The Hand

Question 1

What do intrinsic and extrinsic muscles of the hand actually mean?

Answer 1

Intrinsic muscles: The muscles that move the hand originate from the hand itself

Extrinsic muscles: The muscles that move the hand originate outside the hand in the forearm

Question 2

Function of intrinsic muscles

Answer 2

Fine movement

Question 3

Function of extrinsic muscles

Answer 3

Power

Question 4

Try the following movements with the THUMB:
Abduction
Adduction
Extension
Flexion
Opposition
Reposition

Answer 4

Picture

Question 5

What different kinds of grips are there? Give examples of each

Answer 5

Power:
Prehensile - cylindrical grip (holding a racket), light tool grip (like a push pen), sphere grip (tennis ball)
Non prehensile - hook grip

Precision - key pinch, sphere pinch (inspecting an apple), fine pinch (index and thumb crab), plate (passing over the book)

Question 6

What is the clinical symptom of a radial nerve injury?

Answer 6

Wrist drop

No extension of wrist or digits (unopposed action of FDS and FDP)
Weak flexion at DIP joint from intrinsic muscles of the hand

Question 7

What are precision grips?

Answer 7

When objects are held between the tip of the thumb and 1,2 or 3 fingers

Question 8

What muscles are involved in precision grips?

Answer 8

Intrinsic muscles cooperate with the long flexor and extensor muscles

Question 9

From what age can precision grips happen?

Answer 9

9 months

Question 10

Causes of radial nerve injury

Answer 10

Known as Saturday night palsy

Cause: radial nerve in armpit or upper arm compressed or stretched
Usually due to falling asleep with arm hanging

In infants: prolonged pressure of inferior arm by pelvic brim

Symptoms: wrist drop

Question 11

Symptoms of radial nerve palsy in infants

Answer 11

Wrist drop
Inability to extend thumb and MCP of all digits
Weak extension of elbow

Question 12

General symptom of radial nerve injury

Answer 12

Wrist drop

Question 13

What is an example of a High Median Nerve injury? What are the symptoms?

Answer 13

Hand of benediction

Loss of flexion in MCP in digits 23
Loss of flexion in PIP in digits 123
Loss of flexion in DIP in digits 23
Weak PIP flexion in digits 45 (ulna innervates FDP and FCU)

Question 14

What is an example of a low median nerve injury? Symptoms

Answer 14

Carpal tunnel syndrome
Any condition reducing size of carpal tunnel causing compression of median nerve

Progressive loss of coordination and strength in thumb

Question 15

What muscles are involved in a ulna nerve injury?

Answer 15

Clawhand

Flexor carpi ulnaris
Medial half of FDP
Medial two 
All interossei (palmar and dorsal) 
Adductor pollicis

Question 16

Symptoms of a ulna nerve injury?

Answer 16

Thumb abducted and extended with distal phalanx flexed
First two fingers fully extended, DIPs slightly flexed

Medial 2 fingers hyperextended at MCP joints but flexed at DIP joints

Question 17

What is the difference between a high ulnar lesion and low ulnar lesion?

Answer 17

High lesion - both intrinsic hand and FDP weak (clawing is milder)

Low lesion - only the intrinsic muscles are weak making the clawing more severe

Called the Ulnar paradox

Question 18

Where is the most common site of ulnar nerve injury?

Answer 18

Medial epicondyle of the humerus

Question 19

What percentage of nerve lesions to the upper limb include the ulnar?

Answer 19

27%

Question 20

What is high ulnar nerve palsy called?

Answer 20

Cubital tunnel syndrome

High: all muscles lost

Question 21

Example of low ulnar nerve palsy?

Answer 21

Guyon’s canal syndrome

Low = FDP pulls digit 4 and 5 into flexion

Question 22

What is another name for the knuckles?

Answer 22

Metacarpophalangeal joint

MCP

Question 23

What movements can occur at the MCP joints

Answer 23

Flexion
Extension
Abduction
Adduction

Question 24

What movements occur at PIP and DIPs?

Answer 24

Flexion and extension

Question 25

What is the opposition of the thumb?

Answer 25

Thumb touching any of the other fingers

Question 26

What is abduction of the thumb?

Answer 26

When thumb is at right angles to the palm

Question 27

What is flexion of the thumb?

Answer 27

Thumb to palm

Question 28

What is extension of the thumb

Answer 28

Flat out

Opposite of flexion

Question 29

Where do the flexors of the forearm originate from?

Answer 29

Medial epicondyle

Question 30

Where do the extensors of the forearm originate from?

Answer 30

Lateral epicondyle