PowerPoint Handout: Lab 10, Arm, Cubital Fossa, and Elbow Joint Slide Title Slide Number Slide Title Slide Number Osteology of Elbow Complex Slide 2 Supracondylar Fractures Slide 16 Review of Superficial Veins in Arm Slide 3 Radial Head Fracture Slide 17 Arm: Introduction Slide 4 Median Nerve Lesion at Elbow Slide 18 Arm: Anterior Compartment Muscles Slide 5 Radial Nerve Slide 19 Arm: Posterior Compartment Muscles Slide 6 Humeral Shaft Fracture Slide 20 Cubital Fossa Slide 7 Medial Cutaneous Nerve of Arm Slide 21 Brachial Artery Slide 8 Elbow Joint Complex Slide 22 Brachial Artery Pulse Slide 9 Elbow Capsule & Ligaments Slide 23 Bicipital Aponeurosis Slide 10 Nursemaid’s Elbow Slide 24 Musculocutaneous Nerve Slide 11 Olecranon Bursitis (Student’s Bursitis) Slide 25 Ulnar Nerve Slide 12 Ulnar Nerve Lesion at Elbow Slide 13 Ulnar Nerve Lesion at Wrist Slide 14 Median Nerve Slide 15 Osteology of Elbow Complex To adequately review the learning objectives covering osteology of the distal humerus, radius, and ulna, view the Lower Limb Osteology and Medical Imaging Guide. Review of Superficial Veins in Arm The cephalic and basilic veins are the main superficial veins of the upper limb. They originate from the dorsal venous network on the dorsum of the hand. • The cephalic vein ascends along the anterolateral aspect of the forearm and arm. It then follows the superior border of the pectoralis major muscle to enter the deltopectoral triangle. It ultimately joins the axillary vein after passing through the clavipectoral fascia. • The basilic vein ascends along the medial forearm and the arm. In the arm, it passes deep to the brachial fascia where it courses in close proximity to the brachial artery and medial cutaneous nerve of the forearm along its path into the axilla. In the axilla, it joins with venae comitantes (accompanying axillary artery) to form the axillary vein. • The median cubital vein is a branch of the cephalic vein that passes obliquely across the anterior elbow region (cubital fossa) to join with the basilic vein. CLINICAL ANATOMY: Veins in the dorsal venous network are commonly used for long-term introduction of fluids. Arm: Introduction The arm consists of the humerus, which articulates proximally and distally. Glenohumeral (Shoulder) Joint • Proximally, the humerus articulates with the scapula at the glenohumeral (shoulder) joint. • Distally, the humerus articulates with the forearm at the elbow joint The fascia of the arm separates the arm’s muscles into two compartments. • Anterior: The anterior compartment of the arm contains primarily flexors of the shoulder and elbow. • The muscles of the anterior compartment are innervated by the musculocutaneous nerve (motor and sensory). • Blood supply is from the brachial artery. • Posterior: The posterior compartment of the arm contains primarily extensors of the shoulder and elbow. • The muscles of the posterior compartment are innervated by the radial nerve (motor and sensory). • Blood supply is from the deep brachial artery. Elbow Joint • Humeroulnar Joint • Humeroradial Joint • Radioulnar Joint Arm: Anterior Compartment Muscles MUSCLE INNERVATION BLOOD SUPPLY ACTION Biceps brachii Musculocutaneous n Brachial a Flexes and supinates forearm Coracobrachialis Musculocutaneous n Brachial a Adducts and flexes arm Brachialis Musculocutaneous n Brachial a Flexes forearm FUNCTIONAL ANATOMY: Because the biceps brachii muscle inserts on the radial tuberosity it is capable of supinating the forearm when the elbow is flexed. In this position, the biceps brachii is the most powerful supinator of the forearm. https://3d4medic.al/2gPqFlNq https://3d4medic.al/PPKGOOIE Arm: Posterior Compartment Muscles MUSCLE INNERVATION BLOOD SUPPLY ACTION • Medial Head: Radial n. • Lateral Head: Radial n. Triceps brachii Deep Brachial a Extends forearm • Long Head: Radial n. (in addition to radial, sometimes innervation by axillary n) https://3d4medic.al/7Z6xn1C2 https://3d4medic.al/4pXmeeTR Cubital Fossa The cubital fossa is a depression on the anterior side of the elbow that is a transition area between the arm and the forearm. The boundaries of the cubital fossa are listed below • Lateral: brachioradialis muscle • Medial: pronator teres muscle • Superior: an imaginary line connecting the epicondyles of the humerus • Roof: the bicipital aponeurosis • Floor: brachialis muscle (proximally) supinator muscle (distally) The contents of the cubital fossa are listed below from lateral to medial. • Bicipital tendon • Brachial artery • Median nerve • (Radial nerve: Technically , the radial nerve isn’t considered to be a structure within the cubital fossa, but courses close by as it passes along the deep surface of the brachioradialis muscle. In this area, it bifurcates into the superficial and deep radial nerves.) https://3d4medic.al/CmWeGhiV Brachial Artery The brachial artery is a continuation of the axillary artery after it crosses the tendon of the inferior border of the teres major muscle in the arm. • The profunda brachii artery (deep artery of the arm or deep brachial artery) is the first branch of the brachial artery in the