Pelvis
- See also Human pelvis for extensive details.
The pelvis, or pelvic bone, derived from the Latin word for 'basin', is an anatomical structure found in most vertebrates. It is the name given to both a bony structure or pelvic girdle connecting the base of the spine to the rear limbs, and the region of the body defined by that structure. The muscles and tissue beneath the pelvic girdle are known as the pelvic floor. The rounded epiphysis of the femur called the Head articulates with the pelvic bone at the Hip Joint at the acetabulum.[1]
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Pelvis skeleton [edit]
The pelvic girdle is also known as the pelvis skeleton or bony pelvis. It is a large, bilaterally symmetric, compound bone structure, consisting of the os coxa, sacrum and coccyx. The top or forward part of the pelvis is called the pelvic inlet, and its edge the pelvic brim. A related skeletal structure, found mainly in birds and dinosaurs, is the synsacrum.
In mammals, the pelvic girdle has a gap in the middle, significantly larger in females than in males. Babies pass through this gap when they are born.
Pelvic cavity and lesser pelvis [edit]
The cavity defined by the pelvic girdle up to the pelvic brim, bounded by the pelvic walls is also known as the pelvic cavity. The region of the body defined by the pelvic girdle and the pelvic cavity is called the lesser pelvis (or true pelvis).
As the pelvis is concave, another cavity is defined by the pelvis above and in front of the pelvic brim. This is referred to this as the greater pelvis (or false pelvis). Some authors consider it part of the pelvic cavity, others consider it part of the abdominal cavity, others call both the abdominopelvic cavity.
The pevis has an anteroinferior, a posterior and two lateral pelvic walls; and an inferior pelvic wall, also called the pelvic floor.[2][3]
Evolutionary history [edit]
The pelvis can be traced back to the pelvic girdles of early vertebrates, and to the paired fins of fish that were some of the earliest chordates.[4]
Evolution in primates [edit]
In primates, the pelvis consists of four parts - the left and the right hip bones which meet in the mid-line ventrally and are fixed to the sacrum dorsally and the coccyx. Each hip bone consists of three components, the ilium, the ischium, and the pubis, and at the time of sexual maturity these bones become fused together, though there is never any movement between them. In humans, the ventral joint of the pubic bones is closed.
The most striking feature of evolution of the pelvis in primates is the widening and the shortening of the blade called the ilium. Because of the stresses involved in bipedal locomotion, the muscles of the thigh move the thigh forward and backward, providing the power for bi-pedal and quadrupedal locomotion.[5]
References [edit]
- ^ Princeton Review (29 July 2003). Anatomy Coloring Workbook, Second Edition. The Princeton Review. p. 49. ISBN 978-0-375-76342-7. Retrieved 30 July 2012.
- ^ Moore, Keith L. et al. (2010) Clinically Oriented Anatomy 6th Ed, ch.3 Pelvis and perineum, p.339
- ^ Richard S. Snell Clinical Anatomy By Regions, Pevic cavity p.242
- ^ . doi:10.2307.2F2456838. Missing or empty
|title=(help) - ^ Bernard Grant Campbell (1998). Human Evolution: An Introduction to Mans Adaptations. Transaction Publishers. p. 170. ISBN 978-0-202-02042-6. Retrieved 30 July 2012.
External links [edit]
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