Axilla and Arm Anatomy PDF

Axilla Brachial Plexus Arm Bi-Hung Peng, PhD Department of Neurobiology Surface Anatomy Axilla: Surface Anatomy  Boundaries of the Axilla pyramidal region between arm and chest wall Apex - The triangular space bounded by 1st rib, clavicle, and scap...

Axilla Brachial Plexus Arm Bi-Hung Peng, PhD Department of Neurobiology Surface Anatomy Axilla: Surface Anatomy  Boundaries of the Axilla pyramidal region between arm and chest wall Apex - The triangular space bounded by 1st rib, clavicle, and scapula behind. Base – Skin, dense connective and lymphatic tissue. Medial wall - The Serratus anterior covering the chest wall. Lateral wall - Humerus, more specifically the bicipital groove. Anterior wall - Anterior axillary fold, Pectoralis major and minor Posterior wall - Posterior axillary fold, Latissimus dorsi, Teres major, Subscapularis. Axilla, anterior fold Pectoralis major and minor (hidden) Axilla, Posterior fold Subscapularis Teres major Latissimus dorsi Medial wall axilla, long thoracic nerve Serratus Anterior Protract scapula (point glenoid anteriorly as in pushing) Abduct (raise) arm from horizontal to vertical (point glenoid s uperiorly). If paralyzed by long thoracic nerve damage, cardinal sign is ‘ winged scapula’.  Contents of axilla Axillary artery and its branches (Superior thoracic)-clinically unimportant Thoracoacromial Lateral thoracic Subscapular (largest branch of axillary) Posterior humeral circumflex (often damaged in fracture of surgical neck). Anterior humeral circumflex Brachial plexus (infraclavicular part), Concentrate on: Medial, lateral and posterior cords Long thoracic and thoracodorsal nerves Terminal branches of the plexus (median, radial, ulnar, musculocutaneous, axillary). Both of these are wrapped by the axillary sheath. Contents of the Axilla Axillary Lymph Nodes  Axilla Axillary artery and anastomoses around scapula – Anterior view Suprascapular artery Dorsal scapular artery Thyrocervical trunk Subclavian artery Posterior circumflex 1 Superior humeral artery thoracic artery 2 Anterior circumflex humeral Thoracoacromial artery 3 artery and branc hes: - Clavicular - Acromial Subscapular artery - Deltoid - Pectoral Circumflex scapular artery Lateral thoracic artery Thoracodorsal artery Modified from Netter (2006), Plate 427 Axillary Artery collateral circulation Arterial anastomoses around scapula Brachial Plexus The brachial plexus is the nerve supply to the upper extremity. The roots of the plexus come from C5-T1. The plexus is divided into supraclavicular (roots, trunks, divisio ns) and infraclavicular (cords, terminal nerves) portions. The cords are named from their relation to the axillary artery. L M  Trunks (3) Roots (5) Brachial Plexus Divisions (6) Muscut Ax Rad Cords (3) Med. Ulnar Musculocutaneous n. Median n. Ulnar n.  Thoracoacromial A. Subscapular A. (scapular circumflex and thoracodorsal) Lateral thoracic artery Artery Post and ant humeral circumflex Arteries. Subscapular Artery Brachial Plexus Injuries Upper roots of the plexus - Erb’s Palsy-upper extremity medially rotated and essentially paralyzed except the patient can move the fingers. Lower roots of the plexus -Klumpke’s paralysis-intrinsic muscles of hand paralyzed. Brachial plexus injuries Erb’s palsy Axilla and Arm Musculocutaneous N. Median N. Ulnar N. The M stretched out Arm Arm Muscles Biceps brachii, flex arm, flex forearm, supinate Coracobrachialis, flex arm Brachialis, flex forearm Triceps, extend arm and forearm Arm Innervation Musculocutaneous nerve, nerve to anterior compartment arm muscles, continues as lateral cutaneous nerve of forearm Radial nerve, nerve to posterior compartment muscle (triceps) and skin, continues to extensor forearm and hand Median and ulnar nerves innervate nothing in arm With the anterior part of the brachial plexus completely removed, one can more clearly see t he posterior cord and its 2 terminal nerves, the axillary and the radial. Also one can see the musculocutaneous nerve as it passes through the coracobrachialis muscle to innervate the f lexor muscles of the arm. Musculocutaneous nerve Axillary N., qu adrangular sp ace Radial N. Brachial Artery Thoracoacromial Blood supply to the upper extremity artery Axillary artery Brachial artery Lower margin of teres major muscle Profunda brachii artery  Radial N. Deep artery of arm (profunda brachii) Capsule of glenohumeral joint Arm Deep dissection, posterior Axillary Nerve 2 1 Posterior circumflex humeral artery Radial Nerve 2 Profunda brachii artery 4 3 The radial nerve and deep artery of the arm travel in the spiral groove on the posterior side of the humerus and are thus in jeopardy with fracture of the humeral shaft. Modified from Netter (2006), Plate 432 Questions?