SM_231a: Peripheral Neuropathies of the Upper Limb Flashcards
Describe general features of neuropathies
Neuropathies
- Nerves can be damaged by disease (e.g. diabetes), drugs/toxins (e.g. alcohol), or trauma (cutting, compression, or stretching)
- Disease, drugs, and toxins may affect many nerves at the same time (polyneuropathy) symmetrically on both sides of the body
- Trauma affects one nerve (mononeuropathy) on one side
- Nerves can be cut by penetrating wounds or fractures if a nerve contacts a bone, compressed against a bone by a hard object or swelling in an osseofibrous joint, and stretched by dislocation or excessive movement in a joint
____, ____, and ____ can cause neuropathies
Disease (e.g. diabetes), drugs/toxins (e.g. alcohol), and trauma (cutting, compression, or stretching) can cause neuropathies
Disease, drugs, and toxins affect ____ nerves at the same time ____
Disease, drugs, and toxins affect many nerves at the same time (polyneuropathy) symmetrically on both sides of the body
Trauma typically affects _____ on _____
Trauma typically affects one nerve (mononeuropathy) on one side
Nerves can be damaged by trauma including ____, ____, and ____
Nerves can be damaged by trauma including cutting, compression, or stretching
Injury to a nerve causes muscles and skin supplied by the nerve to lose their innervation, resulting in _____ and _____
Injury to a nerve causes muscles and skin supplied by the nerve to lose their innervation, resulting in paralysis and anesthesia
- Complete paralysis: no movement is detectable because all muscles producing a movement have lost innervation
- Incomplete paralysis: not all muscles producing movement have lost innervation -> muscle can move but movement is weak or paretic
- Anesthesia (numbness): loss of cutaneous sensation tested by pinprick or touch
Knowing _____ and _____ is necessary to evaluate neuropathies
Knowing course and distribution is necessary to evaluate neuropathies
- Course: indicates where nerve has been injured, only muscles and skin areas distal to the site of injury will be affected
- Distribution (muscles and skin innervated): indicates what muscles and skin have been affected by the injury
Upper brachial plexus injuries (Erb-Duchenne / Erb’s palsy) result from ______
Upper brachial plexus injuries (Erb-Duchenne / Erb’s palsy) result from traction or tear of the upper trunk (C5 and C6)
Upper brachial plexus injuries (Erb-Duchenne / Erb’s palsy) result from _____ in adults and _____ in newborns
Upper brachial plexus injuries (Erb-Duchenne / Erb’s palsy) result from a blow to the shoulder producing excessive separation of the neck and shoulder in adults and pulling of head when arm is caught in birth canal in newborns
Injury to the upper brachial plexus (Erb-Duchenne / Erb’s palsy) causes _____, resulting in _____
Injury to the upper brachial plexus (Erb-Duchenne / Erb’s palsy) causes paralysis of proximal limb muscles (C5, C6 myotomes), resulting in waiter’s tip position
Describe waiter’s tip position
Waiter’s tip position
- Results from injury to upper brachial plexus
- Paralysis of proximal limb muscles (C5, C6 myotomes)
- Loss of arm flexion, abduction, and lateral rotation (biceps, deltoid, supraspinatus, infraspinatus, teres minor)
- Loss of forearm flexion and weakness of supination (biceps, brachialis, brachioradialis)
- Weakness of wrist extension (wrist extensors innervated in part by C6)
- Limb hands by side in medial rotation and pronation, hand is flexed
Upper brachial plexus injury (Erb-Duchenne / Erb’s palsy) results in _____ of the _____ dermatomes on the _____ side of the arm, forearm, and hand
Upper brachial plexus injury (Erb-Duchenne / Erb’s palsy) results in anesthesia of the C5-6 dermatomes on the lateral side of the arm, forearm, and hand
Lower brachial plexus injuries (Klumpke’s palsy) result from _____
Lower brachial plexus injuries (Klumpke’s palsy) result from traction or tear of the lower trunk (C8, T1)
