The hip bone (os coxae, innominate bone, pelvic bone or coxal bone) is a large
flat bone
Flat bones are bones whose principal function is either extensive protection or the provision of broad surfaces for muscular attachment. These bones are expanded into broad, flat plates,''Gray's Anatomy'' (1918). (See infobox) as in the cranium ...
, constricted in the center and expanded above and below. In some
vertebrate
Vertebrates () comprise all animal taxa within the subphylum Vertebrata () ( chordates with backbones), including all mammals, birds, reptiles, amphibians, and fish. Vertebrates represent the overwhelming majority of the phylum Chordata, with ...
s (including humans before
puberty
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a ...
) it is composed of three parts: the
ilium,
, and the
pubis.
The two hip bones join at the
pubic symphysis
The pubic symphysis 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 attaches to the pubi ...
and together with the
sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, 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 o ...
and
coccyx
The coccyx ( : coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and othe ...
(the pelvic part of the
spine
Spine or spinal may refer to:
Science Biology
* Vertebral column, also known as the backbone
* Dendritic spine, a small membranous protrusion from a neuron's dendrite
* Thorns, spines, and prickles, needle-like structures in plants
* Spine (zoolo ...
) comprise the
skeletal
A skeleton is the structural frame that supports the body of an animal. There are several types of skeletons, including the exoskeleton, which is the stable outer shell of an organism, the endoskeleton, which forms the support structure inside ...
component of the
pelvis
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
– the
pelvic girdle
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The p ...
which surrounds the
pelvic cavity
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 ...
. They are connected to the sacrum, which is part of the
axial skeleton
The axial skeleton is the part of the skeleton that consists of the bones of the head and trunk of a vertebrate. In the human skeleton, it consists of 80 bones and is composed of six parts; the skull (22 bones), also the ossicles of the middle ...
, at the
sacroiliac joint
The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. T ...
. Each hip bone is connected to the corresponding
femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...
(thigh bone) (forming the primary connection between the bones of the
lower limb and the axial skeleton) through the large
ball and socket joint
The ball-and-socket joint (or spheroid joint) is a type of synovial joint in which the ball-shaped surface of one rounded bone fits into the cup-like depression of another bone. The distal bone is capable of motion around an indefinite number o ...
of the
hip.
Structure
The hip bone is formed by three parts: the
ilium,
, and
pubis. At birth, these three components are separated by
hyaline cartilage
Hyaline cartilage is the glass-like (hyaline) and translucent cartilage found on many joint surfaces. It is also most commonly found in the ribs, nose, larynx, and trachea. Hyaline cartilage is pearl-gray in color, with a firm consistency and h ...
. They join each other in a Y-shaped portion of cartilage in the
acetabulum
The acetabulum (), also called the cotyloid cavity, is a concave surface of the pelvis. The head of the femur meets with the pelvis at the acetabulum, forming the hip joint.
Structure
There are three bones of the ''os coxae'' (hip bone) that c ...
. By the end of
puberty
Puberty is the process of physical changes through which a child's body matures into an adult body capable of sexual reproduction. It is initiated by hormonal signals from the brain to the gonads: the ovaries in a girl, the testes in a ...
the three regions will have fused together, and by the age 25 they will have
ossified
Ossification (also called osteogenesis or bone mineralization) in bone remodeling is the process of laying down new bone material by cells named osteoblasts. It is synonymous with bone tissue formation. There are two processes resulting in t ...
.
The two hip bones
join Join may refer to:
* Join (law), to include additional counts or additional defendants on an indictment
*In mathematics:
** Join (mathematics), a least upper bound of sets orders in lattice theory
** Join (topology), an operation combining two topo ...
each other at the
pubic symphysis
The pubic symphysis 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 attaches to the pubi ...
. Together with the
sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, 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 o ...
and
coccyx
The coccyx ( : coccyges or coccyxes), commonly referred to as the tailbone, is the final segment of the vertebral column in all apes, and analogous structures in certain other mammals such as horses. In tailless primates (e.g. humans and othe ...
