Lesser sciatic foramen
Foramen ischiadicum minus
- Synonym: Lesser ischiatic foramen
Definition
The posterior border of the ischium features a bony opening known as the lesser sciatic foramen. This foramen is created by the sacrotuberous and sacrospinous ligaments, which transform the "incomplete" lesser sciatic notch into a "complete" lesser sciatic foramen.
The boundaries of lesser sciatic foramen include:
Anteriorly → bony lesser sciatic notch
Posteriorly → sacrotuberous ligament
Superiorly → sacrospinous ligament
The lesser sciatic foramen serves as passageway for two significant structures:
The tendon of the obturator internus muscle as it enters the gluteal region
Internal pudendal vessels and nerves as they enter the perineum
References
Standring, S. and Gray, H. (2016). ‘Chapter 80: Pelvic girdle, gluteal region and thigh’ in Gray’s anatomy The anatomical Basis of Clinical Practice. (41st ed.) New York: Elsevier, pp. 1341-1345.
