The Scrotum & Testes Prof. Dr. Imran Qureshi

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1 The Scrotum & Testes Prof. Dr. Imran Qureshi The Scrotum It is a cutaneous pouch of the anterior abdominal wall. Most layers of the abdominal wall are represented in its structure. It contains the testes and parts of the spermatic cords. It is divided on its surface into two lateral portions by a ridge or raphe. This raphe is continued forward to the under surface of the penis at its root, and backward, along the middle line of the perineum to the anus. Due to the greater length of the left spermatic cord, the left lateral portion hangs lower than the right. The external aspect of the scrotum varies under different circumstances. e.g. In warm weather or in old and emaciated persons, it becomes elongated and flaccid; but, during cold weather or in the young and strong individuals, it is short, corrugated, and closely applied to the testes. It consists of two layers, the Integument and the Dartos tunic. The Integument is very thin, and brownish in color. It is generally thrown into folds or rugae. It is provided with sebaceous glands, the secretion of which has a peculiar odor, and is endowed with scattered thin & brittle hairs. The roots of these hairs are visible through the skin. 1 P age The Dartos Tunic (tunica dartos) is composed of a thin layer of non-striped muscle fibers. These fibers are continuous with the two layers of the superficial fascia of the groin and the perineum around the base of the scrotum. It sends inward a septum, which divides the scrotal pouch into two cavities for the testes.

2 This septum is incomplete superiorly. Externally the dartos tunic is closely united to the skin Here it is connected with the subjacent parts by delicate areolar tissue, upon which it can slides easily Clinical features: The subcutaneous tissue of the scrotum is continuous with the fasciae of the abdominal wall and perineum and therefore extravasations of urine or blood deep to this plane will gravitate into the scrotum. Since the septum between the right and left compartments is incomplete superiorly, the extravasations of fluid into this sac are always bilateral. Because of the loose tissues of the scrotum and its dependent position, it tends to fill readily with oedema fluid in cardiac or renal failure. Such a condition must be carefully differentiated from extravasation or from a scrotal swelling due to a hernia or hydrocele The Testes and their Coverings The testes are two glandular organs, which secrete the semen. They are suspended in the scrotum by the spermatic cords. Usually, the left testis hangs somewhat lower than its fellow. In the early fetal life, the testes are located retroperitonealy in the abdominal cavity. Before birth they descend to the inguinal canal, along which they pass with the spermatic cord. Each testis enters the inguinal canal through the deep inguinal ring and emerges at the subcutaneous superficial inguinal ring. During their descent into the scrotum, they become invested in their course by coverings derived from the serous, muscular, and fibrous layers of the abdominal layers, as well as by the scrotum. Average dimensions: 5 cm. (length), 2.5 cm. (breadth), 3 cm. (antero-posterior). Weight: Between 10 to 15 gm. Shape: Oval in form and is compressed laterally. Orientation: It has an oblique position in the scrotum The upper extremity is directed forward and a little laterally. The lower extremity is directed backward and a little medially. The anterior convex border faces forwards and downwards. Thee posterior or straight border, to which the cord is attached, faces backwards and upwards. 2 P age

3 The anterior border, the lateral surfaces, as well as both extremities of the organ, are convex, free, smooth, and invested by the visceral layer of the tunica vaginalis. The posterior border, to which the cord is attached, receives only a partial investment from the tunica vaginalis. A narrow, flattened body, called the epididymis lies upon the lateral edge of this posterior border. The epididymis consists of: An upper enlarged extremity, the head, A central portion or body, and A lower pointed extremity, the tail. The head is firmly connected with the upper end of the testis by means of the efferent ductules of the gland. The tail is connected with the lower end of the testis by cellular tissue, and a reflection of the tunica vaginalis. It is continuous with the ductus deferens. The head and tail of the epididymis are free and covered by the serous membrane The body is also invested by it, except along its posterior border. Here, between the body and the testis is a pouch, called the sinus of the epididymis (digital fossa). The epididymis is connected to the back of the testis by a fold of the serous membrane. Appendages of the Testis and Epididymis: On the upper extremity of the testis, just beneath the head of the epididymis, is a minute oval, sessile body, called the appendix of the testis (hydatid of Morgagni). o It is the remnant of the upper end of the Mullerian duct. On the head of the epididymis, there is a another small stalked appendage, which is sometimes duplicated and is called the appendix of the epididymis (pedunculated hydatid). o It is usually regarded as a detached efferent duct. The testis is invested by three tunics: the tunica vaginalis, tunica albuginea, and tunica vasculosa. The Testes and their Coverings Tunica Vaginalis: It is the serous covering of the testis. In the fetus, a pouch of serous membrane, derived from the saccus vaginalis of the peritoneum preceded the descent of the testis from the abdomen into the scrotum. 3 P age

4 After its descent, that portion of the pouch which extends from the abdominal inguinal ring to near the upper part of the gland becomes obliterated. The lower portion remains as a closed sac, which invests the surface of the testis, and is reflected on to the internal surface of the scrotum; hence it may be described as consisting of a visceral and a parietal laminae. The visceral lamina It covers the greater part of the testis and epididymis, connecting the latter to the testis by means of a distinct fold. From the posterior border of the gland it is reflected on to the internal surface of the scrotum. The parietal lamina It is far more extensive than the visceral lamina, extending upward for some distance in front and on the medial side of the cord, and reaching below the testis. The inner surface of the tunica vaginalis is smooth, and covered by a layer of endothelial cells. The interval between the visceral and parietal laminae constitutes the cavity of the tunica vaginalis. The obliterated portion of the saccus vaginalis may generally be seen as a fibrocellular thread lying in the loose areolar tissue around the spermatic cord Sometimes this may be traced as a distinct band from the upper end of the inguinal canal, where it is connected with the peritoneum, down to the tunica vaginalis. Sometimes it gradually becomes lost on the spermatic cord. Occasionally no trace of it can be detected. In some cases it so happens that the pouch of peritoneum does not become obliterated, but the sac of the peritoneum communicates with the tunica vaginalis. This may give rise to one of the varieties of oblique inguinal hernia. In other cases the pouch may contract, but not become entirely obliterated. 4 P age

