Tuberosity of the ischium

Bone: Tuberosity of the ischium
Capsule of hip-joint (distended). Posterior aspect. (Tuberosity of ischium visible at bottom left.)
The superficial branches of the internal pudendal artery. (Tuber. ischial. visible at center left.)
Latin	tuber ischiadicum
Gray's	subject #57 235
Dorlands / Elsevier	t_21/12827506

Posteriorly, the superior ramus of the ischium forms a large swelling, the tuberosity of the ischium (or ischial tuberosity).

It marks the lateral boundary of the pelvic outlet.

When sitting, the weight is frequently placed upon the ischial tuberosity.

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 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.

File:Tuberosity of the ischium.PNG

Muscles of the gluteal and posterior femoral regions, with tuberosity of the ischium highlighted in red

See also

• Sitting disability

Additional images

• 

  Right hip bone. External surface.

• 

  Right hip bone. Internal surface.

• 

  Plan of ossification of the hip bone.

• 

  Diameters of inferior aperture of lesser pelvis (female).

• 

  Right hip-joint from the front.

• 

  The Obturator externus.

External links

• SUNY Labs 41:st-0204 - "The Female Perineum: Bones"
• SUNY Labs 17:os-0114 - "Major Joints of the Lower Extremity: Hip bone (lateral view)"
• Norman/Georgetown pelvis (pelvisposterior, pelvislateral, pelvisinside)

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained herein may be outdated. Please edit the article if this is the case, and feel free to remove this notice when it is no longer relevant.