Sacrum (Os sacrum)
The sacrum is formed by the five fused sacral vertebrae and the ossified intervertebral discs between them. The downward point (caudal) of the sacrum is called apes ossis sacri, the most prominent point at the base of the sacrum is called promontorium. The sacral canal (Canalis sacralis) represents the continuation of the spinal canal.
The os sacrum also has various surfaces that act as joints to adjacent structures. Laterally, the two facies auricularis are located, which form an articulated connection with the surface of the ilium. In addition, small holes run between the vertebrae (Foramina intervertebralia) in the sacrum, which represent the exit point of the spinal nerves. – anterior concave surface, from one to
- Convex surface at the rear.
Coccyx (Os coccygis)
The coccyx is connected to the sacrum and usually consists of four vertebrae. However, the number can vary. The individual vertebrae are connected by synchondroses so that no movement can take place here. The size of the individual vertebrae decreases towards the bottom.
Pool dimensions
A distinction is made between the outer and inner pelvic dimensions. In addition, transverse and oblique diameters are determined for the inner basin dimensions. These measurements should be determined especially during pregnancy in order to be able to assess whether the child can pass the bony pelvis during birth without any problems.
- The smallest sagittal diameter between the posterior surface of the symphysis and the promontory is approximately 11cm. – The largest transverse diameter along the linea terminalis is 13.5cm on average. – The distance between the lower edge of the symphysis and the promontory is 12.5cm.
Gender differences
The pelvis shows typical sexual differences. The entrance to the pelvis of the man is rather card heart-shaped, that of the woman is transversely oval. In addition, the angle of the pubic bone is acute in men (approx.
70°) and rather obtuse in women (approx. 100°). The iliac crest itself is rather steep in a man, in a woman it is rather laterally protruding and the shape of the pelvic ring is high, narrow and narrow in a man, while in a woman it is low, wide and wide. All these differences serve the optimal conditions for a birth.
Pain in the pelvic bone
Pelvic pain usually affects the hip joint, the lower back, the groin or the ligaments and muscles running along the hip. Only in rare cases is the pain actually attributable to the pelvic bone. Displacements of the sacroiliac joint (ISG) often occur, which can be caused by different leg lengths, back pain, muscle defects or twisting of the bones in the joint.
Tension, irritation of the ligaments or tendons, a pinched nerve, or even defects or injuries of the internal organs can be possible causes for pain in the pelvic bone. Fractures, sprains or strains can also be the cause. The pain often radiates into the leg, back or groin. If the pain is not resolved after a few weeks, a doctor should be consulted.
