the wall of the thorax, the mammary glands (breasts),
and the upper wall of the abdomen.
These lymph nodes are located
cially on the medial side of the elbow. They often
enlarge in children in response to infections acquired
through cuts and scrapes on the hands.
Lymph nodes in the inguinal region
receive lymph from the lower limbs, the external
genitalia, and the lower abdominal wall.
Here lymph nodes primarily follow
the iliac blood vessels. They receive lymph from the
lymphatic vessels of the pelvic viscera.
M cells, through which certain ingested molecules pass by
transcytosis, then face lymphocytes and other immune sys-
tem cells that then may initiate an immune response. The
lymphoid tissues in the appendix, Peyer’s patches, tonsils,
adenoids, and mesenteric lymph nodes are collectively
termed mucosa-associated lymphoid tissues (MALT).
Spaces in a lymph node, called
a complex network of chambers and channels through which
lymph circulates. Lymph enters a lymph node through
moves slowly through the lymph sinuses,
and leaves through
efferent lymphatic vessels
(F g. 16.10
cial lymphatic vessels inF
amed by bacterial in±ection appear
as red streaks beneath the skin, a condition called
ammation o± the lymph nodes, called
ected nodes enlarge and may be pain±ul.
Locations of Lymph Nodes
Lymph nodes are found in groups or chains along the paths
of the larger lymphatic vessels throughout the body, but they
are not in the central nervous system. The major locations of
the lymph nodes, shown in
f gure 16.11
, are as follows:
These lymph nodes follow the lower
border of the mandible, anterior to and posterior to the
ears, and deep in the neck along the paths of the larger
blood vessels. These nodes are associated with the
lymphatic vessels that drain the skin of the scalp and face,
as well as the tissues of the nasal cavity and pharynx.
Lymph nodes in the underarm region
receive lymph from vessels that drain the upper limbs,
Lymph enters and leaves a lymph node through
Lymph node. (
) A section o± a lymph node. (
micrograph o± a lymph node (20×).
(macrophages, B cells)
(macrophages, T cells)