650 A MANUAL OF ANATOMY 



The tunica dartos lies immediately within the skin. It is derived from 

 the fasciae of Camper and of Scarpa of the anterior abdominal wall. It is 

 chiefly composed of plain muscular tissue, but it also contains fibro-areolar 

 and elastic tissues, and it has a brick-red colour. 



The skin is thin, very extensible, somewhat dark in colour, and pro- 

 vided with hairs, sweat-glands, and sebaceous glands. It is more dependent 

 on the left side on account of the lower position of the left testis. In the 

 middle line it presents a raphe, which is continuous behind with that of the 

 anterior part of the perineum, and in front with that on the under surface of 

 the penis. This raphe is an external indication of the bilateral symmetry 

 of the scrotum. On either side of the raphe the skin is thrown into a number 

 of transverse rugae, the corrugated condition being due to the plain muscular 

 tissue of the tunica dartos. 



The interior of the scrotum is divided into two compartments, 

 each of which lodges the corresponding testis. This division is 

 effected by the septum scroti, formed by the fusion of the con- 

 tiguous walls of the two scrotal chambers, except the skin, which 

 forms one continuous investment to both. Inferiorly the septum 

 is attached to the bottom of the scrotal chamber, and superiorly 

 to the under surface of the root of the penis. 



Blood-supply. — ^The scrotum receives its chief arterial supply 

 from the superior and inferior external pudic branches of the 

 common femoral of each side, and the superficial perineal branches 

 of the internal pudic arteries. 



The veins corresponding to these arteries terminate in the long 

 saphenous and internal pudic veins. 



The cremasteric branch of the deep epigastric of each side also 

 takes part in the supply of the scrotal wall, the venous blood being 

 returned into the deep epigastric vein, which at its termination is 

 single. 



Lymphatics. — ^The most of the lymphatics of the scrotum termi- 

 nate in the pubic inguinal glands, but those from the back part pass 

 to the internal iliac glands. 



Nerve-supply. — The nerves of the scrotum are as follows : (i) the 

 external or posterior and internal or anterior superficial perineal 

 branches of the pudic; (2) the long pudenal nerve of Soemmering 

 from the small sciatic; (3) the inguinal nerve (ilio-inguinal) from 

 the lumbar plexus; and (4) twigs of the genital branch of the 

 genito-crural nerve from the lumbar plexus. The two superficial 

 perineal nerves and the long pudendal nerve are known as the 

 long scrotal nerves. 



Development. — The external genital folds. 



Muscles of Abdominal Wall. Obliquus Externus Abdominis — 

 Origin. — ^The outer surfaces of the lower eight ribs by means of 

 eight fleshy slips, the upper five of which interdigitate with slips 

 of the serratus magnus, and the lower three with slips of the 

 latissimus dorsi. 



Insertion. — (i) The anterior half of the outer lip of the iliac crest 

 by fleshy fibres. (2) By means of an aponeurosis into {a) the linea 

 alba ; (6) the pubic spine and crest of the opposite side through 

 means of the triangukir fascia ; (c) the front of the symphysis 

 pubis ; {d) the pubic spine of the same side ; {e) the first inch 



