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Encyclopedia > Coccyx
The coccyx is formed of up to five vertebrae.
The coccyx is formed of up to five vertebrae.

The coccyx (pronounced kok-siks) (Latin: os coccygis), commonly referred to as the tailbone, is the final segment of the human vertebral column, of four fused vertebrae (the coccygeal vertebrae) below the sacrum. It is attached to the sacrum in a fibrocartilaginous joint, which permits limited movement between them. The term coccyx comes originally from the Greek language and means "cuckoo," referring to the shape of a cuckoo's beak[1]. File links The following pages link to this file: Coccyx Wikipedia:Grays Anatomy images with missing articles 2 Categories: Public domain images ... File links The following pages link to this file: Coccyx Wikipedia:Grays Anatomy images with missing articles 2 Categories: Public domain images ... A diagram of a thoracic vertebra. ... The vertebral column seen from the side The vertebral column (backbone or spine) is a column of vertebrae situated in the dorsal aspect of the abdomen. ... A diagram of a thoracic vertebra. ... For the record label, see Sacrum Torch. ... For other uses, see Joint (disambiguation). ... Genera See text. ...

Contents

Function

The coccyx provides an attachment for nine muscles, such as the gluteus maximus, and those necessary for defecation. It also acts as something of a shock absorber when a person sits down, although forceful impact can cause damage and subsequent bodily pains. A top-down view of skeletal muscle Muscle (from Latin musculus little mouse [1]) is contractile tissue of the body and is derived from the mesodermal layer of embryonic germ cells. ... The gluteus maximus is the largest and most superficial of the three gluteal muscles. ... Anatomy of the anus and rectum Defecation is the act or process by which organisms eliminate solid or semisolid waste material (feces) from the digestive tract via the anus. ... Gasfilled Shock absorber. ...


Structure

The coccyx is usually formed of four rudimentary vertebrae; the number may be as high as five or as low as three. It articulates superiorly with the sacrum. In each of the first three segments may be traced a rudimentary body and articular and transverse processes; the last piece (sometimes the third) is a mere nodule of bone. All the segments are destitute of pedicles, laminae, and spinous processes. The first is the largest; it resembles the lowest sacral vertebra, and often exists as a separate piece; the last three diminish in size from above downward. Most anatomy books wrongly state that the coccyx is normally fused in adults. In fact it has been shown[2] [3] that the coccyx may consist of up to 5 separate bony segments, the most common configuration being two or three segments. Only about 5% of the population have a coccyx in one piece, separate from the sacrum, as described in anatomy books. This error in anatomy teaching can lead doctors to diagnose a 'fractured coccyx' when they see a coccyx in several segments on x-ray.[citation needed] A diagram of a thoracic vertebra. ... For the record label, see Sacrum Torch. ... The pedicles are two short, thick processes, which project backward, one on either side, from the upper part of the body, at the junction of its posterior and lateral surfaces. ... The laminæ are two broad plates directed backward and medialward from the pedicles. ... The sacrum is a large, triangular bone at the base of the spine and at the upper and back part of the pelvic cavity, where it is inserted like a wedge between the two hip bones. ...


Surfaces

The anterior surface is slightly concave, and marked with three transverse grooves which indicate the junctions of the different segments. It gives attachment to the anterior sacrococcygeal ligament and the Levatores ani, and supports part of the rectum. In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals. ... The Anterior Sacrococcygeal Ligament consists of a few irregular fibers, which descend from the anterior surface of the sacrum to the front of the coccyx, blending with the periosteum. ... The Levator ani is a broad, thin muscle, situated on the side of the pelvis. ... The rectum (from the Latin rectum intestinum, meaning straight intestine) is the final straight portion of the large intestine in some mammals, and the gut in others, terminating in the anus. ...


The posterior surface is convex, marked by transverse grooves similar to those on the anterior surface, and presents on either side a linear row of tubercles, the rudimentary articular processes of the coccygeal vertebrae. Of these, the superior pair are large, and are called the coccygeal cornua; they project upward, and articulate with the cornua of the sacrum, and on either side complete the foramen for the transmission of the posterior division of the fifth sacral nerve. The English word POSTERIOR is identical to the original Latin adjective, and has two different uses : as an ADJECTIVE, it indicates that someone or something is behind another, either spatially or chronologically it also became a SUBSTANTIVE, indicating the rear-end, especially of a person, i. ... The Sacral Nerves—The posterior divisions of the sacral nerves (rami posteriores) are small, and diminish in size from above downward; they emerge, except the last, through the posterior sacral foramina. ...


