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Ulnar nerve entrapment
compression of ulnar n.
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Is compression of the ulnar n. at the elbow common?
yes
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What does ulnar nerve entrapment produce?
- numbness and tingling of the medial part of the palm and the fourth and fifth digits
- elbow pain that radiates distally
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What could cause radial n. injury?
deep wounds of forearm
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What does severance of the deep branch of the radial n. result in?
- inability to extend thumb and MP joints of other digits
- -no loss of sensation because this nerve is entirely muscular
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What is the result of serverance of the superficial branch of the raidal nerve?
loss of sensation on the posterior surface of the forearm, hand, and proxima phalanges of the lateral 3 and 1/2 digits
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Where is the most common site of radial nerve entrapment?
in the middle of the arm
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What is the result of radial nerve entrapment?
- wrist-drop
- normal strength of triceps m.
- sensory loss is variable and, if present, usually limited to a patch on the dorsum of the hand between the 1st and 2nd digits
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What could cause compressin of hte radial nerve?
- improper positioning of the upper limb during sleeping (Saturday night palsy)
- improper use of a touniquet
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Ganglion:
cystic, usually non-tender swelling of a tendon on dorsum of wrist or hand; size of grape-plum
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Where is a common site for cystic swelling?
distal attachment of extensor carpi radialis brevis tendon into the base of third metacarpal bone
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What bones lie in the floor of the anatomical snuff box?
scaphoid and trapezium
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Which bone is the most frequently fractured carpal bone?
scaphoid
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What occurs with injury to the scaphoid bone?
localized tenderness in the snuff box
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Elbow tendonitis:
painful musculoskeletal condition that may follow repetitive forceful pronation-supination of the forearm
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What characterizes elbow tendonitis?
pain and point tendeness at or just distal to lateral epicondyle of humerus and appears to result from premature degeneration of common extensor attachment of superficial extensor muscles of forearm
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What is the order of force transmission when a person falls on an outstretched hand with the forearm pronated?
main force of fall is transmitted through the carpal bones to distal ends of forearm bones, particularly radius, and then proximally to humeru, scapula, and clavicle
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When a person falls on the outstretched hand with the forearm pronated what injury could occur?
fractures in the wrist, forearm, or clavicle
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Where does the radius tend to break?
proximal to the wrist joint (Colles' fracture)
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When the radius breaks proximal to the wrist joint, the distal fragment of the radius is often:
comminuted (broken into pieces) and the fragments are usually displaces posteriorly and superiorly, producing shortening of the radius
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When there is a single fragment of the radius, it may be:
impacted (the jagged ends of bone are driven into each other)
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Displcement of the distal part of the radius often breaks of the ulnar:
styloid process, owing to the violent pll of the articular disc connecting the radius and ulna
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What is a common injury when a person falls on the palm with the hand abducted?
fracture of the scaphoid bone
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Dupuytren's contracture:
progressive fibrosis (increase in fibrous) tissue of the palmar aponeurosis, resulting in shortening and thickening of the fibrous bands that extend from the aponeurosis to the bases of the phalanges
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What do the fibrotic bands causedby Dupuytren's contracture cause?
pull the digits into such marked flexion at MP joints that they cannot be straightened (extended)
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Why are the potential fascial spaces of the palm clinically important?
they may become infected, the fascial spaces determine the extent and direction of the spread of pus formed by these infections
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If the median n. is severed in the forearm or at the wrist, how does this affect the thumb?
thumb cannot be opposed
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tensoynovitis
inflammation of the tendon and digital synovial sheath
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what happens with tenosynovitis?
digit swells and movement of it becomes painful
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Carpal tunnel syndrome
any lesion that significantly reduces the size of the carpal tunnel may cause compression of the median nerve
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Where does injury to the median nerve frequently occur?
just proximal to the flexor retinaculum, the common site of wrist slashing in suicide attempts
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Where can the median nerve be palpated?
just befre it passes deep to the flexor retinaculum and enters the carpal tunnel
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What movement is impaired when the median nerve is severed at the wrist?
