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Topic 7: Breast and Axilla Ibrahim Al-RomanyThe breast ► The breasts are modified sweat glands that lie in the superficial fascia anterior to the deep fascia of the Pectoralis major, Serratus anterior and Rectus abdominis. ► The space between the breast tissue and deep fascia is called the Retromammary space. ► Borders of the breast:Components of the breast ► The most prominent part of the breast is the nipple ► The coloured area of skin that surrounds the nipple is the areolar. It contains smooth muscle fibres and sebaceous glands to provide lubrication which assists with suckling and pumping of lactation. ► Suspensory ligament of Cooper separates lobes of the breast as well as attaching the breast firmly to the overlying skin.Ducts of the breast ► Each breast has 15-20 lobes and each lobe contains 20-40 lobules ► A single lactiferous duct drains each lobe and they open onto the nipple. ► The lactiferous ducts are dilated under the areola and form a storage for milk called the lactiferous sinus.Changes during pregnancy ► Breast overall size increases and become firmer due to hypertrophy of the mammary gland in response to Prolactin. ► Size of the nipples increases noticeably and their pigmentation may become darkerBorders of the breast and lymph drainage ► Lymphatic drainage is extremely important because of its role in the spread of cancer(Very likely to come up) ► 75% of lymph from the breast flows into the axillary node Neurovascular supply of the breast ► Arterial: ► Anterior and posterior intercostal – branches of internal thoracic ► Lateral thoracic and Thoracoacromial – branches of axillary artery ► Venous: ► Axillary vein(majority) ► Internal thoracic vein ► Innervation: ► 4 to 6 intercostal nervesThe Axilla ► The Axilla is a pyramidal space inferior to the the shoulder joint. It contains neurovascular structures that pass into or away from the upper limb. As its pyramidal, it presents an apex, base and 4 walls.Borders of the Axilla ► The Apex is formed by the constrgence of the clavicle(anterior), the scapula(posterior) and the 1 rib(medially).Borders of the Axilla ► The base of the Axilla is formed by skin and underlying fascia. ► It is bounded by axillary folds: ► Anterior axillary fold - formed by the Pectoralis Major ► Posterior axillary fold - formed by the Latissimus Dorsi and Teres Major Borders of the Axilla ► Anterior wall- Pectoralis major, Minor and Subclavius ► Posterior wall- Subscapularis, Latissimus Dorsi and Teres Major ► Medial wall- Upper 4/5 ribs, intercostal spaces and Serratus anterior ► Lateral wall- Bicipital groove of the humerusContents of the Axilla ► The axillary artery which is a continuation of the subclavian artery extends from the lateral border of the first rib to the lower border of Teres Major. It then becomes the brachial artery. ► The Axillary vein is formed by the union of the Brachial and Basilc veins. It then becomes the subclavian vein at the lateral border of the first ribAxillary lymph nodes ► Pectoral(anterior) – Lies on inferior border of Pec Minor and drains the anterior thoracic wall and breast ► Subscapular(posterior) - lies along posterior axillary fold and drains posterior thoracic wall and scapular region ► Humeral(lateral) – lies posteromedially to axillary vein on lateral wall of the Axilla and drains the upper limb ► Central – lies deep to Pec Major near the base of the Axilla and drains the previous 3 nodes ► Apical – lies at apex of axillary near the start of the axillary artery and drains subclavian trunk.mph then goes into theExtrinsic shoulder muscles ► Extrinsic shoulder muscles unlike intrinsic, are ones that don’t originate from the scapula. ► The Extrinsic shoulder muscles are split into anterior and posterior: ► Anterior - Pec Major, Pec Minor, Serratus anterior and Subclavius(4) ► Posterior - Latissimus Dorsi, Trapezius, Levator Scapulae, Rhomboid Major and Rhomboid Minor(5)Anterior Extrinsic Muscles ► Pectoralis Major: ► Origin: Clavicle(clavicular head), sternum and upper 6 costal cartilages(sternocostal head) ► Insertion: Lateral lip of bicipital groove of humerus ► Action: Flexes, adducts and medically rotates humerus. Also draw the scapula anteroinferiorly. ► Innervation: Lateral and medial Pectoral nerveAnterior Extrinsic Muscles ► Pectoralis Minor ► Origin: 3 to 5 Ribs ► Insertion: Coracoid process of scapula ► Action: Stabilises the Scapula which depresses and protracts shoulder ► Innervation: Medial Pectoral nerveAnterior Extrinisic Muscles ► Serratus Anterior: ► Origin: Ribs 1-8 ► Insertion: Medial border of scapula ► Action: Protracts and holds scapula against thoracic wall. It also rotates the scapula to allow the arm to be raised over 90 degrees. ► Innervation: Long thoracic Nerve. Damage can cause a Winged Scapula(Very common question asked!!!)Anterior Extrinsic Muscles ► Subclavius: ► Origin: 1 Rib ► Insertion: Clavicle(inferior border) ► Action: Depresses the shoulder moving it downward and forward ► Innervation: Subclavian nervePosterior Extrinsic Muscles ► Trapezius: ► Origin: Superior nuchal line, external occipital protuberance, nuchal ligament, spinous process C7-12 ► Insertion: Clavicle, Acromion and spine of scapula ► Actions: Elevates, depresses and retracts the scapula. Also rotates the glenoid cavity superiorly ► Innervation: Spinal Accessory(CN XI)Posterior Extrinsic Muscles ► Latissimus Dorsi: ► Origin: Spinous process of T7-T12, lumbosacral fascia, iliac crest and lower ribs ► Insertion: Floor of intertubercular groove of humerus ► Action: Extends, adducts and medically rotates humerus which raises body towards arm when climbing(important for exam Q) ► Innervation: Thoracodorsal nervePosterior Extrinsic Muscles ► Levator Scapulae: ► Origin: Transverse process of C1-C4 ► Insertion: Medial border of scapula ► Action: Elevates Scapula and inferiority rotates glenoid cavity ► Innervation: Dorsal Scapula nerve and Dorsal rami of spinal nerves C3 and C4Posterior Extrinsic Muscles ► Rhomboid Major: ► Origin: Spinous Process T2-T5 ► Insertion: Medial border of scapula ► Action: Retracts scapula and inferiority rotates glenoid cavity. Also fixes scapula to thoracic wall(like serratus) ► Innervation: Dorsal Scapula nervePosterior Extrinsic Muscles ► Rhomboid Minor: ► Origin: Spinous process of C7 and T1 ► Insertion: Medial border of Scapula ► Action: Retracts scapula and inferiority rotates glenoid cavity. Also fixes scapula to thoracic wall(like serratus) ► Innervation: Dorsal Scapula nerve