, the hip bones form the
pelvis
The pelvis (plural pelves or pelvises) is the lower part of the trunk, between the abdomen and the thighs (sometimes also called pelvic region), together with its embedded skeleton (sometimes also called bony pelvis, or pelvic skeleton).
The ...
.
[
]
Ilium
Ilium (plural
The plural (sometimes list of glossing abbreviations, abbreviated pl., pl, or ), in many languages, is one of the values of the grammatical number, grammatical category of number. The plural of a noun typically denotes a quantity greater than the ...
''ilia'') is the uppermost and largest region. It makes up two fifths of the acetabulum. It is divisible into two parts: the body and the ala or wing of ilium; the separation is indicated on the top surface by a curved line, the arcuate line, and on the external surface by the margin of the acetabulum. The body of ilium forms the sacroiliac joint
The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. T ...
with the sacrum
The sacrum (plural: ''sacra'' or ''sacrums''), in human anatomy, is a large, 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 o ...
. The edge of the wing of ilium forms the S-shaped iliac crest
The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superiolateral margin of the greater pelvis.
Structure
The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the poster ...
which is easily located through the skin
Skin is the layer of usually soft, flexible outer tissue covering the body of a vertebrate animal, with three main functions: protection, regulation, and sensation.
Other animal coverings, such as the arthropod exoskeleton, have different ...
. The iliac crest shows clear marks of the attachment of the three abdominal wall muscles.[
]
Ischium
The ischium forms the lower and back part of the hip bone and is located below the ilium and behind the pubis. The ischium is the strongest of the three regions that form the hip bone. It is divisible into three portions: the body, the superior ramus, and the inferior ramus. The body forms approximately one-third of the acetabulum.
The ischium forms a large swelling, the tuberosity of the ischium
The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large swelling posteriorly on the superior ramus of the ischium. It marks ...
, also referred to colloquially as the "sit bone". When sitting, the weight is frequently placed upon the ''ischial tuberosity''. The gluteus maximus
The gluteus maximus is the main extensor muscle of the hip. It is the largest and outermost of the three gluteal muscles and makes up a large part of the shape and appearance of each side of the hips. It is the single largest muscle in the huma ...
covers it in the upright posture, but leaves it free in the seated position.[
]
Pubis
The ''pubic region'' or ''pubis'' is the ventral and anterior of the three parts forming the hip bone. It is divisible into a body, a superior ramus, and an inferior ramus. The body forms one-fifth of the acetabulum. The body forms the wide, strong, medial and flat portion of the pubic bone which unites with the other pubic bone in the pubic symphysis
The pubic symphysis 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 attaches to the pubi ...
.[ The fibrocartilaginous pad which lies between the symphysial surfaces of the coxal bones, that secures the pubic symphysis, is called the ''interpubic disc''.
]
Pelvic brim
The ''pelvic brim'' is a continuous oval ridge of bone that runs along the pubic symphysis, pubic crests, arcuate lines, sacral alae, and sacral promontory.[Multiple citations to "(J Bridges)" embedded in text.]
False pelvis, pelvic inlet, and ramus
The ''false pelvis'' is that portion superior to the pelvic brim; it is bounded by the alae of the ilia laterally and the sacral promontory and lumbar vertebrae posteriorly.[
The ''true pelvis'' is the region inferior to the pelvic brim that is almost entirely surrounded by bone.][
The ''pelvic inlet'' is the opening delineated by the pelvic brim. The widest dimension of the pelvic inlet is from left to right, that is, along the frontal plane.][ The ''pelvic outlet'' is the margin of the true pelvis. It is bounded anteriorly by the pubic arch, laterally by the ischia, and posteriorly by the sacrum and coccyx.][
The ''superior pubic ramus'' is a part of the pubic bone which forms a portion of the ]obturator foramen
The obturator foramen (Latin foramen obturatum) is the large opening created by the ischium and pubis bones of the pelvis through which nerves and blood vessels pass.
