Transverse part of iliofemoral ligament

At a glance

English

Transverse part of iliofemoral ligament

Latin (TA2)

Pars transversa ligamenti iliofemoralis

System

Ligament

Region

Lower limb

Side

Paired, left and right

About the transverse part of iliofemoral ligament

The iliofemoral ligament, often called the Y ligament of Bigelow, is the strongest ligament in the body and lies over the front of the hip joint capsule. Its stem is attached above to the lower part of the anterior inferior iliac spine and the adjoining rim of the acetabulum. Below, it spreads into two limbs like an inverted Y. The transverse part is the lateral, upper limb; the descending part is the medial, lower limb.

The transverse part runs laterally and slightly downwards across the front of the femoral neck, its fibres set obliquely, to reach the upper end of the intertrochanteric line close to the greater trochanter. It is thick and strong, blending with the fibrous capsule and with fibres of the deep layer of gluteus minimus and the reflected head of rectus femoris near its upper attachment. The descending part reaches the lower end of the intertrochanteric line, and between the two limbs the capsule is thinner.

The ligament becomes taut when the hip is extended, which lets a person stand upright with the pelvis balanced on the femoral heads with little muscle effort. The transverse limb in particular tightens in lateral rotation and limits it, and it also resists adduction of the extended hip. With the pubofemoral and ischiofemoral ligaments it forms a spiral of fibres that winds tighter as the hip extends.

Clinically the ligament is so strong that in a posterior dislocation it usually stays intact, holding the limb flexed, adducted and medially rotated; reduction manoeuvres use it as a fulcrum. In hip arthroscopy and in anterior approaches for joint replacement the surgeon cuts or releases part of it and may repair it afterwards to avoid instability.

Attachments and function

Attaches from

Anterior inferior iliac spine and adjoining rim of the acetabulum, shared with the descending part.

Attaches to

Upper end of the intertrochanteric line, near the greater trochanter.

Function

Tightens in extension and lateral rotation of the hip, limiting lateral rotation and helping to resist adduction of the extended hip.

Nerve supply

Articular branches of the femoral nerve.

Blood supply

Branches of the lateral and medial circumflex femoral arteries.