The ischial tuberosity (or tuberosity of the ischium, tuber ischiadicum), also known colloquially as the sit bones or sitz bones,[1] or as a pair the sitting bones,[2] is a large posterior bony protuberance on the superior ramus of the ischium. It marks the lateral boundary of the pelvic outlet.
| Ischial tuberosity | |
|---|---|
 Capsule of hip-joint (distended). Posterior aspect. (Ischial tuberosity visible at bottom left.) | |
| Details | |
| Identifiers | |
| Latin | tuber ischiadicum, tuberositas ischiadica |
| TA98 | A02.5.01.204 |
| TA2 | 1342 |
| FMA | 17010 |
| Anatomical terms of bone | |
When sitting, the weight is frequently placed upon the ischial tuberosity.[3] The gluteus maximus provides cover in the upright posture, but leaves it free in the seated position.[4] The distance between a cyclist's ischial tuberosities is one of the factors in the choice of a bicycle saddle.
Divisions
editThe tuberosity is divided into two portions: a lower, rough, somewhat triangular part, and an upper, smooth, quadrilateral portion.
- The lower portion is subdivided by a prominent longitudinal ridge, passing from base to apex, into two parts:
- The outer gives attachment to the adductor magnus
- The inner to the sacrotuberous ligament
- The upper portion is subdivided into two areas by an oblique ridge, which runs downward and outward:
- From the upper and outer area the semimembranosus arises
- From the lower and inner, the long head of the biceps femoris and the semitendinosus
Additional images
edit-
Muscles of the gluteal and posterior femoral regions, with ischial tuberosity highlighted in red
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Right hip bone. External surface.
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Right hip bone. Internal surface.
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Plan of ossification of the hip bone
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Diameters of inferior aperture of lesser pelvis (female)
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Right hip-joint from the front
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Anterior view of the pelvis with the ischial tuberosity labelled in the lower part of the image
See also
editNotes
edit- ^ M.D, John R. Schultz (October 28, 2019). "Sit Bones Pain (aka Sitz Bone)". Centeno-Schultz Clinic. Retrieved April 12, 2020.
- ^ Sills, Franklyn (2004). Craniosacral Biodynamics: The Primal Midline and the Organization of the Body (revised, illustrated ed.). Berkeley, CA: North Atlantic Books. p. 99. ISBN 1-55643-390-5.
- ^ Goossens (2005), pp 895–982
- ^ Platzer (2004), p 236
References
edit This article incorporates text in the public domain from page 235 of the 20th edition of Gray's Anatomy (1918)
- Goossens R, Teeuw R, Snijders C (2005). "Sensitivity for pressure difference on the ischial tuberosity". Ergonomics. 48 (7): 895–902. doi:10.1080/00140130500123647. PMID 16076744. S2CID 854065.
- Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1.
External links
edit- pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University) (pelvisposterior, pelvislateral, pelvisinside)