346 TTJE MUSCLES. 



its posterior border it has relation, inferiorly, with the biceps femoris, and 

 higher, with the semiteudinosns, which slightly covers it. 



Ad mi. — This muscle has been justly considered by Lafosse as an abductor 

 of the thigh. Bourgelat wrongly regarded it as an extensor, and Girard and 

 Rigot have repeated his error. Lecoq has proved that it rather produces flexion 

 than extension. The posterior portion is an abductor of the entire limb and an 

 extensor of the thigh, when the sacrum is its fixed point ; it plays a part in 

 rearing, when the fixed point is the leg. 



2. Middle Gluteus (Gluteus Medius, Gluteus Maximus) 

 (Figs. 193, 1 ; 194, 1). 



Synonyms. — Ilio-troclianterius magnus — Girard. Gluteus maximus — Bourgelat, Lafosse, 

 Bigot, etc. Gluteus medius of Man. (Superior portion of the great ilio-trochanterius — Leyh.) 



Volume — Situation. — This muscle, the largest of the glutei, is of considerable 

 volume, and is applied against the iliac fossa, the sacro-sciatic ligament, and the 

 longissimus dorsi. 



Form and Structure. — It is elongated from before to behind, wide and very 

 thick in its middle, prolonged forward by a thin point, and terminated behind 

 by three branches of insertion — two tendinous and one muscular. The muscular 

 fasciculi entering into its composition are generally very thick, and more or less 

 long ; all converge towards the posterior insertions of the muscle. 



Attachments. — 1. By the superior or anterior extremities of the muscular 

 fasciculi, to the internal aspect of the gluteal fascia, the aponeurosis of the 

 longissimus dorsi, the superior face and the two anterior angles of the ilium, 

 the two ilio-sacral ligaments, and a small portion of the sacro-sciatic ligament. 

 2. On the trochanter major by its three posterior branches : the first, or median, 

 is a thick, round tendon fixed on the summit ; the anterior is formed by a 

 second wide, thin, and flat tendon, which is inserted into the crest, after gliding 

 over the convexity ; the posterior is a small, triangular, fleshy slip, aponeurotic 

 at its anterior border, by means of which it is attached behind the trochanter. 

 This slip corresponds to the pjramidalis muscle of Man. 



Relations. — Covered by the gluteal fascia and the superficial gluteal muscle, 

 it covers the longissimus dorsi, which receives its anterior point, the iliac fossa, 

 the deep gluteal, the ilio-sacral and sacro-sciatic ligaments, the sciatic nerves, 

 and the gluteal nerves and vessels. Near the external angle of the ilium it is 

 bordered by the fascia lata and the iliacus, which are closely united to it. 



Action. — When its fixed point is superior, this muscle extends and abducts 

 the thigh ; but when the femur is fixed, it causes the pelvis to rock on the 

 superior extremity of that bone, and assists in the act of rearing. In the first 

 instance it acts as a lever of the first order ; in the second, as one of the third order. 



3. Deep Gluteus (Gluteus Internus) (Fig. 167, 5). 



Synonyms. — Ilio-trochanterius parvus— GiVarcZ. Gluteus medius — Bourgelat. Gluteus 

 minimus — Lafosse and Bigot. The gluteus minimus of anthropotomists. 



Form — Situation. — A small, short, thick, and quadrilateral muscle, flattened 

 above and below, situated beneath the preceding, and above the coxo-femoral 

 articulation. 



Structure and Attachments. — It is composed of voluminous muscular and 

 tendinous fasciculi, which arise from the neck of the ilium and the supra -cotyloid 

 ridge, to be directed outwards and backwards, and terminate within the con- 

 vexity of the trochanter major. 



