vertebrate Vertebrates () are animals with a vertebral column (backbone or spine), and a cranium, or skull. The vertebral column surrounds and protects the spinal cord, while the cranium protects the brain. The vertebrates make up the subphylum Vertebra ...

s, the pubis or pubic bone () forms the lower and anterior part of each side of the

hip bone The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large flat bone, constricted in the center and expanded above and below. In some vertebrates (including humans before puberty) it is composed of three parts: the Ilium (bone) ...

. The pubis is the most forward-facing (

ventral Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...

and

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

) of the three bones that make up the hip bone. The left and right pubic bones are each made up of three sections; a superior ramus, an inferior ramus, and a body.

Structure

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 The pubic symphysis (: symphyses) is a secondary cartilaginous joint between the left and right superior rami of the pubis of the hip bones. It is in front of and below the urinary bladder. In males, the suspensory ligament of the penis attache ...

. It is covered by a layer of

fat In nutrition science, nutrition, biology, and chemistry, fat usually means any ester of fatty acids, or a mixture of such chemical compound, compounds, most commonly those that occur in living beings or in food. The term often refers specif ...

– the

mons pubis In human anatomy, and in mammals in general, the ''mons pubis'' or pubic mound (also known simply as the mons , and known specifically in females as the ''mons Venus'' or ''mons veneris'') is a rounded mass of fatty tissue found over the pubic s ...

. The pubis is the lower limit of the suprapubic region. In the female, the pubis is anterior to the

urethral sponge The urethral sponge is a spongy cushion of biological tissue, tissue, found in the lower genitals, genital area of females, that sits against both the pubic bone and vaginal wall, and surrounds the urethra. Functions The urethral sponge is com ...

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

. The rough upper edge is the

pubic crest Medial to the pubic tubercle is the pubic crest, which extends from this process to the medial end of the pubis (bone), pubic bone. It gives attachment to the conjoint tendon, the rectus abdominis, the abdominal external oblique muscle, and the ...

, ending laterally in the

pubic tubercle The pubic tubercle is a prominent tubercle on the superior ramus of the pubis bone of the pelvis. Structure The pubic tubercle is a prominent forward-projecting tubercle on the upper border of the medial portion of the superior ramus of th ...

. This

tubercle In anatomy, a tubercle (literally 'small tuber', Latin for 'lump') is any round nodule, small eminence, or warty outgrowth found on external or internal organs of a plant or an animal. In plants A tubercle is generally a wart-like projectio ...

, found roughly 3 cm from the pubic symphysis, is a distinctive feature on the lower part of the

abdominal wall In anatomy, the abdominal wall represents the boundaries of the abdominal cavity. The abdominal wall is split into the anterolateral and posterior walls. There is a common set of layers covering and forming all the walls: the deepest being the vi ...

; important when localizing the

superficial inguinal ring The inguinal canal is a passage in the anterior abdominal wall on each side of the body (one on each side of the midline), which in males, convey the spermatic cords and in females, the round ligament of the uterus. The inguinal canals are large ...

and the

femoral canal The femoral canal is the medial (and smallest) compartment of the three compartments of the femoral sheath. It is conical in shape. The femoral canal contains lymphatic vessels, and Adipose tissue, adipose and loose connective tissue, as well as - ...

of the

inguinal canal The inguinal canal is a passage in the anterior abdominal wall on each side of the body (one on each side of the midline), which in males, convey the spermatic cords and in females, the round ligament of the uterus. The inguinal canals are lar ...

. The inner surface of the body forms part of the wall of the

lesser pelvis The pelvic cavity is a body cavity that is bounded by the bones of the pelvis. Its oblique roof is the pelvic inlet (the superior opening of the pelvis). Its lower boundary is the pelvic floor. The pelvic cavity primarily contains the reproduc ...

and joints to the origin of a part of the ''

obturator internus The internal obturator muscle or obturator internus muscle originates on the medial surface of the obturator membrane, the ischium near the membrane, and the rim of the pubis (bone), pubis. It exits the pelvis, pelvic cavity through the lesser sc ...

