The arm1


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The arm1

  1. 1. The Arm Maribel G. Castro-Enano, MD CPU College of Medicine
  2. 2. A. Humerus <ul><li>- a long bone which has a cylindrical shaft which flattens anteroposteriorly downwards </li></ul><ul><li>- distal end has articular and non-articular parts </li></ul><ul><li>Articular part: </li></ul><ul><ul><li>1. Capitulum – for the head of the radius </li></ul></ul><ul><ul><li>2. Trochlea – for the trochlear notch of the ulna </li></ul></ul><ul><li>- 2 projections at the distal end </li></ul><ul><li>1. medial epicondyle </li></ul><ul><li>2. lateral epicondyle </li></ul><ul><li>- 3 fossae </li></ul><ul><li>1. radial fossa anterior </li></ul><ul><li>2. coronoid fossa </li></ul><ul><li>3. olecranon fossa – posterior; receives the olecranon of the ulna when the elbow is extended </li></ul>
  3. 3. A. Humerus <ul><li>- lower half of the body is flattened and is divided by the medial and lateral supracondylar ridges into anterior and posterior surfaces for the brachialis and medial head of the triceps </li></ul><ul><li>- supracondylar ridges give attachment to the intermuscular septa for additional attachment of muscles </li></ul><ul><li>- the lateral ridge ascends to a broad shallow groove, the spiral groove (radial nerve) </li></ul>
  4. 5. B. Muscles <ul><li>muscles are enveloped in a sleeve of tough deep fascia </li></ul><ul><li>sleeve divided into an anterior and a posterior compartment by the medial and lateral intermuscular septa </li></ul>
  5. 6. B. Muscles <ul><li>1. Anterior Compartment </li></ul><ul><li>a. corachobrachialis </li></ul><ul><li>– shares a common tendon from the tip of the coracoid process with the short head of the biceps </li></ul><ul><li>- important mainly as a landmark (e.g. musculocutaneous nerve pierces it) </li></ul><ul><li>- origin: tip of coracoid process </li></ul><ul><li>- insertion: medial surface of humerus </li></ul><ul><li>- action: helps to flex and adduct arm </li></ul>
  6. 7. <ul><li>1. Anterior Compartment cont….. </li></ul><ul><li>b. biceps </li></ul><ul><li>- has 2 heads </li></ul><ul><li>1.) long head – descends in the intertubercular sulcus encased in a synovial sheath continuous with the synovial cavity of the shoulder joint </li></ul><ul><li> - origin: supraglenoid tubercle of the scapula </li></ul><ul><li>2.) short head – origin: tip of coracoid process of scapula </li></ul><ul><li>- insertion: tuberosity of radius and bicipital aponeurosis </li></ul><ul><li>- action: supinates forearm and, when it is supine, flexes forearm </li></ul>
  7. 8. <ul><li>c. brachialis </li></ul><ul><li>- origin: distal half of anterior surface of humerus and intermuscular septa </li></ul><ul><li>- insertion: coronoid process and tuberosity of ulna </li></ul><ul><li>- action: flexes forearm in all positions </li></ul>
  8. 9. <ul><li>2. Posterior Compartment </li></ul><ul><li>a. triceps brachii </li></ul><ul><li>- has 3 heads </li></ul><ul><li>1.) long head – from infraglenoid tubercle of scapula </li></ul><ul><li>2.) lateral head – from posterior surface of humerus, superior to the radial groove </li></ul><ul><li>3.) medial head – from posterior surface of humerus below the level of the spiral groove </li></ul><ul><li>- insertion: olecranon process of ulna </li></ul><ul><li>- action: chief extensor of the forearm </li></ul><ul><li> keep the elbow extended when pushing an object </li></ul><ul><li> long head steadies head of abducted humerus </li></ul>
  9. 10. <ul><li>*b. aconeus </li></ul><ul><li>- appears like an extension of the triceps </li></ul><ul><li>- should be considered as part of the medial head of the triceps </li></ul><ul><li>- origin: lateral epicondyle of humerus </li></ul><ul><li>- insertion: lateral surface of olecranon and superior part of posterior surface of ulna </li></ul><ul><li>- action: assists triceps in extending forearm </li></ul><ul><li> stabilizes elbow joint </li></ul><ul><li> abducts ulna during pronation </li></ul>
  10. 11. C. NERVES <ul><li>1. Musculocutaneous n. </li></ul><ul><li>- arises from the lateral cord of the brachial plexus (C5,6,7) </li></ul><ul><li>- pierces the corachobrachialis and continues between the biceps and brachialis </li></ul><ul><li>- at the lateral border of the tendon of the biceps it emerges as the lateral cutaneous nerve of the forearm </li></ul><ul><li>2. Ulnar n. </li></ul><ul><li>- arises from the medial cord (C7,8,T1) </li></ul><ul><li>- without any branching extends to the posterior surface of the medial epicondyle and onward into the forearm </li></ul><ul><li>- in the elbow region, it is accompanied by the superior ulnar collateral artery and the ulnar collateral nerve , sent by the radial nerve to the medial head of the triceps </li></ul>
