Envelopes of the testicle. —The scrotum, or pouch of integument containing the testicles, including the dartos, has already been de scribed. (Article SCROTUM).
Superficial or external spermatic fascia:— Beneath the loose areolar tissue of the scro tum is situated a delicate layer of fascia, which is continuous with the superficial fascia of the lower part of the abdominal parietes, and, descending so as to form a sheath to the spermatic cord and an envelope to the testicle, becomes continuous behind with the super ficial fascia of the perineum. This fascia is usually very thick and distinct in cases of large and old scrotal hernia.
Cremaster muscle — Directly beneath the superficial fascia is found the cremaster muscle (so named from rcpcp.c'ccu to suspend), or, as it has been appropriately termed by Mr. Hunter, the vnisculus testis. (For description, vide, ABDOMEN, VOI. i. p.6.) The two attachments of this muscle, the external to Poupart's ligament, and the internal to the os pubis, correspond, as I have previously (p. 983.) shown, to those of the muscle of the gubernaculum, being indeed the same structure, with its relations altered. The actions of the cremaster, which, with a few exceptions, are involuntary, appear to be those of giving a tonic support to the testicles, retracting them to the abdominal rings, and compressing them during the sexual act. In some instances, in boys before the approach of puberty, this muscle has been capable of drawing the gland up into the in guinal canal. Persons are occasionally met with who possess a voluntary power over its actions in various degrees of perfection. Some
are able to elevate the testicle on one side but not on the other, whilst others can retract both testicles to the abdominal rings, and retain them there at will. A very remarkable instance of the cremaster muscle being com pletely under the influence of volition is recorded by Mr. Hutchinson.* Deep spermatic fascia. — The tunica vagi nalis and spermatic cord are invested by a thin delicate fascia, which is situated beneath the cremaster muscle, and forms a common fibrous envelope to the testicle, and spermatic cord. It is attached to the back part of the gland. This membrane may be traced as a prolongation of the fascia transversalis, and is probably formed in the process of transition of the testicle from the abdomen to the scrotum.
The spermatic cord. — The parts composing the spermatic cord, are the vas deferens, the artery of the duct, the spermatic artery and veins, the lymphatic vessels, and the spermatic nerves. These parts are connected by loose areolar tissue. A fibro-cellular process, being the remains of the process of serous membrane originally connecting the tunica vaginalis with the peritoneum, may sometimes be perceived in the front part of the cord. The spermatic cord extends from the internal abdominal ring to the back part of the testicle. Its upper portion, therefore, lies in the inguinal canal. The coverings of the cord are the same as those of the testicle : viz., the inte guments, superficial fascia, cremaster muscle, and deep spermatic fascia.
For COMPARATIVE ANATOMY, see the article ORGANS OF GENERATION.