The pubic bone is made up of a
body,
superior ramus, and
inferior ramus (). The left and right coxal bones join at the
pubic symphysis. It is covered by a layer of
fat – the
mons pubis. The pubis is the lower limit of the
suprapubic region. In the female, the pubis is anterior to the
urethral sponge.
Body The body of pubis has: • a superior border or the pubic crest • a pubic tubercle at the lateral end of the pubic crest • three surfaces (anterior, posterior and medial). The body forms the wide, strong, middle and flat part of the pubic bone. The bodies of the left and right pubic bones join at the
pubic symphysis. The rough upper edge is the
pubic crest, ending laterally in the
pubic tubercle. This
tubercle, found roughly 3 cm from the pubic symphysis, is a distinctive feature on the lower part of the
abdominal wall; important when localizing the
superficial inguinal ring and the
femoral canal of the
inguinal canal. The inner surface of the body forms part of the wall of the
lesser pelvis and joins the origin of a part of the
obturator internus muscle.
Superior pubic ramus The superior pubic ramus is the upper of the two rami. It forms the upper edge of the
obturator foramen. It extends from the body to the median plane where it joins with the ramus of the opposite side. It consists of an inner flattened part and a narrow outer prismoid portion.
Medial surface Surfaces • The anterior surface is rough, directed downward and outward, and serves for the origin of various muscles. The
adductor longus arises from the upper and medial angle, immediately below the crest; lower down, the
obturator externus, the
adductor brevis and the upper part of the
gracilis take origin. • The posterior surface, convex from above downward, concave from side to side, is smooth, and forms part of the anterior wall of the pelvis. It gives origin to the
levator ani and
obturator internus, and attachment to the
puboprostatic ligaments and to a few fibers of the
detrusor muscle prolonged from the bladder.
Borders The upper border presents a prominent tubercle, the
pubic tubercle (
pubic spine), which projects forward; the
inferior crus of the
subcutaneous inguinal ring (external abdominal ring), and the
inguinal ligament (Poupart's ligament) are attached to it. Passing upward and laterally from the pubic tubercle is a well-defined ridge, forming a part of the
pectineal line which marks the brim of the
lesser pelvis: to it are attached a portion of the
inguinal falx (conjoined tendon of
obliquus internus and
transversus), the
lacunar ligament (Gimbernat's ligament), and the
reflected inguinal ligament (triangular fascia). Medial to the pubic tubercle is the crest, which extends from this process to the medial end of the bone. It affords attachment to the inguinal falx, and to the
rectus abdominis and
pyramidalis. The point of junction of the crest with the medial border of the bone is called the angle; to it, as well as to the
symphysis, the
superior crus of the subcutaneous inguinal ring is attached. The medial border is articular; it is oval, and is marked by eight or nine transverse ridges, or a series of nipple-like processes arranged in rows, separated by grooves; they serve for the attachment of a thin layer of cartilage, which intervenes between it and the interpubic fibrocartilaginous lamina. The lateral border presents a sharp margin, the obturator crest, which forms part of the circumference of the
obturator foramen and affords attachment to the
obturator membrane.
Lateral portion Surfaces • The superior surface presents a continuation of the
pectineal line, already mentioned as commencing at the
pubic tubercle. In front of this line, the surface of bone is triangular in form, wider laterally than medially, and is covered by the
pectineus. The surface is bounded, laterally, by a rough eminence, the
iliopectineal eminence, which serves to indicate the point of junction of the
ilium and pubis, and below by a prominent ridge which extends from the
acetabular notch to the pubic tubercle. • The inferior surface forms the upper boundary of the
obturator foramen, and presents, laterally, a broad and deep, oblique groove, for the passage of the obturator vessels and nerve; and medially, a sharp margin, the
obturator crest, forming part of the circumference of the obturator foramen, and giving attachment to the
obturator membrane. • The posterior surface constitutes part of the anterior boundary of the
lesser pelvis. It is smooth, convex from above downward, and affords origin to some fibers of the
obturator internus.
Inferior pubic ramus The inferior pubic ramus is a part of the pelvis and is thin and flat. It passes laterally and downward from the medial end of the superior ramus; it becomes narrower as it descends and joins with the
inferior ramus of the ischium below the
obturator foramen.
Surfaces • Its
anterior surface is rough, for the origin of muscles—the
gracilis along its medial border, a portion of the
obturator externus where it enters into the formation of the
obturator foramen, and between these two, the
adductores brevis and magnus, the former being the more medial. • The
posterior surface is smooth, and gives origin to the
obturator internus, and, close to the medial margin, to the
constrictor urethrae.
Borders • In the female pelvis, the
medial border is thick, rough, and everted, and presents two ridges, separated by an intervening space. The ridges extend downwards, and are continuous with similar ridges on the
inferior ramus of the ischium; • to the external ridge is attached the
fascia of Colles • to the internal ridge is attached the inferior fascia of the
urogenital diaphragm • The
lateral border is thin and sharp, forms part of the circumference of the
obturator foramen, and gives attachment to the
obturator membrane. ==Other animals==