152 ABDOMEN 



tuberosities of the ischia rest when the body is in the sitting 

 posture. Intervening between the fascia and each tuberosity 

 there is a bursa, which may be displayed by an incision 

 carried through the fascia to the bone. Not uncommonly 

 the cavity of the bursa is divided .into many loculi by inter- 

 secting fibrous septa. 



In the anterior part of the perineal region, that is in the 

 urogenital area, another change in the character of the 

 superficial fascia becomes manifest. The farther forwards it 

 is traced the scarcer becomes the fat which it contains in its 

 meshes. In the scrotum the fat entirely disappears and gives 

 place to a thin layer of involuntary muscular fibres, which 

 constitute the dartos muscle. They are recognised by their 

 ruddy colour. The rugosity of the scrotal integument is 

 caused by their contraction. 



Over the urogenital triangle also the superficial fascia can 

 be shown to consist of two very definite layers. The superficial 

 layer is fatty and is not confined to that part of the perineal 

 region. In fact, it is simply a portion of the general fatty 

 covering of the body. Posteriorly, it is continuous with the 

 plugs of fat which fill up the ischio-rectal fossae ; on each 

 side, it leaves the perineum and becomes continuous with the 

 fatty tissue on the medial aspects of the thighs. The deep 

 layer is of an altogether different nature. It is a dense 

 membranaceous stratum spread over the urogenital triangle, 

 and it is devoid of fat. It is called the fascia of Colles. 



The fascia of Colles has very definite attachments and 

 connections. (3n each side it is attached to the rami of the 

 pubis and ischium. Posteriorly it turns round the two 

 superficial transverse perineal muscles, which extend from 

 the rami of the ischia to the central point of the perineum 

 (Fig. 77), and then blends with the base of the fascia of 

 the urogenital diaphragm, which fills in the urogenital part 

 of the outlet of the pelvis on a deeper plane than that 

 occupied by the fascia of Colles. Towards the front of the 

 perineum the fascia of Colles is continuous with the dartos 

 tissue of the scrotum, and that in its turn is continuous more 

 anteriorly with the fascia of Scarpa, which is the deep layer 

 of the superficial fascia of the abdomen. Laterally both the 

 fascia of Colles and the fascia of the urogenital diaphragm 

 are attached to the rami of the pubis and ischium, and the 

 attachment of the fascia of Colles is prolonged upwards, as it 