Structure
It is bounded by a thin, uneven margin, to which a strong membran ...
. It extends from the body to the median plane where it articulates with its fellow of the opposite side. It is conveniently described in two portions: a medial flattened part and a narrow lateral prismoid portion. The ''inferior pubic ramus'' 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.
Development and sexual dimorphism
The hip bone is ossified from eight centers: three primary, one each for the ilium, ischium, and pubis, and five secondary, one each for the iliac crest
The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superiolateral margin of the greater pelvis.
Structure
The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the poster ...
, the anterior inferior spine
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position prov ...
(said to occur more frequently in the male than in the female), the tuberosity of the ischium, the pubic symphysis (more frequent in the female than in the male), and one or more for the Y-shaped piece at the bottom of the acetabulum.
The centers appear in the following order: in the lower part of the ilium, immediately above the greater sciatic notch, about the eighth or ninth week of fetal life; in the superior ramus of the ischium, about the third month; in the superior ramus of the pubis, between the fourth and fifth months. At birth, the three primary centers are quite separate, the crest, the bottom of the acetabulum, the ischial tuberosity, and the inferior rami of the ischium and pubis being still cartilaginous.
By the seventh or eighth year, the inferior rami of the pubis and ischium are almost completely united by bone. About the thirteenth or fourteenth year, the three primary centers have extended their growth into the bottom of the acetabulum, and are there separated from each other by a Y-shaped portion of cartilage, which now presents traces of ossification, often by two or more centers. One of these, the os acetabuli, appears about the age of twelve, between the ilium and pubis, and fuses with them about the age of eighteen; it forms the pubic part of the acetabulum. The ilium and ischium then become joined, and lastly the pubis and ischium, through the intervention of this Y-shaped portion.
At about the age of puberty, ossification takes place in each of the remaining portions, and they join with the rest of the bone between the twentieth and twenty-fifth years. Separate centers are frequently found for the pubic tubercle and the ischial spine, and for the crest and angle of the pubis. The proportions of the female hip bone may affect the ease of passage of the baby during childbirth
Childbirth, also known as labour and delivery, is the ending of pregnancy where one or more babies exits the internal environment of the mother via vaginal delivery or caesarean section. In 2019, there were about 140.11 million births glob ...
.
Muscle attachments
Several muscles attach to the hip bone including the internal muscles of the pelvic, abdominal muscles
The abdomen (colloquially called the belly, tummy, midriff, tucky or stomach) is the part of the body between the thorax (chest) and pelvis, in humans and in other vertebrates. The abdomen is the front part of the abdominal segment of the torso. ...
, back muscles, all the gluteal muscles
The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sa ...
, muscles of the lateral rotator group, hamstring muscles
In human anatomy, a hamstring () is any one of the three posterior thigh muscles in between the hip and the knee (from medial to lateral: semimembranosus, semitendinosus and biceps femoris). The hamstrings are susceptible to injury.
In quadrupeds, ...
, two muscles from the anterior compartment of the thigh.
Abdominal muscles
*The abdominal external oblique muscle
The abdominal external oblique muscle (also external oblique muscle, or exterior oblique) is the largest and outermost of the three flat abdominal muscles of the lateral anterior abdomen.
Structure
The external oblique is situated on the latera ...
attaches to the iliac crest
The crest of the ilium (or iliac crest) is the superior border of the wing of ilium and the superiolateral margin of the greater pelvis.
Structure
The iliac crest stretches posteriorly from the anterior superior iliac spine (ASIS) to the poster ...
.
*The abdominal internal oblique muscle
The abdominal internal oblique muscle, also internal oblique muscle or interior oblique, is an abdominal muscle in the abdominal wall that lies below the external oblique muscle and just above the transverse abdominal muscle.
Structure
Its fiber ...
attaches to pecten pubis.
