ANATOMICAL SNUFF BOX: LIMITS, CONTENT, FUNCTIONS, INJURIES - ANATOMY AND PHYSIOLOGY - 2024

The anatomical snuff box is an excavated, triangular surface found on the back of the hand, near the base of the thumb. It can be easily seen by extending the hand, flicking the wrist outward, and rotating the thumb inward and upward.

The boundaries of the region are well established by the tendons of the finger muscles. They are visible as long as the bony limits can be easily palpated.

Anatomical snuffbox location. By Gusloureiro - Own work, Public Domain, commons.wikimedia.org

Both the radial artery and the superficial branches of the homonymous nerve, as well as the cephalic vein, are part of the content of the anatomical snuffbox. Similarly, in the background are two of the small carpal bones of the hand, the trapezoid and the scaphoid.

The characteristics explained make the anatomical snuffbox an easily located area, with important content, which serves as an orientation point for the surgeon who must perform procedures in this area.

Finally, it is important to note that the origin of its curious name comes from the use of this area to place the tobacco dust to inhale it. Inhaled tobacco was a very common way to consume this product between the 17th and 19th centuries.

However, in some anatomy books the name of the radial fossa is used to describe this region, since it is formed at the site where the tendons of the extensor longus and brevis muscles, as well as the abductor pollicis, converge.

Anatomy

An anatomical snuffbox is the triangular-shaped depression on the back of the hand when the thumb is extended and dorsiflexed.

The so-called anatomical snuff box (or radial fossa). By James Heilman, MD - Own work, CC BY-SA 4.0, commons.wikimedia.org

Limits

Its internal part is limited by the tendon of the extensor pollicis longus muscle. While the lateral limit is established by the tendons of the abductor muscle and extensor pollicis brevis.

In depth are the bones that are part of the carpus, specifically the scaphoid and the trapezius. In addition, there are two bony prominences that can be palpated if all the elements that border and form part of the anatomical snuffbox are to be evaluated.

Anatomy of the human hand. By Henry Vandyke Carter - Henry Gray (1918) Anatomy of the Human Body (See «Book» section below) Bartleby.com: Gray's Anatomy, Plate 424, Public Domain, commons.wikimedia.org

Additionally, in its distal part, towards the finger, the head of the first metacarpal bone can be felt and proximally, towards the wrist, the styloid process of the radial.

Content

The radial artery is deep in the floor of the fossa where it makes a superficial course. It is for this reason that your pulse can be palpable in this area.

Similarly, near the artery, the superficial branch of the radial nerve and the cephalic branch of the radial vein break through.

Human hand anatomical drawing. 30 December 2010 (UTC) - Own work, CC0, commons.wikimedia.org

The scaphoid and trapezoid bones are also considered contents of the snuff box because they not only constitute the deep limit of the same, but they can suffer injuries from being so exposed in that area.

Features

Anatomical

The main function of the anatomical snuff box is to facilitate the anatomical study of the structures of the hand, which can be difficult.

In addition to this, it serves as a guide for the surgeon who performs surgical repairs in that area.

Likewise, its content is of the utmost importance for the performance of some trauma and cardiovascular surgery procedures.

It is certainly of the utmost importance for the specialist to know the anatomy of this region in a perfect way to avoid injuring the nearby vascular and neurological structures in surgeries in the area.

Clinics

The anatomical snuff box has the function of guiding the doctor in the suspicion of the diagnosis of some bone injuries such as scaphoid fracture.

This injury is especially relevant, since the scaphoid is the most frequently damaged bone of all the carpal bones. However, your injury may go unnoticed.

Therefore, when bruising is observed in this area, increased depth of the cavity of the fossa or feels soft, there is a high probability of this type of injury.

Thus, when it is suspected, an X-ray of the hand with a projection should be requested to visualize this bone, and thus be able to observe the integrity or lack of continuity of the scaphoid body.

Once the diagnosis of scaphoid fracture is confirmed, it must be treated in a timely manner because when the injury compromises the blood nutrition of the bone, there can be serious complications such as necrosis.

