428 A MANUAL OF ANATOMY 



Three synovial bursne are found underneath the muscle. One, 

 which is single, is situated between the lower border of the muscle 

 and the tuber ischii. Its importance consists in the fact that it is 

 concerned jn the condition known as 'lighterman's bottom.' A 

 second lies between the muscle and the great trochanter, this 

 one being multilocular. The third is found between the muscle 

 and the upper part of the vastus externus, just below the great 

 trochanter. 



Gluteus Medius — Origin.— (i) The dorsum ilii between the crest, 

 superior gluteal line, and middle gluteal line ; and (2) the fascia lata 

 covering the anterior two- thirds of the muscle. 



Insertion. — The oblique impression on the outer surface of the 

 great trochanter, extending from the postero-superior angle down- 

 wards and forwards to the antero-inferior angle. 



Nerve-supply. — The superior gluteal nerve. 



The direction of the anterior fibres of the muscle is downwards 

 and slightly backwards, and of the posterior fibres downwards and 

 forwards. The fibres of the muscle converge from their origin to 

 the fan-shaped tendon of insertion, and they correspond in direction 

 with those of the gluteus minimus. 



Action. — Acting from its origin the muscle abducts the thigh. 

 The anterior fibres also act as an internal rotator, and the posterior 

 fibres as an external rotator, of the thigh. Acting from its insertion 

 it balances the pelvis upon the thigh, as in standing upon one leg, 

 and it is also a lateral flexor of the pelvis. 



The gluteus medius is triangular. The posterior fleshy third is 

 covered by the gluteus maximus, and the anterior two- thirds by 

 the fascia lata. The muscle covers the gluteus minimus except 

 posteriori}^ the deep division of gluteal artery, and the superior 

 gluteal nerve, and a synovial bursa intervenes between it and the 

 upper part of the great trochanter. 



Gluteus Minimus — Origin. — The dorsum ilii between the middle 

 and inferior gluteal lines. 



Insertion. — ^The lower part of the anterior surface of the gieat 

 trochanter. 



Nerve- supply. — The lower division of the superior gluteal 

 nerve. 



The fibres of the muscle correspond in direction, for the most 

 part, with those of the gluteus medius. 



Action. — Acting from its origin the muscle is an abductor 

 and internal rotator of the thigh. Acting from its insertion it 

 balances the pelvis upon the thigh, and is a lateral flexor of the 

 pelvis. 



The gluteus minimus is fan-shaped, and the tendon of insertion 

 spreads out into an aponeurotic expansion over its lower part. 

 It is covered by the gluteus medius except at the posterior part, 

 where the pyriformis rests upon it. Its deep surface is related to 

 the capsular ligament of the hip- joint and the posterior or reflected 

 head of the rectus femoris. The tendon of insertion of the muscle 



