20 - thoracic duct

The thoracic duct

This main lymphatic duct conveys all the lymph from the lower limbs, pelvis, abdomen, left side of the thorax and head and neck and left upper limb to the venous system; that is, all but the right superior quadrant of the body.

It drains the cisterna chyli, which is an elongated sac that lies on the right side of the bodies of the 1^st and 2^nd lumbar vertebrae below the diaphragm.

The thoracic duct passes superiorly from the cisterna chyli through the aortic hiatus in the diaphragm on the right side of the aorta. In the posterior mediastinum, the thoracic duct ascends among the thoracic aorta on its left, the azygos vein on its right, the esophagus anteriorly, and the vertebral bodies and the origins of the right posterior intercostal arteries posteriorly.

At about the level of the sternal angle the thoracic duct deviates to the left, posterior to the esophagus and ascends through the superior mediastinum into the root of the neck to empty into the venous system at the union of the left internal jugular and subclavian veins.

The duct has a number of valves, which prevent lymph flowing downwards and give it a beaded appearance.

The cysterna chyli receives lymph from the lower limbs, pelvis and abdomen. The thoracic duct receives the left bronchomediastinal trunk in the thorax, and in the neck the left jugular and left subclavian lymph trunks. All these trunks can open independently into the left internal jugular or subclavian vein.

Because the thoracic duct is thin walled and may be colorless, it may be difficult to identify during surgical procedures. If the thoracic duct is cut or torn during an accident, chyle (L. chylus, juice) escapes from it. This milky fluid contains a considerable amount of fine fat droplets. Leakage of chyle may be prevented by tying off the thoracic duct. The lymph then returns to the venous system by other lymph channels, which join the duct superior to the ligature. During digestion the thoracic duct is distended with chyle, a product of the small intestine.

A brachiocephalic venous catheterization is inadvisable on the left side since the insertion of a needle into the angle formed by the confluence of the internal jugular and subclavian veins might well encounter the terminal portion of the thoracic duct. The brachiocephalic route for a central venous catheterization on the left-hand side has been known to cause a chylothorax.

19 - breast - lymphatic drainage

The lymphatic and venous drainages of the breast are of great importance in the spread of carcinoma. 

About three quarters of the lymphatic drainage is to the axillary nodes: 

(1) Lymphatics pass around the edge of the pectoralis major and reach the pectoral group of axillary nodes; 

(2) routes through or between the pectoral muscles may lead directly to the apical nodes of the axilla; 

(3) lymphatics follow the blood vessels through the pectoralis major and enter the parasternal (internal thoracic) nodes; 

(4) connections may lead across the median plane and hence to the contralateral breast; 

(5) lymphatics may reach the sheath of the rectus abdominis and the subperitoneal and subhepatic plexuses.

It should be noted that free communication exists between nodes below and above the clavicle and between the axillary and cervical nodes.

check out this mcq :

Q. find the incorrect statement about the lymphatic drainage of the breast ?

1. there is free communication between the subclavicular and supraclavicular lymph nodes
2. the lymph nodes along the internal mammary chain are involved in about half the cases in which the axillary nodes are implicated by carcinoma
3. the thoracic chain of lymph nodes lie along the internal mammary vessels
4. some lymph nodes lie between the greater and lesser pectoral muscles

answer: c .

18 - adamkiewicz's artery

In human anatomy, the Artery of Adamkiewicz is the largest anterior segmental medullary artery.

It has several other names, including Adamkiewicz artery, major anterior segmental medullary artery, artery of the lumbar enlargement,great radicular artery of Adamkiewicz,great anterior radiculomedullary artery and great anterior segmental medullary artery.

It typically arises from a left posterior intercostal artery, which branches from the aorta, and supplies the lower two thirds of the spinal cord via the anterior spinal artery.

In a study of approximately 70 people that examined the spinal cord's blood supply it was found that

1. The Adamkiewicz artery sometimes arises from a lumbar vessel.
2. In approximately 30% of people it arises from the right side.
3. One quarter of people have two large anterior segmental medullary arteries.

When damaged or obstructed, it can result in anterior spinal artery syndrome, with loss of urinary and fecal continence and impaired motor function of the legs; sensory function is often preserved to a degree.

It can be important to identify the location of the artery when treating an abdominal aortic aneurysm. Its location can be identified with computed tomographic angiography.

It is named for Albert Wojciech Adamkiewicz.