'' muscle.

Superior pubic ramus

The superior pubic ramus is the upper of the two rami. It forms the upper edge of the

obturator foramen The obturator foramen is the large, Bilateral symmetry, bilaterally paired opening of the bony pelvis. It is formed by the pubis and ischium. It is mostly closed by the obturator membrane except for a small opening, the obturator canal, through wh ...

. 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 In the human body, the adductor longus is a skeletal muscle located in the thigh. One of the adductor muscles of the hip, its main function is to Adduction, adduct the thigh and it is innervated by the obturator nerve. It forms the medial wall ...

'' arises from the upper and medial angle, immediately below the crest; lower down, the ''

obturator externus The external obturator muscle or obturator externus muscle (; OE) is a flat, triangular muscle, which covers the outer surface of the anterior wall of the pelvis. It is sometimes considered part of the medial compartment of thigh, and sometime ...

'', the ''

adductor brevis The adductor brevis is a muscle in the thigh situated immediately deep to the pectineus and adductor longus. It belongs to the adductor muscle group. The main function of the adductor brevis is to pull the thigh medially. The adductor brevi ...

'' 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 The levator ani is a broad, thin muscle group, situated on either side of the pelvis. It is formed from three muscle components: the pubococcygeus, the iliococcygeus, and the puborectalis. It is attached to the inner surface of each side of the ...

'' and ''

'', and attachment to the

puboprostatic ligament The pubovesical ligament is a ligament that extends from the neck of the urinary bladder to the inferior aspect of the pubis bones. Structure The pubovesical ligament is the continuation of the detrusor muscle and the adventitia surrounding ...

s and to a few muscular fibers prolonged from the bladder.

= Borders

= The upper border presents a prominent tubercle, the

(

pubic spine In vertebrates, the pubis or pubic bone () forms the lower and anterior part of each side of the hip bone. The pubis is the most forward-facing (ventral and anterior) of the three bones that make up the hip bone. The left and right pubic bones ar ...

), which projects forward; the

inferior crus The superficial inguinal ring is bounded below by the crest of the pubis; on either side by the margins of the opening in the aponeurosis, which are called the crura of the ring; and above, by a series of curved intercrural fibers. * The infe ...

of the

subcutaneous inguinal ring The inguinal canal is a passage in the anterior abdominal wall on each side of the body (one on each side of the midline), which in males, convey the spermatic cords and in females, the round ligament of the uterus. The inguinal canals are lar ...

(external abdominal ring), and the

inguinal ligament The inguinal ligament (), also known as Poupart's ligament or groin ligament, is a band running from the pubic tubercle to the anterior superior iliac spine. It forms the base of the inguinal canal through which an indirect inguinal hernia may ...

(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

: to it are attached a portion of the

inguinal falx also known as superior tendon of abdominal cavity. The conjoint tendon (previously known as the inguinal aponeurotic falx) is a sheath of connective tissue formed from the lower part of the common aponeurosis of the abdominal internal oblique muscl ...

(conjoined tendon of ''obliquus internus'' and ''transversus''), the

lacunar ligament The lacunar ligament, also named Gimbernat's ligament, is a ligament in the inguinal region. It connects the inguinal ligament to the pectineal ligament, near the point where they both insert on the pubic tubercle. Structure The lacunar ligame ...

(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 The rectus abdominis muscle, () also known as the "abdominal muscle" or simply better known as the "abs", is a pair of segmented skeletal muscle on the ventral aspect of a person, person's abdomen. The paired muscle is separated at the midline b ...

'' 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 A symphysis (, : symphyses) is a fibrocartilaginous fusion between two bones. It is a type of cartilaginous joint, specifically a secondary cartilaginous joint. # A symphysis is an amphiarthrosis, a slightly movable joint. # A growing together o ...

, the

superior crus The superficial inguinal ring is bounded below by the crest of the pubis; on either side by the margins of the opening in the aponeurosis, which are called the crura of the ring; and above, by a series of curved intercrural fibers. * The infer ...

