148 MUSCULAR SYSTEM. 



intersections, which, at the trochanter, become formed into a 

 broad flat tendon, surrounded by fleshy fibres. 

 Action. — The same as that of the next muscle. 



GLUTEUS INTERN us. — lHo-troclianterius Parvus. 



Situation. — Deeply placed, underneath the preceding muscle. 



Figure. — Fan-shaped ; its fibres describing two contrary 

 curves. 



Attachment. — Superiorly, to the dorsum ilei, as high up as 

 where the gluteus maximus ceases to be attached, and as far 

 back as the border to which the sacro-sciatic ligament is fixed ; 

 inferiorly, to the (anterior protuberance upon the) trochanter 

 major. 



Relations. — Externally, with the gluteus maximus ; internally, 

 with the ilio-femoral articulation. 



Structure. — Principally fleshy : inferior portion intersected at 

 regular distances by layers of tendon, which at the trochanter 

 become united together into one broad flat tendon, curiously 

 grooved (in radii) upon its external surface. 



Action of the Glutei. — These muscles are extensors either of 

 the OS femoris upon the pelvis, or of the |)elvis and loins upon 

 the hind quarter. When the limb has been carried in advance 

 under the body by the muscles of the anterior femoral region, 

 and the toe firmly set down upon the ground, the glutei, by 

 extending the haunch, will carry the trunk forward ; thus, be- 

 coming potent agents in progression ; and of them the maximus 

 is by far the most powerful. In the acts both of rearing and 

 kicking these muscles are thrown into violent and forcible 

 contraction : in the former action, the limbs become the fixed 

 points ; in the latter, the trunk. 



2.— PELVI-TROCHANTERIAN REGION. 



These muscles are but small, and are all attached to the 

 trochanter major. 



PYRiFORMis . — Sacro-trochanterius. 



Situation. — Supero-lateral parts of the pelvic cavity. 



Figure. — Conical : base turned forwards. 



Attachments. — Within the pelvis, to the transverse processes of 

 the sacrum, and infero-internal part of the ileum : without the 

 pelvis, to the hollow behind the trochanter major. 



Relations. — Superiorly and externally, with the pelvis; in- 

 feriorly and internally, with the peritoneum: along its infeiior 

 border run the obturator bloodvessels and nerves. 



