Carpal Tunnel Syndrome Flashcards
What is carpal tunnel syndrome?
A collection of symptoms and signs caused by compression of the median nerve in the carpal tunnel
What is the carpal tunnel?
An anatomical compartment at the base of the palm
What forms the postero-lateral boundary of the carpal tunnel?
Scaphoid and trapezium
What forms the postero-medial boundary of the carpal tunnel?
Hook of the hamate and the pisiform
What forms the anterior boundary of the carpal tunnel?
The flexor retinaculum
What is the contents of the carpal tunnel?
- 9 flexor tendons in synovial sheaths
- Median nerve
What are the 9 flexor tendons in the carpal tunnel?
- 4 of flexor digitorum profundus
- 4 of flexor digitorum superficialis
- Flexor pollicis longus
What happens to the median nerve before entering the carpal tunnel?
It gives of the palmar cutaneous branch
What is the role of the palmar cutaneous branch of the median nerve?
It provides sensation to the lateral palm of the hand
What is true of the palmar cutaneous branch in carpal tunnel syndrome?
It does not travel through the carpal tunnel and so there is often sparing of the lateral palm in carpal tunnel syndrome
Once it has passed through the carpal tunnel what branches are given off by the median nerve?
- Recurrent motor branch
- Palmar digital nerves
What is the role of the recurrent motor branch of the median nerve?
Supplies the thenar muscle group
What is the role of the palmar digital nerve of the median nerve?
- Sensory innervation to the palmar skin and dorsal nail beds of the lateral 3and 1/2 digits
- Motor innervation of the lateral 2 lumbricals
What can lead to compression of the median nerve within the carpal tunnel?
- Decrease in size of the tunnel
- Increase in size of the contents
- Both
Why does increased tunnel pressure lead to compression of the median nerve?
The boundaries of the carpal tunnel are rigid