Pubis

Pubis represents the front-lower portion of the hip bone. It constitutes approximately one-fifth of the acetabulum, where it articulates with the ilium and ischium. Additionally, it forms the front margin of the obturator foramen.

The pubis comprises of a body and two rami, namely superior and inferior.

A. Pubis body: It is flat from the front to the back and has three surfaces: anterior, posterior, and medial, as well as a superior border.

• The anterior surface points forward and downward, facing the adductor region of the thigh. It provides attachment for the adductor longus muscle at its upper portion. From medial to lateral, various structures originate from this surface, including the anterior pubic ligament, gracilis, adductor brevis, and obturator externus muscle.

• The posterior surface faces backward and upward toward the pelvic cavity. It serves as the origin for the levator ani muscle in its middle part and the obturator internus muscle along the margin of the obturator foramen.

• The medial surface, known as the symphyseal surface, articulates with the corresponding pubis on the opposite side to form the pubic symphysis–a secondary cartilaginous joint that serves as the front connection between the two hip bones.

• The body has a superior border called the pubic crest, which projects over the anterior surface of the body. The medial and lateral halves of the pubic crest provide attachment for the medial and lateral heads of the rectus abdominis muscle, respectively. The lateral portion also gives rise to the pyramidalis muscle.

• The pubic crest terminates with a prominent lateral end known as the pubic tubercle. It attaches to the medial end of the inguinal ligament and fibers of the cremasteric muscle. In males, the spermatic cord crosses over the pubic tubercle.

B. Superior ramus of pubis: It lies above the obturator foramen, extending laterally from the upper end of the pubis body to the acetabulum. The superior ramus consists of three borders and three surfaces:

• The sharp upper border (a.k.a. pecten pubis or pectineal line) starts behind the pubic tubercle and extends laterally behind the iliopubic eminence, merging with the arcuate line of the ilium. The pectineal line provides attachment for the conjoint tendon and lacunar ligament medially, and the pectinate ligament laterally.

• The rounded anterior border (a.k.a. obturator crest) extends laterally from the pubic tubercle and terminates at the acetabulum.

• The inferior border forms the sharp upper margin of the obturator foramen.

• The superior or pectineal surface lies between the anterior and superior borders. It has a triangular shape, extending from the pubic tubercle medially to the iliopubic eminence laterally. The pectineus muscle originates from both the pectineal surface and the pectineal line.

• The pelvic surface is smooth and internal, situated between the superior and inferior borders. It is traversed by the ductus deferens in males and the round ligament of the uterus in females.

• The obturator surface is external, located between the superior and inferior borders. It contains an obturator groove through which the obturator vessels and nerves pass.

C. Inferior ramus of pubis: It lies below the obturator foramen, extending laterally from the lower end of the pubis body to merge with the ischial ramus, thereby forming a conjoined ischiopubic ramus.