Wrist Region Flashcards
What are the proximal carpal bones, listed from lateral to medial?
Scaphoid, lunate, triquetrum, pisiform
What are the distal carpal bones, listed from lateral to medial?
Trapezium, trapezoid, capitate, hamate
What are the bones that make up the carpal arch, lateral to medial? What projections make up the walls of it?
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.
Where does the pisiform lie in relation to the triquetrum?
It lies on the anterior aspect of it and articulates with it. Still technically in the same row
What carpal bones articulate at the radioulnar joint? What are the features of the joint?
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
What collateral ligaments support the radioulnar joint?
The ulnar collateral ligament - from styloid process of ulna to pisiform / triquetrum
Radial collateral ligament - from styloid process of radius to scaphoid
What is the flexor retinaculum?
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
What flexors tendons do not pass through the carpal tunnel?
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)
What is carpal tunnel syndrome and how is it treated?
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.
What is the function of the ulnar bursa?
A common sheath with synovial fluid encloding all the tendons of the flexor superficialis and profundus tendons
What is the function of the radial bursa?
A singular continuous sheath surrounds the tendon of the flexor pollicis longus.
What is the third, forgotten synovial sheath of the front of the wrist?
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
Where do the bursae of the flexors stop?
Only continuous for digits 1 and 5, digits 2-4 end about mid-palm level and are then restarted in the digits.
What does dupuytrens contracture do?
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
What is the palmar aponeurosis?
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.
What is the extensor retinaculum?
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.
What are the six compartments of the synovial sheaths containing tendons under the extensor retinaculum?
From lateral (thumbside) to medial:
- Abductor pollicis longus and extensor pollicis brevis
- Extensor carpi radialis longus and extensor carpi radialis brevis
- Extensor pollicis longus
- Extensor digitorum and extensor indicis
- Extensor minimi
- Extensor carpi ulnaris
What’s the anatomical snuff box?
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.
Why is there often no palmar sensory loss even with a pinched median nerve in the carpal tunnel?
Before entering the carpal tunnel, the median nerve sends a palmar cutaneous branch above the flexor retinaculum.
How does the median nerve enter the wrist?
It is found between the tendon of the flexor carpi radialis and palmaris longus, before dipping down into the carpal tunnel.
What does the median nerve innervate in the hand?
Cutaneous sensation of lateral 3-1/2 digits, as well as motor innervation of the thenar muscles
What does ulnar nerve damage cause?
- Sensory impairment of anterior and posterior aspects of medial part of hand (including digits 3.5-5)
- Decreased abduction and adduction of figiners
- Paralysis of two medial lumbricals
- Adductor pollicis paralysis
Where do most wrist fractures occur?
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)
What are the main nerves that you worry about in wrist slash?
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.
What are the zones of ulnar nerve injury in the hand?
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
