What is sacrosky notch

Pool - Pelvis

Lower part of the trunk of the human body between the abdomen and thighs

The pool (several pool or pool ) is either the lower part of the trunk of the human body between the abdomen and thighs (sometimes called Pelvic region of the trunk) or the skeleton embedded in it (sometimes also called bony pelvis designated) or Pelvic skeleton ).

The pelvic region of the trunk includes the bony pelvis, the pelvic cavity (the space enclosed by the bony pelvis), the pelvic floor below the pelvic cavity, and the perineum below the pelvic floor. The pelvic skeleton is formed in the area of ​​the back by the sacrum and coccyx and anterior and left and right by a pair of hip bones.

The two hip bones connect the spine to the lower limbs. They are attached to the sacrum posteriorly, connected to each other anteriorly, and connected to the two femurs at the hip joints. The gap enclosed by the bony pelvis, known as the pelvic cavity, is the part of the body below the abdomen and consists mainly of the reproductive organs (sex organs) and the rectum, while the pelvic floor at the base of the cavity supports the organs of the abdomen.

In mammals, the bony pelvis has a gap in the middle that is significantly larger in women than in men. Your young will go through this void when they are born.


The pelvic region of the trunk is the lower part of the trunk between the abdomen and thighs. It includes several structures: the bony pelvis, the pelvic cavity, the pelvic floor, and the perineum. The bony pelvis (pelvic skeleton) is the part of the skeleton that is embedded in the pelvic region of the trunk. It is divided into the pelvic girdle and the pelvic spine. The pelvic girdle consists of the appended hip bones (ilium, ischium and pubic bone) aligned in a ring and connects the pelvic region of the spine with the lower limbs. The pelvic spine consists of the sacrum and coccyx.

Pelvic bones

The pelvic skeleton is formed posteriorly (in the area of ​​the back), by the sacrum and tailbone, and laterally and anteriorly (forward and side) by a pair of hip bones. Each hip bone is made up of 3 sections: ilium, ischium, and pubic bone. During childhood, these sections are separate bones that are connected by tri-radial cartilage. During puberty, they fuse into a single bone.

Pelvic cavity

The pelvic cavity is a body cavity bounded by the bones of the pelvis and containing mainly reproductive organs and the rectum.

A distinction is made between the smaller or true basin below the end line and the larger or false basin above. The pelvic inlet or upper pelvic opening that leads into the smaller pelvis is bounded by the promontory, the arched line of the ilium, the eminence of the iliopubus, the pectus of the pubic bone, and the upper part of the pubic symphysis. The pelvic outlet or inferior pelvic opening is the area between the subpubic angle or pubic arch, the ischial tuberosities and the coccyx.

Alternatively, the basin is divided into three levels: inlet, middle level and outlet.

pelvic floor

The pelvic floor has two inherently contradicting functions: one is to close the pelvic and abdominal cavities and carry the load on the visceral organs; The other is to control the openings of the rectum and genitourinary organs that penetrate the pelvic floor and make it weaker. To accomplish these two tasks, the pelvic floor is made up of several overlapping layers of muscles and connective tissue.

The pelvic membrane consists of the levator ani and the coccyx muscle. These arise between the symphysis and the sciatic spine and converge on the tailbone and on the anococcygeal ligament that extends between the tip of the tailbone and the anal pause. This leaves a slit for the anal and urogenital openings. Because of the width of the genital opening, which is wider in women, a second locking mechanism is required. The urogenital diaphragm consists mainly of the deep transverse perineal, which arises from the lower ischial and pubic bones and extends to the urogenital pause. The urogenital diaphragm is reinforced posteriorly by the superficial transverse perineal.

The external anal and urethral sphincters close the anus and urethra. The former is surrounded by the bulbospongiosus, which narrows the vaginal introitus in women and the corpus spongiosum in men. Ischiocavernosus pushes blood into the corpus cavernosum of the penis and the clitoris.


Modern humans are largely characterized by bipetal locomotion and large brains. Since the pelvis is critical to both locomotion and childbirth, natural selection has faced two conflicting requirements: a wide birth canal and the efficiency of locomotion, a conflict known as the "obstetric dilemma". The female pelvis or gynecoid pelvis has grown to its maximum width for childbirth - a wider pelvis would make women unable to walk. In contrast, the human male pelvis is not restricted by the necessity of childbirth and is therefore better optimized for the locomotion of the biped.

