capsule formation of the temporomandibular joint (TMJ). Apart from Meckel's cartilage, all the temporomandibular joint and related structures attained their adult shape at 14 weeks. Throughout the embryologic and fetal development, the relative positions of the branches of the mandibular nerve remained unchanged. From 11-12 weeks onwards, the lateral pterygoid muscle became a complex structure which was segmented by aponeuroses dividing the muscle into three main parts: superior, infero-medial and infero-anterior parts. The superior segment was attached to the TMJ disc superiorly and medially. The infero-medial segment was inserted onto the antero-medial aspect of the TMJ condyle and disc. The infero-anterior portion was attached to the anterior aspect of the condyle.