Cap ( lat. Coccyx ), cap bone ( lat. Os coccygis ) - the lower part of the human spine , consisting of four to five fused rudimentary vertebrae.
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Both the Greek name ( dr. Greek κόκκυξ - “ cuckoo ”) and the Russian “tailbone” are associated with the coracoid shape of the bone [1] .
Function
The tailbone appears in humans and other tailless primates , beginning with the papillary (Miocene hominid) [2] , representing a rudimentary tail [3] . Despite the rudimentary nature, the coccyx has a rather important functional value [1] [4] .
The front sections of the coccyx are used to attach the muscles and ligaments involved in the functioning of the organs of the genitourinary system and the distal parts of the large intestine (the coccygeal, iliac-coccygeal and pubic-coccygeal muscles that form the muscle that raises the anus, as well as the anal-coccygeal ligament). A part of the muscle bundles of the gluteus maximus muscle , which is a powerful hip extensor, is also attached to the coccyx [1] .
In addition, the coccyx plays a role in the distribution of physical load on the anatomical structures of the pelvis, serving as an important point of support - when the person is leaning forward, the points of support are the ischial tubercles and lower branches of the ischial bones ; when tilting back, part of the load is transferred to the coccyx [1] .
Building
The coccyx as a whole has the shape of a curved pyramid , facing up with the base, and the top down and forward.
Modified upper articular processes, called the coccygeal horns ( lat. Cornua coccygea ), depart from the first coccygeal vertebra. The coccygeal horns, connecting with the sacral horns, are involved in the formation of the sacrococcygeal joint as a syndesmosis, in which mobility is more pronounced in women. During childbirth, the tailbone can deviate backward, increasing the size of the birth canal.
On the lateral (lateral) surfaces of the body of the first coccygeal vertebra are the rudiments of the transverse processes, the remaining coccygeal vertebrae of the processes do not.
Pathology
One of the most common pathologies of the coccyx is coccyalgia , which is more common in women. The causes of coccyalgia are trauma, inflammatory and degenerative changes in the coccygeal region (including arthrosis of the sacro-coccygeal joint) or a combination of these processes.
Additional Images
Spinal column.
Spinal column.
Left muscle lifting the anus from the inside.
Middle sagittal section of the male pelvis.
Middle sagittal section of the female pelvis.
See also
- Human spine
- Sacrum
- Coccygodynia
Notes
- ↑ 1 2 3 4 Foye (2008), eMedicine
- ↑ Masato (2004), Acquisition of bipedalism
- ↑ Saladin (2003), p 268
- ↑ Questions to a traumatologist and orthopedist: coccyx removal operation
Links
- Sapin M.R. , Nikityuk D.B. Human anatomy. - In 3 volumes. - M. - 1998. - T.1.
- Sinelnikov R. D. Atlas of human anatomy. - In 3 volumes. - M. - 1990. - T.1.
- Coccyx pain on coccyx.org
- “Coccyx Fracture” on al-hikmah.org
- Coccidinia on emedicine.com