breast and pectoral region

Plane type synovial joint

Connects clavicle and scapula

Saddle type joint and connects the scapula to the thorax via clavicle

Functions as ball and socket to accommodate movements of the scapula

Deltoid fascia – descends from clavicle, acromion, and scapular spine, continuous with the pectoral fascia anteriorly infraspinous fascia posteriorly

Pectoral fascia – descends from clavicle and sternum, inveting pectoralis major, become the axillary fascia laterally

Axillary fascia – continuation of pectoral fascia, forms the flood of the axilla

Clavipectoral fascia – descends from clavicle, encloses the subclavius and pectoralis minor, continuous with axillary fascia

A: both heads adduct and medially rotate humerus, clavicular head flexes humerus, sternocostal head extends humerus from flexed position

IV: lateral pectoral nerve and medial pectoral nerve

IN: lateral lip of intertubercular sulcus

O: clavicular head: anterior surface of medial clavicle

Sternocostal head: anterior surface of sternum and superior 6 costal cartilages

A: stabilizes scapula by drawing it inferiorly and anteriorly against the thoracic wall

IV: medial petoral nerve

IN: coracoid process

Origin: ribs 3-5 near their costal cartilages

A: anchor and depresses clavicle

IV: nerve to subclavius

IN: inferior middle clavicle

O: junction of the 1st rib and costal cartilage

A: protects scapula, holds scapula against the thoracic wall, superior rotation of the scapula

IV: long thoracic nerve

IN: anterior surface of medial border of scapula

O: lateral parts of ribs 1-8

C; direct fall onto shoulder, indirect due to transmission of force from arm and forearm to shoulder during fall

S: medial fragment is elevated due to sternomastoid, lateral fragment is depressed due to weight of the arm

*injured subclavian vein causing internal bleeding

• Sleeve like extension of the cervical fascia
• (fascia - a band or sheath of connective tissue investing, supporting, or binding together internal organs or parts of the body)

W: axillary artery and branches, axillary vein and tributaries, brachial plexus (cords and branches)

O: axillary lymph nodes and lymphatic vessels, axillary fat

Arises from the brachiocephalic trunk (which arises from the aorta) on the RIGHT side, &

directly from the arch of the aorta on the LEFT

Becomes the axillary artery at the lateral border of the 1st rib

Subclavian artery becomes acillary artery at lateral border of 1st rib, the axillary artery can be divided into 3 parts, axillary artery becomes the brachial artery at the inferior border of teres major

**First branch:SUPERIOR THORACIC ARTERY

Located between the 1st rib & the medial border of pectoralis minor

Enclosed within the axillary sheath

1st section has 1 branch

• Lies posterior to pectoralix minor
• 2nd section as 2 branches:

Clavicular

Acromial

Deltoid

Pectoral

Lateral thoracic artery

Rom lateral border of pectoralis minor to inferior border of teres major

3 branches are: posterior circumflex humeral artery, anterior circumflex humeral artery, subscapular artery which divides into 2 branches (circumflex (bend around something else) scapular artery, thoracodorsal artery)

union of the brachial vein & basilic vein

changes the name at the lateral border of the 1st rib to subclavian vein (same as subclavian & axillary artery)

**union of the brachial veins & basilic Vein contains 3 parts (corresponds to 3 parts of axillary artery) becomes subclavian vein at the lateral border of the 1st rib (same as subclavian & axillary artery)

a superficial, subcutaneous vein of the lateral aspect of the upper limb

travels through the deltopectoral groove & pierces the clavipectoral fascia at the deltopectoral triangle draining into the axillary vein

**cephalic vein drains into axillary vein, brachial veins accompanying the brachial artery

Polymastia: accessory breast

Polythelia: accessory nipples

Amastia: no breast development

Gynecomastia: breast hypertrophy in males



breast tissue typically extends transversely from the lateral border of the sternum to the midaxillary line & vertically from the 2nd to 6th rib

Branch of axillary artery

Gives lateral mammary branches

Branch of subclavian atery

Gives medial mammary branches from anterior intercostal arteries

Generally branches from thoracic aorta

Gives lateral mammary branches from lateral cutaneous branches

Transmitted from the anterior & lateral cutaneous branches of the 4th-6th intercostal nerves

They pierce the pectoral fascia to reach subcutaneous tissue & skin

Somatic sensory fibers to skin, sympathetic to blood vessels & smooth muscles of skin & nipples

Nipple sits at T4 dermatome (see Brachial Plexus lecture for more on dermatomes

Lymph passes from nipple, areola, & lobules to the Subareolar lymphatic plexus. Axillary lymph nodes receive >75% of lymph from the breast, largely from the lateral quadrants (superior lateral & inferior lateral) most common sites for mestasis from breast cancer From the medial quadrants, lymph passes mostly to the parasternal lymph nodes; lymph can travel via the parasternal lymph nodes to

the contralateral breast. Subdiaphgragmatic lymph nodes receives lymph typically from the inferior quadrant.3 sets of lymph nodes form the base (humeral, subscapular, & pectoral) which drain into central lymph nodes, draining into apical lymph nodes of the lymph traveling to the axillary lymph nodes from the breast, most travels FIRST to the pectoral lymph nodes

Excess fluid in subcutaneous tissue, deviation of nipple leather like appearance of skin, orange peel look to skin, puffy prominent skin between dimples (dimple due to shortening of suspensory ligaments

Large dimple

Dimples caused by shortening or traction placed on suspensory ligaments

Breasts elevates when muscle contract (places hand on hips)

Sign of advanced breast cancer

Invasion of pectoral fascia characteristic of rock hard fixed nodule

Retraction and deviation of nipple caused by shortening of lactiferous ducts

Lumpectomy (radiation therapy)

Mastectomy (remove breast, simple, modified radical)

Less dense, increased breast density, decreased density