MRCS Part B (OSCE) - Online Resources

"The breasts lie over the 2nd to 6th ribs, and extend laterally from the lateral edge of the sternum to the mid axillary line. The tail of Spence (axillary tail) is a small extension of the breast towards the axilla. "

"

• Anterior :           The suspensory ligaments of Cooper adhere the breast to                                  the overlying dermis and provide support.
• Posterior :           Lies the retromammary space; containing loose                                              connective tissue, which separates the breast from its                                      fascial bed (for two thirds of the breast this is formed by                              the deep pectoral fascia overlying pectoralis major; for                                      the remainder of the breast it is the fascia overlying                                      serratus anterior).

"

"

• The arterial supply to the breast comes from branches of the internal thoracic and axillary arteries, as well as the thoracic aorta.
• Namely: medial mammary perforating and anterior intercostal branches (from the internal thoracic artery), lateral thoracic and thoracoacromial arteries (from the axillary artery), and posterior intercostal arteries (from the thoracic aorta).

"

"The venous drainage of the breast is primarily by the axillary vein, with some drainage via the internal thoracic vein. "

"Lymph from the nipples, areola and glandular tissue drains to the subareolar lymphatic plexus. "

"

• More than three quarters of the lymph from the subareolar plexus drains to the axillary lymph nodes.
• However, some drainage can occur to the contralateral axillary nodes, or to interpectoral, deltopectoral, supraclavicular or inferior deep cervical nodes.
• Drainage of the remaining lymph, principally from medial areas, drains to the parasternal (internal mammary) nodes or to the contralateral breast, with some lymph from inferior quadrants draining to the inferior phrenic nodes.

"

"

                                 

Origin:

• Clavicular head :        Anterior border of the medial half of the clavicle
• Sternocostal head :   Anterior surface of the sternum, the superior six                                             costal cartilages, and the aponeurosis of the external                                      oblique muscle

Insertion:

• Lateral lip of the bicipital groove of the humerus.

"

"

Pectoralis major is supplied by the medial pectoral nerve and lateral pectoral nerve.

• Clavicular head :        C5 and C6
• Sternocostal head :    C7, C8 and T1

"

"

• Clavicular head :        Flexion, adduction and medial roation of                                                        humerus
• Sternocostal head :   Downward and forward movement of the                                                        arm; Slight extension but only till anatomical position.
• Both heads acting together : Flexes, adducts and medially rotates the                                                         humerus. Also draws the scapula anteriorly                                                      and inferiorly.
   

"

"

Origin:

• 3^rd-5^th ribs (near their costal cartilages).

Insertion:

• Medial border and superior surface of the coracoid process of the scapula.

"

Pectoralis minor is innervated by the medial pectoral nerve (C8, T1)

Pectoralis minor stabilises the scapula by drawing it inferiorly and anteriorly against the thoracic wall. It also raises the ribs on inspiration.

"Poland syndrome is a congenital anomaly characterised by underdevelopment or absence of the ipsilateral pectoralis major (sternocostal portion), hypoplasia and usually also syndactyly (webbing) of the ipsilateral hand.  "