The anatomical snuffbox is a triangular depression located on the wrist. It lies between the base of the thumb and the radial styloid process on the dorsal side. This structure is named for its historical use in holding finely ground tobacco (snuff) prior to inhaling or snorting. 

Tendons form the anterior and posterior borders of the anatomical snuffbox: abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus. Each muscle originates on the posterior surface of the ulna, crosses the distal radioulnar and radiocarpal joints posteriorly, and inserts on the thumb. This position allows all three muscles to move both the thumb and wrist. Specifically, they extend and abduct the thumb and radially deviate (or abduct) the wrist.

The thumb contains the only saddle joint in the body and allows specialized movements for grasping and gripping. Abduction and extension of the thumb are critical movements for opening the hand and letting go of objects, as well as positioning and manipulating objects held in the hand. Repetitive activities such as typing, texting, and gaming may also lead to stress injuries like tendinitis or tenosynovitis around the anatomical snuffbox.

Because the muscles of the anatomical snuffbox also cross the wrist, they help stabilize and initiate movement in this area. Activities that include radial deviation of the wrist such as bowling, golfing, and shoveling require activation of the muscles in this area and may lead to overuse injuries and muscle strains. Weakness or lack of mobility in the associated synergists (flexor carpi radialis, and extensor carpi radialis longus and brevis) may increase strain on the muscles of the anatomical snuffbox. Soft-tissue manipulation can improve mobility, increase circulation, and prevent or treat overuse injuries to the muscles and tendons associated with the anatomical snuffbox.

Be sure to have a doctor rule out fracture of the scaphoid when clients are experiencing acute pain in the anatomical snuffbox. This hourglass-shaped carpal bone is frequently injured during traumatic injuries, especially falling on an outstretched hand. This type of injury may be difficult to diagnose because of the size and shape of the bone. It is also prone to complications like avascular necrosis due to poor blood supply in the area.

Palpating the Anatomical Snuffbox

Positioning: client seated or supine with forearm neutral (thumb up).

1.
Passively ulnar deviate (adduct) the wrist to create tension in the tissue.

2.
Locate the radial styloid process with your thumb and slide distally onto the tendons leading to the thumb.  

3.
Resist as the client performs thumb extension and abduction to ensure proper location.

Anatomical Snuffbox

Borders

•
Anterior: Extensor pollicis brevis and abductor pollicis longus tendons

• Posterior: Extensor pollicis longus tendon

• Proximal: Radial styloid process

Contents

•
Dorsal cutaneous branch of radial nerve

• Radial artery and cephalic vein

• Scaphoid and trapezium bones

Associated Muscles

• Abductor pollicis longus

• Extensor pollicis brevis

• Extensor pollicis longus

Client Homework—
Snuff Box Stretch

1.
Relax your arm and turn your hand so the knuckle of your thumb points up.

2.
Wrap your fingers around your thumb.

3.
Hold your thumb tucked against your palm.

4.
Gently bend your wrist toward your pinkie finger.

5.
Keep your thumb tucked as you gently stretch the wrist. 

Editor’s note: The Client Homework element in Functional Anatomy is intended as a take-home resource for clients experiencing issues with the profiled muscle. The stretches identified in Functional Anatomy should not be performed within massage sessions or progressed by massage therapists, in order to comply with state laws and maintain scope of practice.