Pubis

The pubis, or pubic bone, is the anteroinferior portion of the hip bone and one of the three bones—along with the ilium and ischium—that fuse to form the os coxae. It plays a key structural role in the formation of the pelvis, contributing to the acetabulum and forming the anterior boundary of the pelvic cavity. The left and right pubic bones meet at the midline through a fibrocartilaginous joint known as the pubic symphysis. This bone not only contributes to pelvic stability but also provides attachment for multiple muscles and supports the pelvic organs.

Structure

The pubis is composed of three parts: the body, the superior ramus, and the inferior ramus. Together, they form a robust structural component of the pelvis and help define the obturator foramen and acetabulum.

1. Body of the Pubis

• Thick, central portion of the pubic bone
• Forms the pubic symphysis at the midline where it articulates with the contralateral pubis
• Forms the anterior portion of the acetabulum

2. Superior Pubic Ramus

• Extends laterally from the body to contribute to the acetabulum and upper margin of the obturator foramen
• Contains the pubic crest and pubic tubercle on its superior surface
• Features the pectineal line (pecten pubis), which is continuous with the arcuate line of the ilium

3. Inferior Pubic Ramus

• Extends posterolaterally from the body and joins the ischial ramus
• Completes the lower border of the obturator foramen

Key Landmarks

Landmark	Description
Pubic Symphysis	Midline fibrocartilaginous joint uniting the two pubic bones
Pubic Crest	Thickened anterior border of the body; provides origin for abdominal muscles
Pubic Tubercle	Prominent lateral projection of the pubic crest; attachment site for the inguinal ligament
Pectineal Line	Ridge on the superior ramus; important for pelvic brim definition

Location

The pubis lies anteroinferiorly in the pelvic girdle. It articulates:

• Anteriorly with the opposite pubis via the pubic symphysis
• Posteriorly and laterally with the ischium at the ischiopubic ramus
• Superiorly with the ilium and acetabulum

It also forms the anteromedial boundary of the obturator foramen.

Function

• Pelvic Support: Contributes to the formation of the pelvic ring and supports pelvic organs such as the bladder and reproductive structures
• Joint Formation: Forms the anterior articulation of the pelvis via the pubic symphysis
• Muscle Attachment: Provides origins for various muscles of the abdomen, hip, and thigh
• Obturator Foramen Boundary: Defines part of the opening that transmits neurovascular structures to the thigh

Muscle and Ligament Attachments

Structure	Attachment Area
Rectus Abdominis	Pubic crest
Adductor Longus	Body of pubis
Adductor Brevis	Body and inferior ramus
Gracilis	Inferior ramus
Pectineus	Pectineal line of superior ramus
Inguinal Ligament	Pubic tubercle

Clinical Significance

• Pubic Symphysis Dysfunction: Painful separation or instability of the symphysis joint, commonly seen during pregnancy
• Osteitis Pubis: Inflammation of the pubic symphysis and surrounding bone, often due to repetitive stress in athletes
• Fractures: Pubic rami are commonly involved in pelvic fractures and may affect the pelvic ring integrity
• Surgical Access Landmark: The pubic tubercle is a key landmark during hernia repairs and other lower abdominal procedures
• Obstetric Relevance: The distance between the pubic bones contributes to the pelvic inlet dimensions important for childbirth