Dictionary.net

is a large notch at the posterior edge of each os innominatum, below the posterior and inferior iliac spine, which is converted into a foramen by the sacrum and sacro-sciatic ligaments. The lesser sciatic notch, Incisu'ra ischiad’ica minor, Luna Albi'ni, (F.) Petite echancrure ischiatique, is much smaller than the last, from which it is separated by the sciatic spine. It gives passage to the tendon of the obturator internus, and to the internal pudic vessels and nerves.