Axilla and Pectoral Region PDF

Axilla and Pectoral Region DPM Program 1. Describe the boundaries and contents of the axilla. 4.0 2. Describe the muscles of the pectoral region in terms of origins, insertions, actions, innervations, and blood supply. 4.0 3. Describe the axillary artery and its branches. 4.0 4. Describe the axillar...

Axilla and Pectoral Region DPM Program 1. Describe the boundaries and contents of the axilla. 4.0 2. Describe the muscles of the pectoral region in terms of origins, insertions, actions, innervations, and blood supply. 4.0 3. Describe the axillary artery and its branches. 4.0 4. Describe the axillary lymph nodes. 4.0 5. Describe the boundaries and contents of the quadrangular space, triangular space, and triangular interval. 4.0 6. Explain winging of the scapula. 4.0 7. Describe the clinical importance of the arterial anastomoses of the shoulder 3.0 8. Describe the arterial anastomoses occurring at the shoulder 4.0 9. Describe the osteological features of the scapula. 4.0 1 Humerus and Scapula: Anterior View 2 Humerus and Scapula: Posterior View Suprascapular notch Clavicle (trapezius, deltoid, p. major) Coracoid process Superior border Acromion (trapezius, deltoid) Supraspinous fossa (supraspinatus) Spine (trapezius, deltoid) Greater tubercle (supraspinatus, infraspinatus, teres minor) Infraspinous fossa (infraspinatus) Head of humerus Spiral (radial) groove (radial nerve, profunda brachii vessels) Vertebral (medial) border (rhomboids) Deltoid tuberosity (deltoid) Scapula Humerus Inferior angle Axillary (lateral) border (teres major, teres minor, long head of triceps off the infraglenoid tubercle) 3 Movements of the Scapula 4 The Axilla Pyramidally shaped space acting as a passageway between the neck and upper limb. Borders: Apex - cervicoaxillary canal (communication between neck and axilla) Anterior - pectoralis major and minor Anterior axillary fold - formed by P. major m. Posterior – subscapularis (scapula), teres major, latissimus dorsi Posterior axillary fold - formed by Latissimus Dorsi & Teres major mm. Medial - Serratus anterior on the thoracic wall Lateral - intertubercular groove (housing tendon of the long head of biceps brachii) Base – skin and axillary fascia between arm and thoracic wall Contents: Fat Lymph Axillary artery and vein Axillary sheath (contains proximal parts of axillary vessels and brachial plexus) Cords and branches of the brachial plexus 5 Muscles that Bound the Axilla 6 Anterior Wall: Pectoralis Major Muscle Pectoralis Major (clavicular & sternocostal heads) O: Clavicular head: anterior surface of medial ½ of clavicle. Sternocostal head: anterior surface of Sternum and upper 7 costal cartilages, sternal end of 6th rib, aponeurosis of external abdominal oblique I: Lateral lip of intertubercular sulcus/groove of humerus Innervation: Medial and lateral pectoral nerve (clavicular head (C5, C6); sternocostal head (C6, C7, C8, T1) Action: Flexion, adduction, and medial rotation of arm (clavicular head: flexes extended arm & sternocostal head: extends flexed arm) 7 Anterior Wall: Pectoralis Minor and Subclavius Muscle Subclavius O: Junction of rib and its costal cartilage I: Inferior surface of middle third of clavicle Innervation: Subclavian n. (C5, C6) Action: Depresses scapula (pulls tip of shoulder down); pulls clavicle medially to stabilize sternoclavicular joint, anteriorly tilts scapula 1st Pectoralis Minor O: Ribs III to V I: Coracoid process of scapula Innervation: Medial pectoral nerve Action: Depresses scapula (pulls tip of shoulder down), protracts scapula, anteriorly tilt scapula (elevates ribs-accessory muscle of respiration) 8 Medial Wall: Serratus Anterior and Long Thoracic Nerve O: Lateral surface of upper 1st-8th ribs I: Costal surface of medial border of scapula Innervation: Long Thoracic Nerve (C5, C6, C7) Action: Protraction and rotation of the scapula upward; keeps medial border & inferior angle of scapula to thoracic wall 9 Posterior Wall 10 Anatomical Spaces of the Pectoral Region Suprascapular foramen -suprascapular a./n. Quadrangular space -axillary nerve -posterior circumflex humeral a/v Triangular interval -Radial nerve -Profunda brachii a. Subscapularis m. Triangular space - circumflex scapular a. Teres major m. Long head of triceps brachii m. Latissimus dorsi m. 11 Contents of the Axilla -Fat -Lymphatics: draining lymph from the upper limb, lateral breast and thoracoabdominal walls above the umbilicus. This lymph drains