Ischial tuberosity

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 swelling posteriorly 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
Latintuber ischiadicum, tuberositas ischiadica
TA98A02.5.01.204
TA21342
FMA17010
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

The 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 upper portion is subdivided into two areas by an oblique ridge, which runs downward and outward:

Additional images
  • Muscles of the gluteal and posterior femoral regions, with ischial tuberosity highlighted in red
    Muscles of the gluteal and posterior femoral regions, with ischial tuberosity highlighted in red
  • Right hip bone. External surface.
    Right hip bone. External surface.
  • Right hip bone. Internal surface.
    Right hip bone. Internal surface.
  • Plan of ossification of the hip bone
    Plan of ossification of the hip bone
  • Diameters of inferior aperture of lesser pelvis (female)
    Diameters of inferior aperture of lesser pelvis (female)
  • Right hip-joint from the front
    Right hip-joint from the front
  • The obturator externus
    The obturator externus
  • Anterior view of the pelvis with the ischial tuberosity labelled in the lower part of the image
    Anterior view of the pelvis with the ischial tuberosity labelled in the lower part of the image

See also

Notes
  1. M.D, John R. Schultz (October 28, 2019). "Sit Bones Pain (aka Sitz Bone)". Centeno-Schultz Clinic. Retrieved April 12, 2020.
  2. 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.
  3. Goossens (2005), pp 895–982
  4. Platzer (2004), p 236

References

Public domain 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.
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