The main differences between male and female true and false pelvis include:

  • The female pelvis is larger and wider than the male pelvis, which is larger, narrower, and more compact.
  • The female inlet is larger and oval, while the male sacral promontory protrudes further (i.e. the male inlet is more heart-shaped).
  • The sides of the male pelvis converge from inlet to outlet, while the sides of the female pelvis are further apart.
  • The angle between the lower pubic bone is acute (70 degrees) in men, but obtuse (90-100 degrees) in women. Accordingly, the angle is called the subpubic angle in men and pubic arch in women. In addition, the bones that form the angle / arch are more concave in women, but straight in men.
  • The distance between the ischial bones is small in men, making the outlet narrow, but large in women, who have a relatively large outlet. The sciatic spines and tuberosity are heavier and in men protrude further into the pelvic cavity. The larger sciatic notch is wider in women.
  • The iliac crests are higher and more pronounced in men, making the male false pelvis deeper and narrower than in women.
  • The male sacrum is long, narrow, straighter and has a pronounced sacral promontory. The female sacrum is shorter, wider, more curved posteriorly and has a less pronounced promontory.
  • The acetabula are wider in women than in men. In men, the acetabulum points more laterally, while in women it points forward. As a result, as the males walk, the leg can move back and forth in a single plane. In women, the leg must swing forward and inward, from where the pivoting head of the femur moves the leg backward in a different plane. This change in the angle of the femoral head gives the female gait its characteristic (i.e., the swaying of the hips).


Each side of the pelvis is shaped as cartilage ossified as three main bones that remain separate during childhood: ilium, ischium, pubic bone. At birth, the entire hip joint (the acetabular area and the top of the femur) is still made of cartilage (but there may be a small piece of bone in the greater trochanter of the femur). This makes it difficult to detect a congenital hip dislocation on x-rays.

"In terms of comparative anatomy, the human shoulder blade represents two bones that are fused together: the actual (dorsal) shoulder blade and the (ventral) coracoid. The line of epiphyses through the glenoid cavity is the line of fusion. They are the counterparts of the ilium and ischium of the pelvic girdle. "

There are initial indications that the pelvis continues to expand over the course of a lifetime.


The skeleton of the pelvis is a pelvic ring of bones that connects the spine with the femora.

Its main functions are to support the weight of the upper body when sitting and standing, to transfer this weight from the axial skeleton to the lower appended skeleton when standing and walking, and to fasten and withstand the forces of the strong muscles of locomotion and posture. Compared to the shoulder girdle, the pelvic girdle is strong and stiff.

Its secondary functions are to contain and protect the bowels of the pelvis and abdominal cavity (lower parts of the urinary tract, internal reproductive organs) and to secure the external reproductive organs and associated muscles and membranes.

As a mechanical structure

Anatomical drawing of the female pelvis

The pelvic girdle consists of the two hip bones. The hip bones are connected to each other at the pubic symphysis anteriorly and behind the sacrum at the sacroiliac joints to form the pelvic ring. The ring is very stable and allows very little mobility, a prerequisite for the transfer of loads from the trunk to the lower limbs.

As a mechanical structure, the basin can be viewed as four roughly triangular and twisted rings. Each upper ring is made up of the pelvic bone; the anterior side extends from the acetabulum to the anterior upper pelvic spine; the posterior side extends from the top of the acetabulum to the sacroiliac joint; and the third side is formed by the palpable iliac crest. The lower ring, which is formed by the rami of the pubic and ischial bones, supports the acetabulum and is rotated 80–90 degrees compared to the upper ring.

An alternative approach is to consider the pelvic part of an integrated mechanical system based on the tensegrity icosahedron as an infinite element. Such a system is able to withstand omnidirectional forces - from stress to birth - and, as a system with low energy requirements, is favored by natural selection.

The angle of inclination of the pelvis is the most important element of a person's posture and is set at the hips. It's also one of the rare things that can be measured when assessing posture. A simple measurement method was described by the British orthopedic surgeon Philip Willes and performed using an inclinometer.