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 The obturator membrane is a thin fibrous sheet, which almost completely closes the obturator foramen. Its fibers are arranged in interlacing bundles mainly transverse in direction; the uppermost bundle is attached to the obturator tubercles and ...

Lateral portion

= Surfaces

= * The superior surface presents a continuation of the pectineal line, already mentioned as commencing at the

. In front of this line, the surface of bone is triangular in form, wider laterally than medially, and is covered by the

pectineus The pectineus muscle (, from the Latin word ''pecten'', meaning comb) is a flat, quadrangular muscle, situated at the anterior (front) part of the upper and medial (inner) aspect of the thigh. The pectineus muscle is the most anterior adductor o ...

. The surface is bounded, laterally, by a rough eminence, the

iliopectineal eminence Medial to the anterior inferior iliac spine is a broad, shallow groove, over which the iliacus and psoas major muscles pass. This groove is bounded medially by an eminence, the iliopubic eminence (or iliopectineal eminence), which marks the point ...

, 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 The acetabular notch is a deep notch in the inferior portion of the rim of the acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur mee ...

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 The anterior border of the superior pubic ramus presents a sharp margin, the obturator crest, which forms part of the circumference of the obturator foramen superiorly and affords attachment to the obturator membrane. The obturator crest extends f ...

, forming part of the circumference of the obturator foramen, and giving attachment to the

. * The posterior surface constitutes part of the anterior boundary of the

. 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 The ischium (; : is ...

below the

Surfaces

* Its ''anterior surface'' is rough, for the origin of muscles—the gracilis along its medial border, a portion of the

where it enters into the formation of the

, 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

, 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 The ischium (; : is ...

; ** to the external ridge is attached the

fascia of Colles The membranous layer of the superficial fascia of the perineum (Colles' fascia) is the deeper layer (membranous layer) of the superficial perineal fascia. It is thin, aponeurotic in structure, and of considerable strength, serving to bind down the ...

** to the internal ridge is attached the inferior fascia of the

urogenital diaphragm Older texts have asserted the existence of a urogenital diaphragm, also called the triangular ligament, which was described as a layer of the pelvis that separates the deep perineal sac from the upper pelvis, lying between the inferior fascia of ...

* The ''lateral border'' is thin and sharp, forms part of the circumference of the

, and gives attachment to the

Other animals

Mammals

Non-

placental Placental mammals (infraclass Placentalia ) are one of the three extant subdivisions of the class Mammalia, the other two being Monotremata and Marsupialia. Placentalia contains the vast majority of extant mammals, which are partly distinguished ...

mammals possess osteological projections of the pubis known as

epipubic Epipubic bones are a pair of bones projecting forward from the pelvic bones of modern marsupials, monotremes and fossil mammals like multituberculates, and even basal eutherians (the ancestors of placentals, who lack them). They first occur in ...

bones. These evolved first among derived

cynodonts Cynodontia () is a clade of eutheriodont therapsids that first appeared in the Late Permian (approximately 260 mya), and extensively diversified after the Permian–Triassic extinction event. Mammals are cynodonts, as are their extinct ances ...

, and evolved as a means of support for muscles flexing the thigh, facilitating the development of an erect gait. However, these prevent the expansion of the torso, preventing pregnancy and forcing the animal to give birth to larval young (the modern

marsupial Marsupials are a diverse group of mammals belonging to the infraclass Marsupialia. They are natively found in Australasia, Wallacea, and the Americas. One of marsupials' unique features is their reproductive strategy: the young are born in a r ...

"joeys" and

monotreme Monotremes () are mammals of the order Monotremata. They are the only group of living mammals that lay eggs, rather than bearing live young. The extant monotreme species are the platypus and the four species of echidnas. Monotremes are typified ...

"puggles"). Placentals are unique among all mammals, including other

eutheria Eutheria (from Greek , 'good, right' and , 'beast'; ), also called Pan-Placentalia, is the clade consisting of Placentalia, placental mammals and all therian mammals that are more closely related to placentals than to marsupials. Eutherians ...

ns, in having lost epipubic bones and having been able to develop proper

pregnancy Pregnancy is the time during which one or more offspring gestation, gestates inside a woman's uterus. A multiple birth, multiple pregnancy involves more than one offspring, such as with twins. Conception (biology), Conception usually occurs ...

