A

• The breasts are paired structures located on the anterior thoracic wall, in the pectoral region
• Breasts are present in both males and females, more prominent in females following puberty
• In females, breasts contain mammary glands, which are involved in lactation
• Breasts extend horizontally from the lateral border of the sternum to the mid-axillary line
• Vertically, breasts span between the 2nd and 6th costal cartilages
• Breasts are composed of a circular body and an axillary tail
• The nipple is at the center of the breast, surrounded by the areolae
• Mammary glands are modified sweat glands, consisting of ducts and secretory lobules
• Connective tissue stroma surrounds the mammary glands, with fibrous and fatty components
• Suspensory ligaments of Cooper attach and secure the breast to the dermis and underlying pectoral fassia they also separate secretory lobules
• Breast arterial supply: internal thoracic artery for the medial aspect, lateral thoracic, thoracoacromial, lateral mammary, and mammary branches for the lateral aspect
• Breast lymphatic drainage: axillary nodes (75%), parasternal nodes (20%), posterior intercostal nodes (5%)
• Breast innervation: anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves
• Breast cancer is the most common cancer in the UK, with lymphatic drainage involvement
• Triple assessment for suspected breast cancer: clinical examination, mammogram, ultrasound scan, and biopsy
• Diaphragm separates thoracic and abdominal cavities, with peripheral and central attachments
• Diaphragm arterial supply: inferior phrenic arteries, superior phrenic, pericardiacophrenic, and musculophrenic arteries
• Diaphragmatic paralysis can occur due to phrenic nerve lesions, cervical spinal cord issues, or brainstem lesions
• Muscles of the thoracic cage include intercostals (external, internal, innermost), subcostals, and transversus thoracis
• Other muscles attached to the thoracic wall are pectoralis major, minor, serratus anterior, and scalene muscles
• External intercostal muscles elevate the ribs, increasing thoracic volume
• Internal intercostal muscles run inferoposteriorly and lie deep to the external intercostals
• Flat muscles lie deep to the external intercostals
• Run from the rib above to the one below, but in an opposite direction (inferoposteriorly)
• Continuous with the internal oblique muscle of the abdominal wall
• Originate from the lateral edge of the costal groove and insert into the superior surface of the rib below
• Innervated by intercostal nerves (T1-T11)
• Innermost Intercostals
• Deepest of the intercostal muscles
• Separated from the internal intercostals by the intercostal neurovascular bundle
• Found in the most lateral portion of the intercostal spaces
• Originate from the medial edge of the costal groove and insert into the superior surface of the rib below
• Transversus Thoracis
• Continuous with transversus abdominis inferiorly
• Originates from the posterior surface of the inferior sternum to the internal surface of costal cartilages 2-6
• Weakly depresses the ribs
• Innervated by intercostal nerves (T2-T6)
• Subcostals
• Found in the inferior portion of the thoracic wall
• Comprise thin slips of muscle running from the internal surface of one rib to the second and third ribs below