General information
The bony pelvis (pelvic bone) consists of the two hip bones (Os coxae), the coccyx (Os coccygis) and the sacrum (Os sacrum). It is used for the articulated connection of the spinal column with the lower extremity. In addition, the bony structure differs between the sexes due to the anatomical requirements for the birth of a child.
Function
The pelvis is mainly used for the articulated connection between the spine and the lower extremities. Especially with the spinal column it is articulated, but very firmly connected, so that hardly any movement is possible here. However, it enables a secure stand and an upright posture. In addition, the bones are the starting and origin points for numerous muscles.
Structure
The bony pelvis consists of the one hip bone in turn consists of three different bones: The pelvis is roughly divided into a large and a small pelvis. The linea terminalis serves to separate these two pelvic parts. This is an imaginary dividing line which begins at the most prominent point of the 5th lumbar vertebra and from there extends to the symphysis.
The space between the two iliac blades above the linea terminalis is known as the great pelvis (pelvis major), the space below as the small pelvis (pelvis minor). The small pelvis narrows towards the bottom and thus represents the actual pelvic funnel. In the following the individual pelvic parts will be explained in more detail. – sacrum (Os sacrum), the
- Coccyx (Os coccygis) and the
- Both hip bones (Os coxae dextrum et sinistrum). – Os ilium (iliac bone),
- Os ischii (ischium) and
- Os pubis.
Hip bone (Os coxae)
The hip bone consists of three parts which fuse together to form a hip bone. The Y-shaped fusion joint of the parts is located in the acetabulum. The two sides of the hip bone are connected via the symphysis (symphysis pubica) and the sacrum (os sacrum) to form a bone ring.
The two hip bones are each connected to the sacrum via the sacroiliac joint (Articulatio sacroiliaca). This is an amphiarthrosis, i.e. the two bones are very firmly connected and hardly allow any room for movement. However, the joint is very important for the suspension of the spinal column.
The ilium (os ilium) takes up the largest part of the hip bone and can be divided into a wide The border between these two parts is formed by a bony groin, the linea arcuata. At the same time this line also represents the border between the large and small pelvis. On the inside of the iliac crest is a small pit, the iliac fossa.
This serves as the origin of the iliac muscle. The outer side is called facies glutea. It carries three bone lines, which serve as attachment points for the gluteal muscles.
The iliac crest has an upper thickened edge, which is called iliac crest (Crista iliaca). This runs out towards the front in the spina iliaca anterior superior, towards the back in the spina iliaca posterior superior. Underneath each is another bony protrusion, which is called the anterior inferior iliac spine and posterior inferior iliac spine.
The ischium (Os ischii) is also integrated into a The body forms the largest part of the acetabulum and ends at the back in the so-called ischial spine (spina ischiadica). This separates the large and small bony incision of the ischium (incisura ischiadica major and minor). Below the smaller incision is the ischial tuberosity (Tuber ischiadicum), which is the origin of the ischiocrural muscles.
The pubic bone (Os pubis) is also divided into three parts: The pubic bones on both sides are connected by the symphysis and thus form the pelvic ring. On the side of the symphysis there is a bony protrusion, the tuberculum pubicum. From there, one bony ridge extends to the symphysis (crista pubica), another to the acetabulum (crista obturatoria).
Together with the ischium (Os ischii), the pubic bone surrounds a hole in the pelvis (Foramen obturatoria). This hole is closed by a membrane (Membrana obturatoria) so that only the obturatorial nerve can pass through. This membrane is the origin of the internal and external obturator muscle.
The acetabulum is formed by all three bone parts and is a bony, circular depression surrounded by a bone bulge. The acetabulum is crescent-shaped and covered with cartilage and represents the articulated connection to the femoral head of the femur. – iliac scoop (Ala ossis ilii) and the
- Structure the body of the ilium (Corpus ossis ilii). – body (Corpus ossis ischii) and a
- Marginal part (Ramus ossis ischii) jointed. – the body of the pubic bone (Corpus ossis pubis) and
- Upper and lower edge of the pubic bone (ramus superior and inferior).