*The transversus abdominis muscle
The transverse abdominal muscle (TVA), also known as the transverse abdominis, transversalis muscle and transversus abdominis muscle, is a muscle layer of the anterior and lateral (front and side) abdominal wall which is deep to (layered below) t ...
attaches to the pubic crest
Medial to the pubic tubercle is the pubic crest, which extends from this process to the medial end of the pubic bone.
It gives attachment to the conjoint tendon, the rectus abdominis, the abdominal external oblique muscle, and the pyramidalis mu ...
and pecten pubis via a conjoint tendon
Back muscles
*The multifidus muscle
The multifidus (multifidus spinae : ''pl. multifidi'' ) muscle consists of a number of fleshy and tendinous fasciculi, which fill up the groove on either side of the spinous processes of the vertebrae, from the sacrum to the axis. While very th ...
in the sacral region attaches to the medial surface of posterior superior iliac spine
The posterior border of the ala, shorter than the anterior, also presents two projections separated by a notch, the posterior superior iliac spine and the posterior inferior iliac spine. The posterior superior iliac spine serves for the attachme ...
, the posterior sacroiliac ligaments and several places to the sacrum.
Gluteal muscles
*The gluteus maximus muscle
The gluteal muscles, often called glutes are a group of three muscles which make up the gluteal region commonly known as the buttocks: the gluteus maximus, gluteus medius and gluteus minimus. The three muscles originate from the ilium and sacr ...
arises from the posterior gluteal line
The gluteal lines are three curved lines outlined from three bony ridges on the exterior surface of the ilium in the gluteal region. They are the anterior gluteal line; the inferior gluteal line, and the posterior gluteal line.
The gluteus mini ...
of the inner upper ilium, and the rough portion of bone including the iliac crest, the fascia covering the gluteus medius
The gluteus medius, one of the three gluteal muscles, is a broad, thick, radiating muscle. It is situated on the outer surface of the pelvis.
Its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeuros ...
(gluteal aponeurosis
The gluteal aponeurosis is a fibrous membrane, from the fascia lata, that lies between the iliac crest and the superior border of the gluteus maximus
The gluteus maximus is the main extensor muscle of the hip. It is the largest and outermost o ...
), as well as the sacrum, coccyx, the erector spinae (lumbodorsal fascia
The thoracolumbar fascia (lumbodorsal fascia or thoracodorsal fascia) is a deep investing membrane throughout most of the posterior thorax and abdomen although it is a thin fibrous lamina in the thoracic region. Above, it is continuous with a simil ...
), the sacrotuberous ligament.
*The gluteus medius muscle
The gluteus medius, one of the three gluteal muscles, is a broad, thick, radiating muscle. It is situated on the outer surface of the pelvis.
Its posterior third is covered by the gluteus maximus, its anterior two-thirds by the gluteal aponeuros ...
: originates on the outer surface of the ilium between the iliac crest and the posterior gluteal line above, and the anterior gluteal line below. The gluteus medius also originates from the gluteal aponeurosis that covers its outer surface.
*Gluteus minimus muscle originates between the anterior and inferior gluteal lines, and from the margin of the greater sciatic notch.
Lateral rotator group
*The piriformis muscle
The piriformis muscle () is a flat, pyramidally-shaped muscle in the gluteal region of the lower limbs. It is one of the six muscles in the lateral rotator group.
The piriformis muscle has its origin upon the front surface of the sacrum, and ins ...
originates from the superior margin of the greater sciatic notch (as well as the sacroiliac joint
The sacroiliac joint or SI joint (SIJ) is the joint between the sacrum and the ilium bones of the pelvis, which are connected by strong ligaments. In humans, the sacrum supports the spine and is supported in turn by an ilium on each side. T ...
capsule and the sacrotuberous ligament and part of the spine and sacrum.
