Blue Boxes II

Question 1

paralysis of serratus anterior

Answer 1

• damage to long thoracic nerve (superficial to serratus anterior)
• causes winged scapula (medial border of scapula moved laterally and posteriorly
• unable to abduct limb above horizontal (serratus anterior is unable to rotate glenoid cavity of scapula superiorly, but trapezius (CN XI) aids in motion and is unaffected)

Question 2

Thoracodorsal n. injury

Answer 2

C6-8

supplies latissimus dorsi

vulnerable in surgery in inferior axilla or mastectomy

causes inability to raise trunk w/ upper limbs (climbing) or use a crutch
^require active depression of scapula

Question 3

Dorsal scapular nerve injury

Answer 3

Innervates rhomboids, damage causes scapula on affected side to sit farther from the midline than the unaffected side

Question 4

Axillary nerve injury (C5-C6)

Answer 4

• passes inferior to humeral head around surgical neck, supplying deltoid, teres minor, and the long head of the triceps brachii

damaged by humeral head fracture OR glenohumeral dislocation

damage causes deltoid atrophy and loss of sensation in proximal, lateral arm due to damage to superior lateral brachial cutaneous n. (branch of axillary n.)

Question 5

Scapular arterial anastomoses

Answer 5

Dorsal scapular a.
suprascapular a.
subscapular a. (via circumflex scapular a.)

subscapular a, receives blood from the suprascapular a., intercostal a., and dorsal scapular a. (via thoracodorsal a.) allowing collateral circulation to reach the 3rd part of the axillary a. during slow occlusion of the axillary a.

Sudden occlusion –> no time for the development of proper collateral circulation, causing arm, forearm, and hand ischemia

Ligation of brachial a.: (between subscapular a. and deep brachial a.) causes ischemia as above due to lack of collateral circulation

Question 6

Enlargement of axillary lymph nodes

Answer 6

upper limb infection causing lymphangitis, usu at humeral nodes first

visible as warm, tender red streaks on skin of limb

cancer in apical nodes can cause adherence to axillary v. –> req excision. Enlargment of apical nodes may obstruct cephalic vein superior to pectoralis minor

Question 7

brachial plexus injuries

Answer 7

damage to lateral cervical triangle in neck or to axilla causing partial/full paralysis and anesthesia

Question 8

superior trunk injury (C5, C6)

Answer 8

damage from inc angle between neck and shoulder, such as falling on shoulder from a horse/motorcycle, causing avulsion of stretching of the superior roots of the brachial plexus

Erb’s palsy (waiter’s tip) - shoulder adducted, arm medially rotated, elbow extended

similar damage w/ shoulder dystocia (during birth) where shoulder is caught on pubic symphysis

Backpacker’s palsy –> shoulder spasms etc

Question 9

injury to long thoracic n.

Answer 9

Paralysis of serratus anterior

inability to laterally rotate the inferior border of the scapula, preventing abduction (via superior movement of the glenohumeral fossa)

Question 10

injury to Suprascapular n.

Answer 10

Paralysis of supraspinatus and infraspinatus, causing loss of abduction initiation and weakened lateral rotation. (But subscapularis is unaffected, allowing medial rotation.)

Question 11

Musculocutaneous n.

Answer 11

paralysis of biceps brachia, brachialis, coricobrachialis causing weakened flexion at elbow

Question 12

axillary n.

Answer 12

paralysis of deltoid and teres minor, prevents aBduction of upper limb

Question 13

acute brachial plexus neuritis

Answer 13

idiopathic neuropathy

severe shoulder pain and inflammation proceeding a trauma or infection

Question 14

cord compression

Answer 14

prolonged hyperabduction of the arm over the head (ceiling painting, etc) causing cord impingement between coracoid process and pectoralis minor tendon

–> radiculopathy down arm with parasthesia, erythema and hand weakness due to compression of axillary artery/vein and nerves

Question 15

Klumpke’s Palsy (Inferior Trunk C8, T1)

Answer 15

Sudden pulling of upper limb superiorly can damage lower plexus nerve roots

Pulling of a newborn’s limb during birth causes similar damage.

