108 THE VOYAGE OF H.M.S. CHALLENGEE. 



7. Ohturator internus. 



L'iliaqiie interne, Vicq dAzyr, 1774, p. 505. 



Der innere Darmbeinmuskel, Wiedemann, p. 98. 



Der innere Darmheinmusliel, Tiedemann, p. 330, No. 9. 



Llobturateur interne, Cuvier, vol. i. p. 357. 



Troisihne adducteur (part of), Meckel, vol. vi. p. 87, No. 1 0. 



Ohturator internus, Owen, p. 35. 



Ohturator internus, Eeid, p. 143. 



Obturator internus, Selenka, vol. vi. p. 140, Xo. 79 (iQcluded along with the Quadratus 



femoris). 

 L'ohturateiir exteme, Gervais and Alix, p. 31. 



Attach'ments. — This muscle is of an elongated oval fomi. It arises from the inner 

 (pelvic) surface of the lower half of the ischium posterior to the obturator foramen, from the 

 inner surface of the pubic bone to a corresponding extent, and from the inner surface of 

 the obturator membrane. The fibres pass forwards, and end on a tendon which, after 

 escaping from the pelvis by the circular aperture which represents the anterior part of 

 the obturator foramen, is inserted into a well-marked depression on the posterior border of 

 the great trochanter of the femur, above and behind the insertion of the obturator exteruus. 



Action. — The internal obtui-ator co-operates with the obturator externus in rotating 

 the femur outwards at the hip joint, in consequence of which the foot is directed inwards 

 t owards that of the opposite side. 



Relations. — Within the pelvis the muscle lies in contact with the abdominal viscera. 

 The tendon of insertion, after escaping from the pelvic ca\'ity, is concealed by the 

 obturator externus. 



Nerve supply. — A branch which is given ofi" from the obturator nerve before the latter 

 escapes from the pelvic cavity. 



8. Gemellus. 



L'Aceessoire de I'iliaqite interne, Vicq d'Azyr, 1774, p. 496, Xo. 9. 

 Troisieme adducteur (part of), Meckel, vol. vi. p. 87, No. 10. 

 Gemellus, Owen, p. 35. 



Attachments.— The gemellus is a small quadrilateral muscle, which arises from the 

 exterior of the pelvis immediately in front of the obturator foramen. It passes outwards, 

 and is inserted, along with the tendon of the obturator internus, into the posterior border 

 of the great trochanter of the femur. 



Action. — Its action resembles and suj^plements that of the internal obturator. 



Relations. — The muscle is concealed by the obturator externus. 



Nerve supply (?) 



Variations. — In Splieniscus minor, Pygosceles tceniatus, and Ap)tenodytes longirostris. 



