Dermatomes and Cutaneous Nerves-Superficial Veins-Nerve Supply of the Veins-Superficial Lymph Vessels-Venipuncture and Blood Transfusion-Intravenous Transfusion and Hypovolemic Shock-Anatomy of Basilic and Cephalic Vein Catheterization-

Dermatomes and Cutaneous Nerves

It may be necessary for a physician to test the integrity of the spinal cord segments of C3 through T1. It is seen that the dermatomes for the upper cervical segments C3 to 6 are located along the lateral margin of the upper limb; the C7 dermatome is situated on the middle finger; and the dermatomes for C8, T1, and T2 are along the medial margin of the limb. The nerve fibers from a particular segment of the spinal cord, although they exit from the cord in a spinal nerve of the same segment, pass to the skin in two or more different cutaneous nerves.

The skin over the point of the shoulder and halfway down the lateral surface of the deltoid muscle is supplied by the supraclavicular nerves (C3 and 4). Pain may be referred to this region as a result of inflammatory lesions involving the diaphragmatic pleura or peritoneum. The afferent stimuli reach the spinal cord via the phrenic nerves (C3, 4, and 5). Pleurisy, peritonitis, subphrenic abscess, or gallbladder disease may therefore be responsible for shoulder pain.

Superficial Veins

The veins of the upper limb can be divided into two groups: superficial and deep. The deep veins comprise the venae comitantes, which accompany all the large arteries, usually in pairs, and the axillary vein.

The superficial veins of the arm lie in the superficial fascia.

The cephalic vein ascends in the superficial fascia on the lateral side of the biceps and, on reaching the infraclavicular fossa, drains into the axillary vein.

The basilic vein ascends in the superficial fascia on the medial side of the biceps. Halfway up the arm, it pierces the deep fascia and at the lower border of the teres major joins the venae comitantes of the brachial artery to form the axillary vein.

Nerve Supply of the Veins

Like the arteries, the smooth muscle in the wall of the veins is innervated by sympathetic postganglionic nerve fibers that provide vasomotor tone. The origin of these fibers is similar to those of the arteries.

Superficial Lymph Vessels

The superficial lymph vessels draining the superficial tissues of the upper arm pass upward to the axilla.

Venipuncture and Blood Transfusion

The superficial veins are clinically important and are used for venipuncture, transfusion, and cardiac catheterization. Every clinical professional, in an emergency, should know where to obtain blood from the arm. When a patient is in a state of shock, the superficial veins are not always visible. The cephalic vein lies fairly constantly in the superficial fascia, immediately posterior to the styloid process of the radius. In the cubital fossa, the median cubital vein is separated from the underlying brachial artery by the bicipital aponeurosis. This is important because it protects the artery from the mistaken introduction into its lumen of irritating drugs that should have been injected into the vein.

The cephalic vein, in the deltopectoral triangle, frequently communicates with the external jugular vein by a small vein that crosses in front of the clavicle. Fracture of the clavicle can result in rupture of this communicating vein, with the formation of a large hematoma.

Intravenous Transfusion and Hypovolemic Shock

In extreme hypovolemic shock, excessive venous tone may inhibit venous blood flow and thus delay the introduction of intravenous blood into the vascular system.

Anatomy of Basilic and Cephalic Vein Catheterization

The median basilic or basilic veins are the veins of choice for central venous catheterization, because from the cubital fossa until the basilic vein reaches the axillary vein, the basilic vein increases in diameter and is in direct line with the axillary vein. The valves in the axillary vein may be troublesome, but abduction of the shoulder joint may permit the catheter to move past the obstruction. The cephalic vein does not increase in size as it ascends the arm, and it frequently divides into small branches as it lies within the deltopectoral triangle. One or more of these branches may ascend over the clavicle and join the external jugular vein. In its usual method of termination, the cephalic vein joins the axillary vein at a right angle. It may be difficult to maneuver the catheter around this angle.

The Breasts-The Breasts at Puberty-Young Women-The Breast atPregnancy-Postmenopause-Blood Supply to Breast-Arteries-Veins-Lymph Drainage-

The Breasts

The breasts, they are situated in the pectoral region so they are not anatomically part of the upper limb and their blood supply and lymphatic drainage is largely into the armpit. Their clinical importance cannot be overemphasized.

The breasts are specialized accessory glands of the skin that secrete milk. They are present in both sexes. In males and immature females, they are similar in structure. The nipples are small and surrounded by a colored area of skin called the areola. The breast tissue consists of a system of ducts embedded in connective tissue that does not extend beyond the margin of the areola.

Puberty

At puberty in females, the breasts gradually enlarge and assume their hemispherical shape under the influence of the ovarian hormones. The ducts elongate, but the increased size of the glands is mainly from the deposition of fat. The base of the breast extends from the 2nd to 6th rib and from the lateral margin of the sternum to the midaxillary line. The greater part of the gland lies in the superficial fascia. A small part, called the axillary tail, extends upward and laterally, pierces the deep fascia at the lower border of the pectoralis major muscle, and enters the axilla.

