The sphenomandibular ligament (internal lateral ligament) is one of the three ligaments of the temporomandibular joint. It is situated medially to - and generally separate from - the articular capsule of the joint.[1]: 671 Superiorly, it is attached to the spine of the sphenoid bone; inferiorly, it is attached to the lingula of mandible.[2][1]: 671 The SML acts to limit inferior-ward movement of the mandible.[2]
The SML is a tough,[3]'flat,[1][3] thin band.[1] It broadens inferiorly,[1][3] measuring about 12 mm in width on average at the point of its inferior attachment.[1]
The SML is pierced by the mylohyoid nerve (a branch of the inferior alveolvar nerve) and the accompanying mylohyoid artery and vein.[3]
Any remaining space between the SML and mandible is taken up by the parotid gland.[3] Between the SML and the pharynx are situated adipose tissue, and a pharyngeal vein.[1]
Function
The function of the sphenomandibular ligament is to limit distension of the mandible in an inferior direction. It is slack when the temporomandibular joint (TMJ) is in closed position; it is taut when the condyle of the mandible is situated anterior to the temporomandibular ligament.[2] The SML has about 5 mm of slack when the jaw is closed; it becomes taut when the jaw is open roughly half-way.[1]