. In some groups, remnants of these pre-pubic bones can be found as

os penis The baculum (: bacula), also known as the penis bone, penile bone, ''os penis'', ''os genitale'', or ''os priapi'', is a bone in the penis of many placental mammals. It is not present in humans, but is present in the penises of some primates, ...

es.

Dinosaurs

The

clade In biology, a clade (), also known as a Monophyly, monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach t ...

Dinosaur Dinosaurs are a diverse group of reptiles of the clade Dinosauria. They first appeared during the Triassic Geological period, period, between 243 and 233.23 million years ago (mya), although the exact origin and timing of the #Evolutio ...

ia is divided into the

Saurischia Saurischia ( , meaning "reptile-hipped" from the Greek ' () meaning 'lizard' and ' () meaning 'hip joint') is one of the two basic divisions of dinosaurs (the other being Ornithischia), classified by their hip structure. Saurischia and Ornithi ...

and

Ornithischia Ornithischia () is an extinct clade of mainly herbivorous dinosaurs characterized by a pelvic structure superficially similar to that of birds. The name ''Ornithischia'', or "bird-hipped", reflects this similarity and is derived from the Greek ...

based on hip structure, including importantly that of the pubis. An opisthopubic pelvis is a condition where the pubic bone extends back towards the tail of the animal, a trait that is also present in birds. In a propubic pelvis, however, the pubic bone extends forward towards the head of the animal, as can be seen in the typical saurischian pelvic structure pictured below. The

acetabulum The acetabulum (; : acetabula), also called the cotyloid cavity, is a wikt:concave, concave surface of the pelvis. The femur head, head of the femur meets with the pelvis at the acetabulum, forming the Hip#Articulation, hip joint. Structure The ...

, which can be thought of as a "hip-socket", is an opening on each side of the pelvic girdle formed where the

ischium The ischium (; : is ...

, ilium, and pubis all meet, and into which the head of the femur inserts. The orientation and position of the acetabulum is one of the main morphological traits that caused dinosaurs to walk in an upright posture with their legs directly underneath their bodies.Martin, A.J. (2006). Introduction to the Study of Dinosaurs. Second Edition. Oxford, Blackwell Publishing. pg. 299-300. . The ''prepubic process'' is a bony extension of the pubis that extends forward from the hip socket and toward the front of the animal. This adaptation is thought to have played a role in supporting the abdominal muscles. Ornithischia pelvis structure.svg, Ornithischian pelvic structure (left side) Saurischia pelvis structure.svg, Saurischian pelvic structure (left side).

Additional images

File:Skeletal pelvis-pubis.svg, The

sacrum The sacrum (: sacra or sacrums), in human anatomy, is a triangular bone at the base of the spine that forms by the fusing of the sacral vertebrae (S1S5) between ages 18 and 30. The sacrum situates at the upper, back part of the pelvic cavity, ...

and pelvic bone, with parts labelled. The pubic bone consists of the body and superior pubic ramus (4), and the inferior pubic ramus (3), which join at the

. The gap between them is the

. File:Gray235.png, Right hip bone. External surface. File:Gray236.png, Right hip bone. Internal surface. File:Gray237.png, Plan of ossification of the hip bone. File:Gray321.png, Symphysis pubis exposed by a coronal section. File:Gray404.png, Left levator ani from within. File:Gray436.png, The obturator externus. File:Gray341.png, Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis. File:Slide16A.JPG, Pubis

References

External links

* - "The Male Pelvis: Hip Bone" {{Authority control Bones of the pelvis

Structure

Body

Superior pubic ramus

Medial surface

= Surfaces

= Borders

Lateral portion

= Surfaces

Inferior pubic ramus

Surfaces

Borders

Other animals

Mammals

Dinosaurs

Additional images

See also

References

External links