Lecture Two Pectoral Region

Landmarks Sternum –Manubrium –Sternal angle (T4 vertebra) –Body –Xiphoid process

Landmarks Clavicle –Acromial end and sternal end

Landmarks Ribs –Shaft –Head – posterior end; articulates with vertebrae –Tubercle – articulates with vertebrae –Costal cartilage – hyaline cartilage

Breast nipple: fourth intercostal space about 10 cm lateral to the sternum areola: rounded, pigmented elevation of skin (pink in nulliparous women - no child bearing women, turn brown permanently in whites) Breast doesn't have a distinct connective tissue capsule (because it is a modified sweat gland). Embedded in the general subcutaneous fatty tissue. Separated from deep muscle by retromammary space.

Breast Breast is partitioned radically around the nipple into lobes by dense, fibrous connective tissue septa. Each has a single lactiferous duct, lactiferous sinus (dilation of duct) near nipple.

Infections

Arterial supply of breast Breast has abundant blood supplies. Arteries are mainly from internal thoracic artery (branch from subclavian artery) via its perforating branches, which pierce the second to fourth intercostal spaces. The breast also receives blood from branches of axillary artery (lateral thoracic and thoracoacromial branches) and lateral and anterior cutaneous branches from the intercostal arteries.

Veins Venous drainage of the breast Veins from the breast drain into the axillary, internal thoracic, lateral thoracic, and intercostal veins

Lymphatic drainage Most (75%) of the lymphatic drainage is to the axillary lymph nodes, mainly the pectoral group), From deep surface of the breast, the lymphatics pass through the pectoralis major and drain into the apical group of axillary lymph nodes. Lymph from the medial part of the breast drains into parasternal lymph nodes. Lymph from the skin may pass to the abdominal wall and the opposite breast.

Breast cancer Risk factors (according to American Cancer Society) –Uncontrollable Age Gender Family history Breast cancer genes? Previous abnormal breast biopsy Previous breast radiation Early menstruation, late menopause

Risk factors Life style related factors –No children –Pills –Hormone replacement therapy –Not breast feeding (long period) –Alcohol –Obesity, high fat diet (especially after menopause) –Physical inactivity

Myth factors Antiperspirant Underwire bras Induced abortion Breast implants Environmental pollutants Smoking Night work antibiotics

Signs Early symptoms of breast cancer –A lump –A swell, unusual appearance –Veins more prominent on one breast. –nipple inverted, rash, changes texture, or has a discharge. –A depression on the breast surface (dimpling)

Treatment options Surgery Radiation Chemotherapy Combination of above

Mastectomy w Reconstruction This 42 yr old had a small breast cancer dx at the age of 29 - She had a reoccurence 5 years ago and had a right mastectomy with reconstruction and augmentation on the left

Prophylactic This 46 year old had a small lump biopsied in '00. She has a strong family history though BRCA negative and elected to have prophylactic mastectomies. It took her over a year to feel comfortable with implants but now she does and will talk and show them to new patients. 12/03

PECTORALIS MAJOR ORIGIN Upper fibers (clavicular portion): anterior surface of sternal one half of clavicle Lower fibers (sterocostal portion): anterior surface of sternum, cartilage of first six or seven ribs, and aponeurosis of the external oblique. INSERTION Insertion (both upper and lower fibers) crest of greater tubercle of humerus. Upper fibers are more anterior and caudal than the lower fibers which twists and more posterior and cranial

PECTORALIS MAJOR ACTION –Action of whole muscle: With origin fixed, it adducts and medially rotates the humerus. With insertion fixed, it assists in elevating thorax. In crutch walking or in parallel bar, it supports the body.: Action of upper fibers: Flex and medially rotate the shoulder joint, and horizontally adduct the humerous toward the opposite shoulder –Action of lower fibers: Depress the shoulder girdle by virtue of attachment on the humerus NERVE –Upper : Lateral Pectoral, C5, 6, 7 –Lower: Lateral and medial pectoral, C6, 7, 8, T1

PECTORALIS MINOR ORIGIN Superior margins, outer surfaces of third, fourth, and fifth ribs near cartilage, and from fascia over corresponding intercostal muscles INSERTION Medial, superior surface of coracoid process of scapula ACTION With origin fixed, tilts the scapula anteriorly, i.e. rotates the scapula about a coronal axis so that the coracoid process moves anteriorly and caudally, while the inferior angle moves posteriorly and medially With the scapula stabilized to fix the insertion, pectoralis minor assists in forced inspiration NERVE medial pectoral nerve with fiber from a communicating branch of the lateral pectoral, C(6), 7, 8, T1