*The superior gemellus muscle
The gemelli muscles are the inferior gemellus muscle
and the superior gemellus muscle, two small accessory fasciculi to the tendon of the internal obturator muscle. The gemelli muscles belong to the lateral rotator group of six muscles of the h ...
arises from the outer surface of the ischial spine
The ischial spine is part of the posterior border of the body of the ischium bone of the pelvis. It is a thin and pointed triangular eminence, more or less elongated in different subjects.
Structure
The pudendal nerve travels close to the ischia ...
*The obturator internus muscle
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.
It exits the pelvic cavity through the lesser sciatic foramen.
The ...
arises from the inner surface of the antero-lateral wall of the hip bone, where it surrounds the greater part of the obturator foramen
The obturator foramen (Latin foramen obturatum) is the large opening created by the ischium and pubis bones of the pelvis through which nerves and blood vessels pass.
Structure
It is bounded by a thin, uneven margin, to which a strong membran ...
, being attached to the inferior rami of the pubis and ischium, and at the side to the inner surface of the hip bone below and behind the pelvic brim
The pelvic brim is the edge of the pelvic inlet. It is an approximately Mickey Mouse head-shaped line passing through the prominence of the sacrum, the arcuate and pectineal lines, and the upper margin of the pubic symphysis.
Structure
The pel ...
, reaching from the upper part of the greater sciatic foramen
The greater sciatic foramen is an opening (foramen) in the posterior human pelvis. It is formed by the sacrotuberous and sacrospinous ligaments. The piriformis muscle passes through the foramen and occupies most of its volume. The greater sci ...
above and behind to the obturator foramen below and in front. It also arises from the pelvic surface of 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 ...
except in the posterior part, from the tendinous arch, and to a slight extent from the obturator fascia
The obturator fascia, or fascia of the internal obturator muscle, covers the pelvic surface of that muscle and is attached around the margin of its origin.
Above, it is loosely connected to the back part of the arcuate line, and here it is conti ...
, which covers the muscle.
*The inferior gemellus muscle
The gemelli muscles are the inferior gemellus muscle
and the superior gemellus muscle, two small accessory fasciculi to the tendon of the internal obturator muscle. The gemelli muscles belong to the lateral rotator group of six muscles of the h ...
arises from the upper part of the tuberosity of the ischium
The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large swelling posteriorly on the superior ramus of the ischium. It marks ...
, immediately below the groove for the obturator internus tendon.
*The obturator externus muscle
The external obturator muscle, 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 sometimes c ...
arises from the margin of bone immediately around the medial side of the obturator foramen, from the rami of the pubis, and the inferior ramus of the ischium; it also arises from the medial two-thirds of the outer surface of the obturator membrane, and from the tendinous arch.
Hamstrings
*The long head biceps femoris
The biceps femoris () is a muscle of the thigh located to the posterior, or back. As its name implies, it has two parts, one of which (the long head) forms part of the hamstrings muscle group.
Structure
It has two heads of origin:
*the ''long h ...
arises from the lower and inner impression on the back part of the tuberosity of the ischium
The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones, or as a pair the sitting bones, is a large swelling posteriorly on the superior ramus of the ischium. It marks ...
, by a tendon common to it and the semitendinosus
The semitendinosus () is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus.
Structure
The semitendinosus, r ...
, and from the lower part of the sacrotuberous ligament;
*The semitendinosus
The semitendinosus () is a long superficial muscle in the back of the thigh. It is so named because it has a very long tendon of insertion. It lies posteromedially in the thigh, superficial to the semimembranosus.
Structure
The semitendinosus, r ...
arises from the lower and medial impression on the tuberosity of the ischium, by a tendon common to it and the long head of the biceps femoris; it also arises from an aponeurosis which connects the adjacent surfaces of the two muscles to the extent of about 7.5 cm. from their origin.