^Both result in Claw Hand, or an inability to flex the small and ring fingers when attempting to make a fist, and weakness flexing the thumb, index and middle fingers

Question 16

damage to ulnar n.

Answer 16

Paralysis of flexor carpi ulnaris, ulnar half of flexor digitorum profundus and many intrinsic hand muscles, along with cutaneous anesthesia of the hand medial to the axial line of the ring finger

Question 17

damage to medial brachial cutaneous n.

Answer 17

anesthesia off the medial aspect of the arm (until medial epidcondyle of humerus and olecranon of ulna)

Question 18

damage to medial antebrachial cutaneous n.

Answer 18

anesthesia of the medial aspect of the forearm (until wrist)

Question 19

rotator cuff injury

Answer 19

SItS

supraspinaturs
infraspinatus
teres minor
subscapularis 
^ tendons blend to strengthen GH joint capsule

• trauma most comm tears supraspinatus

degenerative tendonitis of rotator cuff –> via xs raising of upper limb above horizontal

Question 20

bicipital myotactic reflex

Answer 20

relaxed limb passively pronated/extended at elbow

thumb on distal biceps tendon, tap hammer on thumb

confirms integrity of C5-C6 and musculocutaneous n.

Question 21

rupture of tendon of long head of biceps

Answer 21

tendon sits in inter tubercle sulcus on lateral aspect of humerus

attaches to supraglenoid tubercle of scapula (above glenoid labrum)

rupture snaps –> muscle belly forms a ball in center of anterior arm (Popeye deformity) caused by xs forceful flexion during weight lifting or due to prolonged tendonitis

Question 22

Interruption of blood flow in brachial a.

Answer 22

compression of brachial a. to control hemorrhage medial to humerus near middle of elbow prevents flow down artery, but allows collateral flow thru deep brachial a. and elbow anastomoses supplying ulnar and radial arteries

sudden occlusion: surgical emergency –> collateral flow is not sufficient, ischemia of elbow/forearm occurs (>6 hrs leads to scar tissue formation, permanent muscle shortening and flexion deformity
^ischemic compartment syndrome (Volkmann/ischemic contracture)

Question 23

Injury of radial n. in arm

Answer 23

supplies triceps brachii, brachioradialis, supinator extensor muscles of forearm (wrist/fingers)

• damage –> paralysis and loss of sensation supplied by radial n. (posterior hand from thumb to midline of ring finger)
• also loss of sensation via posterior antebrachial cutaneous n. (arises from radial n. in radial groove of humerus
• injury causes WRIST DROP (int extend wrist & fingers at MP joints) wrist remains flexed

Question 24

Injury to musculocutaneous n.

Answer 24

supplies coricobrachialis, brachialis, and biceps brachii

damage –> weakened flexion and supination at elbow, still possible via brachioradialis and supinator m. (via supplied radial n.)

Question 25

venipuncture in cubital fossa

Answer 25

median cubital vein --> used for venipuncture, cardiac catheter introduction and coronary angiography --> crosses bicipital aponeurosis, protecting brachial a. and median n. underneath, allowing protection against arterial hemorrhage

Question 26

elbow tendonitis

Answer 26

extensive use of superficial extensor muscles of forearm causing pain over lateral epicondyle radiating to posterior surface of forearm - causes pain when opening door/lifting a glass - repeated flexion/extension at the wrist strains common extensor tendon causing LATERAL epicondylitis (inflammation of periosteum)

Question 27

median n. injury

Answer 27

presents as HAND OF BENEDICTION or MEDIAN N. PALSY inability to... - flex PIP joints of thumb (flexor pollicis longus) - flex PIP joints of index and middle finger (via flexor digitorum superficialis) - flex DIP joints of index and middle finger (via flexor digitorum profundus; medial head is supplied by ulnar n. so ring and small finger are unaffected) - flex metacepophslangeal joints of index and middle finger (via digital branches of median n. --> innervate 1st and 2nd lumbricals)

Question 28

anterior interosseous n. injury

Answer 28

(branch of median n.) - paresis of flexor digitorum profundus and flexor pollicus longus - prevents normal OK sign (causing a pinch instead due to weakened flexion of interphalangeal joint of thumb and distal interphalangeal joint of index finger - thenar muscles unaffected (innervated by recurrent branch of median n.)

