The anterior inferior iliac spine (AIIS) is a bony eminence on the anterior border of the hip bone

Hip bone

The hip bone, innominate bone or coxal bone is a large, flattened, irregularly shaped bone, constricted in the center and expanded above and below...

, or, more precisely, the wing

Wing of ilium

The wing of ilium is the large expanded portion which bounds the greater pelvis laterally. It presents for examination two surfaces—an external and an internal—a crest, and two borders—an anterior and a posterior.-External surface:...

 of the ilium

Ilium (bone)

The ilium is the uppermost and largest bone of the pelvis, and appears in most vertebrates including mammals and birds, but not bony fish. All reptiles have an ilium except snakes, although some snake species have a tiny bone which is considered to be an ilium.The name comes from the Latin ,...

 (i.e. the upper lateral parts of the pelvis

Pelvis

In human anatomy, the pelvis is the lower part of the trunk, between the abdomen and the lower limbs .The pelvis includes several structures:...

).

Function and context

The upper portion of the spine gives origin to the straight head of the rectus femoris muscle

Rectus femoris muscle

The rectus femoris muscle is one of the four quadriceps muscles of the human body. The others are the vastus medialis, the vastus intermedius , and the vastus lateralis...

, while a teardrop-shaped lower portion gives origin to the iliofemoral ligament

Iliofemoral ligament

The iliofemoral ligament is a ligament of the hip joint which extends from the ilium to the femur in front of the joint. It is also referred to as the Y-ligament or the ligament of Bigelow, and any combinations of these names....

 of the hip joint and borders the rim of the acetabulum

Acetabulum

The acetabulum is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.-Structure:...

.

Antero-medially and inferiorly to the AIIS is the iliopsoas groove, the passage for the iliopsoas

Iliopsoas

-External links:*...

 muscle as it passes down to the lesser trochanter

Lesser trochanter

The lesser trochanter of the femur is a conical eminence, which varies in size in different subjects-Anatomy:It projects from the lower and back part of the base of the femur neck.From its apex three well-marked borders extend:...

 of the femur

Femur

The femur , or thigh bone, is the most proximal bone of the leg in tetrapod vertebrates capable of walking or jumping, such as most land mammals, birds, many reptiles such as lizards, and amphibians such as frogs. In vertebrates with four legs such as dogs and horses, the femur is found only in...

. A vague line, the inferior gluteal line

Inferior gluteal line

The inferior gluteal line , the least distinct of the three gluteal lines, begins in front at the notch on the anterior border, and, curving backward and downward, ends near the middle of the greater sciatic notch....

, might run from the AIIS to the greater sciatic notch

Greater sciatic notch

Above the ischial spine is a large notch, the greater sciatic notch, converted into a foramen by the sacrospinous ligament.It transmits the Piriformis, the superior and inferior gluteal vessels and nerves, the sciatic and posterior femoral cutaneous nerves, the internal pudendal vessels, and the...

 which delineates the inferior extent of the gluteus minimus

Gluteus minimus muscle

The gluteus minimus , the smallest of the three gluteal muscles, is situated immediately beneath the gluteus medius.-Origin and insertion:...

origin.

The AIIS is formed from a separate apophysis.