Week 3 - Severson Flashcards
How do fractures of the olecranon process of the elbow usually occur?
Fall on the elbow combined with sudden powerful contraction of the triceps brachii
How does a Colles’ and Smith’s fracture differ?
- Colles
- displacement of the distal radius posteriorly (dorsally)
- Smith’s
- a.k.a. reverse Colles
- displacement of the distal radius anteriorly (ventrally)
What nerve is responsible for supplying most of the forearm flexors?
Median nerve
What forearm muscles are supplied by the ulnar nerve?
Flexor carpi ulnaris
&
Medial part of: Flexor digitorum profundus
How would the clinical manifestations of injury to the median nerve differ when it occurs in the arm or proximal forearm versus the distal forearm?
- Proximal:
- flexion of the PIP joints of the 1st-3rd digits is lost and flexion of the 4th & 5th digits is weakened
- flexion of the DIP joints of the 2nd & 3rd digits is also lost
- unable to make a fist, 2nd & 3rd fingers remain partially extended (“hand of benediction”)
- Distal:
- paresis of the flexor digitorum profundus and flexor pollicis longus occurs
- Abnormal “ok” sign (“pinch ok”)
Why is the median nerve involved in pronator syndrome?
nerve entrapment syndrome: caused by compression of the median nerve near the elbow
(compression by pronator teres)
What is Volkmann’s contracture?
ischemic compartment syndrome
- 6+ hours of ischemia of muscles/nerves
- fibrous scar tissue replaces necrotic tissue
- involved muscles shorten permanently
- flexion deformity
Where is ulnar nerve injury most likely to occur?
where the nerve passes posterior to the medial epicondyle of the humerus
What muscles would be affected with ulnar nerve injury in the proximal forearm?
intrinsic hand muscles
Why is adduction (medial or ulnar deviation) of the hand difficult following ulnar nerve injury in the arm or elbow?
no FCU
How would ulnar injury differ if it occurs in the distal forearm?
atrophy of the interosseous muscles = claw hand
What is cyclist’s palsy and how does it occur?
- Ulnar neuropathy, known to cyclists as handlebar palsy, is caused by compression of the ulnar nerve at the hand and wrist (medal to hypothenar eminence)
- Causes numbness and tingling in 4th & 5th digits
- Compression is the result of direct pressure on the ulnar nerve from the grip on the handlebars
What is cubital tunnel syndrome?
ulnar nerve entrapment in the cubital tunnel formed by the tendinous arch joining the humeral and ulnar heads of attachment of the FCU
Why is flexion of the distal interphalangeal (DIP) joints of the fourth and fifth digits impaired with ulnar nerve injuries?
flexion of the 4th & 5th DIP’s is controlled by the flexor digitorum profundus, which is innervated by the ulnar nerve
Why does injury to the ulnar nerve produce “clawhand” when a patient attempts to make a fist?
in the absence of opposition, the metacarpophalangeal joints become hyperextended, and the patient cannot flex the 4th & 5th digits at the distal interphalangeal joints when trying to make a fist
(distal lesion of the ulnar nerve)
What vessel is usually used to measure the pulse rate?
Radial artery
What general dysfunction is produced by injury to the radial nerve?
Wrist drop
What two muscles are involved in supinating the forearm?
Supinator & Biceps brachii
What nerve(s) innervate the two muscles that supinate the forearm?
Supinator: Deep branch of radial nerve
Biceps brachii: Musculocutaneous nerve
The tendons of what three muscles are responsible for forming the anatomical “snuffbox”?
Extensor pollicus longus, Abductor pollicis longus, Extensor pollicis brevis
What group of muscles is involved with lateral epicondylitis or “tennis elbow”?
Extensor tendons from the lateral epicondyle:
- Extensor carpi radialis
- Extensor carpi ulnaris
What group of muscles is inolved with medial epicondylitis or “golfer’s elbow”?
