The sphenomandibular ligament (internal lateral ligament) is one of the three ligaments of the

temporomandibular joint In anatomy, the temporomandibular joints (TMJ) are the two joints connecting the jawbone to the skull. It is a bilateral synovial articulation between the temporal bone of the skull above and the mandible below; it is from these bones that it ...

. It is situated medially to - and generally separate from - the articular capsule of the joint. Superiorly, it is attached to the

spine of the sphenoid bone The sphenoidal spine (Latin: "''spina angularis''") is a downwardly directed process at the apex of the great wings of the sphenoid bone that serves as the origin of the sphenomandibular ligament. Additional images File:Spine of sphenoid bone. ...

; inferiorly, it is attached to the

lingula of mandible The lingula of the mandible is a prominent bony ridge on the medial side of the mandible. It is next to the mandibular foramen. It gives attachment to the sphenomandibular ligament. Structure The lingula of the mandible is a prominent bony ri ...

. The SML acts to limit inferior-ward movement of the mandible. The SML is derived from

Meckel's cartilage In humans, the cartilaginous bar of the mandibular arch is formed by what are known as Meckel's cartilages (right and left) also known as Meckelian cartilages; above this the incus and malleus are developed. Meckel's cartilage arises from the fir ...

Anatomy

The SML is a flat, thin band. It widens/broadens inferiorlybefore as it reaches its inferior attachment, measuring about 12 mm in width on average at the point of its inferior attachment.

Attachments

Superiorly, the SML is attached to the spine of the sphenoid bone (spina angularis. Inferiorly, it is attached at to

(which occurs just proximally to the

mandibular foramen The mandibular foramen is an opening on the internal surface of the ramus of the mandible. It allows for divisions of the mandibular nerve and blood vessels to pass through. Structure The mandibular foramen is an opening on the internal surfa ...

Anatomical relations

The

lateral pterygoid muscle The lateral pterygoid muscle (or external pterygoid muscle) is a muscle of mastication. It has two heads. It lies superior to the medial pterygoid muscle. It is supplied by pterygoid branches of the maxillary artery, and the lateral pterygoid ne ...

auriculotemporal nerve The auriculotemporal nerve is a branch of the mandibular nerve (CN V3) that runs with the superficial temporal artery and vein, and provides sensory innervation to various regions on the side of the head. Structure Origin The auriculotempor ...

, and the

maxillary artery The maxillary artery supplies deep structures of the face. It branches from the external carotid artery just deep to the neck of the mandible. Structure The maxillary artery, the larger of the two terminal branches of the external carotid artery, ...

and maxillary vein are situated laterally to the SML (the vessels and nerve coursing betwixt the SML, and the neck of the

mandibular condyle The condyloid process or condylar process is the process on the human and other mammalian species' mandibles that ends in a condyle, the mandibular condyle. It is thicker than the coronoid process of the mandible and consists of two portions: the ...

). The

chorda tympani nerve The chorda tympani is a branch of the facial nerve that originates from the taste buds in the front of the tongue, runs through the middle ear, and carries taste messages to the brain. It joins the facial nerve (cranial nerve VII) inside the facia ...

is situated medially to the SML near its upper end. The medial pterygoid muscle is situated inferolaterally to the SML. The

inferior alveolar nerve The inferior alveolar nerve (IAN) (also the inferior dental nerve) is a branch of the mandibular nerve, which is itself the third branch of the trigeminal nerve. The inferior alveolar nerves supply sensation to the lower teeth. Structure The in ...

artery An artery (plural arteries) () is a blood vessel in humans and most animals that takes blood away from the heart to one or more parts of the body (tissues, lungs, brain etc.). Most arteries carry oxygenated blood; the two exceptions are the pu ...

and vein, and a parotid lobule are situated anteroinferiorly to the SML (all being interposed between the SML and the

ramus of mandible In anatomy, the mandible, lower jaw or jawbone is the largest, strongest and lowest bone in the human facial skeleton. It forms the lower jaw and holds the lower teeth in place. The mandible sits beneath the maxilla. It is the only movable bone ...

). Between the SML and the pharynx are situated adipose tissue, and a pharyngeal vein.

Function

The function of the sphenomandibular ligament is to limit distension of the mandible in an inferior direction. It is slack when the

(TMJ) is in closed position; it is taut when the condyle of the mandible is situated anterior to the temporomandibular ligament. The SML has about 5 mm of slack when the jaw is closed; it becomes taut when the jaw is open roughly half-way.

References

External links

* * http://ect.downstate.edu/courseware/haonline/labs/l27/070105.htm {{Authority control Ligaments of the head and neck