Index
It is a triangular depression found on the lateral aspect of the back of the hand.
Its French name tabatière sometimes knows it. The anatomical snuffbox (also known as the radial fossa) is located at the level of the carpal bones and is best seen when the thumb is abducted.
This depression was used to hold snuff (ground tobacco) before inhaling through the nose, hence the name ‘snuff box’ or ‘anatomical snuffbox.’
Structure of the anatomical snuffbox
Limits
Since the snuff box is triangular, it has edges, a floor, and a ceiling:
Ulnar (medial) border: of the snuffbox is the tendon of the extensor pollicis longus.
Radial (lateral) border: a pair of parallel and tight tendons, the extensor pollicis brevis, and the abductor pollicis longus. The proximal edge is formed by the styloid process of the radius.
Lateral (anterior) limit: The tendons of the abductor pollicis longus and the extensor pollicis brevis indicate the lateral boundary of the anatomical snuffbox.
Distal edge: consists of the approximate vertex of the isosceles snuffbox schematic triangle.
Proximal border: the styloid process of the radius.
Floor: carpal, scaphoid, and trapezium bones.
Ceiling: skin.
The terms medial and lateral are used in the context of the anatomical position, where the forearm is supine. Be careful when describing these edges, as when looking at a patient’s anatomical snuffbox, the forearm is usually pronation.
It is important to note that the tendons of the muscles form the borders, not the forces themselves.
Neurovascular anatomy
Deep within the tendons that form the edges of the anatomical snuffbox is the radial artery, which passes through the anatomical snuffbox from the normal radial pulse detection area to the proximal space between the first and second metacarpals to contribute to the superficial and deep palmar arches.
The cephalic vein arises within the anatomic snuffbox. At the same time, the dorsal cutaneous branch of the radial nerve can be palpated by stroking along the extensor pollicis longus with the dorsal aspect of a fingernail.
Contents
The main contents of the anatomical snuffbox are the radial artery, a branch of the radial nerve, and the cephalic vein. The radial artery crosses the floor of the anatomical snuffbox obliquely.
Run deep to the extensor tendons. The radial pulse can be palpated in some people by placing two fingers on the proximal portion of the anatomical snuffbox.
Subcutaneously, the terminal branches of the superficial branch of the radial nerve extend through the roof of the anatomical snuffbox, providing innervation to the skin of the 3 1/2 lateral digits on the back of the hand and the palm area. Associated.
Also, subcutaneously, the cephalic vein crosses the anatomical snuffbox, which has just emerged from the dorsal venous network of the hand.
Clinical significance
The radius and scaphoid articulate deeply in the snuffbox to form the base of the wrist joint. In the event of a fall onto the outstretched hand, this is the area through which the weight of the force will be focused.
This makes these two bones the most fractured in the wrist. In a case where there is localized tenderness within the snuff box, knowledge of the anatomy of the wrist leads to the early conclusion that the fracture is probably scaphoid.
This is understandable as the scaphoid is a small, oddly shaped bone whose purpose is to facilitate mobility rather than impart stability to the wrist joint.
In the case of excessive force applied to the wrist, this small scaphoid is probably the weak link. A scaphoid fracture is one of the most frequent causes of medicolegal problems.
An anatomical abnormality in the vascular supply to the scaphoid is the area where the blood supply is first administered. 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. If no action is taken, it will necrotize vascularly within a patient’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 fractured from an x-ray. Other complications include; carpal instability (ligament disruption) and fracture dislocations.
If localized pain is reported in the anatomical snuffbox, the most likely cause is a scaphoid fracture. The scaphoid has a unique blood supply, extending from distal to proximal.
A scaphoid fracture can interrupt the blood supply to the proximal portion; this is an emergency. If the scaphoid is not revascularized, avascular necrosis and future arthritis can occur in the patient.
The function of the anatomical snuffbox
The three muscles that act on the thumb (abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus) run deep to the superficial extensors and emerge (exit) from a groove in the lateral part of the forearm that divides the extensors.
Due to this characteristic, they are known as blooming muscles. The tendons of the abductor pollicis longus and the extensor pollicis brevis are attached laterally to the anatomical triangular snuffbox, and the tendon of the extensor pollicis longus delimits it medially.
The tobacco box is visible as a hollow in the lateral aspect of the wrist when the thumb is fully extended; This draws the abductor pollicis longus, extensor pollicis brevis, and extensor pollicis longus upwards and produces a concavity between them.
The radial styloid process can be palpated proximally, and the base of the first metacarpal can be palpated distally in the snuffbox. The scaphoid and trapezius can be felt on the floor of the tobacco-box between the radial styloid process and the first metacarpal.
Associated injuries
Idiopathic radial artery aneurysm in the anatomical snuffbox
Radial artery aneurysms are sporadic. They are usually associated with trauma, usually penetrating or iatrogenic.
Although this discrepancy is inexplicable, they are less common than ulnar artery aneurysms. Incidents after blunt trauma have been described.
Scaphoid fractures
In the anatomical snuffbox, the scaphoid and radius articulate to form part of the wrist joint. In the event of a blow to the wrist (for example, landing on an outstretched hand), the navicular takes most of the force.
If localized pain is reported in the anatomical snuffbox, the most likely cause is a scaphoid fracture.