As an anchor for muscles

The lumbosacral joint between the sacrum and the last lumbar vertebra, like all vertebral joints, has an intervertebral disc, anterior and posterior ligaments, ligamenta flava, interspinous and supraspinous ligaments and synovial joints between the articular processes of the two bones. In addition to these ligaments, the iliolumbar and lateral lumbosacral ligaments strengthen the joint. The iliolumbar ligament runs between the tip of the transverse process of the fifth lumbar vertebra and the back of the iliac crest. The lateral lumbosacral ligament, which is partially continuous with the iliolumbar ligament, runs from the lower edge of the transverse process of the fifth vertebra to the ala of the sacrum. The movements that are possible in the lumbosacral joint are flexion and extension, a slight lateral flexion (from 7 degrees in children to 1 degree in adults), but no axial rotation. Between the ages of 2 and 13, the joint is responsible for up to 75% (approx. 18 degrees) of flexion and extension of the lumbar spine. From the age of 35, the ligaments restrict the range of motion considerably.

The three extracapsular ligaments of the hip joint - the iliofemoral, the ischiofemoral, and the pubofemoral ligament - form a twisting mechanism that surrounds the femoral neck. When sitting with the hip joint flexed, these ligaments become slack, which allows a high degree of mobility in the joint. When standing with the hip joint extended, the ligaments are twisted around the femoral neck, which presses the head of the femur firmly into the acetabulum and stabilizes the joint. The zona orbicularis helps maintain contact in the joint by acting like a buttonhole on the femoral head. The intracapsular ligament, the ligamentum teres, carries blood vessels that nourish the head of the femur.


Coronal cut through pubic hair

In the pubic symphysis, the two hip bones are connected anteriorly by fibrous cartilage, which is covered by hyaline cartilage, the interpubus disc, in which a nonsynovial cavity may be present. Two ligaments, the upper and lower pubic ligament, strengthen the symphysis.

Both Sacroiliac joints form between the ear surfaces of the sacrum and the two hip bones. are amphiarthroses, almost immobile joints that are enclosed by very tight joint capsules. This capsule is strengthened by the ventral, interosseous, and dorsal sacroiliac ligaments. The most important accessory ligaments of the sacroiliac joint are the sacrospinous and sacrotuberous ligaments, which stabilize the hipbone on the sacrum and prevent the promoter from tilting forward. Additionally, these two ligaments transform the larger and smaller sciatic notches into the larger and smaller foramina, a pair of important pelvic openings. The iliolumbar ligament is a strong ligament that connects the tip of the transverse process of the fifth lumbar vertebra to the back of the inner lip of the iliac crest. It can be thought of as the lower edge of the thoracolumbar fascia and is occasionally accompanied by a smaller ligament that runs between the fourth lumbar vertebra and the iliac crest. The lateral lumbosacral ligament is partially continuous with the iliolumbar ligament. It runs between the transverse process of the fifth vertebra to the ala of the sacrum, where it merges with the anterior sacroiliac ligament.

The joint between the sacrum and tailbone, the sacrococcygeal symphysis, is strengthened by a series of ligaments. The anterior cruciate ligament is an extension of the anterior longitudinal ligament (ALL) that runs along the front of the vertebral bodies. Its irregular fibers mix with the periosteum. The posterior cruciate ligament has a deep and a superficial part, the former is a flat ligament that corresponds to the posterior longitudinal ligament (PLL), and the latter corresponds to the ligamenta flava. Several other ligaments complete the foramen of the last sacral nerve.

Shoulder and intrinsic back

Intrinsic back muscles

The lower parts of the latissimus dorsi, one of the muscles of the upper extremity, arise from the back third of the iliac crest. Its effect on the shoulder joint is internal rotation, adduction and retroversion. It also contributes to breathing (i.e. coughing). When the arm is adducted, the latissimus dorsi can pull it back and medial until the back of the hand covers the buttocks.

In an osteofibrous longitudinal canal on either side of the spine is a group of muscles called the erector spinae, which are divided into a lateral superficial and a medial deep tract. In the lateral tract, Iliocostalis lumborum and Longissimus thoracis arise on the back of the sacrum and in the back of the iliac crest. When these muscles contract bilaterally, the spine is elongated, and unilateral contraction bends the spine on the same side. The medial tract has a "straight" (interspinales, intertransversarii and spinalis) and an "oblique" (multifidus and semispinalis) component, both of which extend between vertebral processes; The former works in a similar way to the muscles of the side tract, while the latter acts on one side as a spinal extensor and bilaterally as a spinal rotator. In the medial tract, the multifidi arises on the sacrum.


