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Table of Contents:-

Notes on PECTORAL REGION AND MAMMARY GLAND(BREAST)

pectoral region
Fig.1:-   Muscles of Pectoral region
Muscles of the pectoral region.

 

1. Pectoralis major muscle
2. Pectoralis minor muscle
3. Subclavius muscle

Pectoralis major:-
Pectoralis major
               Fig.2:- Dissection of Pectoralis Major

Origin:-
(1).Clavicular head;from the front of the medial third of the clavicle.     (2).Sternocostal head; from the anterior aspect of the sternum and the upper six costal cartilages.

Insertion:- Lateral lip of bicipital groove of the humerus

Action:- 1.Adduction and medical rotation of the arm.  (2).Flexation of the arms (Clavicular portion)

Nerve supply:-1.Lateral pectoral nerve C5,C6,C7    (2).Medial pectoral nerve C8,T1

Pectoralis minor:-
Pectoralis minor
      Fig.3:- Dissection of Pectoralis Minor

Origin:- 3rd,4th,and 5th ribs near cartilage.

Insertion:- medial aspect of coracoid process of the scapula.

Action:- depresses point of shoulder ;if scapula is fixed it elevates the ribs of origin.

Nerve supply:- medial pectoral nerve C8,T1

Subclavius muscle:-


Origin:- first costal cartilage

Insertion:- lower surface of clavicle( subclavius groove)

Action:- depresses the clavicle and steadies this bone during movements of the shoulder girdle.

Nerve supply:- Nerve to the subclavius, from the root of branchial plexus C5,C6.

Click here to Read more:-  Notes on Axilla and Brachial plexus
Serratus anterior muscle:-

Origin:- from the outer surface of upper 8 ribs.

Insertion:- costal aspect of medial border and inferior angle of scapula.

Action:- draws the scapula forward around the thoracic wall (protrusion); rotate scapula

Nerve supply:- long thoracic nerve,C5,C6,C7.

Clavipectoral fascia:-

The clavipectoral fascia is a strong sheet of connective tissue that is attached to the clavicle.
Below, it splits to enclose the pectoralis minor muscle and then continuous downward as the suspensory ligament of the axilla and joints the facial floor of the armpit.

Applied aspect:-

1.Serratus anterior is called the Boxer’s muscle since it is responsible for pushing and punching movements.

2. Paralysis of this muscle results in a “winged scapula” , results in protrusion of the scapula on the affected side when the patient is asked to push against the wall with both arm extended.

3. Winged scapula occur in lateral thoracic nerve paralysis.



THE MAMMARY GLAND OR THE BREAST

extent of breast
                           Fig.4:- Extent of Breast
The mammary gland or The breast:-

– modified sweat gland

– lies in superficial fascia of pectoral region. But extension known as axillary tail or Spence pierces the axillary fascia through a small Foramen and called the foramen and of Langer and lies in the axilla.

Extent:-

Vertically:- from 2nd to 6th rib in midclavicular line.
Horizontally:- from lateral border of sternum to mid axillary line along the fourth rib.

Deep relations:-

The base of the mammary gland called memory bed rest upon the following structures.

a. Retromemmary space

b. Deep fascia or pectoral fascia

c. Muscles- pectoralis major, Serratus anterior, External oblique.

Retromammary space:-  a space deep to the base of the gland, lies superficial to Deep fascia, contain loose areolar tissue, makes the gland freely movable.

Presenting parts:-

Nipple:- lies in 4th intercostal space, has high nervous innervation and opening of 15 – 20 lactiferous duct.
Areola:- pigment red area at the base of nipple ,contains modified sebaceous glands which become enlarged during pregnancy and lactation forming Tubercles of Montgomery.

Components:-

Fibrous tissue
Glandular tissue
Areolar tissue

Fibrous tissue:- from suspensory ligaments of Cooper which anchor gland to overlying skin and underlying Deep fascia.

-Divided the gland into 15- 20 lobs.

-They may become contracted from fibrosis around a carcinoma and produce a characteristic pitting of the skin of the breast( Peu d orange)

Glandular tissue:-

-Consists of 15 – 20 lobs

-Arranged in a radiating manner around the areola.

-In lobes are alveoli with secret milk

-Alveoli lined by myoepithelial cells under Oxytocin control

-Each lobe has one lectiferous duct.

-The lectiferous duct dilates near its opening in the nipple to form lactiferous sinus which acts as reservoir of milk.

Axillary lymph node:-

– Anterior or factorial group receive lymph from upper half of anterior wall trunk and from major part of breast.

– Posterior or scapular group receive lymph from posterior wall of upper half of trunk and from axillary tail of breast.

– Lateral group receive lymph from upper limb.

– Central group receive lymph from preceding groups and drain into apical group.

– Apical or infraclavicular( subclavian) group lie deep to clavipectoral fascia. They receive Lymph from the central group, from upper part of the breast and from the thumb.

Lymph nodes draining the breast:-
lymph node of breast
              Fig.5:- Lymph nodes draining in to breast

 

 

 

Lymphatic drainage of breast:-
route of lymph from the breast
            Fig.6:- Routes of lymph from the breast.

-Superficial portion of the breast drain into the subareolar plexus of sappey.

-Deep portion of the breast drain to submammary plexus.

-All the lymphatic of the breast converge into the sappey plexus.

-The lateral quadrant drain into the anterior axillary or pectoral group of lymph node(75%).

-The medial quadrant drain by internal thoracic group of nodes(20%).

-A few lymph vessels follow posterior intercostal arteries and drain into posterior intercostal nodes.(5%).

-Some Vesseles communicate with lymph vessels of opposite breast and with lymph vessels of anterior abdominal wall.( subdiaphragmatic and subperitoneal lymph plexus)

Arterial supply of breast:-

-Perforating branches of the internal thoracic artery

-Lateral mammary branches from the lateral thoracic artery.

-Twings from the intercostal arteries.
Pectoral branch of the Thoracoacromial artery.

Venous supply of breast:-

-Venous drainage of the breast is mainly accomplished by the axillary vein.

-The subclavian, intercostal and internal thoracic veins also aid in returning blood to the heart.

Nerve supply:-  4th through 6th intercoastal nerve.

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Applied aspects of breast:-

1. Mammography is a radiographic examination of the breast. This technique is used for screening the breast for benign and malignant tumors of the breast.

2. Breast cancer in upper lateral quadrant(60%) and forms a palpable mass in later stages.
– it enlarges, attaches to Cooper’s ligaments and produces shortening of ligaments, causing depression or dimpling of overlying skin.

– it may attach to and shorten lactiferous duct and cause retraction of nipple.

– obstruction of superficial lymph vessels by cancer cells may produce edema of skin giving rise to an orange skin appearance called Peaud’orange appearance.

– the cancer can spread through veins to the vertebrae and brain because the veins draining the breast communicate with the vertebral venous plexus.

– localised cancer is treated by simple mastectomy.

– localised cancer of breast with early matter stasis of axillary lymph nodes, radial mastectomy is done to remove the primary tumor and the lymph vessels and nodes that drain the area. These are removed a large of skin overlying the tumor and including the nipple, all the breast tissue.

In a breast abscess an acute infection of the mammary gland occur in which pathogenic bacteria gain entrance to the breast tissue through a crack in the nipple.
The abscess is localised do a log which drained through a radial incision to avoid damage radially arranged ducts.

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