Flashcards in Nerve Palsies in Limbs Deck (61)
Where does each peripheral nerve start from?
Sensory area of the skin supplied by a single spinal nerve
How do dermatomes develop?
-Adjacent dermatomes overlap considerably
-Embryological development of limb buds growing out from body wall results in axial lines (anterior and posterior) - there is no overlap between adjacent pre- and post-axial dermatomes
What are the dermatomes of the lower limb?
-STAND on S1
-SLEEP on S2
-SIT on S3
-**** on S4
Why are the dermatomes of the lower limb distorted?
Lower limb dermatomes distorted by rotation and extension, and “borrowing” of skin from trunk
What is Hilton's law?
The nerve crossing a joint supply the muscles acting on it and joint itself
What are the implications of Hilton's Law?
-May supply 2 joints, eg. hip and knee supplied by femoral, sciatic and obturator nerves
Therefore, HIP DISEASE MAY GIVE RISE TO KNEE PAIN
What is the hip joint supplied by?
-Obturator nerve (predominantly)
-Lateral femoral cutaneous nerve
Group of muscles supplied by one segment of the spinal cord
What is the brachial plexus?
Large network of nerves supplying the upper limb, extending from the cervical spine to the axilla
How is the brachial plexus divided?
How does Erb's palsy occur?
Downward traction such as a fall on the side of the neck
What happens if C5 and C6 are damaged?
-Deltoid and shoulder muscles, brachialis and biceps all affected
How does Klumpke's paralysis occur?
Upward traction for example in a breech delivery
What happens if T1 is damaged?
-Intrinsic muscles are damaged
Give examples of brachial plexus injuries?
Where is the axillary nerve at most risk of injury?
Surgical neck of the humerus
What is Saturday night palsy?
-Complication of humeral neck fracture, and shoulder dislocation
-Caused by pressure on the posterior cord of the brachial plexus
What does axillary nerve injury result in?
-Motor deficit: loss of shoulder abduction (deltoid)
-Sensory deficit over the badge area
What are the roots of the radial nerve?
What is the radial nerve closely associated with in the arm?
Profunda brachii artery
How does the radial nerve enter the forearm?
Enters forearm by passing between - brachioradialis & brachialis (and posterior interosseous branch of radial nerve passes between 2 planes of supinator)
Where is the radial nerve most at risk?
Spiral groove of humerus and lateral intermuscular septum (and posterior interosseous branch at radial neck)
How does radial nerve injury present?
-Motor deficit: wrist drop (extensors)
-Sensory deficit in the 1st web space dorsally
What are the roots of the median nerve?
What is the median nerve closely associated with in the arm?
How does the median nerve enter the forearm?
Enters forearm by passing between - two heads of pronator teres
Where is the median nerve most at risk?
Volar aspect of wrsit (and cubital fossa)
What can median nerve injury occur as a result of?
-Carpal tunnel syndrome
-Wrist lacerations (and supracondylar fractures, Struther;s ligament)