This anatomic study examines the attachment of the lateral muscle to the capsule and disc of the temporomandibular joint. The anatomy of the temporomandibular joint and its surroundings, in particular the insertion of the superior head of the lateral pterygoid muscle, was studied by dissection and conventional histologic techniques. The material consisted of 16 cadaver specimens from individuals 60 years or older. The results showed that only a part of the superior head of the lateral pterygoid muscle is attached to the anterior portion of the capsule, which, in turn, is firmly attached to the disc, giving the impression that the muscle and the disc are directly connected. All specimens showed attachment of the superior head of the lateral pterygoid muscle to the anterior medial portion of the capsule, but they showed varying degrees of attachment to the lateral aspect of the temporomandibular joint capsule. The remaining part of the superior head of the lateral pterygoid muscle attached to the mandibular condyle. Serial sectioning in no instance showed direct insertion into the disc of the fibers of the superior head of the lateral pterygoid muscle.