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hiatus in the right crus of diaphragm. It goes up along the right
semicircle of thoracic vertebra, anteriorly from the right
posterior intercostal arteries, posteriorly and to the right from
esophagus, from the side of the thoracic duct and to the
middle of the right sympathetic trunk.
At the level of the 4th thoracic vertebra it shifts anteriorly
and turning the root of the right lung goes into v. cava
superior.
The branches of v. azygos drain into:
1) vv. intercostales posterior dextri;
2) v. haemiazygos;
3) v. haemiazygos accessoria;
4) vv. oesophageales;
5) vv. bronchiales;
6) vv. pericardiacae;
7) vv. mediastinales;
8) vv. phrenicae superiores;
9) pl. vertebrales internus et externus.
The hemiazygos vein
(v. haemiazygos)
is the continuation of
ascending lumbar vein. It goes up along
the left semicircle of
thoracic vertebra and from the side and behind the thoracic
part of aorta, anteriorly and to the middle of sympathetic trunk.
At the level of the 6th – 10th thoracic vertebrae it shifts to the
middle, goes behind the aorta and sinks into v. azygos.
ACCESSORY HEMIAZYGOS VEIN
(v. hemiazygos accessoria)
takes blood from the left upper posterior intercostal veins. It
can sink into hemiazygos vein or azygos vein or into left
brachiocephalic vein.
THORACIC SECTION OF SYMPATHETIC TRUNK
is formed by
the 9th – 11th ganglia thoracica which are joined with the help of
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interganglionic rami communicantes (rr. interganglionares). The
upper thoracic node merges with the inferior cervical node
forming common ganglion cervicothoracicum or g. stellatum.
Communicating branches (rr. communicantes) branch off from
the nodes to the spinal nerves. From the nodes of sympathetic
trunk depart many internal branches
which are the part of
abdominal and thoracic autonomic plexuses (pl. aorticus
thoracicus,
pl. cardiacus,
pl. oesophageus,
pl. pulmonalis, pl. coeliacus, etc.). N. splanchnicus major and
n. splanchnicus minor are the biggest branches among the ones of
sympathetic trunk.
The visceral branches of the 5th – 11th thoracic vertebrae and
their interganglionic rami communicantes go downwards and to
the middle along the lateral surface of vertebra and connect to
each other forming n. splanchnicus major which penetrates into
retroperitoneal space through the hiatus in the crus of
diaphragm and is the part of abdominal plexus (plexus coeliacus).
N. splanchnicus minor is formed due to 1 – 4 roots from the
9th to the 11th thoracic nodes. N. splanchnicus imus is formed
from the 10th – 11th thoracic nodes. Nn. splanchnicus minor
are located from the side of nn. splanchnicus major. Having
penetrate into retroperitoneal space they go to the renal and
abdominal plexuses.
Both sympathetic trunks are located on the heads of the
6th – 7th upper ribs. They are limited from pleural cavity with
parietal pleura, subserous layer and endothoracic fascia.
Posterior intercostal arteries
and veins cross sympathetic
trunks at the posterior surface and v. azygos and hemiazygos
are located anteriorly and to the middle of them.
N. splanchnicus major crosses v. azygos on the right, is
attached to anteromedial surface and is located on the anterior
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surface of thoracic vertebrae. The left n. splanchnicus major
crosses v. hemiazygos accessoria, goes downwards and is located
between the vein and aorta. Through the diaphragm the
sympathetic trunks go behind and to the side of abdominal
nerves.
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