Scaphoid fracture. By Mohamed Jarraya, Daichi Hayashi, Frank W. Roemer, Michel D. Crema, Luis Diaz, Jane Conlin, Monica D. Marra, Nabil Jomaah, and Ali Guermazi - (2013). "Radiographically Occult and Subtle Fractures: A Pictorial Review". Radiology Research and Practice 2013: 1–10. DOI: 10.1155 / 2013/370169. ISSN 2090-1941. CC-BY 3.0, CC BY 3.0, commons.wikimedia.org

Surgical

In this area, both the radial artery and the cephalic vein provide a fairly straightforward approach.

This allows the performance of cardiovascular surgery procedures such as those performed in patients suffering from kidney diseases, in whom vascular accesses that are durable, safe and easily accessible for dialysis are sought, requirements that perfectly meet the vessels that pass through the anatomical snuff box.

Arteriovenous fistula. By BruceBlaus. When using this image in external sources it can be cited as: Blausen.com staff (2014). "Medical gallery of Blausen Medical 2014". WikiJournal of Medicine 1 (2). DOI: 10.15347 / wjm / 2014.010. ISSN 2002-4436. - Own work, CC BY 3.0, commons.wikimedia.org

Among the procedures performed in the anatomical snuff box, the most common is arterio-venous bypass, in which the cephalic vein joins the radial artery. In this way, the pressure of the artery improves the composition of the vascular wall of the vein and can withstand the continuous accesses that a person who needs hemodialysis must make.

Injuries

Neuritis

Neuritis caused by compression of tendons is a pathology that causes many discomforts such as numbness of the hands, among others.

It can be diagnosed from the history and physical examination in a patient who presents mild pain at the base of the thumb and refers to a history of having received a direct trauma, usually by falling and cushioning the impact with the outstretched hand.

Quervain's tenosynovitis

Quervain's tenosynovitis is another of the pathologies that can be observed in this region. This consists of the inflammation of the tendons of the abductor and the extensor pollicis brevis.

When a patient presents with this disease, the lateral limit of the anatomical snuffbox is much more defined, as well as an increase in consistency, since there is inflammation of these tendons.

Affected radial fossa. By Enterim - Own work, CC BY-SA 4.0, commons.wikimedia.org

As a consequence of the inflammation that compresses the nerves of the hand, there is pain with movements. Thus, the clinical diagnosis is made by instructing the patient to move the wrist, especially in the horizontal plane from right to left.

In this way, the patient may present tingling or numbness of the hand after a few minutes due to the performance of this exercise, and in this case de Quervain's tenosynovitis may be suspected.

At the beginning, it can be treated with non-invasive outpatient therapy, which is the treatment par excellence. However, if the case is complicated, surgical treatment that provides a definitive cure is preferred.

References

1. Hallett, S; Ashurst JV (2019). Anatomy, Shoulder and Upper Limb, Hand Anatomical Snuff Box. StatPearls. Treasure Island (FL). Taken from: ncbi.nlm.nih.gov
2. Thwin, S. S; Fazlin, F; Than, M. (2014). Multiple variations of the tendons of the anatomical snuffbox. Singapore medical journal. Taken from: ncbi.nlm.nih.gov
3. Cerda, A; del Sol, M. (2015). Anatomical Snuffbox and it Clinical Significance: A Literature Review. International Journal of Morphology. Taken from: scielo.conicyt.cl
4. Roh, J. H; Lee, JH (2018). Distal Radial Approach through the Anatomical Snuff Box for Coronary Angiography and Percutaneous Coronary Intervention. Korean circulation journal. Taken from: ncbi.nlm.nih.gov
5. Kim, Y; Ahn, Y; Kim, I; Lee, D. H; Kim, M. C; Sim, D. S; Jeong, MH (2018). Feasibility of Coronary Angiography and Percutaneous Coronary Intervention via Left Snuffbox Approach. Korean circulation journal. Taken from: ncbi.nlm.nih.gov