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Home , Ape hand deformity, Bicipital aponeurosis, Bicipital groove

PowerPoint Handout: Lab 10, , , and 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 Lesion at Elbow Slide 18

Arm: Anterior Compartment Muscles Slide 5 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 Slide 10 Nursemaid’s Elbow Slide 24

Musculocutaneous Nerve Slide 11 Bursitis (Student’s Bursitis) Slide 25 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 , , and , 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 . They originate from the dorsal venous network on the dorsum of the . • The cephalic vein ascends along the anterolateral aspect of the and arm. It then follows the superior border of the muscle to enter the deltopectoral triangle. It ultimately joins the axillary vein after passing through the clavipectoral . • 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 . 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 () Joint • Proximally, the humerus articulates with the 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 (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 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 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. 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: muscle • Medial: • Superior: an imaginary line connecting the epicondyles of the humerus • Roof: the bicipital aponeurosis • Floor: (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 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 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 , 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 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 . 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. • If an ulnar nerve lesion occurs BELOW the elbow BEYOND the point at which the flexor digitorum profundus receives its ulnar innervation, hand can occur. Ulnar claw hand describes the position of the hand when at REST (This is an important distinction from Hand of Benediction in which the examiner is asking the patient to make a fist.) • The 4th and 5th MP joints are extend due to the unopposed action of extensor digitorum. The extensor digitorum is normally opposed by the actions of the lumbricals and interossei flexing the MP joints. • The 4th and 5th IP joints are flexed due to the unopposed action of flexor digitorum profundus. Normally the flexor digitorum is opposed by the actions of lumbricals extending the IP joints. For a nice overview of “Ulnar Claw Hand” and how it differs from “Hand of Benediction,” visit Dr. Nabil Ebraheim’s YouTube video: https://www.youtube.com/watch?v=GyqaKGg3HmM Median Nerve • On the medial side of the arm, the median nerve courses with brachial artery in a groove between the biceps brachii and brachialis. Along its path in the arm, it doesn’t give off any branches. • It enters the cubital fossa by passing inferior to the bicipital aponeurosis. After entering the cubital fossa, it passes between the two heads of the pronator teres muscle to enter the anterior compartment of the forearm. In the anterior compartment of the forearm, it begins innervating muscles, beginning with the pronator teres muscle. The anterior interosseous nerve branches from the median nerve soon after passing between the heads of the pronator teres muscle.

https://3d4medic.al/DDP9bPKH https://3d4medic.al/JzuRZ0kq Supracondylar Fractures

CLINICAL ANATOMY: Elbow fractures can occur in direct falls on the elbow or when Falling On an Outstretched Hand (the clinical acronym is FOOSH). In children (esp 5-8-years-old), such falls may result in a supracondylar fracture of the distal humerus. If displacement of the distal segment occurs at the fracture site, nerves traversing the elbow and the brachial artery are at risk of injury.

Depending upon which direction the distal segment displaces, different structures are at risk of injury. • Due to its location deep within the cubital fossa, the median nerve (and/or its anterior interosseous branch in cases where this nerve leaves the nerve superiorly) is at risk of injury in supracondylar fracture when the distal segment displaces posterolaterally. In addition, the brachial artery is at risk in this location. • A posteromedial displacement of the distal segment, puts the radial nerve at risk of injury.

CLINICAL ANATOMY: Radial head and neck fractures are the most common elbow fractures in adults, comprising approximately 33%–50% of elbow fractures, and are seen in roughly 20% of elbow trauma cases. The majority of radial head fractures result from a fall on an outstretched hand (FOOSH), but may also result from direct impact on the elbow, a twisting injury, or dislocation. A fracture of the radial head results in localized pain at the radial head that is worse during supination. Localized edema due to hemarthrosis is usually present Anteroposterior radiograph along with limited passive motion of the of a displaced impaction fracture of the articulating elbow. Fracture of the capitellum may surface of the radial head. occur simultaneously. Radial Head Fracture

CLINICAL ANATOMY: Radial head and neck fractures are the most common elbow fractures in adults, comprising approximately 33%–50% of elbow fractures, and are seen in roughly 20% of elbow trauma cases (Figures 1 and 2). The majority of radial head fractures result from a fall on an outstretched hand (FOOSH), but may also result from direct impact on the elbow, a twisting injury, or dislocation. A fracture of the radial head results in localized pain at the radial head that is worse during supination. Localized edema due to hemarthrosis is usually present along with limited passive motion of the elbow. Fracture of the capitellum may occur simultaneously.

Extra information if you are interested… (Figure 3) Type I: The fracture consists of a simple split-wedge fragment which may be displaced or non-displaced. It is also called a chisel fracture. Type II: In this fracture pattern, part of the head and neck remain intact. The portion involved in the fracture is tilted and impacted. Comminution is variable. Figure 1 Figure 2 Type III: A severely comminuted fracture. The hallmark of this fracture is that no portion of the head or neck remains in continuity. Type IV: Fracture of the radial head with dislocation of the elbow joint.

