Human Anatomy Vol 1

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At the root of the aorta there are three dilatations of
the vessel wall called the aortic sinuses. The sinuses are
anterior, left posterior and right posterior.

Relolions

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1 Sternum.
2 Right lung and pleura.
3 Infundibulum of the right ventricle.
4 Root of the pulmonary trunk (Fig. 19.3).
5 Right auricle.

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Transverse sinus of pericardium.

Left atrium.

Right pulmonary artery.

Right bronchus (Fig. 19.3).

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1 Superior vena cava.
2 Right atrium.

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1 Pulmonary trunk above.
2 LeIt atrium below.

Bronches

L The right coronary artery arises from anterior aortic
sinus (see Fig. 78.22a).
2 Left coronary artery arises from the left posterior
aortic sinus.

Aortic knuckle: In posteroanterior view of

radiographs of the chest, the arch of the aorta is

seen as a projection beyond the left margin of the

mediastinal shadow. The projection is called the

aortic knuckle. It becomes prominent in old age

(see Fig.21..12).

Coarctation of the aorta is a localised narrowing of

the aorta opposite to or justbeyond the attachment

of the ductus arteriosus. An extensive collateral

circulation develops between the branches of the

subclavian arteries and those of the descending

aorta. These include the anastomoses between the

anterior and posterior intercostal arteries. These

arteries enlarge greatly and produce a

characteristic notching on the ribs (Fig. 19.6).

D uctus ar t er io sus, lig nmentum ar t er io sum and p at ent

ductus arteriosus: During foetal life, the ductus

arteriosus is a short wide channel connecting the

beginning of the left pulmonary artery with the

arch of the aorta immediately distal to the origin

of the left subclavian artery. It conducts most of

SUPEBIOFI VENA CAVA, AOHIA AND PULMONARY TBUNK

the blood from the right ventricle into the aorta,

thus short circuiting the lungs. After birth it is

closed functionally within about a week and

anatomically within about eight weeks. The

remnants of the ductus form a fibrous band called

tli.e ligamentum arteriosum (Fig. 19.7). The left

recurrent laryngeal nerve hooks around the

ligamentum arteriosum.

The ductus may remain patent after birth. The

condition is calledpatent ductus arteriosus and may

cause serious problems. The condition can be

surgically treated.

. Aortic arch aneurysz is a localised dilatation of the
aorta which may press upon the left recurrent
laryngeal nerve ieiaing to paralysis of left vocal
cord and hoarseness. It may also press upon the
surrounding structures and cause the mediastinal
syndrome (Fig. 19.8), i.e. dyspnoea, dysphagia,
dysphonia, etc.

ARCH OF THE AORTA

Arch of the aorta is the continuation of the ascending

aorta. It is situated in the superior mediastinumbehind

the lower half of the manubrium sterni.

Course

1 It begins behind the upper border of the second right

sternochondral joint (see Figs 17.2 to 17.4).

2 It runs upwards, backwards and to the left across

the left side of the bifurcation of trachea. Then it

passes downwards behind the left bronchus and on

the left side of the body of the fourth thoracic

vertebra. It thus arches over the root of the left lung.

3 It ends at the lower border of the body of the fourth

thoracic vertebra by becoming continuous with the

descending aorta.

Thus the beginning and the end of arch of aorta are

at the same level although it begins anteriorly and

ends posteriorly.

Relotions

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1 Four nerves from before backwards:

a. Left phrenic.

b. Lower cervical cardiac branch of the left vagus.

c. Superior cervical cardiac branch of left

sympathetic chain.

d. Left vagus (Fig. 19.9).

2 Left superior intercostal vein, deep to the phrenic

nerve and superficial to the vagus nerve.

3 Left pleura and lung.

4 Remains of thymus.

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