Lower brachial plexus injuries (Klumpke’s palsy) result from _____ in adults and _____ in newborns
Lower brachial plexus injuries (Klumpke’s palsy) result from grasping something to break a fall in adults and forceful upward pull of the shoulder during birth by pulling on the arm when the head is caught in the birth canal in newborns
Lower brachial plexus injuries (Klumpke’s palsy) may cause _____ due to compression of the _____ and _____ against the first rib by a cervical rib
Lower brachial plexus injuries (Klumpke’s palsy) may cause thoracic outlet syndrome due to compression of the trunk and subclavian artery against the first rib by a cervical rib
Lower brachial plexus injuries (Klumpke’s palsy) result in _____, causing _____
Lower brachial plexus injuries (Klumpke’s palsy) result in paralysis of distal limb muscles (C8, T1 myotomes) primarily affecting intrinsic hand muscles innervated by median and ulnar nerves, causing Klumpke’s total claw hand
Lower brachial plexus injuries (Klumpke’s palsy) result in _____ in the _____ dermatomes along the _____ side of the arm, forearm, and hand
Lower brachial plexus injuries (Klumpke’s palsy) result in anesthesia in the C8 and T1 dermatomes along the medial side of the arm, forearm, and hand
Describe Klumpke’s total claw hand
Klumpke’s total claw hand
- Caused by lower brachial plexus injuries
- Paralysis of distal limb muscles (C8, T1) primarily affecting intrinsic hand muscles innervated by the median and ulnar nerves
- Loss of flexion of MCP joints (interossei, lumbricals)
- Loss of extension of PIP and DIP joints (lumbricals) in fingers
- Paralysis of thenar and hypothenar muscles
Interossei function to _____ and _____ the fingers and _____ the MCP joints
Interossei function to adduct and abduct the fingers and flex the MCP joints
Lumbricals ____ the PIP and DIP joints and assist interossei in ____ the MCP joints
Lumbricals extend the PIP and DIP joints and assist the interossei in flexing the MCP joints
In Klumpke’s total claw hand, patients cannot ____ the MCP joints or ____ the IP joints
In Klumpke’s total claw hand, patients cannot flex the MCP joints or extend the IP joints
(unopposed actions of long extensors and flexors pull the MCP joints of all digits into hyperextension and the IP joints into flexion, causing Klumpke’s total claw hand)
____ can compress or cut the median nerve proximally
Fractures of the supracondylar humerus can compress or cut the median nerve proximally
____ is the most common cause of injury to the median nerve distally
Carpal tunnel syndrome is the most common cause of injury to the median nerve distally
(produced by repetitive hand and finger movements that lead to swelling of the long flexor tendons and their synovial sheaths, compressing the median nerve)
Repetivie hand and finger movements cause carpal tunnel syndrome by promoting ____ of the long flexor tendons and their synovial sheaths, ____ the nerve
Repetivie hand and finger movements cause carpal tunnel syndrome by promoting swelling of the long flexor tendons and their synovial sheaths, compressing the nerve
Median nerve innervates _____ and the _____ intrinsic hand muscles
Median nerve innervates all flexor forearm muscles except for the 1.5 innervated by the ulnar nerve and the med. LOAF intrinsic hand muscles
- med - median nerve
- L - 1st and 2nd lumbricals
- O - opponens pollicis
- A - abductor pollicis brevis
- F - flexor pollicis brevis (superficial head)
Med. LOAF stands for _____, all of which are _____ hand muscles
Med. LOAF stands for median nerve, 1st and 2nd lumbricals, opponens pollicis, abductor pollicis brevis, and flexor pollicis brevis (superficial head)
(innervated by median nerve)
_____ lesions of the median nerve produce _____ caused by long of thumb opposition (flexion and abduction) with atrophy of thenar eminence
Proximal and distal lesions of the median nerve produce ape hand caused by long of thumb opposition (flexion and abduction) with atrophy of thenar eminence
