Arteria Princeps Cervicis, br. of occipital, from the external carotid, with the Vertebral, br. of subclavian, and the Profunda Cervicis, br. of the superior intercostal, from the subclavian. What is the Longest Anastomosis in the Body? That between the subclavian and the external iliac by the anastomosis of the Superior Epigastric, br. of the internal mammary, with the Deep Epigastric, br. of the external iliac. [The circle of Willis has been described on page 106; the palmar and plantar arches on pages 108 and 113 respectively; and the anastomosis on the membrana tympani on page 105.] THE VEINS. What are the Veins? Vessels carrying blood towards the heart. Their walls are composed of 3 coats, an internal, serous; a middle, muscular; and an external, fibrous. They all carry carbonized or venous blood, except the pulmonary veins, which bring oxygenated blood to the left side of the heart. The deep veins accompany the arteries, generally in the same sheath, and are given the same names. The secondary arteries, as the radial, ulnar, brachial, etc., have each two veins, called Vena Comites. The superficial veins are usually unaccompanied by arteries, and lie, as a rule, between the layers of the superficial fascia, terminating in the deep veins. Many veins are so irregular in their origin that they cannot be accurately described; they all anastomose with each other much more freely than do the arteries. What are Sinuses? They are venous channels, differing from veins in structure, but answering the same purpose. Those of the cranium are formed by the separation of the layers of the dura mater. How are the Veins divided? Into the Pulmonary, Systemic, and Portal Systems; the latter being an appendage of the systemic, its capillaries ramifying in the liver. What Veins have no Valves? The venæ cavæ, hepatic, portal, renal, uterine, ovarian, cerebral, spinal, pulmonary, umbilical, and the very small veins. (1.) Exterior veins. Name the principal Veins of the Head and Neck. They are the- Facial. Temporal. Internal Maxillary. Cerebral and Cerebellar. Transverse Sinus. Cavernous Sinus. Superior Petrosal Sinus. Lateral Sinus. (3.) Veins of the neck draining the above-named. External Jugular, terminating in the subclavian vein.1 Posterior External Jugular, opens into the external jugular. Anterior Jugular, enters the subclavian vein near the external jugular. Internal Jugular,5 formed by the junction of the two last-named sinuses at the jugular foramen, and uniting with the subclavian vein to form the innominate, at the root of the neck. In its course it receives the facial, lingual, pharyngeal, superior and middle thyroid veins, and the occipital. Vertebral, descends the foramina in the transverse processes of the cervical vertebræ, and empties into the innominate vein. Name the Veins of the Upper Extremity. They are in two sets, superficial and deep. The deep follow the arteries, generally as venæ comites, beginning in the hand as Digital, Interosseous, and Palmar veins, they unite in the Deep Radial and Ulnar which unite to form the Vena Comites of the brachial artery at the bend of the elbow. The superficial veins lie in the superficial fascia; they are as follows: Radial...... Median.. Median Cephalic. Cephalic. Anterior and Posterior Ulnar...... Median Basilic. Basilic. AXILLARY Name the principal Veins of the Thorax. They are as follows, viz.— What are the Azygos Veins? They supply the place of the venæ cavæ in the region where these trunks are deficient, being connected with the heart. The Right Azygos 17 begins by a branch from the right lumbar veins usually, passes through the aortic opening in the diaphragm, and ends in the superior vena cava, having drained or 10 right lower intercostals, the vena azygos minor, the right bronchial, œsophageal, mediastinal, and vertebral veins. The Left Lower Azygos 18 begins by a branch from the left lumbar or renal, passes the left crus of the diaphragm, crosses the vertebral column and ends in the right azygos, having drained 4 or 5 lower intercostals. The Left Upper Azygos drains 2 or 3 left intercostals and empties into either of the other two. It is often wanting, its place being filled by the left superior intercostal vein.21 Name the Spinal Veins. They may be arranged into 4 sets, as follows, viz. Medulli-spinal, the veins of the spinal cord, which lie in plexus form between the pia mater and arachnoid. They unite into 2 or 3 small trunks near the base of the skull, which terminate in the inferior cerebellar veins or in the petrosal sinuses. Vena Basis Vertebrarum, empty into the anterior longitudinal. Longitudinal, in two plexuses, anterior and posterior, running the whole length of the spinal canal. The posterior join the dorsi-spinal veins, the anterior empty into the vertebral, intercostal, lumbar, and sacral veins in their various regions. Dorsi-spinal, form a plexus around the spines, processes, and laminæ of all the Describe the Subclavian Vein. It is the continuation of the axillary, extending from the outer margin of the 1st rib to the sternoclavicular articulation, where it unites with the internal jugular to form the innominate vein. At the angle of junction enters the thoracic duct on the left side of the body and the right lymphatic duct on the right side. In its course it receives the external and anterior jugular veins and a branch from the cephalic. The Describe the Venæ Innominatæ. two innominate veins are each formed by the union of the subclavian and internal jugular, and unite below the 1st costal cartilage to form the superior vena cava. The Right Innominate is about 11⁄2 inch long, and receives, besides its constituent branches, the right internal mammary, right inferior thyroid, and right superior intercostal veins. The Left Innominate is about 3 inches long, and in its course it receives the vertebral, inferior thyroid, internal mammary, and superior intercostal veins of the left side. Describe the Superior Vena Cava.1 It is 136 FIG. 60. 