Flexor tendons of the forearm
Why does “wrist drop” occur with injury to the radial nerve?
the radial nerve innervates the extensors
when damaged, there is no opposing force to the forearm flexors
Why is there an inability to extend the thumb and MCP joints, but not the PIP and DIP joints following injury to the radial nerve?
the interphalangeal joints can be extended weakly through the action of the intact lumbricals and interossei which are supplied by the median and ulnar nerves
How do the clinical symptoms differ following severance of the radial nerve in the radial groove versus the distal arm?
- Radial groove:
- wrist drop
- Distal arm: ?
- inability to extend the thumb and MCP joins of the other digits
How do the clinical symptoms differ following severance of the superfical and deep branches of the radial nerve?
- Superficial:
- coin-shaped area of anesthesia distal to the bases of the 1st & 2nd metacarpals
- Deep:
- inability to extend the thum and the MCP joints
What blood vessel accompanies the radial nerve?
Arm: Profunda brachii artery
Forearm: Deep branch of the radial nerve is accompanied by the Posterior interosseous artery
What are the three major joints of the forearm?
- Humero-ulnar joint (hinge type)
- Proximal radio-ulnar joint
- Humero-radial joint
What are the three major ligaments of the forearm?
- Radial collateral ligament
- lateral epicondyle to radius
- Ulnar collateral ligament
- medial epicondyle to ulna
- Anular ligament
- a circular ligament holding the head of the radius to the ulna
How does bursitis occur in the elbow region?
injury during falls on the elbow and infection from abrasions of the skin covering the olecranon
What nerve may be injured with avulsion of the medial epicondyle?
Ulnar nerve
What clinical symptoms would result from avulsion of the medial epicondyle?
- severe abduction of the extended elbow
- ulnar collateral ligament pulls the medial epicondyle distally
- epiphysis for the medial epicondyle may not fuse with the distal end of the humerus
What is a “pulled elbow”?
Subluxation (incomplete dislocation) of the head of the radius
How does subluxation or dislocation of the radial head usually occur?
A child is suddently lifted (jerked) by the upper lim while the forearm is pronated.
What ligament is torn in subluxation or dislocation of the radial head?
distal attachment of the anular ligament
What carpal bones articulate with the distal radius?
Lunate & Scaphoid
What carpal bone is most frequently fractured?
Scaphoid
What bone lies in the floor of the anatomical snuffbox?
Scaphoid
What blood vessel is found in the anatomical snuffbox?
Palmar carpal branch of the Radial artery
What clinical complaint would you expect from the patient following fracture of this bone?
Pain to lateral wrist,
especially with dorsiflexion and abduction
What bones are injured in a patient with a “boxer’s fracture”?
5th metacarpal
What nerve is involved in carpal tunnel syndrome?
Median nerve
What are the clinical manifestations of carpal tunnel syndrome?
Unable to oppose thumb
difficulty buttoning a shirt
trouble gripping things (comb)
Why is there loss of flexion of the PIP joints of all digits with severance of the median nerve in the proximal forearm or arm?
the median nerve innervates the flexor digitorum superficialis, which flexes the middle phalanges at PIP joints of four digits
Why is there loss of flexion of only the DIP joints of the index and middle fingers and not the ring and middle fingers with severance of the median nerve?
the median nerve only innervates the thenar muscles and first two (lateral) lumbricals
Why is flexion of the MCP joints and extension of the PIP/DIP joints of the index and middle fingers affected by injuries of the median nerve in the elbow region?
digital branches of the median nerve supply the 1st and 2nd lumbricals
When and where does injury to the median nerve usually occur?
Laceration of the wrist
- attempted suicides
- wrist slashing
What is the relationship of the median nerve to the tendons of the flexor carpi radialis and the palmaris longus?
Medial to FCR
Deep to Palmaris longus
What clinical signs with respect to the median nerve may one expect with pronator syndrome?
- pain and tenderness in the proximal aspect of the anterior forearm
- hypesthesia (decreased sensation) of palmar aspects of the radial three and half digits and adjacent palm
What is a “ganglion”?
swelling or knot
non-tender cystic swelling on the dorsum of the wrist
(often from carpal tunnel syndrome)
What is meant by “hand of benediction”?
partially extended 2nd and 3rd MCP joints when trying to make a fist (inability to flex digits 2/3 into a compact fist)
(occurs in median nerve injury near the elbow)