(thumb remains extended and adducted)
Sensory changes caused by injury to median nerve are ____
Sensory changes caused by injury to median nerve are on the dorsal and palmar surfaces of the thumb, index, middle, and lateral half of the ring fingers (lateral 3.5 digits) and adjacent portion of the palm
_____ lesions to the median nerve produce _____ when the patient is asked to _____ the fingers
Proximal lesions to the median nerve produce Pope’s hand / hand of benediction when the patient is asked to flex the fingers
- Cannot flex digits 2 and 3 (index and middle fingers) due to paralysis of flexor digitorum superficialis and lateral half of flexor digitorum profundus
Distal lesions to the median nerve produce _____
Distal lesions to the median nerve produce median claw hand of digits 2 and 3
- Unopposed actions of long flexors (flexor digitorum superficialis and lateral half of flexor digitorum profundus) and extensors (extensor digitorum, extensor incisis) pull the MCP joints of the index and middle fingers into extension and the IP joints into flexion
Describe proximal lesions of the ulnar nerve
Proximal lesions of the ulnar nerve
- Fractures of the medial epicondyle can cut the ulnar nerve
- Ulnar nerve can be compressed in the ulnar groove of the humerus or between two heads of flexor carpi ulnaris (cubital tunnel syndrome)
Fractures of the _____ can cut the ulnar nerve proximally
Fractures of the medial epicondyle can cut the ulnar nerve proximally
Ulnar nerve can be compressed proximally in the ____ or between ____
Ulnar nerve can be compressed proximally in the ulnar groove of the humerus or between two heads of flexor carpi ulnaris (cubital tunnel syndrome)
Describe distal lesions of the ulnar nerve
Distal lesions of the ulnar nerve
- Ulnar nerve can be compressed or cut at wrist in tunnel of Guyon deep to pisohamate ligament
- Fracture of hook of hamate (falling onto outstretched hand) can cut ulnar nerve
Ulnar nerve can be compressed or cut distally at the wrist in the _____ deep to the pisohamate ligament
Ulnar nerve can be compressed or cut distally at the wrist in the tunnel of Guyon deep to the pisohamate ligament
Fracture of _____ while falling onto an outstretched hand can cut the ulnar nerve distally
Fracture of hook of hamate while falling onto an outstretched hand can cut the ulnar nerve distally
Describe the ulnar nerve
Ulnar nerve
- Innervates 1.5 flexor forearm muscles (flexor carpi ulnaris, medial half of flexor digitorum profundus)
- Innervates all of the intrinsic hand muscles not innerved by med. LOAF
- Supplies skin on the dorsal and palmar surfaces on the medial side of hand, little finger, and middle side of ring finger (medial 1.5 finger)
Both proximal and distal lesions of ulnar nerve lead to loss of _____ and _____ of the fingers with atrophy of the intermetacarpal spaces, loss of thumb _____, and loss of PIP and DIP joint _____ of the ring and little fingers
Both proximal and distal lesions of ulnar nerve lead to adduction and abduction of the fingers with atrophy of the intermetacarpal spaces, loss of thumb abduction, and loss of PIP and DIP joint extension of the ring and little fingers
- Loss of adduction: palmar interossei
- Loss of abduction: dorsal interossei
- Loss of thumb adduction: adductor pollicis
- Loss of PIP and DIP joint extension of ring and little fingers: 3rd and 4th lumbricals
Proximal and distal lesions of the ulnar nerve lead to sensory changes _____
Proximal and distal lesions of the ulnar nerve lead to sensory changes on the dorsal and palmar surfaces of the medial side of the hand, the little finger, and the medial side of the ring finger (medial 1.5 fingers)
Distal lesions of ulnar nerve produce _____
Distal lesions of ulnar nerve produce ulnar claw hand of digits 4 and 5
Ulnar claw hand happens when patient is asked to ____ the fingers
Ulnar claw hand happens when patient is asked to extend the fingers
