Pterygospinous ligament

At a glance

English

Pterygospinous ligament

Latin (TA2)

Ligamentum pterygospinale

System

Ligament

Region

Head

Side

Paired, left and right

About the pterygospinous ligament

The pterygospinous ligament lies in the infratemporal fossa, the space deep to the ramus of the mandible. It is a short band of fibrous tissue that runs backwards from high on the rear edge of the lateral pterygoid plate as far as the sphenoid spine, the small downward point of bone at the back of the greater wing.

Its course takes it just below and medial to the foramen ovale, the opening through which the mandibular nerve leaves the skull. As they emerge, branches of that nerve pass close to the ligament on their way to the muscles of mastication. The lateral pterygoid muscle, which arises from the same plate, lies just beside it.

The ligament has no meaningful role in movement. Its interest lies in its tendency to turn to bone. When it ossifies, a bony bar runs between the pterygoid plate and the sphenoid spine, and the gap enclosed above this bar, beneath the skull base, becomes a foramen, the pterygospinous foramen, first described by Civinini. The motor branches of the mandibular nerve for the chewing muscles then run through this foramen.

Such a bar is usually found by chance on a dry skull or a CT scan, but it can matter clinically. It may hinder a needle aimed at the foramen ovale, as in procedures for trigeminal neuralgia, and it can narrow the route of nerves in the infratemporal fossa, being proposed as a cause of entrapment of the lingual or inferior alveolar nerve and of numbness or pain in their territories.

Attachments and function

Attaches from

The back edge of the lateral pterygoid plate, near its upper end.

Attaches to

The spine of the sphenoid bone.

Function

Has little mechanical role; when ossified it forms a bony bar that encloses the pterygospinous foramen.