Transverse acetabular ligament
Ligamentum transversum acetabuli
A strong band bridging the notch in the lower rim of the hip socket, completing the ring of the acetabular labrum.
At a glance
- English
- Transverse acetabular ligament
- Latin (TA2)
- Ligamentum transversum acetabuli
- System
- Ligament
- Region
- Lower limb
- Side
- Paired, left and right
About the transverse acetabular ligament
The rim of the acetabulum, the socket of the hip, is not a complete circle of bone: at its lower edge there is a gap, the acetabular notch. The transverse acetabular ligament spans this gap. It is made of strong, flattened fibres that run straight across from one side of the notch to the other.
The ligament is continuous with the acetabular labrum, the ring of fibrocartilage that deepens the socket, and is often described as part of it. It differs from the rest of the labrum, however, because its fibres contain no chondrocytes; it is true ligament. With the labrum it completes a ring around the femoral head and makes the socket deeper and more enclosing. It lies inside the joint capsule.
Bridging the notch converts it into a foramen. Through this opening the acetabular branch of the obturator artery, small veins and a nerve twig enter the joint to reach the fat of the acetabular fossa and the round ligament of the femoral head. That ligament attaches by its base to both sides of the notch and blends with the transverse ligament between them.
Its function is to complete the lower margin of the socket and to stop the femoral head slipping downwards out of it. The ligament has a practical use in hip replacement: because its position is fairly constant, surgeons use it as a landmark to set the depth and angle of the artificial cup, which helps to reduce the risk of dislocation after the operation.
Attachments and function
- Attaches from
- One margin of the acetabular notch.
- Attaches to
- The opposite margin of the acetabular notch, continuous at each end with the acetabular labrum.
- Function
- Completes the lower rim of the socket, deepens it with the labrum and prevents downward displacement of the femoral head.
- Nerve supply
- Articular twigs of the obturator nerve passing through the foramen beneath it.
- Blood supply
- Small branches of the acetabular branch of the obturator artery.
Anthromica
See the transverse acetabular ligament where it really sits, with every layer of the body around it.
- Every layer, one body. Peel from muscle to bone, nerve, vessel and organ, and turn it any way.
- English and Latin. Every structure named the way your exam names it.
- Quiz until it sticks. Short drills on the structures you keep missing.
Free to start. No card.
