Thorax Breasts

Breasts

Breast Modified sweat glands Glandular tissue embedded within superficial fascia of anterior chest wall Modified sweat glands Overlying pectoral muscles Rudimentary in males and pre-pubertal females Size and shape of adult female breast varies Determined by amount of fat surrounding glandular tissue

Extent- Base Extending from lateral border of sternum to midaxillary line and from 2nd to 6th ribs. Majority of breast overlies deep pectoral fascia of pec major muscle, with remainder overlying fascia of serratus anterior Retromammary space A potential space filled with loose connective tissue Breast is separated from pectoralis major muscle Axillary tail (of Spence) A small part of mammary gland extend toward axilla

Axillary tail (of Spence)

Structure of Breast Areola Surrounds the nipple Circular pigmented area of skin Breast composed of 15 to 20 lobules of glandular tissue Formed by septa of suspensory ligaments Each lobule is drained by a lactiferous duct Each lactiferous duct opens on nipple Firmly attached to overlying skin by Suspensory ligaments (of Cooper)

Nipple location 4th intercostal space

Cooper’s Suspensory Ligaments

Vasculature of Breast Arterial supply Anterior intercostal A. (from internal thoracic artery) Lateral thoracic A. (from axillary artery) Posterior intercostal A. Branch of thoracic aorta 2nd, 3rd, & 4th P.I.C.

Arterial Supply to the Breast

Lateral thoracic drain into Axillary vein (main) Venous drainage- Lateral thoracic drain into Axillary vein (main) Anterior intercostal drain into Internal thoracic vein Posterior intercostal drain into Azygous vein

Veins of mammary gland

NERVE Supply of breast From T4-T6 nerves [somatic nerves] (anterior and lateral branches) sensory fibers to skin Sympathetic to : Smooth muscle: in dermis of areola and nipple Blood vessels

Lymphatic Drainage of Breast Lymph from nipple, areola, and lobules of mammary glands- subareolar lymphatic plexus From there, a system of interconnecting lymphatic channels drains lymph to various lymph nodes Majority (75%) of lymph, especially from lateral quadrants→ pectoral nodes→ axillary nodes Remaining lymph, especially from medial quadrants→ parasternal lymph nodes along internal thoracic vessels

Breast Quadrants

Lymphatic drainage of breast

Some lymph from lower quadrants→ inferior phrenic nodes Lymph from medial quadrants can cross to opposite breast via parasternal nodes Secondary metastases of breast carcinoma can spread to opposite breast in this way

Major Routes of Metastasis Channels to Contralateral Breast Axillary Lymph Channels 6. Lymph Vessels of Mammary Glands (41) Subdiaphragmatic Lymph Channels

Examination of Breast Clinically breast is divided into quadrants: UI: upper inner UO: upper outer (includes axillary tail) LI: lower inner LO: lower outer Breast palpation- Circular fashion, beginning with nipple and moving outward Palpation should extend into axilla to palpate axillary tails After palpation of one breast, other should be palpated in same way Examine skin of breast for a change in texture or dimpling (peau d'orange sign) and nipple for retraction→ these signs indicate an underlying pathology

Breast self exam

Mammography Mammography is a radiographic examination of the breast This technique is extensively used for screening the breasts for benign and malignant tumors and cysts. Extremely low doses of x-rays are used so that the dangers are minimal and the examination can be repeated often. Its success is based on the fact that a lesion measuring only a few millimeters in diameter can be detected long before it is felt by clinical examination.

Carcinoma of the Breast Approximately 60% of carcinomas of the breast occur in the upper lateral quadrant. The cancer cells are swept along the lymph vessels and follow the lymph stream. The entrance of cancer cells into the blood vessels accounts for the metastases in distant bones. The lymphatic spread of cancer to the opposite breast, to the abdominal cavity, or into lymph nodes in the root of the neck is caused by obstruction of the normal lymphatic pathways by malignant cells or destruction of lymph vessels by surgery or radiotherapy.

Peau d’orange sign Leathery thickening of the skin Often dimpled and has prominent pores That gives the skin the appearance of orange peel The dimples and the pores results from shortening of the suspensory ligament Because of cancerous invasion

Peau d’orange sign:

Carcinoma of the Breast

Mastectomy A simple mastectomy in which the pectoral muscles are left intact. The axillary lymph nodes, fat, and fascia are removed. Radical mastectomy is designed to remove the primary tumor and the lymph vessels and nodes that drain the area.

Mastectomy

Radical mastectomy