PECTORAL REGION
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It is the region presents in the front of the upper part of the
chest.
Superfecial fascia of the pectoral region contains the
following structures:
Supraclavicular nerves arise from C3-C4 and pierce the deep
fascia of the neck, then they cross the clavicle and run
downwards to supply the skin over the upper ½ of deltoid and
the front of the chest down to the level of sternal angle. They are
named medial, middle and lateral.
Anterior cutaneous branches of intercostal nerves are very
slender and pierce the pectorais major and deep fascia close to
the sternum
Lateral cutaneous branches of intercostal nerves are larger
than the anterior branches and appear on the side of the chest a
little behind the anterior axillary fold. The lateral cutaneous
branch of the second intercostal nerve is callled the
intercostobrachial nerve which supplies the skin of the floor of
axilla and upper part of medial aspect of the arm
Cutaneous vessels are the perforating branches of the internal
thoracic artery and intercostal arteries
5. Platysma muscle: is a thin muscular sheet
that is present in the superficial fascia of the
side of the neck and the front of the chest
• Origin: from the fascia covering pectoralis
major and deltoid. The muscle ascend
upwards, forwards and medially crossing the
clavicle to the side and front of the neck
• Insertion: into the lower border of mandible
and the lower lip
• Nerve supply: crevical branch of facial nerve
• Action: wrinkles the skin of the side of the
neck, depresses the mandible and draws the
angle of the mouth downwards.
6. The mammary gland
The breast
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It lies in the pectoral region and is composed of:
Mammary gland
Superficial fascia in which the gland is embedded
The covering skin including the areola and nipple
The male breast is rudimentary, the nipple is small
and pointed and the areola is surrounded by sparse
hairs.
The female breast:
• Shape: is conical or hemispherical in shape.
• Site: the base of the breast extends from the 2nd to
the 6th costal cartilages and from the sternum to the
midaxillary line. About 2/3rds of the base lies on the
deep fascia covering the pectoralis major while the
inferolateral third lies on serratus anterior.
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The axillary tail: is an extension from the upper lateral part
of the gland that runs along the lower border of the
pectoralis major, pierces the deep fascia and end in the
axilla
Structure: the mammary gland is composed of stroma and
glandular tissue. It has no capsule. It is divided into lobes
and lobules by fibrous septa that pass from the deep fascia
overlying the pectoralis major muscle to the overlying skin.
Ductules collect to form lactiferous ducts that vary in
number according to the number of lobes. Lactiferous ducts
converge towards the nipple. Each duct is dilated forming
sinus of lactiferous duct and then is narrowed again and
passes to open on the summit of the nipple.
Arteries of the breast:
perforating branches of the internal thoracic artery
Pectoral branches of thoracoacromial artery.
Mammary branches of lateral thoracic artery
lateral branches of the posterior intercostal arteries
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Veins of the breast: axillary, internal thoracic and
posterior intercostal veins
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Lymphatic drainage:
1. The central part and the lateral quadrant of the breast drain
into the anterior axillary or pectoral group of nodes
(situated just posterior to the lower border of the pectoralis
major muscle).
2. Few lymphatics from the upper part go to the supraclavicular
lymph nodes.
3. The medial quadrant drains to the internal thoracic group
of nodes (situated within the thoracic cavity along the course
of the internal thoracic artery) of the same and opposite sides.
4. The inferolateral part of the breast drains into the posterior
intercostal nodes (situated along the course of the posterior
intercostal arteries);
5. The inferomedial part of the breast drains through
anastomosis with those of linea alba to the peritoneum and
through the anastomosis with those of the falciform ligament
and diaphragm into of the liver and umbilicus.
Deep fascia of the pectoral region
1. The pectoral fascia is a thin membrane that invests
the pectoralis major. It is attached above to the
clavicle, medially to the front of the sternum and is
continuous inferiorly with the fascia of the anterior
abdominal wall and laterally with the fascia covering
deltoid muscle. The pectoral fascia leaves the lateral
border of the pectoralis major and becomes the
axillary fascia, which forms the floor of the axilla.
2. The clavipectoral fascia occupies the gap between
the clavicle and pectoralis minor, It is attached
medially to the 1st rib, laterally to the coracoid
process, above, it splits into 2 layers (anterior and
posterior) that are attached to the clavicle and
encloses the subclavius muscle. Below it is
continuous with the fascial sheath of pectoralis minor
and is connected posteriorly with the facial sheath of
the axillary vessels then it becomes continuous
inferiorly with axillary fascia.
Clavipectoral
fascia
Clavipectoral fascia
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The part of the clavipectoral fascia between
the pectoralis minor and the subclavius, the
costocoracoid membrane, is pierced by
1. cephalic vein, 2. thoraco-acromial artery,
3. lateral pectoral nerve, 4. few lymphatics
from the breast to the apical group of axillary
lymph nodes.
The part of the clavipectoral fascia inferior to
the pectoralis minor, the suspensory
ligament of the axilla, supports the axillary
fascia and pulls it and the skin inferior to it
upward during abduction of the arm, forming
the axillary fossa.
Muscle of the pectoral region
1. pectoralis major muscle
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Origin: by two heads:
a) Clavicular head: from medial half of the front of clavicle
b) Sterno-costal head: from anterior surface of sternum,
upper six costal cartilages and the aponeurosis of
external oblique muscle of the abdomen.
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Insertion: by flat bilaminar tendon into the lateral lip of
intertubercular groove of humerus
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Nerve supply: Medial and lateral pectoral nerves
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Action:
1. The muscle as a whole is an adductor and medial rotator
of the arm
2. Clavicular head flexes of the arm
3. Sternocostal head extends the flexed arm
2. pectoralis minor muscle
• Origin: from the 3rd, 4th and 5th ribs close to their cartilages
• Insertion: into the medial border and superior surface of
coracoid process of scapula
• Nerve supply: medial pectoral nerve (C8, T1)
• Action: draws the scapula downwards and forwards and
depress the shoulder.
3. Subclavius
• Origin: form the upper surface of the1st rib at its junction
with its costal cartilage
• Insertion: into the subclavius groove on the inferior
surface of middle third of clavicle
• Nerve supply: Nerve to sub-clavius (C5, C6)
• Action: steadies the clavicle during movements of the
shoulder girdle. It acts as a soft bad that protects axillary
vessels and nerves from the clavicle.
Clavipectoral
fascia