Agriculture Reference
In-Depth Information
nodes, together with efferents from the prescapular;
thus, all lymph from the head and neck passes through
the prepectoral lymph nodes.
E:
Thoracic duct.
Nodes of the head and neck
Submaxillary
P:
One on each side, just inside the angle of the jaw and
embedded in fat.
D:
Head, nose and mouth.
E:
Lateral
retropharyngeal nodes.
Costocervical
P:
This may be found on the inner side or just anterior to
the first rib and close to its junction with the first dorsal
vertebra. It lies adjacent to the oesophagus and trachea
and is frequently removed with these in the dressing of
the carcase, being then found anterior to the heart and
lungs.
D:
Neck, shoulder, parietal pleura and first few
intercostal nodes.
E:
Thoracic duct.
Parotid
P:
One on each side, on the edge of the masseter muscle,
and covered by the parotid salivary gland which must be
incised to expose it. It is a flat node 7.5 cm long by 2.5 cm
wide and should always be examined in old cows.
D:
Muscles of the head, eye and ear, tongue and cranial
cavity.
E:
Lateral retropharyngeal nodes.
Prescapular
P:
This node is elongated, commonly 7.5-10 cm long and
2.5 cm or more in width. It lies about 10 cm in front of the
point of the shoulder, and a deep incision 15 cm long and
5 cm deep must be made to expose it. The node is embed-
ded in fat, and its exposure is greatly facilitated if the
carcase is examined before the onset of rigor mortis.
D:
Head, neck, shoulder and forelimb.
E:
Thoracic duct.
The importance of the prescapular lymph node in rela-
tion to bovine tuberculosis lies in the fact that it drains
not only the head, neck, shoulder and forelimb but also
the muscle and bone. When lesions of tuberculosis,
therefore, are found in the prescapular node without
lesions being present in the head or its lymph nodes, it is
strongly suggestive that the infection of the node is the
result of either local inoculation or haematogenous
dissemination.
Retropharyngeal
These are divided into two groups:
1
The internal retropharyngeal nodes, two to four in
number and situated between the hyoid bones.
D:
Pharynx, tongue and larynx.
E:
Lateral retropharyn-
geal nodes
2
The lateral retropharyngeal nodes situated beneath
each wing of the atlas and therefore usually located
at the neck end of the dressed carcase.
D:
Tongue
and receive efferents from the submaxillary, parotid
and internal retropharyngeal nodes.
E:
Tracheal
lymph duct
Middle cervical
P:
Situated in the middle of the neck on each side of the
trachea and often absent in cattle. They vary in number
from one to seven and also in position and size.
D:
Lateral retropharyngeal nodes.
E:
Prepectoral nodes.
Intercostal
P:
Known also as the
dorso-costal
, these are situated in
the intercostal spaces at the junction of the ribs with
their vertebrae and are deep-seated, being covered by the
intercostal muscle. Most of these nodes are small, and
not all of the spaces may contain nodes.
D:
Muscles of
the dorsal region, intercostal muscles, ribs and parietal
pleura.
E:
Mediastinal lymph nodes.
Nodes of the chest and forequarter
(Fig. 2.10 and Fig. 2.12)
Prepectoral
These are known also as the lower cervicals and may be
considered anatomically as a continuation of the upper
and middle cervical chain. The middle cervical group
may, in fact, extend to the upper group or may reach
back almost to the prepectorals.
P:
The prepectorals are
two to four in number on each side and are embedded in
fat along the anterior border of the first rib. The main
node of this group is superficially situated about the
middle of the first rib and just anterior to it; the haemal
lymph nodes are usually present in the fat around this
group. The second node of this group is on the same
level and just anterior to the main node but is deep-
seated and is exposed by making an incision 10 cm long
and 5 cm deep through the triangular-shaped scalenus
muscle.
D:
Efferents from upper and middle cervical
Subdorsal
P:
This superficial group lies in the fat between the
aorta and the dorsal vertebrae. The nodes are irregular
in arrangement, varying in length from 12 to 25 mm,
and are frequently removed with the lungs in the dress-
ing of the carcase; they may then be found by incising
the upper surface of the mediastinal fat between the
lungs. In some areas, the thoracic portion of the poste-
rior aorta is left attached, and the subdorsal lymph
nodes, which run down on each side of the vessel wall,
will then be found on the carcase. The more posterior
nodes of the group, no matter how the carcase is dressed,
usually remain on the forequarter and can be found
