Wrist Region

Question 1

What are the proximal carpal bones, listed from lateral to medial?

Answer 1

Scaphoid, lunate, triquetrum, pisiform

Question 2

What are the distal carpal bones, listed from lateral to medial?

Answer 2

Trapezium, trapezoid, capitate, hamate

Question 3

What are the bones that make up the carpal arch, lateral to medial? What projections make up the walls of it?

Answer 3

Trapezium, trapezoid, capitate, hamate, triquetum, pisiform.

The pisiform and tubercule of trapezium make up the arched walls.

Scaphoid and lunate are not found as they articulate with the radius.

Question 4

Where does the pisiform lie in relation to the triquetrum?

Answer 4

It lies on the anterior aspect of it and articulates with it. Still technically in the same row

Question 5

What carpal bones articulate at the radioulnar joint? What are the features of the joint?

Answer 5

scaphoid, lunate, and triquetrum. The carpal bones are convex and the radius is concave. The joint capsule has articular cartilage and is reinforced by the palmar and dorsal radiocarpal ligaments

Question 6

What collateral ligaments support the radioulnar joint?

Answer 6

The ulnar collateral ligament - from styloid process of ulna to pisiform / triquetrum
Radial collateral ligament - from styloid process of radius to scaphoid

Question 7

What is the flexor retinaculum?

Answer 7

A layer of the deep antebrachial fascia, forms the roof of the carpal tunnel. All intermediate and deep flexors go through the carpal tunnel, all superficial flexors pass anterior to it.

From pisiform and hamate on medial side to scaphoid and trapezium on the lateral side

Question 8

What flexors tendons do not pass through the carpal tunnel?

Answer 8

All the superficial flexors. That is, flexor carpi ulnaris (most medial), flexor carpi radialis (most lateral, passes through the flexor retinaculum), and palmaris longus (passes just above carpal tunnel)

Question 9

What is carpal tunnel syndrome and how is it treated?

Answer 9

Results from decrease in size of carpal tunnel due to swelling of tendons, overuse of digits, or compression by broken bone. Flexor retinaculum can be incized to relieve the condition.

Question 10

What is the function of the ulnar bursa?

Answer 10

A common sheath with synovial fluid encloding all the tendons of the flexor superficialis and profundus tendons

Question 11

What is the function of the radial bursa?

Answer 11

A singular continuous sheath surrounds the tendon of the flexor pollicis longus.

Question 12

What is the third, forgotten synovial sheath of the front of the wrist?

Answer 12

The tendon of the flexor carpi radialis (extends to base of metacarpals II and II) which passes through the flexor retinaculum but is not technically part of the carpal tunnel since it’s a superficial muscle

Question 13

Where do the bursae of the flexors stop?

Answer 13

Only continuous for digits 1 and 5, digits 2-4 end about mid-palm level and are then restarted in the digits.

Question 14

What does dupuytrens contracture do?

Answer 14

It is a progressive fibrosis of the palmar aponeurosis which can cause it to shorten / thicken and ultimately result in the slight flexion of the fingers at the metacarpophalangeal joints

Question 15

What is the palmar aponeurosis?

Answer 15

It has longitudinal and transverse fibers, and is an extension of the deep fascia. It is attached to the palmaris longis muscle (superficial flexor) and extends as four slips covering the flexor tendons of the four medial fingers.

Question 16

What is the extensor retinaculum?

Answer 16

Antebrachial fascia including six synovial compartments just proximal to it. Holds the extensors, and runs laterally from the anterior border of the radius to the styloid process of the ulna.

Question 17

What are the six compartments of the synovial sheaths containing tendons under the extensor retinaculum?

Answer 17

From lateral (thumbside) to medial:

1. Abductor pollicis longus and extensor pollicis brevis
2. Extensor carpi radialis longus and extensor carpi radialis brevis
3. Extensor pollicis longus
4. Extensor digitorum and extensor indicis
5. Extensor minimi
6. Extensor carpi ulnaris

Question 18

What’s the anatomical snuff box?

Answer 18

Just distal to the styloid process, it’s where three thumb tendons form a triangular interval. Abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus. The ceiling contains the superficial radial nerve, and the floor is the radial artery (you can find a pulse here). It is easily palpatable.

Question 19

Why is there often no palmar sensory loss even with a pinched median nerve in the carpal tunnel?

Answer 19

Before entering the carpal tunnel, the median nerve sends a palmar cutaneous branch above the flexor retinaculum.

Question 20

How does the median nerve enter the wrist?

Answer 20

It is found between the tendon of the flexor carpi radialis and palmaris longus, before dipping down into the carpal tunnel.

Question 21

What does the median nerve innervate in the hand?

Answer 21

Cutaneous sensation of lateral 3-1/2 digits, as well as motor innervation of the thenar muscles

Question 22

What does ulnar nerve damage cause?

Answer 22

1. Sensory impairment of anterior and posterior aspects of medial part of hand (including digits 3.5-5)
2. Decreased abduction and adduction of figiners
3. Paralysis of two medial lumbricals
4. Adductor pollicis paralysis

Question 23

Where do most wrist fractures occur?

Answer 23

At the distal end of the radius. Rarely, the scaphoid will fracture when the stress occurs during wrist abduction (scaphoid is stressed by styloid process of radius)

Question 24

What are the main nerves that you worry about in wrist slash?

Answer 24

Median nerve, since it runs superficially before dipping into carpal tunnel (between palmaris longus and flexor carpi radialis tendons)
Ulnar nerve, it always runs superficially medially.

Question 25

What are the zones of ulnar nerve injury in the hand?

Answer 25

The ulnar nerve branches in the hand. If you injure it after it branches, sensory or motor loss will depend on which strand (anterior / sensory or posterior / motor) you damaged. If you injure it proximal to that, you will have both sensory and motor damage