Breast, Axilla & Arm Muscles Anatomy PDF

🦴 breast, axilla & muscles of the arm and shoulder Describe the gross and microscopic anatomy of the breast and the lymphatic drainage, innervation and vasculature The breasts are paired structures located on the anterior tho...

🦴 breast, axilla & muscles of the arm and shoulder Describe the gross and microscopic anatomy of the breast and the lymphatic drainage, innervation and vasculature The breasts are paired structures located on the anterior thoracic wall in pectoral region - located in males and females, more prominent in females after puberty. In females, breasts contain mammary glands - an accessory gland of female reproductive system and key structures involved in lactation. Surface Anatomy Extends horizontally from the lateral border of sternum to the mid- axillary line. Vertically, spans between 2nd and 6th costal cartilages. Superficial to the fascia covering the pectoralis major and serratus anterior muscles. Breast has 2 regions: 1. Circular body - large and prominent part of breast breast, axilla & muscles of the arm and shoulder 1  2. Axillary tail - smaller part running along inferior laterla edge of pectoralis major towards axillary fossa. Centre of breast is the nipple (made from mainly smooth muscle fibres). Surrounding nipple is the areola (pigmented area). Areola contains numerous sebaceous glands which enlarge in pregnancy secreting an oily substance - acts as a protective lumbricant for nipple. Milk production and secretion regulated by hormones prolactin and oxytocin - secreted from the pituitary. Anatomical Structure Breast composed of mammary glands surrounded by a connective tissue stroma. Mammary Glands Mammary glands are modified sweat glands - made from series of ducts and 15-20 secretory lobules. breast, axilla & muscles of the arm and shoulder 2  Each lobule has many alveoli drained by a single lactiferous duct - these ducts converge at the nipple. Connective Tissue Stroma Supporting structure which surrounds the mammary glands - fibrous and fatty component. Fibrous stroma condenses to form suspensory ligaments of Cooper. These ligaments: 1. Attach and secure the breast to the dermis and underlying pectoral fascia. 2. Seperate the secretory lobules of the breast. Pectoral Fascia Base of breast lies on pectoral fascia (flat sheet of connective tissue associated with pectoralis major muscle). It acts as an attachment point for the suspensory ligaments of Cooper. Retromammary space - layer of loose connective tissue between breast and pectoral fascia. Potential space often used in reconstructive plastic surgery. breast, axilla & muscles of the arm and shoulder 3  Arterial Supply and Venous Drainage of the Breasts Arterial supply to medial aspect of breast via the internal thoracic artery (internal mammary artery) which is a branch of the subclavian artery. Lateral part of the breast gets blood from: 1. Lateral thoracic and thoraco acromical branches - branch from the axillary artery. 2. Lateral mammary branches - branch from the posterior intercostal arteries derived from aorta. Supply lateral aspect of breast in 2nd, 3rd and 4th intercostal spaces. breast, axilla & muscles of the arm and shoulder 4  3. Mammary branch - branches from anterior intercostal artery. Venous drainage occurs into the axillary and internal thoracic veins - correspond to the arteries. Lymphatic Drainage of the Breasts Lymphatic drainage is very important due to its role in the metastasis of breast cancer cells. 3 groups of lymph nodes which get lymph from breast tissue: 1. Axillary nodes (75%) Five groups of axillary lymphatic nodes, all groups drain into the apical nodes. 2. Parasternal nodes (20%) 3. Posterior intercostal nodes (5%) Skin of the breast get lymphatic drainage: breast, axilla & muscles of the arm and shoulder 5  1. Skin - drains to axillary, inferior deep cervical and infraclavicular nodes. 2. Nipple and areola - drains to subareolar lymphatic plexus. Innervation of the Breasts Breast innervated by the anterior and lateral cutaneous branches of the 4th to 6th intercostal nerves. Nerves contain both sensory and autonomic nerve fibres. The autonomic fibres regulate smooth muscle and blood vessel tone. Nerves do not control the production and secretion of milk. Clinical Relevance: Breast Cancer Breast cancer is the most common type of cancer to be diagnosed within the UK. After lung cancer it has the second highest death rate due to cancer. It is more common in women than men. Clinical Presentation and Causes Common presentations associated with breast cancer are due to blockages of the lymphatic drainage. Excess lymph builds up in the subcutaneous tissue, resulting in clinical features such as nipple deviation and retraction, and prominent skin between small dimpled pores (peau d’orange). Larger dimples are generally caused by cancerous invasions and fibrosis. This causes traction of the suspensory ligaments, causing them to shorten. Metastasis commonly occurs through the lymph nodes. It is most likely to be the axillary lymph nodes