Innominate Documentation – Anatomy Software
· The innominate/hip bone is a large, flattened, irregular shaped bone, constricted in the center and expanded above and below
· It consists of three parts, the ilium, ischium, and pubis
· It presents two surfaces—an external (Gluteal surface )and an internal (iliac fossa)—a crest, and two borders; anterior and posterior
· This external surface is crossed in an arched direction by three lines: the posterior, anterior, and inferior gluteal lines
· The internal surface of the ilium is bounded above by the crest, below, by the arcuate line; in front and behind, by the anterior and posterior borders.
· Shortest of the three lines.
· Behind this line is a narrow semilunar surface, gives origin to the gluteus maximus.
· Longest of the three lines.
· Begins at the crest, about 4 cm. behind the ASIS, and, taking a curved direction downward and backward ending at the upper part of the greater sciatic notch.
· The space between the anterior and posterior gluteal lines and the crest is concave, and gives origin to the gluteus medius.
· Least distinct of the three lines.
· Begins in front at the notch on the anterior border between ASIS and AIIS, curving backward and downward ending near the middle of the greater sciatic notch.
· It presents a large, smooth, concave surface, which gives origin to the Iliacus.
· Resembles the shape of an ear.
· Covered with hyaline cartilage.
· Articulates with a similar surface on the side of the sacrum to form the SI joint.
· Rough for the attachment of the posterior sacroiliac and interosseous ligaments and for the origins of the sacrospinalis and multifidus.
· Is convex in outline but is sinuously curved, being concave inward in front, concave outward behind.
· Ends in the anterior (ASIS) and posterior (PSIS) superior iliac spines.
· It is a prominent tubercle on the outer lip of the iliac crest.
· About 5 cm. posterior to the anterior superior iliac spine (ASIS).
· The uppermost projection of the anterior border.
· Gives attachment to the inguinal ligament and the sartorius.
· The lowermost projection of the anterior border.
· Ends in the upper lip of the acetabulum.
· Gives attachment to the straight tendon of the rectus femoris and to the iliofemoral ligament of the hip-joint.
· The uppermost projection of the posterior border.
· Gives attachment to the oblique portion of the posterior sacroiliac ligaments and the multifidus.
· The lowermost projection of the posterior border.
· Below the PIIS is the greater sciatic notch.
· The posterior border of the iliac crest after the PIIS forms the upper part of a large notch.
· Its lower border is continuous with the ischial spine.
· A small notch below the ischial spine.
· Bounded by the ischial spine above and the ischial tuberosity below.
· it is a curved line.
· It divides the ilium into two parts, the body and the ala on the internal surface.
· A gentle elevation that marks the point of union of the ilium and pubis.
· Forms the lower and back part of the hip bone.
· It is divisible into three portions—a body and two rami.
· Divided into two portions: a lower, rough, triangular part and an upper, smooth, quadrilateral portion.
· The lower portion is subdivided by a prominent longitudinal ridge, passing from base to apex, into two parts.
· The outer gives attachment to the adductor magnus, the inner to the sacrotuberous ligament.
· The upper portion is subdivided into two areas by an oblique ridge, which runs downward and outward; from the upper and outer area the semimembranosus arises; from the lower and inner, the long head of the biceps femoris and the semitendinosus.
· The posterior border forms a sharp well defined triangular projection.
· Located between the greater and lesser sciatic notches.
· The body forms one-fifth of the acetabulum, contributing by its external surface both to the lunate surface and the acetabular fossa.
· Its internal surface enters into the formation of the wall of the lesser pelvis and gives origin to a portion of the obturator internus.
· Medial to the pubic tubercle is the crest, which extends from this process to the medial end of the bone (pubic symphysis).
· The upper border presents a prominent tubercle which projects forward.
· Lateral on each side to the pubic crest.
· Passing upward and lateral from the pubic tubercle is a well-defined ridge.
· Found along the superior edge of the superior pubic ramus.
· The superior ramus extends from the body superior and lateral toward the anterior border.
· The margin of the acetabulum shows an inferior deep notch.
· The notch is converted into a foramen by the transverse ligament.
· The floor of the acetabulum shows a non-articular area at the bottom of the cavity.
· A foramen which is bounded by the different parts of the pubis, ischium and ilium.
· A large aperture, situated between the ischium and pubis.
· In the male it is large and of an oval form.
· In the female it is smaller, and more triangular.
· Is an amphiarthrodial joint, formed between the auricular surfaces of the sacrum and the ilium.
· Supported by ligaments: The Anterior Sacroiliac, The Posterior Sacroiliac and the Interosseous Sacroiliac ligaments.