5 5 P age It then forms a minute canal leading from the peritoneum to the tunica vaginalis Tunica Albuginea: It is the fibrous covering of the testis. It is a dense bluish-white membrane, composed of bundles of white fibrous tissue which interlace in every direction. It is covered by the tunica vaginalis, except at the points of attachment of the epididymis to the testis, and along its posterior border, where the spermatic vessels enter the gland. It is applied to the tunica vasculosa over the glandular substance of the testis, and, at its posterior border, is reflected into the interior of the gland, forming an incomplete vertical septum, called the mediastinum testis (corpus Highmore). The mediastinum testis extends from the upper to near the lower extremity of the gland, and is wider above than below. From its front and sides numerous imperfect septa (trabeculae) are given off, which radiate toward the surface of the organ, and are attached to the tunica albuginea. They divide the interior of the organ into a number of incomplete spaces which are somewhat cone-shaped, being broad at their bases at the surface of the gland, and becoming narrower as they converge to the mediastinum. The mediastinum supports the vessels and duct of the testis in their passage to and from the substance of the gland. Tunica Vasculosa: It is the vascular layer of the testis, consisting of a plexus of bloodvessels, held together by delicate areolar tissue. It lies on the inner surface of the tunica albuginea and the different septa in the interior of the gland. It, therefore forms an internal investment to all the spaces of which the gland is composed. Applied Anatomy (Undescended Testis / Testes) The testis, developed in the lumbar region, may be arrested or delayed in its transit to the scrotum (cryptorchism). It may: Be retained in the abdomen, Be arrested at the deep inguinal ring, Remain in the inguinal canal; or It may just pass out of the superficial inguinal ring but fails to find its way to the bottom of the scrotum. When retained in the abdomen it produces no symptoms, other than the absence of the testis from the scrotum. However, when it is retained in the inguinal canal it is subjected to pressure and may become inflamed and painful. The retained testis does not function. A man in whom both testes are retained (anorchism) is sterile, though he may not be impotent. The absence of one testis is termed monorchism.

6 When a testis is retained in the inguinal canal it is often complicated with a congenital hernia, the funicular process of the peritoneum is not obliterated in this case. Sometimes, the testis may descend through the inguinal canal, but misses the scrotum and assume some abnormal position. The most common form of this is where the testis, emerges at the superficial inguinal ring, but slips down between the scrotum and thigh and comes to rest in the perineum. This is known as perineal ectopia testis. With each variety of abnormality in the position of the testis, it is very common to find a concurrent congenital hernia, In case, a hernia is not actually present, the funicular process is usually patent, and it is always so if the testis is in the inguinal canal. Finally if the testis, reaches the scrotum, it may occupy an abnormal position in it. It may be inverted, so that its posterior or attached border is directed forward and the tunica vaginalis is situated behind. Applied Anatomy (Hydrocele) Serous fluid collections (hydrocele) are very frequently found in the scrotum. The most common form is the ordinary vaginal hydrocele, in which the fluid is contained in the sac of the tunica vaginalis, which is separated, in its normal condition, from the peritoneal cavity by the whole extent of the inguinal canal. In another form, called the congenital hydrocele, the fluid is in the sac of the tunica vaginalis, but this cavity communicates with the general peritoneal cavity, because its tubular process remains pervious. A third variety known as an infantile hydrocele, in which, the tubular process becomes obliterated only at its upper part, at or near the deep inguinal ring. It resembles the vaginal hydrocele, except as regards its shape, the collection of fluid extending up the cord into the inguinal canal. 6 P age

7 The fourth variety is called the encysted hydrocele of the cord. In this, the funicular process may become obliterated both at the deep inguinal ring and above the epididymis, leaving a central unobliterated portion, which may become distended with fluid. Blood supply The testicular artery arises from the aorta at the level of the renal vessels. It anastomoses with the artery to the vas, supplying the vas deferens and epididymis, which arises from the inferior vesical branch of the internal iliac artery. The pampiniform plexus of veins becomes a single vessel, the testicular vein, in the region of the internal ring. On the right this drains into the inferior vena cava, on the left into the renal vein. Lymph drainage The lymphatic drainage of the testis obeys the usual rule It accompanies the venous drainage and thus passes to the para aortic lymph nodes at the level of the renal vessels. Free communication occurs between the lymphatics on the two sides. There is also a plentiful anastomosis with the para aortic, intrathoracic nodes and, in turn, with the cervical nodes, so that spread of malignant disease from the testis to the nodes at the root of the neck is not rare. Nerve supply T10 sympathetic fibres via the renal and aortic plexus. These convey afferent (pain) fibres hence referred pain from the testis to the loin. Vas deferens (ductus deferens) It is 18 inches (45 cm) long (a distance which one may remember is also the length of the thoracic duct, the spinal cord and the femur, and the distance from the incisor teeth to the cardiac end of the stomach). It passes from the tail of the epididymis, traverses the scrotum, the inguinal canal and so comes to lie upon the side wall of the pelvis. Here, it lies immediately below the peritoneum of the lateral wall, extends almost to the ischial tuberosity then turns medially to the base of the bladder. 7 P age

8 Here it joins the more laterally placed seminal vesicle to form the ejaculatory duct which traverses the prostate to open into the prostatic urethra at the verumontanum on either side of the utricle. 8 P age