to the subclavian trunk, then to either the right lymphatic duct or the thoracic duct (left upper limb) -Axillary vessels: axillary artery/vein that begin/end at the lateral border of the 1st rib -Brachial plexus: Cords & branches of the brachial plexus (composed of the ventral rami of C5-T1 spinal nerves0 -Axillary sheath: A lateral continuation of the prevertebral layer of deep cervical fascia that contains the proximal parts of the axillary vessels and the brachial plexus 12 Axillary Vessels The axillary artery is a short vessel that begins at the lateral border of the first rib as a distal continuation of the subclavian artery. It ends at the inferior border of the teres major muscle where it changes its name to the brachial artery. It is surrounded by the cords and branches of the brachial plexus. -The axillary vein lies on the medial/anterior side of axillary artery. It begins at the inferior border of teres major by the union of the brachial veins and the basilic vein and ends at the lateral border of the first rib where it becomes the subclavian vein. -The proximal parts of the axillary vessels and the surrounding brachial plexus are enclosed in the axillary sheath (a distal continuation of the prevertebral fascia in the neck). For descriptive purposes, the axillary artery is divided into three parts by the presence of the pectoralis minor muscle. The part number also indicates its number of branches. Part I: (lateral border of the first rib to the medial border of pectoralis minor) i). Superior thoracic artery - supplies muscles in the 1st and 2nd intercostal spaces Part II: (posterior to the pectoralis minor muscle) i). Thoracoacromal trunk - pierces the clavipectoral fascia has four branches: - acromial, deltoid, pectoral, clavicular ii). Lateral thoracic a. - supplying the pectoral muscles, lymph nodes and the breast Part III: (lateral border of pectoralis minor to the inferior border of teres major) i). Subscapular has two terminal branches: Circumflex scapular (in triangular space), Thoracodorsal (to latissimus dorsi) ii). Anterior Circumflex humeral iii). Posterior circumflex humeral (quadrangular space with axillary nerve) 13 Blood Supply to the Upper Limb Subclavian Artery -right is a terminal branch off the brachiocephalic trunk, left is a direct continuation off aortic arch -ends at the lateral border of 1st rib Axillary Artery -begins at lateral border of 1st rib as a distal continuation of the subclavian artery Brachial Artery -begins at inferior border of teres major as a distal continuation of the axillary artery -ends at elbow by bifurcating into radial and ulnar arteries Profunda brachii (deep artery of the arm) -branch off brachial a. to the posterior compartment of the arm -travels in the spiral groove of the humerus with the radial n. Superior ulnar collateral Radial Artery -to anterior, posterior forearm, dorsum of hand and palm Inferior ulnar collateral Ulnar Artery -to anterior forearm and palm Deep Palmar Arterial Arch Superficial Palmar Arterial Arch Ulnar collateral aa. participate in the anastomotic network around the elbow, supplying, in part, the elbow joint 14 Axillary Artery 15 Collateral Circulation of the Scapula (anastomoses around the scapula) There is an extensive arterial anastomosis around the scapula formed by branches of the subclavian artery, axillary artery, and the aorta. The clinical importance of this collateral circulation becomes apparent when it is necessary to ligate an injured subclavian or axillary artery. The axillary artery may be ligated between the thyrocervical trunk and the subscapular artery. This results in the reversal of blood flow in the subscapular artery so that blood can reach the third part of the axillary artery and all points distal. Please note that ligation of the axillary artery distal to the subscapular artery (and proximal to the profunda brachii artery of the brachial artery) will severely compromise the blood flow to the upper extremity resulting in gangrene if prolonged. The major arteries involved in this anastomotic network include the: 1. transverse cervical artery (thyrocervical trunk off the subclavian artery*) 2. suprascapular artery (thyrocervical trunk off the subclavian artery*) 3. circumflex scapular artery (subscapular artery off the axillary artery) 4. posterior intercostal arteries (aorta) *arteries off of subclavian a. were discussed in the neck lecture please go back and review if you need a refresher 16 17