Anatomy, Shoulder and Upper Limb, Hand Anatomical Snuff Box

The anatomical snuffbox is bordered medially by the tendons of the muscle named the extensor pollicis longus, and laterally by the tendons of the muscles named the extensor pollicis brevis and the abductor pollicis longus. The floor of the anatomical snuffbox is partially formed by the tendons of the muscle named the extensor carpi radialis longus and the muscle named the extensor carpi radialis brevis.[6]

Through anatomical research, multiple variations of the tendons of the anatomical snuffbox have been discovered. Both the extensor pollicis longus and the abductor pollicis longus have been shown to have not only numerous tendon slips but also different areas of insertion. This is clinically significant because it may predispose an individual patient to the development of tendinopathy of either the extensor pollicis longus or the abductor pollicis longus. Surgical management, if needed, would also be affected because of these numerous variations in tendon location.[6][7]

Through similar cadaveric research, multiple variations have been noted in the location of the cephalic vein and the radial artery. Clinically this is important because intravenous access can be obtained in the anatomical snuffbox and inadvertent arterial puncture may cause a pseudo-aneurysm, arterial occlusion, or hematoma.[8]

The superficial branch of the radial nerve is the third most common peripheral nerve injury and will cause an area of paresthesia over the dorsum of the first web space on the hand. Surgeons should be aware of its varied location within the anatomical snuffbox to avoid injury.[9]

The anatomical snuffbox is clinically significant when there is pain with palpation within its boundaries. Scaphoid fractures account for two-thirds of all carpal bone fractures and are commonly misdiagnosed. The most common form of injury is when a patient falls onto an outstretched hand when it is pronated and deviated ulnarly. The hallmark of anatomic snuffbox tenderness is highly sensitive for scaphoid fractures but lacks specificity. Due to the lack of specificity, those with snuffbox tenderness should undergo radiographic studies of the wrist. Those with initial negative imaging can be managed with either a thumb spica short armed splint or advanced imaging by MRI or CT to determine if a fracture exists. Given the unique blood flow to the scaphoid, fracture location is important in determining treatment options to prevent avascular necrosis of the bone.

De Quervain tenosynovitis is a second diagnosis that is clinically significant in relation to the anatomical snuffbox. De Quervain tenosynovitis is a stenosing tendinopathy that affects the first dorsal compartment, which includes the muscle named the abductor pollicis longus and the muscle named the extensor pollicis brevis, both of which are lateral borders of the anatomical snuffbox. Diagnosis can be made based on a thorough history and physical examination. History may include repetitive hand motions in which repeated radio-ulnar deviation occurs. Patients will typically present with pain or swelling over the dorsal aspect of the wrist with associated aggravation of symptoms with the forced resistance of the thumb. Treatment typically includes conservative therapy with NSAIDs, corticosteroids, physical therapy, or splinting in a thumb spica splint. Surgery is reserved for refractory symptomology.[10]