Each breast consists of 15 to 20 lobes, which radiate out from the nipple. The main duct from each lobe opens separately on the summit of the nipple and possesses a dilated ampulla just before its termination. The base of the nipple is surrounded by the areola. Tiny tubercles on the areola are produced by the underlying areolar glands.

The lobes of the gland are separated by fibrous septa that serve as suspensory ligaments. Behind the breasts is a space filled by loose connective tissue called the retromammary space.

Young Women

In young women, the breasts tend to protrude forward from a circular base.

Pregnancy

Early In the early months of pregnancy, there is a rapid increase in length and branching in the duct system. The secretory alveoli develop at the ends of the smaller ducts, and the connective tissue becomes filled with expanding and budding secretory alveoli. The vascularity of the connective tissue also increases to provide adequate nourishment for the developing gland. The nipple enlarges, and the areola becomes darker and more extensive as a result of increased deposits of melanin pigment in the epidermis. The areolar glands enlarge and become more active.

Late During the second half of pregnancy, the growth process slows. The breasts, however, continue to enlarge, mostly because of the distention of the secretory alveoli with the fluid secretion called colostrum. Postweaning Once the baby has been weaned, the breasts return to their inactive state. The remaining milk is absorbed, the secretory alveoli shrink, and most of them disappear. The interlobular connective tissue thickens. The breasts and the nipples shrink and return nearly to their original size. The pigmentation of the areola fades, but the area never lightens to its original color.

Postmenopause

After the menopause, the breast atrophies. Most of the secretory alveoli disappear, leaving behind the ducts. The amount of adipose tissue may increase or decrease. The breasts tend to shrink in size and become more pendulous. The atrophy after menopause is caused by the absence of ovarian estrogens and progesterone

Blood Supply

Arteries

The branches to the breasts include the perforating branches of the internal thoracic artery and the intercostal arteries. The axillary artery also supplies the gland via its lateral thoracic and thoracoacromial branches.

Veins

The veins correspond to the arteries.

Lymph Drainage

The lymph drainage of the mammary gland is of great clinical importance because of the frequent development of cancer in the gland and the subsequent dissemination of the malignant cells along the lymph vessels to the lymph nodes.

The lateral quadrants of the breast drain into the anterior axillary or pectoral group of nodes (situated just posterior to the lower border of the pectoralis major muscle). The medial quadrants drain by means of vessels that pierce the intercostal spaces and enter the internal thoracic group of nodes (situated within the thoracic cavity along the course of the internal thoracic artery). A few lymph vessels follow the posterior intercostal arteries and drain posteriorly into the posterior intercostal nodes (situated along the course of the posterior intercostal arteries); some vessels communicate with the lymph vessels of the opposite breast and with those of the anterior abdominal wall.

Vagina-Supports of the Vagina-Blood Supply-Vulva-Nerve Supply-Vulval Infection-The Vulva and Pregnancy-Urethral Infection-Urethral Injuries-Catheterization

Vagina

The vagina not only is the female genital canal but also serves as the excretory duct for the menstrual flow from the uterus and forms part of the birth canal. This muscular tube extends upward and backward between the vulva and the uterus (see Fig. 8.4). It measures about 3 in. (8 cm) long. The cervix of the uterus pierces its anterior wall. The vaginal orifice in a virgin possesses a thin mucosal fold, called the hymen, which is perforated at its center. The upper half of the vagina lies above the pelvic floor within the pelvis between the bladder anteriorly and the rectum posteriorly; the lower half lies within the perineum between the urethra anteriorly and the anal canal posteriorly
.

Supports of the Vagina

■■ Upper third: Levatores ani muscles and transverse cervical, pubocervical, and sacrocervical ligaments

■■ Middle third: Urogenital diaphragm

■■ Lower third: Perineal body

Blood Supply

Arteries

The vaginal artery, a branch of the internal iliac artery, and the vaginal branch of the uterine artery supply the vagina.

Vulva

The term vulva is the collective name for the female external genitalia and includes the mons pubis, labia majora and minora, the clitoris, the vestibule of the vagina, the vestibular bulb, and the greater vestibular glands.

Blood Supply

Branches of the external and internal pudendal arteries on each side.

The skin of the vulva is drained into the medial group of superficial inguinal nodes.

Lymph Drainage

Medial group of superficial inguinal nodes
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Nerve Supply

The anterior parts of the vulva are supplied by the ilioinguinal nerves and the genital branch of the genitofemoral nerves. The posterior parts of the vulva are supplied by the branches of the perineal nerves and the posterior cutaneous nerves of the thigh.

