The Scrotum is a cutaneous pouch which contains the testes and parts of the spermatic cords.
It is divided on its surface into two lateral portions by a ridge or raphé, which is continued forward to the under surface of the penis, and backward, along the middle line of the perineum to the anus. Of these two lateral portions the left hangs lower than the right, to correspond with the greater length of the left spermatic cord. Its external aspect varies under different circumstances: thus, under the influence of warmth, and in old and debilitated persons, it becomes elongated and flaccid; but, under the influence of cold, and in the young and robust, it is short, corrugated, and closely applied to the testes.
The scrotum consists of two layers, the integument and the dartos tunic.
The Integument is very thin, of a brownish color, and generally thrown into folds or rugæ. It is provided with sebaceous follicles, the secretion of which has a peculiar odor, and is beset with thinly scattered, crisp hairs, the roots of which are seen through the skin
The Dartos Tunic (tunica dartos) is a thin layer of non-striped muscular fibers, continuous, around the base of the scrotum, with the two layers of the superficial fascia of the groin and the perineum; it sends inward a septum, which divides the scrotal pouch into two cavities for the testes, and extends between the raphé and the under surface of the penis, as far as its root. The dartos tunic is closely united to the skin externally, but connected with the subjacent parts by delicate areolar tissue, upon which it glides with the greatest facility.
The scrotum forms an admirable covering for the protection of the testes. These bodies, lying suspended and loose in the cavity of the scrotum and surrounded by serous membrane, are capable of great mobility, and can therefore easily slip about within the scrotum and thus avoid injuries from blows or squeezes. The skin of the scrotum is very elastic and capable of great distension, and on account of the looseness and amount of subcutaneous tissue, the scrotum becomes greatly enlarged in cases of edema, to which this part is especially liable as a result of its dependent position.