Breast
The breast is an apocrine gland seen in both males and females. However, in females it has a specific function which is the production of milk for neonatal nutrition and immune function.
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Gross anatomy
Composition
The breast has an inhomogeneous structure which is predominantly composed of adipose tissue and glandular tissue. In addition, there are also suspensory Cooper's ligaments and connective tissue such as collagen and elastin. The adult breast has nearly 14-18 lactiferous lobes which drain into lactiferous ducts which further converge to drain at the nipple-areola complex.
The glandular parenchyma is estrogen dependent, thus on attaining menopause the glandular parenchyma atrophies.
Location
The breasts are seen to overlie on the pectoralis major muscles and extend from the level of the second-to-sixth ribs:
- superior: clavicle
- inferior: middle of sternum
- lateral: midaxillary line
- medial: sternum
There is often an extension of breast tissue into the axilla called the axillary tail.
Arterial supply
- internal thoracic artery perforators (second-to-fifth perforators)
- thoracoacromial artery
- vessels to serratus anterior
- lateral thoracic artery
- terminal branches of third-to-eighth intercostal perforators
Venous drainage
Nerve supply
- thoracic intercostal nerve T3-T5
- supraclavicular nerve from the cervical plexus
Lymphatic drainage
The drainage of lymph from the breast has significant impact on spread of malignancy and as such has a separate article: lymphatic drainage of the breast.
Development
During embryological development, breast tissue first appears as ectoderm ridges during the 6th week of gestation. This ridge grows thicker and leads to mesodermal compression. With further proliferation of the ectodermal cells there is a growth of the same into the mesodermal layer leading to a formation of clusters which further form lobules. In the fifth month of gestation some cords of ectodermal cells sprout from each of these lobules with the central parts undergoing apoptosis leading to formation of ducts. Similarly on the surface apoptosis occurs leading to formation of pits which protrude through the nipples after connecting with the formed ducts.
Variant anatomy
- breast hypoplasia
- amastia
- amazia
- polythelia (supranumerary nipple)
- polymastia (accessory breast tissue)
Radiographic appearance
Mammography
- a wide variation of homogeneously dense, milky structures (representing glandular tissue) interrupted by areas of curved or round radiolucent fat
- Cooper's ligaments appears as curved, linear radiopacities
- duct system is not normally visualized except near the nipple 2
See articles: mammography views; breast density.
Ultrasound
- glandular tissue appears variably hyperechoic and fat appears hypoechoic
- ducts appear as regular interspersed tubular, hypoechoic structures
- Cooper's ligaments appear as hyperechoic, linear structures and may cause acoustic shadowing 2-3
- nipple can also cause acoustic shadowing, sometimes creating a pseudomass 3
See article: breast ultrasound.
MRI
- T1: fat has moderate high signal; glandular, ductal and connective tissue has low signal
- T1C+: normal breast tissue is typically non-enhancing 2
See article: breast MRI.
Related pathology
Related Radiopaedia articles
Anatomy: Thoracic
- thoracic skeleton
- thoracic cage
- thoracic spine
- articulations
- muscles of the thorax
- diaphragm
- intercostal space
- intercostal muscles
- variant anatomy
- spaces of the thorax
- thoracic viscera
- tracheobronchial tree
-
lungs
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
- left lung
- right lung
- variant anatomy
- lung parenchyma
- hilum
- pleura
-
bronchopulmonary segmental anatomy (Boyden Classification) (mnemonic)
-
heart
- cardiac chambers
- heart valves
- pectinate muscles
- cardiac fibrous skeleton
-
coronary arteries
- coronary arterial dominance
- myocardial segments
-
left main coronary artery (LMCA)
- ramus intermedius artery (RI)
-
circumflex artery (LCx)
- obtuse marginal branches (OM1, OM2, etc))
- Kugel's artery
-
left anterior descending artery (LAD)
- diagonal branches (D1, D2, etc)
- septal perforators (S1, S2, etc)
-
right coronary artery (RCA)
- conus artery
- sinoatrial nodal artery
- acute marginal branches (AM1, AM2, etc)
- inferior interventricular artery (PDA)
- posterior left ventricular artery (PLV)
- congenital anomalies
- innervation of the heart
- fetal circulation
- atrial septum
- endocardium
- myocardium
-
pericardium
- epicardium
- epicardial fat pad
- pericardial space
- oblique pericardial sinus
- transverse pericardial sinus
-
pericardial recesses
- aortic recesses
- pulmonic recesses
- postcaval recess
- pulmonary venous recesses
- pericardial ligaments
- esophagus
- thymus
- breast
- blood supply of the thorax
- arteries
- veins
- superior vena cava (SVC)
- inferior vena cava (IVC)
-
coronary veins
- cardiac veins which drain into the coronary sinus
- great cardiac vein
- middle cardiac vein
- small cardiac vein
- posterior vein of the left ventricle
- vein of Marshall (oblique vein of the left atrium)
- anterior cardiac veins
- venae cordis minimae (smallest cardiac veins or thebesian veins)
- cardiac veins which drain into the coronary sinus
- pulmonary veins
- thoracoepigastric vein
- lymphatics
- innervation of the thorax