The muscles of the abdominal wall are divided into a superficial and a deep group.

The superficial group is divided into a lateral and a medial group. In the medial superficial group, the rectus abdominis extends on both sides of the middle of the abdominal wall ( Linea alba ) from the cartilages of the ribs V-VII and the sternum to the pubic bone. At the lower end of the rectus abdominis, the pyramidalis spans the Linea alba an . The lateral superficial muscles, the transversus and external and internal oblique muscles, originate in the rib cage and pelvis (iliac crest and inguinal ligament) and are attached to the anterior and posterior layers of the attached sheath of the rectus.

Trunk flexion (leaning forward) is essentially a movement of the rectus muscles, while lateral flexion (lateral flexion) is achieved by contracting the obliques along with the quadratus lumborum and intrinsic back muscles. The lateral rotation (either turning the trunk or the pelvis to the side) is achieved by contracting the inner slope on one side and the outer slope on the other. The main function of the transversus is to create abdominal pressure to narrow the abdominal cavity and pull the diaphragm upward.

There are two muscles in the deep or rear group. Quadratus lumborum arises from the rear part of the iliac crest and extends to rib XII and the lumbar vertebrae I - IV. It bends the trunk to one side and bilaterally pulls the 12th rib downwards and supports exhalation. The iliopsoas consists of the greater psoas (and occasionally the minor psoas) and iliac muscles, muscles with separate origins but a common insertion at the lesser trochanter of the femur. Of these, only the iliac is attached to the pelvis (the iliac fossa). However, psoas passes through the pelvis and is classified topographically as the posterior abdominal muscle but functionally as the hip muscle because it acts on two joints. Iliopsoas flexes and rotates the hip joints outward, while the unilateral contraction bends the trunk sideways and the bilateral contraction lifts the trunk from the supine position.

Hips and thighs

Muscles of the hip. Front view for the top left and right diagrams. Rear view for the diagram at the bottom left,

The muscles of the hip are divided into a dorsal and a ventral group.

The dorsal hip muscles are inserted into either the lesser trochanter (anterior or inner group) or the greater trochanter (posterior or outer group). In front, the psoas major (and occasionally the psoas minor) arises along the spine between the rib cage and pelvis. The iliac arises at the iliac fossa and connects with psoas at the iliopubic eminence to form the iliopsoas, which are inserted into the lesser trochanter. The iliopsoas is the strongest hip flexor.

The posterior group includes the gluteus maximus, gluteus medius, and gluteus minimus. Maximus has a broad origin extending from the back of the iliac crest and along the sacrum and coccyx, and has two separate insertions: a proximal one that radiates into the iliotibial tract and a distal one that extends into the gluteal tuberosity on the posterior side of the iliac crest inserts the femoral shaft. It is primarily an extensor and lateral rotator of the hip joint, but due to its bipartite insertion it can both adduct and abduct the hip. The medius and minimus arise on the outer surface of the ilium and are both inserted into the greater trochanter. Your anterior fibers are medial rotators and flexors, while the posterior fibers are lateral rotators and extensors. The piriformis has its origin on the ventral side of the sacrum and is inserted on the greater trochanter. It abducts and turns the hips sideways in an upright position and helps to straighten the thigh. The tensor fasciae latae arises on the anterior upper pelvic spine and is inserted into the iliotibial tract. It pushes the head of the femur into the acetabulum and flexes, rotates medially and abducts the hip.

The ventral hip muscles are important for maintaining balance. The internal and external obturator muscles, along with the quadratus femoris, are lateral rotators of the hip. Together they are stronger than the medial rotators and therefore the feet point outward in the normal position for better support. The obturators originate on either side of the obturator foramen and are inserted into the trochanteric fossa on the femur. Quadratus arises from the ischial tuberosity and is inserted into the intertrochanteric ridge. The upper and lower gemelli, which arise from the sciatic spine and ischial tuberosity, respectively, can be thought of as the marginal heads of the internal obturator, and their main function is to support this muscle.

Front and back thigh muscles

The muscles of the thigh can be divided into adductors (medial group), extensors (anterior group), and flexors (posterior group). The extensors and flexors act on the knee joint, while the adductors act mainly on the hip joint.

