Obturator Internus

Fig. 1.9a-c. Anterior compartment, a Macroscopic preparation of a 23-week-old female fetus with the pubovesical ligament (arrow) and the tendinous arch (arrowhead). x9. b In an axial section (5 mm) of an adult female with the paravisceral fat pad (asterisks), x. c Axial section (400 pm) of a 24-week-old female fetus with the developing paravisceral fat pad (asterisks). X8. b, bladder u, urethra pbo, pubic bone oi, obturator internus muscle... 

The lateral rotator muscles of the hip include the piriformis and the obturator internus. The piriformis muscle has its medial attachment to the lateral border of the sacrum and is often involved in sacral dysfunctions. 

Internal and external rotation can be tested with the patient seated and the resistance applied to the ankle of the leg being tested. External rotation occurs with contraction of the obturator ex-lernus and internus, piriformis, gluteus maximus, and gemeiii muscles. Internal rotation is provided by the giuteus minimus and tensor fascia iata muscles. 

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