Base: from ribs 2-6; from sternal edge to near midaxillary lines;
Overlies: pec major, serratus anterior, small part of rectus and external oblique.
A modified sweat gland, breast is confined between superficial and deep layers of superficial fascia.
Axillary tail extends to axilla, lying in subcutaneous fat
- rarely may penetrate deep fascia of axillary floor to lie adjacent to axillary lymph nodes
The retromammary bursa = space between post. aspect of breast, between deep layer of superficial fascia and pectoralis fascia; contains lymphatic channels.
Suspensory ligs of Cooper - fibrous septae from superficial to deep layer of superficial fascia; cause the protuberance of the young breast (atrophy with age), contraction in carcinoma & peau d’orange.
Male breast has no lobules or alveoli, small nipple over 4th ICS.
Mainly lateral thoracic – branches curl round or perforate pec major.
- also Branches of internal thoracic (largest via 2nd & 3rd spaces)
- small perforators penetrate from posterior intercostals.
- and also pectoral branches of the thoracoacromial branch of axillary artery ® upper part.
Veins: intercostal veins 2-6 (& on to vertebral veins ® metastatic spread), deep veins parallel with lat thoracic & thoracoacromial arteries; internal thoracic vein.
Anastomoses exist with abdominal wall (and hence ® posterior mediastinal nodes through diaphragm)
75% drains to axilla (mainly anterior axillary nodes, but some directly ® central or apical).
- few channels pass deep with intercostal perforators ® intercostal nodes.
- some drainage to supraclavicular nodes possible
- medial part can ® parasternal nodes.
Alternative pathways usually only occur when normal breast ducts blocked.
Cutaneous via T4-T6; sympathetics to vessels & glands with these. Lactation is hormonal.
~20 lactiferous ducts each drain a lobe, converge on the nipple surrounded by areola
- each lactiferous duct has a dilated sinus at its terminus; smooth muscle cells in nipple ® erect
- each duct connected at other end to tree of ducts and lobules, formed into lobes by c.t.
Sebaceous / areolar glands form small elevations (tubercles of Montgomery) ® enlarge in pregnancy.
The resting breast is mostly fibro/fatty tissue/ Size variations are due to fat content.
- during pregnancy alveoli bud off and organ hypertrophies
Modified sweat gland, begins as early as 4th week:
- mammary ridge develops (ectoderm) from axilla to inguinal region.
- ® supernumerary nipples or even glands proper.
Lobules form after puberty in the female.