Surgical Anatomy and Physiology.—Lymph is essentially blood plasma, which has passed through the walls of capillaries. After bathing and nourishing the tissues, it is collected by lymph vessels, which return it to the blood stream by way of the thoracic duct. These lymph vessels take origin in the lymph spaces of the tissues and in the walls of serous cavities, and they usually run alongside blood vessels—perivascular lymph vessels. They have a structure similar to that of veins, but are more abundantly provided with valves. Along the course of the lymph trunks are the lymph glands, which possess a definite capsule and are composed of a reticulated connective tissue, the spaces of which are packed with leucocytes. The glands act as filters, arresting not only inert substances, such as blood pigment circulating in the lymph, but also living elements, such as cancer cells or bacteria. As it passes through a gland the lymph is brought into intimate contact with the leucocytes, and in bacterial infections there is always a struggle between the organisms and the leucocytes, so that the glands may be looked upon as an important line of defence, retarding or preventing the passage of bacteria and their products into the general circulation. The infective agent, moreover, in order to reach the blood stream, must usually overcome the resistance of several glands.

Lymph glands are, for the most part, arranged in groups or chains, such as those in the axilla, neck, and groin. In any given situation they vary in number and size in different individuals, and fresh glands may be formed on comparatively slight stimulus, and disappear when the stimulus is withdrawn. The best-known example of this is the increase in the number of glands in the axilla which takes place during lactation; when this function ceases, many of the glands become involuted and are transformed into fat, and in the event of a subsequent lactation they are again developed. After glands have been removed by operation, new ones may be formed.

The following are the more important groups of glands, and the areas drained by them in the head and neck and in the extremities.

Head and Neck.The anterior auricular (parotid and pre-auricular) glands lie beneath the parotid fascia in front of the ear, and some are partly embedded in the substance of the parotid gland; they drain the parts about the temple, cheek, eyelids, and auricle, and are frequently the seat of tuberculous disease. The occipital gland, situated over the origin of the trapezius from the superior curved line, drains the top and back of the head; it is rarely infected. The posterior auricular (mastoid) glands lie over the mastoid process, and drain the side of the head and auricle. These three groups pour their lymph into the superficial cervical glands. The submaxillary—two to six in number—lie along the lower order of the mandible from the symphysis to the angle, the posterior ones (paramandibular) being closely connected with the submaxillary salivary gland. They receive lymph from the face, lips, floor of the mouth, gums, teeth, anterior part of tongue, and the alæ nasi, and from the pre-auricular glands. The lymph passes from them into the deeper cervical glands. They are frequently infected with tubercle, with epithelioma which has spread to them from the mouth, and also with pyogenic organisms. The submental glands lie in or close to the median line between the anterior bellies of the digastric muscles, and receive lymph from the lips. It is rare for them to be the seat of tubercle, but in epithelioma of the lower lip and floor of the mouth they are infected at an early stage of the disease. The supra-hyoid gland lies a little farther back, immediately above the hyoid bone, and receives lymph from the tongue. The superficial cervical (external jugular) glands, when present, lie along the external jugular vein, and receives lymph from the occipital and auricular glands and from the auricle. The sterno-mastoid glands—glandulæ concatinatæ—form a chain along the posterior edge of the sterno-mastoid muscle, some of them lying beneath the muscle. They are commonly enlarged in secondary syphilis. The superior deep cervical (internal jugular) glands—from six to twenty in number—form a continuous chain along the internal jugular vein, beneath the sterno-mastoid muscle. They drain the various groups of glands which lie nearer the surface, also the interior of the skull, the larynx, trachea, thyreoid, and lower part of the pharynx, and pour their lymph into the main trunks at the root of the neck. Belonging to this group is one large gland (the tonsillar gland) which lies behind the posterior belly of the digastric, and rests in the angle between the internal jugular and common facial veins. It is commonly enlarged in affections of the tonsil and posterior part of the tongue. In the same group are three or four glands which lie entirely under cover of the upper end of the sterno-mastoid muscle, and surround the accessory nerve before it perforates the muscle. The deep cervical glands are commonly infected by tubercle and also by epithelioma secondary to disease in the tongue or throat. The inferior deep cervical (supra-clavicular) glands lie in the posterior triangle, above the clavicle. They receive lymph from the lowest cervical glands, from the upper part of the chest wall, and from the highest axillary glands. They are frequently infected in cancer of the breast; those on the left side also in cancer of the stomach. The removal of diseased supra-clavicular glands is not to be lightly undertaken, as difficulties are liable to ensue in connection with the thoracic duct, the pleura, or the junction of the subclavian and internal jugular veins. The retro-pharyngeal glands lie on each side of the median line upon the rectus capitis anticus major muscle and in front of the pre-vertebral layer of the cervical fascia. They receive part of the lymph from the posterior wall of the pharynx, the interior of the nose and its accessory cavities, the auditory (Eustachian) tube, and the tympanum. When they are infected with pyogenic organisms or with tubercle bacilli, they may lead to the formation of one form of retro-pharyngeal abscess.

Upper Extremity.The epi-trochlear and cubital glands vary in number, that most commonly present lying about an inch and a half above the medial epi-condyle, and other and smaller glands may lie along the medial (internal) bicipital groove or at the bend of the elbow. They drain the ulnar side of the hand and forearm, and pour their lymph into the axillary group. The epi-trochlear gland is sometimes enlarged in syphilis. The axillary glands are arranged in groups: a central group lies embedded in the axillary fascia and fat, and is often related to an opening in it; a posterior or subscapular group lies along the line of the subscapular vessels; anterior or pectoral groups lie behind the pectoralis minor, along the medial side of the axillary vein, and an inter-pectoral group, between the two pectoral muscles. The axillary glands receive lymph from the arm, mamma, and side of the chest, and pass it on into the lowest cervical glands and the main lymph trunk. They are frequently the seat of pyogenic, tuberculous, and cancerous infection, and their complete removal is an essential part of the operation for cancer of the breast.

Lower Extremity.The popliteal glands include one superficial gland at the termination of the small saphenous vein, and several deeper ones in relation to the popliteal vessels. They receive lymph from the toes and foot, and transmit it to the inguinal glands. The femoral glands lie vertically along the upper part of the great saphenous vein, and receive lymph from the leg and foot; from them the lymph passes to the deep inguinal and external iliac glands. The femoral glands often participate in pyogenic infections entering through the skin of the toes and sole of the foot. The superficial inguinal glands lie along the inguinal (Poupart's) ligament, and receive lymph from the external genitals, anus, perineum, buttock, and anterior abdominal wall. The lymph passes on to the deep inguinal and external iliac glands. The superficial glands through their relations to the genitals are frequently the subject of venereal infection, and also of epithelioma when this disease affects the genitals or anus; they are rarely the seat of tuberculosis. The deep inguinal glands lie on the medial side of the femoral vein, and sometimes within the femoral canal. They receive lymph from the deep lymphatics of the lower limb, and some of the efferent vessels from the femoral and superficial inguinal glands. The lymph then passes on through the femoral canal to the external iliac glands. The extension of malignant disease, whether cancer or sarcoma, can often be traced along these deeper lymphatics into the pelvis, and as the obstruction to the flow of lymph increases there is a corresponding increase in the swollen dropsical condition of the lower limb on the same side.

The glands of the thorax and abdomen will be considered with the surgery of these regions.