arm. After branching from the brachial artery, it courses posteriorly to pass through the triceps hiatus along with the radial nerve to supply the posterior compartment of the arm. • The brachial artery courses through the arm in the medial bicipital groove along its path to the cubital fossa where it typically terminates by bifurcating into the radial and ulnar arteries. • It supplies blood to structures in the anterior compartment of the arm • At the elbow it gives off several collateral branches that supply the elbow joint. The elbow joint is also supplied by recurrent arteries that branch from the ulnar and radial arteries. CLINICAL ANATOMY: In approximately 3% of limbs, the bifurcation of the brachial artery occurs in the arm. When it does, the ulnar artery may course superficial to the superficial group of flexor muscles, where it can be mistaken for a superficial vein. A quick check for a pulse prevents such a mishap. https://3d4medic.al/sQCe946a https://3d4medic.al/Fhm3HUJE https://3d4medic.al/4pXmeeTR Brachial Artery Pulse CLINICAL ANATOMY: The best place to compress the brachial artery to control hemorrhage (bleeding) is in the middle of the arm, in what is known anatomically as the medial bicipital groove. In the proximal portion of the medial bicipital groove, the brachial artery is coursing between the biceps brachii and and the triceps brachii. In the distal part of the medial bicipital groove the brachial artery courses between brachialis and biceps brachii. The brachial pulse can be palpated easily in the proximal medial bicipital groove by pushing the biceps brachii muscle anteriorly to compress the brachial artery against the humerus. Bicipital Aponeurosis The bicipital aponeurosis (an aponeurosis is a broad, flat tendon) fuses with deep fascia of the proximal, medial forearm. The biceps brachii tendon crosses the cubital fossa deep to the bicipital aponeurosis on its path to its attachment on the radial tuberosity. https://3d4medic.al/hszyWLgA CLINICAL ANATOMY: The bicipital aponeurosis is located between the more superficial median cubital vein and the brachial artery, which is deep. Because of this location, the brachial artery is protected when blood is drawn from the median cubital vein during venipuncture. Musculocutaneous Nerve The musculocutaneous nerve pierces coracobrachialis and descends through the arm by passing between the biceps brachii and brachialis muscles. Ultimately, it emerges from between the biceps brachii, pierces the deep fascia, and continues into the forearm as the lateral antebrachial cutaneous nerve. • Motor innervation • Coracobrachialis • Biceps brachii https://3d4medic.al/idCSLm3n • Brachialis • Sensory innervation via lateral cutaneous nerve of forearm • Anterior lateral forearm CLINICAL ANATOMY: The musculocutaneous nerve is rarely injured because of its protected position beneath the biceps brachii muscle. If it is injured high up in the arm, this results in weakness of supination (biceps brachii) and forearm flexion (brachialis and biceps brachii) Ulnar Nerve In the arm, the Ulnar nerve pierces the medial intermuscular septum to course on the anterior surface of the medial head of the triceps brachii. It then passes https://3d4medic.al/DDP9bPKH posterior to the medial epicondyle of the humerus to enter the cubital tunnel, which is a fibro-osseous passage along the ulnar groove of the medial epicondyle of the humerus. It doesn’t give off any branches in the arm. The tunnel is bounded by the following structures: • Roof: humero-ulnar arcade (arcuate ligament of Osborne) • Floor: elbow joint capsule • Medial border: medial epicondyle • Lateral border: olecranon It enters the anterior compartment of the forearm by passing between the two heads of the flexor carpi ulnaris muscle. Ulnar Nerve Lesion at Elbow CLINICAL ANATOMY: • The most common site of ulnar nerve entrapment is at or near the elbow, especially in the the cubital tunnel. Cubital tunnel syndrome results from a narrowing of the cubital tunnel, which is reduced in size when the elbow is flexed. This reduction in size, increases pressure on the ulnar nerve and results in an ulnar neuropathy. The arcuate ligament of Osborne is thought to be the point of maximum compression in this condition. Cubital tunnel syndrome is diagnosed based on signs and symptoms of ulnar neuropathy. • Common symptoms include: • Pain and numbness in the elbow • Paresthesia/numbness on palmar and dorsal aspects of ulnar (medial) half of ring finger and all of little finger • More severe symptoms can include: • Weakened flexion of wrist (hand will deviate towards radial side during flexion) • Inability to flex MCP joints and extend PIP and DIP joints of ring and little finger • Inability to abduct and adduct the digits Ulnar Nerve Lesion at Wrist The second most likely site for ulnar nerve entrapment is at or near the wrist, especially in the area of the anatomic structure called the ulnar tunnel (canal of Guyon), which will be studied in detail in the next lab. However, it makes sense to compare an ulnar lesion at the elbow to a lesion at the wrist at this point in time.