INTERNAL MALE SEXUAL ANATOMY
The male reproductive anatomy consists of the following parts:
- the penis
- the corpora cavernosa & corpus spongiosum
- the corpus spongiosum
- the testicles and scrotum
- the epididymis
- the vas deferens
- the seminal vesicles
- the cowper's glands
- and the prostate gland
The Penis:
Is a pendulous organ suspended of the pubic arch and containing the greater part of the urethra. In the flaccid condition it is cylindrical in shape, and erect assumes the form of a triangular prism with rounded angles. It is composed of three cylindrical masses covered with skin. Two of the masses are lateral, and are known as the corpora cavernosa; the third is the corpus spongiosum.
The Corpora Cavernosa:
Form the greater part of the substance of the penis, and are surrounded by an envelope of superficial and deep fibers. The superficial fibers are longitudinal in direction, and form a single tube which encloses both corpora; the deep fibers are arranged circularly around each corpus.
The Corpus Spongiosum:
Contains the urethra. The urethra enters the bulb. The portion of the corpus spongiosum in front of the bulb lies in a groove of the corpora cavernosa. This expansion, the glans penis, is moulded on the rounded ends of the corpora cavernosa. At the summit of the glans is the external urethral orifice. The circumference of the base of the glans forms the corona glandis, behind which is the neck of the penis.
The Testicles and Scrotum:
Testes are located inside the scrotum, a loose bag of skin underneath the penis. They produce male sex hormones and sperm cells for reproduction; also they secrete the hormone testosterone that plays a key role in male body development. The location of the testicles in the scrotum, keeps them at a temperature lower than that within the abdominal cavity. The lower temperature is needed for adequate sperm production.
The Epididymis:
The epididymis is part of the human male reproductive system. It is a narrow tube connecting the rear of each testicle to its vas deferens. It can be divided into three regions, the head, body and tail. Sperm formed in the testes enter the epididymis, progress to the corpus, and finally reach the cauda region, where they are stored. The inflammation of the epididymis is called epididymitis.
The Vas Deferens:
During ejaculation, sperm flow from the lower portion of the epididymis. They are transported within the vas deferens and mixed with the diluting fluids of the seminal vesicles forming semen. They are muscular tubes connecting the left and right epididymis to the ejaculatory ducts in order to move sperm. Each tube is about 30 centimeters long. During ejaculation the wall of the vas deferens thickens and thins itself, thus propelling the sperm forward. Vasectomy is a method of contraception where the vasa deferensa are permanently cut.
The Cowper’s Glands:
The bulbourethral glands -or Cowper's glands- are placed behind and lateral to the urethra. They secrete a clear fluid known as pre-ejaculate or Cowper's fluid --colloquially known as "pre-cum"-- which is generated upon sexual arousal. They gradually diminish in size as age advances. The excretory duct of each gland opens by a minute orifice on the floor of the urethra in front of the urogenital diaphragm.
The Prostate Gland:
Its main function is to secrete and store a clear, slightly basic fluid that is part of semen. A healthy human prostate is slightly larger than a walnut. It surrounds the urethra just below the urinary bladder. It is located in front of the rectum and part of it can be felt during a rectal exam.
The male urethra has two functions: to carry urine from the bladder during urination and to carry semen during ejaculation. Within the prostate, the urethra coming from the bladder merges with the two ejaculatory ducts. Semen is composed of sperm and seminal fluid; about 10-30% of the seminal fluid is produced by the prostate gland, the rest is produced by the two seminal vesicles. The prostate also contains some smooth muscle tissue which helps to expel semen during ejaculation.
Regions of the penis
It is convenient to divide the penis into three regions to understand it better: the root, the body, and the extremity. Lets see:
· The root of the penis consists of the diverging crura, and the median urethral bulb. The root of the penis lies in the perineum.
· The body extends from the root to the ends of the corpora cavernosa, and in it these corpora cavernosa are intimately bound to one another. The body is ensheathed, and below with the scrotum.
· The extremity is formed by the glans penis, the expanded anterior end of the corpus cavernosum urethra. It is separated from the body by the neck, which is overhung by the corona glandis.
The integument covering the penis is remarkable for its thinness, dark color, looseness of connection with the deeper parts of the organ, and its absence of adipose tissue. At the root of the penis it is continuous with pubes, scrotum, and perineum. At the neck it leaves the surface and becomes folded to form the prepuce or foreskin. Immediately behind the external urethral orifice it forms a small secondary reduplication, the frenulum of the prepuce.
Structure of the Penis
From the internal surface of the corpora cavernosa, numerous bands cross the interior in all directions, subdividing them into a number of separate compartments, and giving the entire structure a spongy appearance.
These bands consist of fibrous tissue, elastic fibers, and plain muscular fibers. In them are contained numerous arteries and nerves. The fibers are larger and stronger around the circumference than at the centers of the corpora cavernosa; they are also thicker behind than in front. The interspaces -cavernous spaces- on the contrary, are larger at the center than at the circumference. They are filled with blood.
Arteries, Vessels and Nerves
The arteries bringing the blood to the cavernous spaces are the deep arteries of the penis and branches from the dorsal arteries of the penis.
The blood from the cavernous spaces is returned by a series of vessels, some of which form the deep dorsal vein; but the greater numbers passes out at the root of the penis and join the prostatic plexus. The nerves are derived from the pelvic plexus.
Sumarize
Summarizing all the above, the penis, the male copulatory organ, is a cylindrical pendant organ located anterior to the scrotum and functions to transfer sperm to the vagina. The penis consists of three columns of erectile tissue wrapped and covered with skin. The two dorsal columns are the corpora cavernosa. The single, surrounds the urethra and is called the corpus spongiosum.
The penis has a root, body, and glans penis. The root of the penis attaches it to the pubic arch and the body is the visible, pendant portion. The corpus spongiosum expands at the end to form the glans penis. The urethra, which extends throughout the corpus spongiosum, opens through the external urethral orifice at the tip of the glans penis. A loose fold of skin, called the prepuce, or foreskin, covers the glans penis.
The male sexual response includes erection and orgasm accompanied by ejaculation of semen. Orgasm is followed by a variable time period during which it is not possible to achieve another erection.
Other topics
· How ejaculation occurs
· How an erection occurs
Conditions of the penis include:
- Peyronie's disease -a curve during erection-
- Double penis -during development, the penis is divided by the urethral groove-
- Hypospadias -the opening of the urethra is on the underside of the penis, rather than at the tip-
- Epispadias -the opening of the urethra is on the top or side of the penis, rather than at the tip-
- Palmatus or webbed penis -the penis is enclosed by the scrotum-
- Chordee
- Priapism
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