Vulval Infection

In the region of the vulva, the presence of numerous glands and ducts opening onto the surface makes this area prone to infection. The sebaceous glands of the labia majora, the ducts of the greater vestibular glands, the vagina (with its indirect communication with the peritoneal cavity), the urethra, and the paraurethral glands can all become infected. The vagina itself has no glands and is lined with stratified squamous epithelium. Provided that the pH of its interior is kept low, it is capable of resisting infection to a remarkable degree.

The Vulva and Pregnancy

An important sign in the diagnosis of pregnancy is the appearance of a bluish discoloration of the vulva and vagina as a result of venous congestion. It appears at the 8th to 12th week and increases as the pregnancy progresses.

Urethral Infection

The short length of the female urethra predisposes to ascending infection; consequently, cystitis is more common in females than in males.

Urethral Injuries

Because of the short length of the urethra, injuries are rare. In fractures of the pelvis, the urethra may be damaged by shearing forces as it emerges from the fixed urogenital diaphragm.

Catheterization

Because the female urethra is shorter, wider, and more dilatable, catheterization is much easier than in males. Moreover, the urethra is straight, and only minor resistance is felt as the catheter passes through the urethral sphincter.

Penis-Root of the Penis-Body of the Penis-Blood Supply-Arteries-Veins-Lymph Drainage-Rupture of the Urethra- Erection and Ejaculation after Spinal Cord Injuries -Urethral Infection

Penis

The penis has a fixed root and a body that hangs free

Root of the Penis

The root of the penis is made up of three masses of erectile tissue called the bulb of the penis and the right and left crura of the penis. The bulb is situated in the midline and is attached to the undersurface of the urogenital diaphragm. It is traversed by the urethra and is covered on its outer surface by the bulbospongiosus muscles. Each crus is attached to the side of the pubic arch and is covered on its outer surface by the ischiocavernosus muscle. The bulb is continued forward into the body of the penis and forms the corpus spongiosum. The two crura converge anteriorly and come to lie side by side in the dorsal part of the body of the penis, forming the corpora cavernosa.

 

Body of the Penis

The body of the penis is essentially composed of three cylinders of erectile tissue enclosed in a tubular sheath of fascia (Buck’s fascia). The erectile tissue is made up of two dorsally placed corpora cavernosa and a single corpus spongiosum applied to their ventral surface. At its distal extremity, the corpus spongiosum expands to form the glans penis, which covers the distal ends of the corpora cavernosa. On the tip of the glans penis is the slitlike orifice of the urethra, called the external urethral meatus.

The prepuce or foreskin is a hoodlike fold of skin that covers the glans. It is connected to the glans just below the urethral orifice by a fold called the frenulum.

The body of the penis is supported by two condensations of deep fascia that extend downward from the linea alba and symphysis pubis to be attached to the fascia of the penis.

 

Blood Supply

Arteries

The corpora cavernosa are supplied by the deep arteries of the penis; the corpus spongiosum is supplied by the artery of the bulb. In addition, there is the dorsal artery of the penis. All the above arteries are branches of the internal pudendal artery.

 

Veins

The veins drain into the internal pudendal veins.

Lymph Drainage

The skin of the penis is drained into the medial group of superficial inguinal nodes. The deep structures of the penis are drained into the internal iliac nodes

Nerve Supply

The nerve supply is from the pudendal nerve and the pelvic plexuses.

Rupture of the Urethra

Rupture of the urethra may complicate a severe blow on the perineum. The common site of rupture is within the bulb of the penis, just below the perineal membrane. The urine extravasates into the superficial perineal pouch and then passes forward over the scrotum beneath the membranous layer of the superficial fascia,. If the membranous part of the urethra is ruptured, urine escapes into the deep perineal pouch and can extravasate upward around the prostate and bladder or downward into the superficial perineal pouch.

  Erection and Ejaculation after Spinal Cord Injuries

Erection of the penis is controlled by the parasympathetic nerves that originate from the 2nd, 3rd, and 4th sacral segments of the spinal cord. Bilateral damage to the reticulospinal nerve tracts in the spinal cord will result in loss of erection. Later, when the effects of spinal shock have disappeared, spontaneous or reflex erection may occur if the sacral segments of the spinal cord are intact.

Ejaculation is controlled by sympathetic nerves that originate in the 1st and 2nd lumbar segments of the spinal cord. As in the case of erection, severe bilateral damage to the spinal cord results in loss of ejaculation. Later, reflex ejaculation may be possible in patients with spinal cord transections in the thoracic or cervical regions.

Urethral Infection

The most dependent part of the male urethra is that which lies within the bulb. Here, it is subject to chronic inflammation and stricture formation.

The many glands that open into the urethra—including those of the prostate, the bulbourethral glands, and many small penile urethral glands—are commonly the site of chronic gonococcal infection.

Injuries to the penis may occur as the result of blunt trauma, penetrating trauma, or strangulation. Amputation of the entire penis should be repaired by anastomosis using microsurgical techniques to restore continuity of the main blood vessels.