Page 166 - Clinical Anatomy

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The posterior abdominal wall 151

swelling (Fig. 109). Occasionally, in completely neglected cases, pus tracks
along the femoral vessels, along the subsartorial canal and eventually
appears in the popliteal fossa.
The retroperitoneal organs are: the pancreas, kidneys and ureters
(which have already been considered), the suprarenals, the aorta and infe-
rior vena cava and their main branches, the para-aortic lymph nodes and
the lumbar sympathetic chain.

The suprarenal glands (Fig. 81)
The suprarenal glands cap the upper poles of the kidneys and lie against
the crura of the diaphragm. The left is related anteriorly to the stomach
across the lesser sac, the right lies behind the right lobe of the liver and
tucks medially behind the inferior vena cava.
Each gland, although weighing only 3 to 4g, has three arteries supply-
ing it:
1◊◊a direct branch from the aorta;
2◊◊a branch from the phrenic artery;
3◊◊a branch from the renal artery.
The single main vein drains from the hilum of the gland into the nearest
available vessel— the inferior vena cava on the right, the renal vein on the
left. The stubby right suprarenal vein, coming directly from the inferior
vena cava, presents the most dangerous feature in performing an adrena-
lectomy — the tiro should always choose the easier left side and leave the
right to his chief.
The suprarenal gland comprises a cortex and medulla, which represent
two developmentally and functionally independent endocrine glands
within the same anatomical structure. The medulla is derived from the
neural crest (neuroectoderm) whose cells also give rise to the sympathetic
ganglia. The cortex, on the other hand, is derived from the mesoderm.
The suprarenal medulla receives preganglionic sympathetic fibres from the
greater splanchnic nerve and secretes adrenaline and noradrenaline. The
cortex secretes the adrenocortical hormones.

Abdominal aorta (Fig. 110)
The aorta enters the abdomen via the aortic hiatus in the diaphragm at the
level of the 12th thoracic vertebra and ends at L4 in the transcristal plane
(Fig. 42). It lies throughout this course against the vertebral bodies and is
easily palpable in the midline.
Anteriorly, from above down, it is related to the pancreas (separating it
from the stomach), the third part of the duodenum and coils of small intes-
tine. It is crossed by the left renal vein. A large tumour of pancreas or
stomach, a mass of enlarged para-aortic nodes, or a large ovarian cyst may
transmit the pulsations of the aorta and be mistaken for an aneurysm.
The branches of the aorta are:
1◊◊three anterior unpaired branches passing to the viscera:
(a) the coeliac axis—giving off the