Principles of Human Body Structure Module (Anatomy) PDF

# Principles of Human Body Structure Module (Anatomy) ## Chapter 8: Lymphatic System **N.B: For illustrated diagrams check your anatomy atlas (chapter 8)** ## ILOs: By the end of this chapter the student will be able to: 1. Identify the different groups of lymph nodes in the body and identify...

# Principles of Human Body Structure Module (Anatomy) ## Chapter 8: Lymphatic System **N.B: For illustrated diagrams check your anatomy atlas (chapter 8)** ## ILOs: By the end of this chapter the student will be able to: 1. Identify the different groups of lymph nodes in the body and identify their drainage areas. 2. Define parts of the Waldeyer's ring of lymphoid tissue and identify anterior & posterior boundaries of the tonsillar fossa. 3. Identify the appendix. 4. Define the surfaces and borders of the spleen and describe its anatomical position. 5. Define lymph trunks and lymphatic ducts. 6. Define the beginning and end of the thoracic duct and right lymphatic duct. ### Lymph Nodes - **Axillary:** anterior, posterior, lateral, central, infraclavicular and apical for the upper limb & breast. - **Mediastinal:** for the thoracic organs. - **Aortic (pre & paraortic):** for abdominal organs. - **Iliac:** for the pelvic organs. - **Inguinal (superficial and deep) and femoral:** for the lower limbs. ### Thymus gland: - It is a small triangular organ found just posterior to the sternum and Infront to the heart. - It grows until puberty then atrophies. ### Spleen: - It is the largest lymphoid organ in the body. - It is soft in consistency and reddish in colour. - It lies in the upper left part of the abdomen between the stomach and diaphragm. #### Surface Anatomy: - It lies opposite 9th, 10th and 11th ribs and its long axis lies along the left 10th rib. - Its medial end lies 1.5 inches from the 10th spine and lateral end lies in the midaxillary line. - It has 2 ends: medial and lateral, 2 borders: superior and inferior and 2 surfaces: diaphragmatic and visceral. #### Borders of the spleen: - **Superior border:** is sharp and notched and its lateral end shows the splenic notch. - **Inferior border:** is blunt and rounded and corresponds to lower margin of 11th rib. #### Surfaces of the spleen: - **Diaphragmatic surface:** is the convex posterior surface related to the diaphragm, left pleura and lung and 9th, 10th, 11th ribs. - **Visceral surface:** is the concave anterior surface related to the stomach, tail of pancreas, left colic flexure and left kidney. It is marked by the hilum which receives the splenic vessels. #### Blood supply of spleen: - **Arterial supply:** splenic artery is the largest branch of celiac artery of abdominal aorta. It divides into about six branches, which enter the spleen at its hilum. - **Venous drainage:** splenic vein leaves the hilum and joins the superior mesenteric vein of intestine to form the portal vein. ### Lymphatic nodules: - They are masses of non-capsulated lymphatic tissue. - The lymphatic nodules are associated with the mucous membranes of the body, where they protect it from pathogens entering through open body cavities. - They include Waldeyer's ring, Peyer's patches of the intestine and appendix. ### Waldeyer's ring of lymphatic tissue: - It is a ring of lymphatic tissue that surrounds the opening of respiratory and digestive systems. - It is formed of: - **Palatine tonsils:** are collections of lymphoid tissue on the lateral wall of oropharynx. They are lying in tonsillar fossa that bounded by the palatoglossal fold anteriorly and palatopharyngeal fold posteriorly. - **Adenoid (pharyngeal tonsil):** is median lymphoid tissue in the roof of nasopharynx. - **Lingual tonsils:** are numerous lymphoid nodules on the posterior 1/3 of the tongue. - **Tubal tonsil:** is a lymphoid tissue around the opening of the auditory tube in the lateral wall of the nasopharynx. ### Peyer's patches (tonsils of the intestine): - They are masses of lymphatic tissue found lining the wall of the ileum of the small intestine. ### Appendix: - It is a wormlike extension of the cecum with an average length 8-10 cm. - Several lymphoid follicles are scattered in its mucosa. Such follicles increase in number when individuals are aged 8-20 years. - The appendix runs into a peritoneal fold called the mesoappendix. ## LYMPHATIC VESSELS ### Lymph capillaries: - They are networks of fine vessels that begin blindly in the tissue spaces to drain lymph from the tissues. - These capillaries are in turn drained by small lymph vessels, which unite to form large lymph vessels. ### Lymph vessels (Lymphatics): - They have a beaded appearance because of the presence of numerous valves along their course. - They are absent in the brain, spinal cord, eyeballs, bone marrow, hyaline cartilage, nails and hair. - **Afferent lymph vessel:** carries lymph to the lymph nodes. - **Efferent lymph vessel:** carries lymph away from the lymph nodes. ### Lymph Trunks & Ducts: - **Lymph trunks:** they are right and left jugular, subclavian trunks, right and left broncho mediastinal, left lumbar and intestinal trunks. - **Lymph ducts:** all of the lymphatic vessels of the body carry lymph toward the 2 lymphatic ducts: the thoracic duct and the right lymphatic duct. These ducts serve to return lymph back to the venous blood. ### Thoracic duct: - It drains lymph from the lower limbs, pelvic cavity, abdominal cavity, left side of the thorax, and left side of the head, neck, and left arm. - It begins as a dilated sac called cisterna chyli in the abdomen. - It enters the thorax though the aortic opening of the diaphragm. - It courses upwards in the posterior mediastinum of the thorax behind the esophagus till 5th T.V. where it deviates to its left side. - It ends in the root of the neck at the junction between the left internal jugular and left subclavian veins. ### Right lymphatic duct: - It drains lymph from the right side of head, neck, thorax, right arm and upper surface of right lobe of the liver. - It ends in the root of the neck at the junction between the right internal jugular and right subclavian veins.