Figure 3 Median Nerve Lesion at Elbow • A lesion of the median nerve at the elbow (supracondylar fracture) can result in the following deficits. • Motor • Weakened pronation of forearm (loss of pronator quadratus) • Weakened flexion at wrist along with hand deviation to ulnar side during flexion (loss flexor carpi radialis, but flexor carpi ulnaris still intact) • Hand of Benediction: Active flexion of the digits (making a fist) results in ONLY digits 4 and 5 flexing at MCP, DIP, and PIP. • Inability to flex index and middle finger at MCP, PIP and DIP joints (loss of flexor digitorum superficialis, flexor pollicis longus, radial ½ of flexor digitorum profundus) • Inability to abduct, oppose and flex the (loss of flexor pollicis longus, flexor pollicis brevis, opponens pollicis, abductor pollicis) • Atrophy of the thenar muscles • Ape Hand Deformity: loss of thenar muscles causes the thumb to fall into the same plane as the other digits • Thumb is adducted due to unopposed action of the adductor pollicis muscle. • Sensory • Loss of sensation on palmar and dorsal aspects of index, middle, and lateral half of ring fingers • Loss of sensation to palmar aspect of thumb

Video that clearly describes Ulnar Claw Hand, Ape Hand, and Hand of Hand of Benediction Benediction: https://www.youtube.com/watch?v=0AAligXLJ1A

Thenar Atrophy Ask patient to Thumb in same make a fist. plane as fingers

Ape Hand Radial Nerve The Radial nerve exits the axilla by passing through the triceps hiatus (triangular interval) along with the deep brachial artery. Both structures pass between the medial and long heads of the triceps brachii to enter the radial groove of the humerus. After exiting the radial groove, it courses between the brachialis and brachioradialis muscles. Ultimately it enters the forearm by crossing the anterior to the capsule of the elbow joint. • Motor innervation: triceps brachii (all 3 heads) NOTE: The long head of triceps brachii can also be innervated by the axillary nerve • Cutaneous innervation: cutaneous branches to posterior arm and forearm. CLINICAL ANATOMY: Because of their relationship to the posterior surface of the humerus, the radial nerve and profunda brachii artery are at risk of injury in fractures of the humeral shaft. Compression of the radial nerve against the humerus for extended periods, such as when falling asleep with the back of the arm compressed against a solid object (“Saturday night palsy”, “honeymoon palsy”) or when fitted improperly for crutches (“crutch palsy”) results in a temporary mononeuropathy characterized by numbness of the back of the hand and digits, and an inability to extend the wrist and digits. Humeral Shaft Fracture

CLINICAL ANATOMY: Midshaft humerus fractures can involve injury to the radial nerve and is the most common peripheral nerve injury associated with long fractures. The radial nerve is most likely to be damaged in humerus fractures that have a lateral displacement of the distal fracture segment because the nerve is tethered to the bone and cannot withstand the forces applied to it as a result of the displacement.

On physical exam, patients with a radial nerve injury may have the following signs/symptoms. • (loss or weakness of wrist extensors) • loss or weakness of finger extension • decreased or absent sensation to the posterior forearm, digits 1 to 3, and the radial half of the fourth digit.

Up to 90% of patients with a closed humeral fracture with radial nerve injury will have a resolution of neuropraxia within three to four months following the injury. Medial Cutaneous Nerve of Arm

Medial Cutaneous nerve of Arm: The medial cutaneous nerve of the arm branches from the medial cord of the brachial plexus and supplies the anteromedial skin of the arm. Elbow Joint Complex

In comparison to the shoulder, motion at the elbow joint is relatively restricted. The elbow joint consists of three articulations.

1. Humeroulnar articulation Proximal Radioulnar Joint Humeroradial • Joint between the trochlea of the humerus and Joint the of the ulna • movements: flexion and extension

2. Humeroradial articulation • Joint between the capitulum of the humerus and the head of the radius • Movements: flexion and extension Humeroulnar Joint

3. Proximal radioulnar articulation: This articulation is also Proximal Radioulnar enclosed within the elbow joint capsule. Joint • Joint between the head of the radius and a notch on the ulna called the . The radial head is held in place by the annular ligament, which forms a collar-like ring around the joint • Distal Radioulnar Movements: supination and pronation Joint (i.e., rotation around the long axis of the radius) The radius and ulna also articulate near the wrist. This joint is called the distal radio-ulnar joint. Elbow Capsule & Ligaments Capsule: A single capsule encloses all three joints of the elbow joint complex. The capsule of the elbow joint is loose, which accommodates a large degree of flexion and extension. However, the capsule is reinforced by ligaments.

Elbow Complex Ligaments • The ulnar collateral ligament spans from the medial epicondyle of the humerus to the proximal ulna. It functions to provide medial stability to the joint. • The radial collateral ligament spans from the lateral epicondyle of the humerus to the annular ligament and the olecranon process of the ulna. It functions to provide lateral stability to the joint. • The annular ligament is attached to the anterior and posterior surfaces of the radial notch. Along its path from one attachment to the next, it forms a ring around the radial head.

https://3d4medic.al/3RVlCiHz https://3d4medic.al/FHJS4mq6 Nursemaid’s Elbow

CLINICAL ANATOMY: Subluxation and/or dislocation of the proximal radio-ulnar joint, so-called nursemaid's elbow, may occur with excessive force with sudden pull upward on a child's arm. It is a common injury in children 5- to 7- years-old, but with increasing age, the ligaments become stronger and the risk of such injury is reduced. Olecranon Bursitis (Student’s Bursitis)

CLINICAL ANATOMY: Elbow (olecranon) bursitis involving the subcutaneous bursa (student’s bursitis) results from repeated excessive pressure on the elbow. Bursitis of the subtendinous bursa is due to excessive friction between the tendon and the olecranon. Pain from the latter form increases substantially during elbow flexion due to compression of the bursa by the triceps tendon.