Borders

The lateral borders are thin, and exhibit a series of small eminences, which represent the transverse processes of the coccygeal vertebrae. Of these, the first is the largest; it is flattened from before backward, and often ascends to join the lower part of the thin lateral edge of the sacrum, thus completing the foramen for the transmission of the anterior division of the fifth sacral nerve; the others diminish in size from above downward, and are often wanting. The borders of the coccyx are narrow, and give attachment on either side to the sacrotuberous and sacrospinous ligaments, to the Coccygeus in front of the ligaments, and to the gluteus maximus behind them. The sacrotuberous ligament (great or posterior sacrosciatic ligament) is situated at the lower and back part of the pelvis. ... The Coccygeus is situated behind the levator ani. ... The gluteus maximus is the largest of the gluteus muscles which are located in the buttock. ...


Apex

The apex is rounded, and has attached to it the tendon of the Sphincter ani externus. It may be bifid. The Sphincter ani externus (external anal sphincter) is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the integument surrounding the margin of the anus. ... Spina bifida (Latin: split spine) is a developmental birth defect involving the neural tube: incomplete closure of the embryonic neural tube results in an incompletely formed spinal cord. ...


Sacrococcygeal and intercoccygeal joints

The joints are variable and may be: (1) synovial joints; (2) thin discs of fibrocartilage; (3) intermediate between these two; (4) ossified.[4] [5] Synovial joints (or diarthroses, or diarthroidal joints) are the most common and most moveable type of joints in the body. ... Cartilage is type of dense connective tissue. ...


Pathology

Injuring the coccyx can give rise to a condition called coccydynia. [6] [7] Coccydynia is a medical condition characterized by pain in the coccyx or tailbone area. ...


Additional images

See also

Coccydynia is a medical condition characterized by pain in the coccyx or tailbone area. ... This article is about the skeletal organs. ... In zootomy, several terms are used to describe the location of organs and other structures in the body of bilateral animals. ... The pelvic portion of each sympathetic trunk is situated in front of the sacrum, medial to the anterior sacral foramina. ... The muscles connected to the ears of a human do not develop enough to have the same mobility allowed to monkeys. ...

References

  1. ^ Coccyx, Dorland's Illustrated Medical Dictionary
  2. ^ Idiopathic coccygodynia. Analysis of fifty-one operative cases and a radiographic study of the normal coccyx. The Journal of bone and joint surgery. American volume. 1983 Oct; 65(8): 1116-1124. Postacchini F, Massobrio M
  3. ^ Clinical and radiological differences between traumatic and idiopathic coccygodynia. Yonsei Medical Journal, 1999 Jun, 40:3, 215-20. Kim NH; Suk KS
  4. ^ Maigne JY, Molinie V, Fautrel B. (1992). "Anatomie des disques coccygiens.". Revue de Médecine Orthopedique 28: 34-35. 
  5. ^ Saluja PG. (1988). "The incidence of ossification of the sacrococcygeal joint.". Journal of Anatomy 156: 11-15. 
  6. ^ Causes and Mechanisms of Common Coccydynia. Spine, 2000, volume 25, number 23, 3072-3079. Maigne, J-Y, Doursounian, L, Chatellier, G.
  7. ^ Foye P, Buttaci C, Stitik T, Yonclas P (2006). "Successful injection for coccyx pain.". Am J Phys Med Rehabil 85 (9): 783-4. PMID 16924191. 

External links


  Results from FactBites:
 
Coccyx Injuries | AHealthyMe.com (871 words)
The coccyx-or tailbone-is the last bone of the vertebral column, and usually consists of three to five fused vertebrae that connect with the sacrum, a part of the pelvis.
The coccyx consists of fused vertebrae, which are not flexible like the other vertebrae of the vertebral column which are all interspaced by intervertebral disks and joined together by elastic ligaments.
In the coccyx, the vertebrae generally fuse together in early adulthood and may also fuse with the sacrum, the bone located between the 5th lumbar vertebra and the coccyx, as a person ages.
The Coccyx (1727 words)
When the coccyx is under stress, whether from a fall or an accumulation of factors, it usually seems to be stuck primarily forward.
Another useful tool for a coccyx that is not releasing easily is postisometric contraction.
Once I find the coccyx, I palpate, and ask the patient where the coccyx is tender.
  More results at FactBites »

 
 

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