  11. 12. <ul><li>3. Median n. </li></ul><ul><li>- the 2 roots unite in the axilla on the lateral side of the artery </li></ul><ul><li>- slowly slips across the brachial artery, lying medial to it at the elbow </li></ul><ul><li>- no branches in the axilla or the arm </li></ul><ul><li>- commonly receives a large communication from the musculocutaneous n. and occasionally gives one to it </li></ul><ul><li>4. Radial n. </li></ul><ul><li>- “continuation” of the posterior cord (C5,6,7,8 (T1)) </li></ul><ul><li>- largest branch of the brachial plexus </li></ul><ul><li>- lies posterior to the axillary artery and then the brachial artery anterior to the long head of the triceps </li></ul><ul><li>- passes inferolaterally with the profunda brahii artery around the body of the humerus in the radial groove </li></ul>
  12. 13. <ul><li>4. Radial n. cont….. </li></ul><ul><li>- as it reaches the lateral border of the humerus, it pierces the lateral intermuscular septum between the brachialis and brachioradialis lateral epicondyle divides into deep and superficial branches </li></ul><ul><li>a. superficial radial nerve – sensory branch to the dorsum of the hand and digits </li></ul><ul><li>b. posterior interosseous nerve (deep radial nerve) </li></ul><ul><li> - entirely motor </li></ul><ul><li> - disappears into the substance of the supinator just below the elbow </li></ul><ul><li>- at the lateral side of the arm and at the elbow, branches pass from the radial and posterior interosseous nerves to </li></ul><ul><li>a. brachioradialis </li></ul><ul><li>b. extensor carpi radialis longus </li></ul><ul><li>c. extensor carpi radialis brevis </li></ul><ul><li>d. supinator </li></ul>
  13. 15. D. BLOOD VESSELS <ul><li>1. Brachial Artery </li></ul><ul><li>- arises from the axillary artery </li></ul><ul><li>- pulsations and walls can be felt readily </li></ul><ul><li>- divides into its 2 terminal branches at the level of the neck of the radius, 2-3 cm distal to the crease of the elbow </li></ul><ul><li>a. ulnar artery </li></ul><ul><li>b. radial artery – smaller </li></ul>
  14. 16. <ul><li>Collateral Branches of the Brachial Artery </li></ul><ul><li>1. Profunda brachii a. </li></ul><ul><li>- largest and most superior branch </li></ul><ul><li>- accompanies the radial nerve in the radial groove </li></ul><ul><li>- posterior to the humerus, divides into anterior and posterior descending branches which help to form the arterial anastomoses of the elbow region </li></ul><ul><li>2. Superior ulnar collateral a. </li></ul><ul><li>- arises from brachial a. near the middle of the arm </li></ul><ul><li>- accompanies the ulnar n. posterior to the medial epicondyle </li></ul><ul><li>- anastomoses with the posterior ulnar recurrent branch of the ulnar artery and the inferior ulnar collateral a. </li></ul>
  15. 17. <ul><li>3. Inferior ulnar collateral a. </li></ul><ul><li>- arises from the brachial a. about 5 cm proximal to the elbow crease </li></ul><ul><li>- passes inferomedially anterior to the medial epicondyle , where it joins the anastomoses of the elbow region </li></ul><ul><li>4. Nutrient humeral a. </li></ul><ul><li>- arises from the brachial artery around the middle of the arm </li></ul><ul><li>- enters the nutrient canal on the anteromedial surface of the humerus </li></ul><ul><li>5. Muscular branches </li></ul>
  16. 18. The brachial artery and its collaterals
  17. 19. <ul><li>VEINS </li></ul><ul><li>1. Venae comitantes – accompany the brachial artery and make a very open network around it </li></ul><ul><li>2. Cephalic vein – located in the superficial fascia along the anterolateral surface of the biceps and is often visible through the skin </li></ul><ul><li>3. Basilic vein – also located in the superficial fascia and passes on the medial side of the inferior part of the arm </li></ul><ul><li> - near the middle and inferior 3 rd of the arm, it passes deep to the brachial fascia and runs superiorly to the axilla </li></ul><ul><li>4. Medial cubital vein – forms the communication between the basilic and cephalic veins in the cubital fossa </li></ul><ul><li> - lies anterior to the bicipital aponeurosis </li></ul>
  18. 20. Good Afternoon!