that are involved. They become stony hard and fixed. Following this, the cancer can spread to distant places such as the liver, lungs, bones and ovary. Diagnosis To assess a suspected breast cancer a triple assessment is carried out. This involves clinical examination, imaging using a mammogram and ultrasound scan and finally a biopsy. breast, axilla & muscles of the arm and shoulder 6  The staging of breast cancer uses the I-IV system or the Tumour Node Metastasis (TNM) system. Treatment Surgical treatment with adjuvant radiotherapy is the recommended treatment option. The operation is local and aims to remove only the affected tissue area. Failing this it is considered that a mastectomy is the best option. Adjuvant chemotherapy is also known to improve survival rates. [Mammogram]: (L) Normal breast appearance (R) Breast lesion where suspicious for malignancy. Describe the lymphatic drainage of the upper limb Lymphatic system functions to drain tissue fluid, plasma proteins and cellular debris back into bloodstream and is involved in immune defence. Lymph filtered by lymph nodes from which it returns to circulation via venous system. Superficial and Deep Lymphatic Vessels Superficial Lymphatic Vessels breast, axilla & muscles of the arm and shoulder 7  Superficial lymphatic vessels of upper limb arise from lymphatic plexuses in the skin of the hand. These vessls then travel up the arm in close proximately to major superficial veins. 1. Lymphatic vessels shadowing basilic vein go on to enter cubital lymph nodes (found medially to the vein). Vessels then continue up the arm, terminating in the lateral axillary lymph nodes. 2. Lymphatic vessels shadowing the cephalic vein cross the arm and shoulder to enter the apical axillary lymph nodes or more superficial deltopectoral lymph nodes. Deep Lymphatic Vessels Deep lymphatic vessels of upper limb follow the major deep veins (e.g. radial, ulnar and brachial veins) terminating in the humeral axillary lymph nodes. Drains lymph from joint capsules, periosteum, tendons and muscles. Lymph Nodes Majority of the upper extremity lymph nodes are in the axilla. breast, axilla & muscles of the arm and shoulder 8  Divided into 5 anatomical groups: 1. Pectoral (anterior): 3-5 nodes located in medial wall of axilla. They recieve lymph from anterior thoracic wall, including most of breast. 2. Subscapular (posterior): 6-7 nodes located along posterior axillary fold and subscapular blood vessels. They recieve lymph from posterior anterior wall and scapular region. 3. Humeral (lateral): 4-6 nodes located in lateral wall of axilla, posterior to axillary vein. They recieve most of lymph drained from upper limb. 4. Central: 3-4 large nodes located near base of axilla. They recieve lymph via efferent vessels from pectoral, subscapular and humeral axillary lymph node groups. breast, axilla & muscles of the arm and shoulder 9  5. Apical: Located in apex of axilla, close to axillary vein and 1st part of axillary artery. They recieve lymph from efferent vessels of central axillary lymph nodes, so all axillary lymph nodes. Also recieves lymph from lymphatic vessels accompanying the cephalic vein. Efferent vessels from the apical axillary nodes travel through the cervico- axillary canal, before converging to form the subclavian lymphatic trunk. The right subclavian trunk continues to form the right lymphatic duct and enters the right venous angle (junction of the internal jugular and subclavian veins) directly. The left subclavian trunk drains directly into the thoracic duct. List and identify the contents of the axilla Axilla is the area that lies underneath the glenohumeral joint - at the junction of the upper limb and thorax. It is a passageway by which neurovascular and muscular structure can enter and leave the upper limb. breast, axilla & muscles of the arm and shoulder 10  Anterior view of the right axilla region. Note the pyramidal shape, with 6 borders. Borders of the Axilla Overall 3D shape of the axilla looks like a pyramid - made from 4 sides, open apex and base. Apex (axillary inlet) - formed by lateral border of 1st rib, superior border of scapula and posterior border of clavicle. Lateral wall - formed by intertubercular groove of humerus. Medial wall - consists of serratus anterior and thoracic wall (ribs and intercostal muscles). Anterior wall - consists of pectoralis major, pectoralis minor and subclavius muscles. Posterior wall - formed by subscapularis, teres major and latissimus dorsi. Size and shape of arm axilla varies with arm abduction. breast, axilla & muscles of the arm and shoulder 11  Apex decreases in size when arm is fully abducted - leaving contents of axilla at risk of compression. Tranverse region of axilla region. Contents of Axilla Contents include muscles, nerves, vasculature and lymphatics: Axillary artery (and branches) - main artery supplying upper limb. How many parts does it have? Has 3 parts: one medial to the pectoralis minor, one posterior to pectoralis minor, and one lateral to pectoralis minor. The medial and posterior parts travel in the axilla. Axillary vein (and tributaries) - main vein draining upper limb. Two largest tributaries are cephalic and basilic veins. Brachial plexus (and branches) - collection of spinal nerves that form the peripheral nerves of upper limb. Axillary lymph nodes - filter lymphatic fluid that has drained from upper limb and pectoral region. Axillary lymph node enlargement is a non- specific indicator of breast cancer. breast, axilla & muscles of the arm and shoulder 12  Biceps brachii (short head) and coracobrachialis - these muscle tendons move through the axilla, where they attach to the coracoid process of the scapula. Contents of axilla region Passageways Exiting the Axilla There are 3 main routes by which structures leave the axilla. 