PECTORAL

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					PECTORAL REGION
**The superficial fascia:
*Contains: 1. Cutaneous
nerves and vessels.
2. The breast (the
mammary gland).
Cutaneous nerves:
a. Supraclavicular nerves:
* They are branches from the cervical plexus
(C3,4) .
* They are arranged as anterior (medial),
intermediate and posterior (lateral) nerves.
* They supply the skin over the upper half of the
deltoid muscle and the front of the thoracic
wall down to the level of the 2nd costal
cartilage (sternal angle).
 b. Anterior cutaneous nerves:
* They are the terminal branches of the
intercostal nerves (ventral rami of T2-T6).
* They pierce the pectoralis major muscle &
the deep fascia close to the sternum and
divide into
short medial & long lateral branches to
supply the skin from the midsternal line to
the midclavicular line.
 c. Lateral cutaneous nerves:
* They are branches of the intercostal
nerves (T3-T6).
* They pierce the intercostal muscles and
divide into anterior and posterior
branches which
appear between the digitations of serratus
anterior muscle.
* They supply the skin on the side of the
thoracic wall.
 *N.B.: The lateral cutaneous •
branch of the 2nd intercostal
nerve is called the
intercostobrachial nerve. It
supplies the skin of the floor of
the axilla and the medial side of
the upper arm.
*Cutaneous arteries: Include: •
1. Perforating branches of the •
internal thoracic artery.
2. Lateral branches of the •
posterior intercostal arteries.
3. Superior thoracic, •
thoracoacromial & lateral
thoracic arteries (from axillary
artery).
**The deep fascia (Pectoral fascia)
* This is a thin membrane that invests the
pectoralis major muscle.
*Attachments:
*Superiorly: to the clavicle.
*Inferiorly: continuous laterally with the axillary
fascia and medially with the fibrous sheath of
the rectus abdominis.
 *Medially: to the front of the sternum.
*Laterally: continuous with fascia that covers the
deltoid muscle (shoulder).
**The Clavipectoral fascia:
*Definition: A strong sheet of
fibrous tissue, that lies deep to
the clavicular head of pectoralis
major muscle, filling the gap
between the subclavius and
pectoralis minor muscles and
covering the axillary vessels and
nerves.
*Attachments: * Superiorly:
It splits to enclose the subclavius muscle and is attached
to the lips of the subclavius groove.
* Inferiorly:
It splits to ensheath the pectoralis minor muscle. The two
layers fuse at the lower border of pectoralis minor and
continue as the suspensory ligament of the axilla
which fuses with the axillary fascia. *
 Medially:
 It blends with fascia over the first two intercostal spaces
and is attached to the 1st rib medial to subclavius. *
Laterally:
it is thick and dense and is attached to the coracoid
process.
*N.B.: Between the 1st rib
and coracoid process the
fascia often thickens to
form a band known as the
costocoracoid ligament or
membrane.
Functions of the
clavipectoral
fascia:
1. It protects the
contents of the
axilla. 2. The
suspensory
ligament raises the
skin of the floor of
the axilla when
the clavicle is
elevated and thus
it maintains
the hollow of the
axilla.
**Structures piercing the
clavipectoral fascia:
1. Thoracoacromial artery and
vein.
2. Cephalic vein to terminate into
the axillary vein.
3. Lateral pectoral nerve.
4. Lymph vessels.
Functions of the
clavipectoral
fascia:
1. It protects the
contents of the
axilla. 2. The
suspensory
ligament raises the
skin of the floor of
the axilla when
the clavicle is
elevated and thus
it maintains
the hollow of the
axilla.
Pectoralis Major
A. Clavicular Head:
From anterior surface of medial ½ of the
clavicle.
B. Sternocostal Head:
From:
a. corresponding ½ of anterior surface of
sternum.
b. 2nd to 6th costal cartilages.
c. Aponeurosis of ext. oblique muscle of anterior
    abdominal wall.
Insertion
By flat bilaminar tendon into the lateral lip of
bicipital groove.
* Anterior lamina is formed of clavicular & upper
sternal fibers.
Posterior lamina is from of lower costal and •
abdominal fibers.* Both laminae are
continuous inferiorly.
 Nerve supply •
      Medial Pectoral nerve
      Lateral Pectoral nerve
Action
1. The whole muscle adducts &medially rotates
the shoulder joint. It also brings the extended
arm to the resting position.
2. The clavicular head flexes
the shoulder joint.
3. The Sternocostal head
brings the flexed arm to the resting position
4. When insertion is fixed, the muscle draws the
trunk upwards towards the upper limb, as in
     climbing.
1. Superficial to it:
Breast & pectoral fascia.
2. It shares in the
formation of the anterior
wall of the axilla.
3. Its upper border is separated from deltoid
muscle by the deltopectoral groove.
This groove contains:
a. cephalic vein.
b. deltoid branch of Thoracoacromial artery.
 c. deltopectoral L.Ns.
      2. Pectoralis Minor
O/3rd, 4th & 5th ribs (just lateral to costal cartilages).
I/Upper surface and medial border of coracoid process.
A/Protraction & depression of the scapula (or shoulder
  girdle).
 N.B.: Both pectoralis minor and pectoralis major muscles
  assist in deep forced inspiration.
      R/ 1.It divides the axillary artery into 3 parts.
2. Its upper border is related to clavipectoral fascia
                        & Thoracoacromial artery.
     3. Its lower border is related to lateral thoracic
                                             vessels.
3. Subclavius
ORIGIN :Junction of 1st rib and its costal cartilage
(1st costochondral junction).

INSERTION:Groove of subclavius in the inferior surface
 of the middle third of the clavicle.

Nerve to subclavius.

ACTION:It steadies the clavicle during movements of
  shoulder girdle.

				
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