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, tuberositas ischiadica
Gray's	subject #57 235

Posteriorly, the superior ramus of the ischium forms a large swelling, the tuberosity of the ischium (or ischial tuberosity or Tuber ischiadicum in latin, also known as the sitz bone^[1], or as a pair the sitting bones).

It marks the lateral boundary of the pelvic outlet.

When sitting, the weight is frequently placed upon the ischial tuberosity.^[2] The gluteus maximus covers it in the upright posture, but leaves it free in the seated position.^[3]

1 Divisions
2 See also
3 Additional images
4 Notes
5 References
6 External links

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.

Additional images

Notes

^ Sills, Franklyn (2004). Craniosacral Biodynamics: The Primal Midline and the Organization of the Body (revised, illustrated ed.). Berkeley, CA: North Atlantic Books. pp. 99. ISBN 1556433905. http://books.google.com/?id=cEMVaxzHNXcC.
^ Goossens (2005), pp 895-982
^ Platzer (2004), p 236

References

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.
Platzer, Werner (2004). Color Atlas of Human Anatomy, Vol. 1: Locomotor System (5th ed.). Thieme. ISBN 3-13-533305-1.

This article was originally based on an entry from a public domain edition of Gray's Anatomy. As such, some of the information contained within it may be outdated.

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)"
pelvis at The Anatomy Lesson by Wesley Norman (Georgetown University) (pelvisposterior, pelvislateral, pelvisinside)

Bones of pelvis / pelvic cavity (TA A02.5.01–03, GA 2.231–241)

General

sacrum · coccyx · hip bone

Ilium

body	arcuate line

wing	gluteal lines (posterior, anterior, inferior) iliac spines (anterior superior, anterior inferior, posterior superior, posterior inferior) other: crest · tuberosity · tubercle · fossa