Wrist and Hand: Superficial Radial Dissection, N455, Anatomy, Upper Limb, Wrist and Hand

Wrist and Hand: Superficial Radial Dissection, N455, Anatomy, Upper Limb, Wrist and Hand

Lateral (Radial) View

Nerves:

1. Superficial branch of the Radial Nerve with its medial and lateral branches 
1. Lateral branches to the Lateral Thumb
2. Medial branch to the medical aspect of the thumb - Dorsal Digital branches of the radial nerve

Muscles and tendons

1. Abductor Pollicis longus tendon
2. Insertion of extensor Pollicis Brevius Tendon
3. Insertion of extensor pollicis Longus tendon
1. 1st Dorsal Interosseous Muscle
2. Extensor Carpi Radialis longus tendon
3. Extensor Carpi radialis Brevis tendon

Arteries

1. Radial Artery in the Anatomical Snuffbox with its dorsal carpal branch

Anatomical Snuffbox:

• Radial Nerve (dorsal digital branch)
• Cephalic Vein branches
• Radial Artery and branches
• Scaphoid  bone

Anatomical snuff box
anatomical snuff box
The mucous sheaths of the tendons on the back of the wrist. (Anatomical snuff box not labeled, but visible at right.)
Artery	radial artery
Vein	cephalic vein
Nerve	radial nerve

Pathology

The radius and scaphoid articulate deep to the snuffbox to form the basis of the wrist joint. In the event of a fall onto an outstretched hand, this is the area through which the brunt of the force will focus. This results in these two bones being the most often fractured of the wrist. In a case where there is localized tenderness within the snuffbox, knowledge of wrist anatomy leads to the speedy conclusion that the fracture is likely to be of the scaphoid. This is understandable as the scaphoid is a small, oddly shaped bone whose purpose is to facilitate mobility rather than confer stability to the wrist joint. In the event of inordinate application of force over the wrist, this small scaphoid is clearly likely to be the weak link. Interestingly, scaphoid fracture is one of the most frequent causes of medico-legal issues.

Anatomical peculiarity

An interesting anatomical anomaly in the vascular supply to the scaphoid is the area to which the blood supply is first delivered. Blood enters the scaphoid distally. Consequently, in the event of a fracture the proximal segment of the scaphoid will be devoid of a vascular supply, and will—if action is not taken—avascularly necrose within a sufferer's snuffbox. Due to the small size of the scaphoid and its shape, it is difficult to determine, early on, whether or not the scaphoid is indeed fractured with an x-ray. Further complications include; carpal instability (ligament disruption) and fracture-dislocations.