Agriculture Reference
In-Depth Information
by incising the fat below the dorsal vertebrae just ante-
rior to the diaphragm.
D:
The same structures as the
intercostals and also the mediastinum, pericardium,
diaphragm and efferents from the intercostal lymph
nodes.
E:
Thoracic duct.
Posterior mediastinal (Fig. 2.10)
These nodes are 8-12 in number and situated in the fat
along the dorsal wall of the oesophagus. The largest and
most posterior of these nodes lies posterior to the heart,
being up to 20 cm long and extending almost to the dia-
phragm; in some cases, this large node is replaced by two
smaller ones.
D:
Lungs, diaphragm and, via the dia-
phragm, the peritoneum, surface of the liver and spleen.
They receive efferents from the right bronchial node.
E:
Thoracic duct.
Suprasternal
P:
Known also as the sternocostal, these nodes lie
between the costal cartilages and are covered by muscle.
They may be exposed by an incision 7.5 cm from and
parallel to the cut surface of the sternum and are found
at the junction of the internal thoracic vein with a line
continuing the posterior border of each rib. The node in
the fourth intercostal space is large and readily exposed,
but the nodes are not present in every intercostal space.
The largest of this group, known as the
presternal
or
anterior sternal node, is superficially placed and embed-
ded in fat on the first segment of the sternum.
D:
Diaphragm, abdominal muscles, intercostal muscles,
parietal and visceral pleura and peritoneum.
E:
Thoracic
duct and prepectoral nodes.
Axillary
P:
Known also as the brachial, this node is about 2.5 cm
long, covered by the scapula and situated in the muscle
external to and about midway along the second rib.
D:
Muscles of shoulder and forelimb.
E:
Prepectoral node.
Xiphoid (ventral mediastinal)
P:
Found in the loose fat at the junction of the sternum
and diaphragm at the level of the sixth rib and related
anatomically to the apex of the heart. This node is absent
in 50% of cases.
D:
Pleura, diaphragm and ribs.
E:
Suprasternal lymph nodes.
Bronchial (Fig. 2.10)
P:
There are two main bronchial nodes, the right and
left, together with two smaller nodes. The left bronchial
is 4 cm × 2.5 cm in size, often irregular in shape and
found close to the left bronchus, being embedded deeply
in fat and partly covered by the aorta. The right bron-
chial is related to the right bronchus, is usually smaller
than the left and is partly hidden by the right lung; it is
absent in 25% of cases, while in others, two nodes may
be found. The middle bronchial node is situated in the
middle line above the bifurcation of the trachea but is
absent in 50% of cases; a further node, the
apical
, is
placed on the accessory bronchus where it enters the api-
cal lobe of the right lung.
D:
Lungs.
E:
The left bronchial
node discharges into the thoracic duct, the right bron-
chial node into the posterior mediastinal node or tho-
racic duct, and the middle bronchial or apical into the
anterior mediastinal nodes. When the right bronchial
node is absent, the lymphatics of the diaphragmatic lobe
of the right lung discharge into the posterior mediastinal
and left bronchial node. A node known as the
inspector's
node
is present in 75% of cases and is situated at the junc-
tion of the two cardiac lobes of the right lung.
Nodes of the abdomen
and hindquarter (Fig. 2.12)
The position of these nodes is described as if the hind-
quarters were suspended by the hock in the normal
manner.
Lumbar
P:
These are situated in the fat covering the lumbar
muscles and are related anatomically to the aorta and
posterior vena cava. Some of these nodes are superficial,
others being embedded in the loin fat; the haemal lymph
nodes are common in this region.
D:
Lumbar region and
peritoneum. They receive efferent vessels from the inter-
nal and external iliac, sacral and popliteal nodes.
E:
Receptaculum chyli.
Portal
P:
Known also as the hepatic, these form a group around
the portal vein, hepatic artery and bile duct and are cov-
ered by the pancreas. Another group, which includes the
lymph node draining the pancreas, lies between the edge
of the pancreas and the caudate lobe of the liver. The
portal nodes vary from 10 to 15 in number.
D:
Liver,
pancreas and duodenum.
E:
Receptaculum chyli.
Anterior mediastinal (Fig. 2.10)
P:
These are numerous, lying in the mediastinal space
anterior to the heart, and are related anatomically to the
oesophagus, trachea and anterior aorta.
D:
Heart, peri-
cardium, mediastinum and thoracic wall and receive
efferents from the apical and middle bronchial lymph
nodes.
E:
Thoracic duct.
Renal
P:
This node belongs in reality to the lumbar group and
is found in the fat at the entrance to the kidney. In this
position, a split blood vessel is found, and the node can
