The lunate surface of acetabulum is the articular surface of the

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

which makes contact with the

femoral head The femoral head (femur head or head of the femur) is the highest part of the thigh bone (femur The femur (; : femurs or femora ), or thigh bone is the only long bone, bone in the thigh — the region of the lower limb between the hip and the ...

as part of the

hip joint In vertebrate anatomy, the hip, or coxaLatin ''coxa'' was used by Celsus in the sense "hip", but by Pliny the Elder in the sense "hip bone" (Diab, p 77) (: ''coxae'') in medical terminology, refers to either an anatomical region or a joint o ...

. It forms an incomplete ring that is deficient inferiorly - opposite the

acetabular notch The acetabular notch is a deep notch in the inferior portion of the rim of the acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur mee ...

. The lunate surface surrounds the central, non-articular depression - the

acetabular fossa The acetabular fossa is the non-articular depressed region at the centre of the floor of the acetabulum. It is surrounded by the articular lunate surface. The floor of the fossa is formed mostly by the ischium; it is rough and thin (often to the ...

- which does not make contact with the femoral head in the articulated hip joint. Its surface consists of articular cartilage. It is widest (and the cartilage thickest) anterosuperiorly where weight is transmitted from the lower limb in an upright position; it is narrowest at its pubic portion.

References

{{Authority control Pelvis