*The semimembranosus
The semimembranosus muscle () is the most medial of the three hamstring muscles in the thigh. It is so named because it has a flat tendon of origin. It lies posteromedially in the thigh, deep to the semitendinosus muscle. It extends the hip j ...
arises from the lower and medial impression on the tuberosity of the ischium
Anterior compartment of thigh
*The rectus femoris muscle
The rectus femoris muscle is one of the four quadriceps muscles of the human body. The others are the vastus medialis, the vastus intermedius (deep to the rectus femoris), and the vastus lateralis. All four parts of the quadriceps muscle attach t ...
arises by two tendons: one, the anterior or straight, from the anterior inferior iliac spine; the other, the posterior or reflected, from a groove above the rim of the acetabulum.
*The sartorius muscle arises by tendinous fibres from the anterior superior iliac spine,
Shoulder muscles
*The latissimus dorsi muscle
The latissimus dorsi () is a large, flat muscle on the back that stretches to the sides, behind the arm, and is partly covered by the trapezius on the back near the midline. The word latissimus dorsi (plural: ''latissimi dorsorum'') comes from L ...
attaches to the iliac crest and several places on the spine and ribs.
Clinical significance
Fractures
Fractures of the hip bone are termed pelvic fracture
A pelvic fracture is a break of the bony structure of the pelvis. This includes any break of the sacrum, hip bones (ischium, pubis, ilium), or tailbone. Symptoms include pain, particularly with movement. Complications may include internal bl ...
s, and should not be confused with hip fracture
A hip fracture is a break that occurs in the upper part of the femur (thigh bone). Symptoms may include pain around the hip, particularly with movement, and shortening of the leg. Usually the person cannot walk.
They most often occur as a res ...
s, which are actually femoral fracture
A femoral fracture is a bone fracture that involves the femur. They are typically sustained in high-impact trauma, such as car crashes, due to the large amount of force needed to break the bone. Fractures of the diaphysis, or middle of the femu ...
s that occur in the proximal end of the femur
The femur (; ), or thigh bone, is the proximal bone of the hindlimb in tetrapod vertebrates. The head of the femur articulates with the acetabulum in the pelvic bone forming the hip joint, while the distal part of the femur articulates ...
.
Preparation for childbirth
Pelvimetry
Pelvimetry is the measurement of the female pelvis. It can theoretically identify cephalo-pelvic disproportion, which is when the capacity of the pelvis is inadequate to allow the fetus to negotiate the birth canal. However, clinical evidence indi ...
is the assessment of the female pelvis in relation to the birth
Birth is the act or process of bearing or bringing forth offspring, also referred to in technical contexts as parturition. In mammals, the process is initiated by hormones which cause the muscular walls of the uterus to contract, expelling the f ...
of a baby in order to detect an increased risk for obstructed labor
Obstructed labour, also known as labour dystocia, is the baby not exiting the pelvis because it is physically block during childbirth although the uterus contracts normally. Complications for the baby include Perinatal asphyxia, not getting enoug ...
.
Evolution of the pelvis in animals
The hip bone first appears in fishes, where it consists of a simple, usually triangular bone, to which the pelvic fin articulates. The hip bones on each side usually connect with each other at the forward end, and are even solidly fused in lungfish
Lungfish are freshwater vertebrates belonging to the order Dipnoi. Lungfish are best known for retaining ancestral characteristics within the Osteichthyes, including the ability to breathe air, and ancestral structures within Sarcopterygii, i ...
es and shark
Sharks are a group of elasmobranch fish characterized by a cartilaginous skeleton, five to seven gill slits on the sides of the head, and pectoral fins that are not fused to the head. Modern sharks are classified within the clade Selachi ...
s, but they never attach to the vertebral column.
