1918 



HUMAN ANATOMY. 



before piercing the superficial layer, gives off the artery to the bulb. This latter 

 artery may come off from the accessory puclic when that vessel is present (page 818), 

 and will then be more anterior, and less exposed to division in lithotomy, than 

 usual ; or it may come off from the internal pudic before the latter has penetrated 

 tli- MijK-rticiul layer of the triangular ligament, and will then be behind its usual 

 position and more likely to be wounded. When the superior or deep layer of the 

 triangular ligament is opened, the prostate partly covered by the median fibres of 

 the levator ani and the neck of the bladder are exposed (Fig. 1631). this deep layer 

 being continuous with the prostatic sheath. 



It will be seen that in reaching this point by dissection there will have been 

 exposed certain alternating layers of fascial and muscular structures (Cunning- 

 ham) as follows : (a) superficial fascia (superficial and deep layers) ; (b\ super- 

 ficial perinea! muscles ; (c) inferior or superficial layer of the triangular ligament 



FIG. 1628. 



Crut penli 



^ 



Ischlo-cavemosus muscle, 

 turned aside 



Cms penis 



Dorsal artery of penis, artery of 

 corpus cavernosum to the right 

 Bulb of penis 



Superficial perinea! artery 



Superficial perineal nerves 



-Tuber ischii 



-Dorsal nerve of penis 



-Perineal division of 



pudic nerve 

 "Internal pudic artery 



Inf. hemorrhoidal nerv 



- Inferior hemorrhoidal 



artery 



EHssnti..n of prrinrmn. showing inferior layer of triangular ligament 

 and inner wall of ischio-rectal fossa partially exposed. 



la-da trinoni uroucnitalis inferior); (</) compressor urethra muscle; f superior 

 or deep layer of the triangular ligament (fascia trigoni urogenitalis superior (/) 

 levator am muscle ; ( #} prostatic fascia (sheath). 



Landmarks. With the patient in the lithotomy position: (i) The pubis, 

 coccyx, tuberosities, ischio-pubic rami, and greater sacro-sciatic ligaments may be 

 The transverse diameter, between the tuberosities, is 9 cm. (3^ in.) ; 

 tli.- antero-posterior diameter, from the coccyx to the pubis, is also 9 cm. (3^ in.) 

 on the skeleton, 10 cm. (4 in. > as measured on the living person. (3) The centre 

 of the anus is about 4 cm. ( i # in. ) from the tip of the coccyx, and is on a line drawn' 

 between the tips of the ischial tuberosities. (4) The perineal centre is approxi- 

 " M " lv " n .' ' ' ' m > in fattt ^ the anus. (5) The bulb (and its artery) are just 

 its |..,siti..n may be indicated by a slight median surface elevation ; 

 ttM .n t.-ry passes inward between the layers of the triangular ligament about a half 



