Anatomy Bones and Muscles · MU Pleven

116. Lymph nodes. Thymus.

Covers lymph nodes as secondary lymphatic organs, their main regional groups and their layered structure from capsule and subcapsular sinus through cortex, paracortex and medulla to the hilum. Tonsils are also described, with their types and microscopic features. The thymus section deals with its location, age-related involution, cortical and medullary organisation, thymic corpuscles, and its role in T-cell maturation and selection.

Inside: 7 sections · 5 labelled pictures · 13 flashcards · 4 min

Topic 115 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 5 sections, about 524 words (4 min of reading), with 13 flashcards.

In this note

  1. LYMPH NODE
  2. Structure :
  3. TONSILS
  4. THYMUS
  5. Functions :

LYMPH NODE

  • Lymph nodes are secondary lymphatic organs
  • Small kidney-shaped organs.
  • Size from 1-25 mm.
  • The total number in the body ~ 500 Distributed throughout the body along the network of lymphatic vessels.
  • Function : filters the lymph, stores lymphocytes (T & B and other WBCs)
  • They are common in the :
  1. 1. Armpits ⟶ Called the axillary lymph nodes.
  2. 2. Groins ⟶ " " inguinal " "
  3. 3. Neck ⟶ " " cervical " ".
  4. 4. Knees ⟶ " " popliteal " ".

Structure :

  1. 1. Capsule : - Outer layer
  • - Dense connective tissue
  • - Providing structural support and protection.
  1. 2. Subcapsular Sinus : - Space beneath the capsule
  • - Receive afferent lymphatic vessels (ducts).
  • - Contains macrophages help filter and capture debris and foreign particles in the lymph.
  1. 3. Trabeculae : - fibrous extensions from the capsule that divide the lymph node into compartments.
  • - Contains Blood vessels & lymphatic vessels.
  1. 4. Cortex. - Outer cortex
  • ↳ Contains follicles of B cells (1°, 2°)
  • ↳ have Germinal center. areas where B-cells differentiate into plasma cells.
  • - Inner cortex : No follicles (Paracortex) ↘ T-cells area.
  1. 6. Medulla : - Innermost part.
  • - Medullary cords : Extends from the cortex to the medulla. containing B cells, T cells & plasma cells.
  • - Medullary Sinuses : Spaces contain lymph.
  1. 7. Hilum : Area where blood vessels and efferent lymphatic vessels.

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