- unable to oppose thumbs owing to paralysis of thenar muscles
- lumbricales 1 and 2 are paralyzed, weakening flexion of MP joints and extension of IP joints of 2nd and 3rd digits
- loss of cutaneous sensation in lateral portion of palm, palmar surface of thumb, and lateral two and 1/2 digits
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What does a laceration of the ulnar nerve produce?
- sensory alteration in medial part of hand, 5th digit, and medial half of 4th digit
- impaired power adduction and abduction of the fingers (paralysis of interossei)
- adduction of thumb is lost (paralysis of adductor pollicis)
- 4th ad 5th digits are hyperextended at MP joints and flexed at IP joints =clawhand
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Where might the ulnar nerve get compressed?
as it passes through a connective tissue canal (of Guyon), that is located superficial to the flexor retinaculum
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What is the result of ulnar nerve entrapment in the canal of Guyon?
pure motor neuropathy, which affects the hand muscles that are supplied by the ulnar nerve
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Does the radial nerve supply any muscles of the hand?
no
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Does the radial nerve injury in the arm or forearm produce serious disability of the hand?
yes
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Where is radial nerve injury seen on the hand?
anesthesia confined to small area on the lateral part of the dorsum of the hand
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What could cause dislocation of the acromioclavicular joint?
hard fall on the shoulder
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When the coracoclavicular ligament ruptures, the shoulder...
falls away from the clavicle owing to the weight of the upper extremity
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With dislocation of the acromioclavicular joint, the fibrous capsule ruptures, resulting in acromion passing:
infeior to the lateral end of the clavicle
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Dislocation of the acromioclavicular joint makes the acromion more:
obvious
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Calcific Supraspinatus Tendonitis:
inflammation and clacification of subacromial bursa
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What is the result of calcific supraspinatus tendonitis?
- pain, tenderness, and limitation of movement of the shoulder joint
- increased local pressure (during abduction of arm)
- irritation to subacromial bursa
- inflammatory recation (subacromial bursitis)
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What is another name for calcific supraspinatus tendonitis?
calcific scapulohumeral bursitis
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What causes rupture of the rotator cuff?
- when older person strains to lift something
- athletes owing to strain on shoulder joint
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Causes of dislocation of shoulder joint:
- excessive extension and lateral rotation of humerus
- head of humerus driven anteriorly, and fibrus capsule and glenoid labrum are stripped from anterior aspect of glenoid cavity
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Which nerve may be injured when the shoulder is dislocated?
axillary nerve because of its close relation to the inferior part of the articular capsule of this joint
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What exposes the subcutaneous olecranon bursa to injury?
falls on the elbow and to infction from abrasions of skin covering the olecranon process
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Friction bursitis (student's elbow)
repeated excessive friction that causes the bursa to become inflamed
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What are radioulnar bursitis a result of?
repeated or violent extension of the wrist with the forearm pronated
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With radioulnar bursitis, where does the pain occur?
on elbow extension when forearm is pronated
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What is bicipitoradial bursitis caused by?
when forearm is pronated, compressing bicipitoradial bursa against anterior half of radial tuberosity
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Fracture-separation of proximal radial epiphysis can result when a young person falls and...
exerts compression and abduction forces on the elbow joint
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What causes avulsion of the medial epicondyle of the humerus in children?
- a fall that causes abduction of extended elbow joint
- abnormal movement of this articulation
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When does the epiphysis for the medial epicondyle fuse with the distal end of the humerus?
may not until up to 20 years of age
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How does a child dislocate the elbow joint posteriorly?
fall on hands with elbows flexed
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Pulled elbow:
- subluxation (incomplete dislocation) of head of radius
- aka: slipped elbow, nursemaids elbow
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Is it common to fracture the lunate bone?
no
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Is it common to dislocate the lunate bone anteriorly?
yes
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What might a displaced lunate bone do?
compress the median nerve against flexor retinaculum
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