In the early tetrapod
Tetrapods (; ) are four-limbed vertebrate animals constituting the superclass Tetrapoda (). It includes extant and extinct amphibians, sauropsids ( reptiles, including dinosaurs and therefore birds) and synapsids ( pelycosaurs, extinct t ...
s, this early hip bone evolved to become the ischium and pubis, while the ilium formed as a new structure, initially somewhat rod-like in form, but soon adding a larger bony blade. The acetabulum is already present at the point where the three bones meet. In these early forms, the connection with the vertebral column is not complete, with a small pair of ribs connecting the two structures; nonetheless the pelvis already forms the complete ring found in most subsequent forms.[
In practice, modern amphibians and reptiles have substantially modified this ancestral structure, based on their varied forms and lifestyles. The obturator foramen is generally very small in such animals, although most reptiles do possess a large gap between the pubis and ischium, referred to as the ''thyroid fenestra'', which presents a similar appearance to the obturator foramen in mammals. In ]bird
Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweig ...
s, the pubic symphysis is present only in the ostrich
Ostriches are large flightless birds of the genus ''Struthio'' in the order Struthioniformes, part of the infra-class Palaeognathae, a diverse group of flightless birds also known as ratites that includes the emus, rheas, and kiwis. There ...
, and the two hip bones are usually widely separated, making it easier to lay large eggs.[
In ]therapsid
Therapsida is a major group of eupelycosaurian synapsids that includes mammals, their ancestors and relatives. Many of the traits today seen as unique to mammals had their origin within early therapsids, including limbs that were oriented more ...
s, the hip bone came to rotate counter-clockwise, relative to its position in reptiles, so that the ilium moved forward, and the pubis and ischium moved to the rear. The same pattern is seen in all modern mammals, and the thyroid fenestra and obturator foramen have merged to form a single space. The ilium is typically narrow and triangular in mammals, but is much larger in ungulate
Ungulates ( ) are members of the diverse clade Ungulata which primarily consists of large mammals with hooves. These include odd-toed ungulates such as horses, rhinoceroses, and tapirs; and even-toed ungulates such as cattle, pigs, giraffes, ...
s and human
Humans (''Homo sapiens'') are the most abundant and widespread species of primate, characterized by bipedalism and exceptional cognitive skills due to a large and complex brain. This has enabled the development of advanced tools, cultu ...
s, in which it anchors powerful gluteal muscles. Monotremes and marsupials also possess a fourth pair of bones, the prepubes or "marsupial bones", which extend forward from the pubes, and help to support the abdominal muscles and, in marsupials, the pouch. In placental mammals, the pelvis as a whole is generally wider in females than in males, to allow for the birth of the young.[
The pelvic bones of cetaceans were formerly considered to be vestigial, but they are now known to play a role in sexual selection.][Dines, James P., et al.]
Sexual selection targets cetacean pelvic bones
" Evolution 68.11 (2014): 3296-3306.
Additional images
Hip bone animation.gif, Position of the hip bones (shown in red). Animation.
Hip bone - close-up - animation (right hip bone).gif, Right hip bone. Animation.
Gray235.png, Right hip bone. External surface.
Gray236.png, Right hip bone. Internal surface.
Gray341.png, Left hip-joint, opened by removing the floor of the acetabulum from within the pelvis.
Slide12DEN.JPG, Hip bone.Medial view.
Slide14DEN.JPG, Hip bone. Lateral view.
See also
* Brachiocephalic artery
The brachiocephalic artery (or brachiocephalic trunk or innominate artery) is an artery of the mediastinum that supplies blood to the right arm and the head and neck.
It is the first branch of the aortic arch. Soon after it emerges, the brachioce ...
( Innominate artery)
* Brachiocephalic vein
The left and right brachiocephalic veins (previously called innominate veins) are major veins in the upper chest, formed by the union of each corresponding internal jugular vein and subclavian vein. This is at the level of the sternoclavicular j ...
( Innominate vein)
References
External links
*
hip/hip%20bones/bones3
at the Dartmouth Medical School
The Geisel School of Medicine at Dartmouth is the graduate medical school of Dartmouth College in Hanover, New Hampshire. The fourth oldest medical school in the United States, it was founded in 1797 by New England physician Nathan Smith. It is o ...
's Department of Anatomy
{{Authority control
Bones of the lower limb
Flat bones
Skeletal system