Question 29

ulnar n. injury

Answer 29

- often damaged posterior to med epicondyle where ulnar n. passes through cubital tunnel (covered by arch connecting humeral and ulnar heads of flexor carpi ulnaris) or at the wrist/hand. - damage superior to medial epicondyle: paraesthesia to medial side of anterior hand - lose ability to aDduct (Palmar interossei 1-3) or aBduct (dorsal interossei 1-4), since they are suppl by deep branch of ulnar n.

Question 30

Claw hand

Answer 30

inability to flex any metacarpophalangeal joints due to paralysis of 3rd and 4th lumbricals, innervated by deep branch of ulnar n. inability to flex little and ring finger at DIP joints due to paralysis of medial head of flexor digitorum profundus

Question 31

cubital tunnel syndrome

Answer 31

cubital tunnel --> between medial epicondyle and olecranon by the tendinous arch of the humeral and ulnar heads of flexor carpi ulnaris ulnar n. can be compressed here --> prod. same sx as superior lesion in ulnar groove on posterior aspect of medial epicondyle of humerus

Question 32

radial n. injury

Answer 32

comm injured by fracture of humeral shaft (radial n. passes around posterior humerus with deep brachial artery in radial groove, anastomosing w/ radial recurrent artery in forearm) causes WRIST-DROP by denervation of wrist extensors in forearm

Question 33

Damage to Deep Branch of Radial Nerve

Answer 33

radial n. splits to deep and superficial branches beneath brachioradialis m. by lateral epicondyle deep radial n. pierces supinator to become posterior interosseous n. causes inability to extend thumb (denervation of extensor pollicis longus and extensor pollicis brevis via posterior interosseous n.) and digital MP joints (denervation of extensor digitorum, extensor digiti minimi) test by looking for visible long extensor tendons when extending MP joints NO loss of sensation - deep radial --> entirely motor

Question 34

Damage to Superficial Branch of Radial Nerve

Answer 34

anesthesia around region of 1st-2nd metacarpals or slightly distal

Question 35

Carpal Tunnel Syndrome

Answer 35

caused by reduction of size of carpal tunnel/increase of size of 9 structures in carpal tunnel (8 tendons of flexor digitorum superficialis and flexor digitorum profundus and tendon of flexor pollicis longus) impinging on Median n. may cause paraesthesia, hypoesthesia or anesthesia over region from thumb to middle of ring finger (lateral 3.5 digits) palmar cutaneous branch of median n. arises proximal to carpal tunnel, leaving sensation on central palm unaffected recurrent branch of median n. (serving 3 of 4 thenar muscles; opponens pollicis, abductor pollicis brevis, flexor pollicis brevis) branches distal to carpal tunnel, may be affected - -> weakness in thumb opposition and thumb abduction. - -> tx: poss. surgical resection of flexor retinaculum (carpal tunnel release)

Question 36

Dupuytren Contracture of Palmar Fascia

Answer 36

disease of palmar fascia --> progressive shortening, thickening, and fibrosis of palmar fascia and aponeurosis fibrous degeneration of longitudinal bands of palmar aponeurosis on medial side of hands --> pulls 4th and 5th fingers into partial flexion at the MCP and PIP joints first manifests as painless nodular thickenings of palmar aponeurosis that adhere to skin, then raised ridges in palmar skin that extend from proximal hand to base of 4th and 5th digits contracture is freq bilateral, seen in some men >50 y/o, possibly hereditary tx: survival excision of fibrotic parts of Palmar fascia to free fingers

Question 37

Hand infections

Answer 37

usu on dorsal of hand (where fascia is thinner) pus may accumulate in thenar, hypothenar, midpalmar, or aDductor compartments tx: abx therapy. no tx --> can spread proximally thru carpal tunnel into forearm, anterior to pronator quadratus and its fascia

Question 38

laceration of palmar arches

Answer 38

causes perfuse bleeding, may not be sufficient to ligate only one forearm artery may need to compress brachial a. and its branches proximal to elbow (use pneumatic tourniquet) to prevent blood from reaching ulnar/radial a. thru elbow anastamoses