1. Main route is immediately inferiorly and laterally, into the upper limb - majority of contents leave through here. 2. Quadrangular space - gap in posterior wall of axilla, allowing access to posterior arm and shoulder area. Structures passing through include axillary nerve and posterior circumflex humeral artery. breast, axilla & muscles of the arm and shoulder 13  Posterior view of the shoulder region, showing the quadrangular space. The subscapularis muscle lies anteriorly, and so cannot be seen. 3. Clavipectoral triangle - opening in the anterior wall of the axilla. Bounded by the pectoralis major, deltoid and clavicle. Cephalic vein enters axilla via this triangle. Medial and lateral pectoral nerves leave. Boundaries and contents of the clavipectoral triangle. Identify the muscles of the shoulder and state their attachment sites, action and innervation breast, axilla & muscles of the arm and shoulder 14  The muscles of the shoulder are associated with movements of the upper limb. They can be divided into two groups: Extrinsic - originate from the torso, and attach to the bones of the shoulder (clavicle, scapula or humerus). Intrinsic - originate from the scapula and/or clavicle, and attach to the humerus. The extrinsic muscles of the shoulder originate from the trunk and attach to the bones of the shoulder. They are located in the back and also known as the superficial back muscles. The muscles are organised into 2 layers - a superficial and deep layer. breast, axilla & muscles of the arm and shoulder 15  Identify the muscles of the pectoral region and state their attachment sites, action and innervation breast, axilla & muscles of the arm and shoulder 16  Identify the muscles of the arm and state their attachment sites, action and innervation The upper arm is located between the shoulder joint and elbow joint. It contains four muscles – three in the anterior compartment (biceps brachii, brachialis, coracobrachialis), and one in the posterior compartment (triceps brachii). Draw out the brachial plexus and recall the nerves that come off each chord The brachial plexus is a network of nerve fibres that supplies the skin and musculature of the upper limb. It begins in the root of the neck, passes through the axilla and runs through the entire upper extremity. The plexus is formed by the anterior rami (divisions) of cervical spinal nerves C5, C6, C7 and C8, and the first thoracic spinal nerve, T1. The brachial plexus is divided into five parts; roots, trunks, divisions, cords and branches→ Read That Damn Cadaver Book. breast, axilla & muscles of the arm and shoulder 17 breast, axilla & muscles of the arm and shoulder 18  5 Major Branches Musculotaneous Nerve (C5, C6, C7) Innervates brachialis, biceps brachii and coracobrachialis muscles. Gives off lateral cutaneous branch of forearm which innervates lateral half of anterior forearm. Axillary Nerve (C5 and C6) Innervates teres minor and deltoid muscles. Gives off superior lateral cutaneous nerve of arm which innervates inferior region of deltoid. Median Nerve (C6-T1) Innervates most of the flexor muscles in the forearm, the thenar muscles, and the two lateral lumbricals associated with the index and middle fingers. breast, axilla & muscles of the arm and shoulder 19  Gives off the palmar cutaneous branch, which innervates the lateral part of the palm. Gives off the digital cutaneous branch, which innervates the lateral three and a half fingers on the anterior (palmar) surface of the hand. Radial Nerve (C5-T1) Innervates the triceps brachii, and the muscles in the posterior compartment of the forearm (which are primarily, but not exclusively, extensors of the wrist and fingers). Innervates the posterior aspect of the arm and forearm, and the posterolateral aspect of the hand. Ulnar Nerve (C8 and T1) Innervates the muscles of the hand (apart from the thenar muscles and two lateral lumbricals), flexor carpi ulnaris and medial half of flexor digitorum profundus. Innervates the anterior and posterior surfaces of the medial one and half fingers, and associated palm area. Minor Branches breast, axilla & muscles of the arm and shoulder 20  Brachial Plexus Diagrams breast, axilla & muscles of the arm and shoulder 21 breast, axilla & muscles of the arm and shoulder 22 breast, axilla & muscles of the arm and shoulder 23