The thigh adductors originate in the lower ramus of the pubic bone and, with the exception of gracilis, are inserted along the femoral shaft. Together with Sartorius and Semitendinosus, gracilis extends beyond the knee to their joint introduction into the tibia.

The anterior thigh muscles make up the quadriceps, which are inserted into the patella with a common tendon. Three of the four muscles have their origin on the femur, while the rectus femoris starts from the anterior lower pelvic spine and is therefore the only one of the four that acts on two joints.

The hamstrings originate in the inferior ischial branch with the exception of the short head of the biceps femoris. The semitendinosus and semimembranosus are inserted into the tibia on the medial side of the knee, while the biceps femoris are inserted into the fibula on the lateral side of the knee.

In pregnancy and childbirth

In the later stages of pregnancy, the fetus's head aligns in the pelvis. Bone joints also soften due to the effects of pregnancy hormones. These factors can Cause pain in the pelvic joint (Pubic symphysis dysfunction or SPD). As the end of pregnancy approaches, the sacroiliac joint ligaments loosen and the pelvic outlet becomes slightly wider. This can easily be seen in the cow.

During childbirth (except by caesarean section), the fetus happens to be maternal Pelvic opening .

Clinical Significance

Hip fractures often affect the elderly and are more common in women, often due to osteoporosis. There are also several types of pelvic fractures, which are often the result of traffic accidents.

Pelvic pain can generally affect anyone and has a variety of causes; Endometriosis in women, intestinal adhesions, irritable bowel syndrome, and interstitial cystitis.

There are many anatomical variations of the pelvis. In women, the pelvis can be much larger than normal, known as Giant pool or Basin Justo Major, or it can be known as a lot smaller reduced pelvis or Basin Justo Minor . Other variations include a Android pool with the normal shape of the male pelvis. In women, this form can be problematic at birth.


Caldwell-Moloy classification

Pelvimetric measurements were performed on pregnant women throughout the 20th century to determine whether natural birth would be possible. This practice is now limited to cases in which a specific problem is suspected or after a caesarean delivery. William Edgar Caldwell and Howard Carmen Moloy examined collections of skeletal pelvises and thousands of stereoscopic radiograms and eventually identified three types of female pelvis plus the male type. In 1933 and 1934 she published her typology, including the Greek name, since then frequently cited in various manuals: gynaecoid ( gyne , Woman), anthropoid ( anthropos , Human), platypelloid ( platys , flat) and Android ( aner , Man) .

  • The gynecoid pelvis is the so-called normal female pelvis. Its inlet is either slightly oval with a larger transverse diameter or round. The inner walls are straight, the subpubic arch broad, the sacrum shows an average backward slope, and the larger sciatic notch is well rounded. Because this type is spacious and well proportioned, there is little or no difficulty in the birthing process. Caldwell and his co-workers found gynecoid pelvis in about 50 percent of the specimens.
  • The platypelloid basins has a transversely wide, flattened shape, is anteriorly wide, has larger male-type sciatic notches, and a short sacrum that curves inward, reducing the diameters of the lower pelvis. This is similar to the rachitic pelvis, where the softened bones widen laterally due to the weight of the upper body, resulting in a decreased anteroposterior diameter. Childbirth with this type of pelvis is fraught with problems such as: B. a lateral standstill. Less than 3 percent of women have this type of pelvis.
  • The Android basin is a female pelvis with male characteristics including a wedge or heart shaped inlet caused by a protruding sacrum and triangular anterior segment. The reduced pelvic outlet often causes problems during child birth. In 1939, Caldwell found this type in one-third of white women and one-sixth of non-white women.
  • The anthropoid pelvis is characterized by an oval shape with a larger anteroposterior diameter. It has straight walls, a small sub-pubic arch, and large sacrosky notches. The sciatic spines are widely spaced and the sacrum is usually straight, resulting in a deep, unclogged pelvis. Caldwell found this type in a quarter of white women and nearly half of non-white women.

However, Caldwell and Moloy complicated this simple four-fold scheme by dividing the basin inlet into posterior and anterior segments. They named a basin after the anterior segment and attached a different type according to the character of the posterior segment (i.e. anthropoid android) and ended up with no less than 14 morphologies. Despite the popularity of this simple classification, the pelvis is much more complicated because the pelvis can have different dimensions at different levels of the birth canal.