(resembles Pope’s blessing / hand of benediction seen in median nerve injury except that Pope’s blessing occurs upon flexing)
Proximal lesions of ulnar nerve result in paralysis of the forearm and hand muscles innervated by the ulnar nerve and differ from distal lesions in that there is _____ and _____
Proximal lesions of ulnar nerve result in paralysis of the forearm and hand muscles innervated by the ulnar nerve and differ from distal lesions in that there is mild claw ulnar claw hand of digits 4 and 5 and weakness of wrist flexion (flexor carpi ulnaris)
Summarize injuries to the median and ulnar nerves
Injuries of the median and ulnar nerves
Describe causes of radial nerve injury
Radial nerve injury causes
- Fractures of humeral shaft can cut radial nerve
- Compression of nerve in radial groove by back of chair (Saturday night palsy), someone’s head (honeymoon palsy), and poorly fitting crutches (crutch palsy)
- When nerve is injured in radial groove, triceps is not completely paralyzed because only the medial head is affected
Fractures of the humeral shaft can cut the ____ nerve
Fractures of the humeral shaft can cut the radial nerve
Saturday night palsy, honeymoon palsy, and crutch palsy refer to _____
Saturday night palsy, honeymoon palsy, and crutch palsy refer to compression of the nerve in the radial groove
(when the radial nerve is injured in the radial groove, the triceps is not completely paralyzed because only the medial head is affected)
Radial nerve innervates the muscles that extend the _____ and _____ and supplies the skin on the _____
Radial nerve innervates the muscles that extend the elbow (triceps), wrist, and MCP joints (posterior forearm muscles) and supplies the skin on the posterior surface of the arm, forearm, and radial half of the back of the hand
Injury to radial nerve causes paralysis of _____ muscles causing a _____ and inability to _____ the _____ joints
Injury to radial nerve causes paralysis of forearm extensor muscles causing a wrist drop and inability to extend the MCP joints
Describe what would happen to a patient with radial nerve injury due to a midshaft fracture of the humerus
Patient with radial nerve injury due to a midshaft fracture of the humerus
- Paralysis of forearm extensor muscles causes a wrist drop and inability to extend the MCP joints
- Anesthesia is limited to a small patch on the radial half of the dorsum of the hand because of overlap from adjacent cutaneous nerves
_____ and _____ can cause injury to the axillary nerve (C5, C6)
Fractures of the humeral surgical neck cutting the nerve and dislocations of the shoulder joint stretching the nerve can cause injury to the axillary nerve (C5, C6)
Axillary nerve injury to axillary nerve causes loss of _____ and weakness of _____ and anesthesia over the _____
Axillary nerve injury to axillary nerve causes loss of abduction (deltoid) and weakness of lateral rotation (teres minor) of the arm and anesthesia over the lateral surface of the shoulder
(rounded contour of shoulder is lost)
Long thoracic nerve (C5-7) is commonly injured during _____
Long thoracic nerve (C5-7) is commonly injured during surgery (mastectomy, thoracic surgery)
Injury to long thoracic nerve causes _____ but no _____ loss
Injury to long thoracic nerve causes paralysis of serratus anterior causing loss of protraction and upward rotation of scapula leading to winging of scapula and no sensory loss
Injury to the long thoracic nerve causes ____ of the scapula
Injury to the long thoracic nerve causes winging of the scapula
Musculacutaneous nerve (C5-7) is injured by _____
Musculacutaneous nerve (C5-7) is injured by penetrating wounds in the axilla
Musculocutaneous nerve (C5-7) injury leads to _____, _____, and _____
Musculocutaneous nerve (C5-7) injury leads to severe weakness of forearm flexion (brachialis, biceps), weakness of supination (biceps) and arm flexion (coracobrachialis, biceps), and anesthesia on the lateral surface of the forearm (lateral antebrachial cutaneous nerve)