20 18 19 a short trunk about 22 or 3 inches in length, formed by the union of the venæ innominatæ, and receives all the blood from the upper half of the body, terminating in the right auricle of the heart. It is half covered by the pericardium, and receives the vena azygos major and small pericardiac and mediastinal veins. Name the Principal Veins of the Lower Extremity. They are in two sets, superficial and deep. The deep are the Vena Comites of the anterior and posterior tibial and peroneal arteries, which collect the blood from the deep parts of the foot and leg, and unite in the Popliteal, which becomes the Femoral, and it the External Iliac in the same manner as the respectively-named arteries. The superficial veins of the lower extremity are the— Internal or Long Saphenous, on the inside of the leg and thigh, enters the femoral at the saphenous opening 11⁄2 inch below Poupart's ligament. In its course it receives the following :— Cutaneous Branches. Superficial Epigastric. Pudic. Superficial Circumflex Iliac. External or Short Saphenous, formed by branches from the dorsum and outer side of the foot, it ascends behind the outer malleolus, up the middle of the back of the leg, and empties into the popliteal vein. Describe the Internal Iliac Vein.10 It is formed by the venæ comites of the branches of the internal iliac artery, except the umbilical. It terminates with the external iliac, at the sacro-iliac articulation, to form the common iliac vein. It receives the following veins : Gluteal. Internal Pudic. Hemorrhoidal and Vesico- Uterine and Vaginal Plexuses, in the female. Describe the Common Iliac Veins. They are each formed by the union of the two iliac veins as above described, and unite between the 4th and 5th lumbar vertebræ to form the inferior vena cava, the right common iliac being the shortest of the two. Each receives the Ilio-lumbar, sometimes the Lateral Sacral, and the left one in addition the Middle Sacral Vein, which sometimes ends in the vena cava. Describe the Inferior Vena Cava. It extends from the junction of the two common iliac veins, passing along the front of the spine, through the tendinous centre of the diaphragm, to its termination in the right auricle of the heart. It receives the following veins : Lumbar.12 Right Spermatic.13 Renal.15 Phrenic. Hepatic,16 Describe the Portal System. The portal system is formed by the Superior and Inferior Mesenteric, Splenic, and Gastric Veins, which collect the blood from the digestive viscera, and by their union behind the head of the pancreas form the Portal Vein, which enters the transverse fissure of the liver, where it divides into 2 branches, and these again subdivide, ramifying throughout that organ, therein receiving blood also from the branches of the hepatic artery. Its contents enter the inferior vena cava by the hepatic vein. The portal vein is about 4 inches long, receives the Gastric and Cystic Veins, and is formed by the union of the superior mesenteric and splenic veins, the inferior mesenteric joining the splenic, which also receives one of the gastric, the other emptying into the portal. Coronary Sinus, is a dilatation of the great cardiac vein, receiving the posterior cardiac and an oblique vein from the left auricle. Describe the Pulmonary Veins. They alone of the veins carry arterial blood, beginning in the capillaries of the lungs, forming a single trunk for each lobule, which, uniting into a single trunk for each lobe, form two main trunks from each lung which open separately into the left auricle. Sometimes the 3 lobe-trunks of the right lung remain separate to their termination in the auricle, and not unfrequently a common opening serves for the 2 left pulmonary veins. THE ABSORBENTS. What are the Lymphatics? They are very delicate, transparent vessels, formed of three coats like arteries and veins, found in nearly every part of the body, except the brain, spinal cord, eyeball, cartilage, tendons, membranes of the ovum, placenta, umbilical cord, nails, cuticle, hair, and bone. They are nourished by nutrient vessels, and have valves, but no nerves, so far as known. They convey lymph to the blood. What are the Lacteals? They are the lymphatics of the small intestine, conveying the chyle therefrom into the blood. What are the Lymphatic Glands? Small solid bodies placed in the course of the absorbent vessels, and found chiefly in the mesentery, along the great blood-vessels, in the mediastina, axilla, neck, front of the elbow, groin, and popliteal space. The lymphatics and lacteals before entering these glands break up into smaller branches, the afferent vessels, which form a plexus in the gland, and pass out as efferent vessels to unite again in one trunk. They also contain spheroidal bodies about inch in diameter. These glands are named after the regions in which they are situated, as the axillary, inguinal, mesenteric, etc. Describe the Thoracic Duct. It is the main channel for the lymph and chyle from the whole body except the right arm and lung, right side of the head, heart, neck, and thorax, and the convex surface of the liver. It begins in the Receptaculum Chyli, in front of the 2d lumbar vertebra, passes through the aortic opening in the diaphragm, and at the upper border of the 7th cer |