Caldwell and Moloy also classified women's physiques according to their type of pelvis: the gynecoid type has small shoulders, a small waist, and broad hips; The Android guy looks square from the back. and the anthropoid type has broad shoulders and narrow hips. Finally, in their article, they described all non-gynecoid or "mixed" types of pelvis as "abnormal," a word that has gotten bogged down in the medical world even though at least 50 percent of women have these "abnormal" pelvis.

The Caldwell and Moloy classification was influenced by previous classifications that attempted to define the ideal female pelvis, with deviations from this ideal treated as a dysfunction and cause of handicapped labor. In the 19th century, anthropologists and others saw an evolutionary scheme in these basin typologies, a scheme that has since been refuted by archeology. Since the 1950s, malnutrition has been considered a major contributor to pelvic shape in the developing world, although the variation in pelvic morphology has at least one genetic component.

Nowadays the obstetric suitability of the female pelvis is assessed by ultrasound. The dimensions of the head of the fetus and the birth canal are accurately measured and compared, and the feasibility of labor can be predicted.

Other animals

The pelvic girdle was present in early vertebrates and can be traced back to the paired fish fins, which were among the earliest chord dates.

The shape of the pelvis, in particular the alignment of the iliac crests and the shape and depth of the acetabula, reflect the locomotion style and body mass of an animal. In two-legged mammals, the iliac crests run parallel to the vertically aligned sacroiliac joints, in four-legged mammals parallel to the horizontally aligned sacroiliac joints. In heavy mammals, especially four-legged friends, the pelvis tends to be more vertical, as this allows the pelvis to carry greater weight without moving the sacroiliac joints or twisting the spine.

In ambulatory mammals, the acetabula are flat and open to allow a wider range of hip movements, including significant abduction, than in cursor mammals. The lengths of the ilium and ischium and their angles relative to the acetabulum are functionally important as they determine the moment arms for the hip extensor muscles that provide momentum during locomotion.

In addition, the relatively wide shape (front to back) of the pelvis provides greater leverage for the gluteus medius and minimus. These muscles are responsible for hip abduction, which is essential for maintaining upright balance.


In primates, the pelvis consists of four parts - the left and right hip bones, which meet ventrally in the midline and are attached dorsally to the sacrum and coccyx. Each hip bone is made up of three components, the ilium, isschium, and pubic bone, and at the time of sexual maturity these bones fuse together, although there is never any movement between them. In humans, the ventral joint of the pubic bones is closed.

Bigger monkeys like Pongo ( Orangutans ), Gorillas (Gorillas), Australopithecus afarensis and Pan cave dwellers (Chimpanzees) have longer three-pelvic planes with a maximum diameter in the sagittal plane.


Today's pelvis morphology is inherited from the pelvis of our four-legged ancestors. The most striking feature of the development of the pelvis in primates is the widening and shortening of the blade, which is called the ilium. Because of the loads involved in locomotion of the bipedal, the muscles of the thigh move the thigh back and forth and provide the power to move the two pedals and quadrupeds.

With the drying up of the East African environment since the formation of the Red Sea and the African Rift Valley, open forests replaced the former closed canopy forest. The monkeys in this area were forced to travel from one log to another across open land. This led to a number of complementary changes in the human pelvis. It is believed that bipedalism was the result.

Additional pictures

See also



  • Cunningham, Daniel John; Robinson, Arthur (1818). Cunningham's Textbook of Anatomy . William Wood and Company. Retrieved on August 14, 2010.
  • Ebrall, Phillip S .; Sportelli, Louis; Donato, Phillip R. (2004). Assessment of the spine . Elsevier Health Sciences. ISBN. Retrieved on August 14, 2010.
  • Hall, Brian Keith (2007). Fins in Limbs: Evolution, Development and Transformation . University of Chicago Press. ISBN. Retrieved on August 14, 2010.
  • Holm, Niels J. (1980). "The Internal Stress Pattern of the Os Coxae". Acta Orthopedica . 51 (51: 1): 421-8. doi: 10.3109 / 17453678008990818. PMID 7446021.
  • Levin, Stephen M. (2007). "Stay tuned !: The statics and dynamics of the pelvic mechanics". Bio integrity. Archived from the original on June 10, 2010.