UPPER LIMBCuloneous Nerves of the Pectorol Region
The cutaneous nerves of the pectoral (Latin pectus,
chest) regron are as follows (Figs 3.3 and 3.4).
1 The medial, intermediate and lateral supraclauicular
nerl)es are branches of the cervical plexus (C3, C4).
They supply the skin over the upper half of the
deltoid and from the clavicle down to the second rib.(^2) The anterior and lateral cutaneous branches of the
second to sixth intercostal nerves supply the skin
below the level of the second rib. The inter-
Supraclavicular
nerves (C3, C4)
costobrachial nerve of T2 supplies the skin of the
floor of the axilla and the upper half of the medial
side of the arm (Fig.3.3).
It is of interest to note that the area supplied by spinal
nerves C3 and C4 directly meets the area supplied by
spinal nerves T2 and T3. This is because of the fact that
the intervening nerves (C5, C6, C7, C8 and T1) have
been'pulled away'to supply the upper limb. It may
also be noted that normally the areas suPPlied by
adjoining spinal neroes overlap, but because of what has
been said above there is hardly any overlap between
the areas supplied by C3 and C4 above andT2 and T3
below (Fig.3.a).
Cutoneous Vessels
The cutaneous vessels are very small. The anterior
cutaneous nerves are accompanied by the perforating
branches of the internal thoracic artery. The second, third
and fourth of these branches are large in females for
supplying the breast. The lateral cutaneous nerves are
accompanied by the lateral cutaneous branches of the
posterior intercostal arteries.
Plotysmo
The platysma (Greek broad) is a thin, broad sheet of
subcutaneous muscle. The fibres of the muscle arise
from the deep fascia covering the pectoralis major; run
upwards and medially, crossing the clavicle and the
side of the neck; and are inserted into the base of the
mandible, and into skin over the posterior and lower
part of the face. The platysma is suppliedby a branch
of t}re facial nerae.Whenthe angle of the mouth is pulled
down, the muscle contracts and wrinkles the skin of
the neck. The platysma may protect the external jugular
vein (which underlies the muscle) from external
pressure.
lntercosto-
brachial
nerve
Lateral
cutaneous
nerves
(T3-r6)
\
-\
Sternal
angle
Anterior
cutaneous
nefves
(r2-T6)
Xlphoid
process
ll
.E
o
CL
CL
f
c
.o
oo
a
Fig. 3.4:
region
Fig. 3.3: Cutaneous nerves of the pectoral region
Sternal angle
Ventral rami of
thoracic 2-6 nerves
Ventral rami of
thoracic 3-6 nerves
Thebreast, or manunary gland (Latin breast) is the most
important structure present in the pectoral region. Its
anatomy is of great practical importance and has to be
studied in detail.
The breast is found in both sexes, but is rudimentary
in the male. It is well developed in the female after
puberty. The sweat gland. It forms
in important the female reProduc-
tive system, a on to the newborn in
the form of milk.
Siluotion
The breast lies in the superficial fascia of the pectoral
region. It is divided into four quadrants, i.e. upPer
medial, upper lateral, lower medial and lower lateral.
Areas supplied by cutaneous nerves of the pectoral