The anatomical snuff box or snuffbox or foveola radialis is a triangular deepening on the
radial
Radial is a geometric term of location which may refer to:
Mathematics and Direction
* Vector (geometric), a line
* Radius, adjective form of
* Radial distance, a directional coordinate in a polar coordinate system
* Radial set
* A bearing f ...
,
dorsal
Dorsal (from Latin ''dorsum'' ‘back’) may refer to:
* Dorsal (anatomy), an anatomical term of location referring to the back or upper side of an organism or parts of an organism
* Dorsal, positioned on top of an aircraft's fuselage
* Dorsal co ...
aspect of the
hand
A hand is a prehensile, multi-fingered appendage located at the end of the forearm or forelimb of primates such as humans, chimpanzees, monkeys, and lemurs. A few other vertebrates such as the koala (which has two opposable thumbs on each "h ...
—at the level of the
carpal bones
The carpal bones are the eight small bones that make up the wrist (or carpus) that connects the hand to the forearm. The term "carpus" is derived from the Latin carpus and the Greek καρπός (karpós), meaning "wrist". In human anatomy, th ...
, specifically, the
scaphoid
The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone ...
and
trapezium bones forming the floor. The name originates from the use of this surface for placing and then sniffing powdered
tobacco
Tobacco is the common name of several plants in the genus '' Nicotiana'' of the family Solanaceae, and the general term for any product prepared from the cured leaves of these plants. More than 70 species of tobacco are known, but the ...
, or "
snuff
Snuff may refer to:
Tobacco
* Snuff (tobacco), fine-ground tobacco, sniffed into the nose
** Moist snuff or dipping tobacco
** Creamy snuff, an Indian tobacco paste
Media and entertainment
* Snuff film, a type of film that shows a murder
Literat ...
." It is sometimes referred to by its
French name ''tabatière''.
Structure
Boundaries
* The medial border (ulnar side) of the snuffbox is the
tendon
A tendon or sinew is a tough, high-tensile-strength band of dense fibrous connective tissue that connects muscle to bone. It is able to transmit the mechanical forces of muscle contraction to the skeletal system without sacrificing its ability ...
of the
extensor pollicis longus
In human anatomy, the extensor pollicis longus muscle (EPL) is a skeletal muscle located dorsally on the forearm. It is much larger than the extensor pollicis brevis, the origin of which it partly covers and acts to stretch the thumb together with ...
.
* The lateral border (radial side) is a pair of parallel and intimate tendons, of the
extensor pollicis brevis
In human anatomy, the extensor pollicis brevis is a skeletal muscle on the dorsal side of the forearm. It lies on the medial side of, and is closely connected with, the abductor pollicis longus. The extensor pollicis brevis (EPB) belongs to the ...
and the
abductor pollicis longus
In human anatomy, the abductor pollicis longus (APL) is one of the extrinsic muscles of the hand. Its major function is to abduct the thumb at the wrist. Its tendon forms the anterior border of the anatomical snuffbox.
Structure
The abductor p ...
.
(Accordingly, the anatomical snuffbox is most visible, having a more pronounced concavity, during thumb
extension
Extension, extend or extended may refer to:
Mathematics
Logic or set theory
* Axiom of extensionality
* Extensible cardinal
* Extension (model theory)
* Extension (predicate logic), the set of tuples of values that satisfy the predicate
* E ...
.)
* The
proximal
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
border is formed by the
styloid process of the
radius
In classical geometry, a radius ( : radii) of a circle or sphere is any of the line segments from its center to its perimeter, and in more modern usage, it is also their length. The name comes from the latin ''radius'', meaning ray but also the ...
* The
distal
Standard anatomical terms of location are used to unambiguously describe the anatomy of animals, including humans. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...
border is formed by the approximate apex of the schematic snuffbox
isosceles
In geometry, an isosceles triangle () is a triangle that has two sides of equal length. Sometimes it is specified as having ''exactly'' two sides of equal length, and sometimes as having ''at least'' two sides of equal length, the latter versio ...
triangle.
* The floor of the snuffbox varies depending on the position of the wrist, but both the
trapezium and primarily the
scaphoid
The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone ...
can be palpated.
Neurovascular anatomy
Deep to the tendons which form the borders of the anatomical snuff box lies the
radial artery
In human anatomy, the radial artery is the main artery of the lateral aspect of the forearm.
Structure
The radial artery arises from the bifurcation of the brachial artery in the antecubital fossa. It runs distally on the anterior part of the f ...
, which passes through the anatomical snuffbox on its course from the normal radial pulse detecting area, to the proximal space in between the first and second
metacarpals
In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeleton, skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpa ...
to contribute to the superficial and deep palmar arches. In the anatomical snuffbox, the radial artery is closely related (<2 mm) with the
superficial branch of radial nerve
The superficial branch of the radial nerve passes along the front of the radial side of the forearm to the commencement of its lower third. It is a sensory nerve.
It lies at first slightly lateral to the radial artery, concealed beneath the Brac ...
near the styloid process of radius in 48%, while in 24% the radial artery is closely related to the
lateral cutaneous nerve of forearm
The lateral antebrachial cutaneous nerve (or lateral cutaneous nerve of forearm) (branch of musculocutaneous nerve, also sometimes spelled "antebrachial") passes behind the cephalic vein, and divides, opposite the elbow-joint, into a volar and ...
.
The
cephalic vein
In human anatomy, the cephalic vein is a superficial vein in the arm. It originates from the radial end of the dorsal venous network of hand, and ascends along the radial (lateral) side of the arm before emptying into the axillary vein. At the ...
arises within the anatomical snuffbox, while the
dorsal cutaneous branch of the
radial nerve
The radial nerve is a nerve in the human body that supplies the posterior portion of the upper limb. It innervates the medial and lateral heads of the triceps brachii muscle of the arm, as well as all 12 muscles in the posterior osteofascial comp ...
can be palpated by stroking along the extensor pollicis longus with the dorsal aspect of a fingernail.
Clinical significance
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 (FOOSH), 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
The scaphoid bone is one of the carpal bones of the wrist. It is situated between the hand and forearm on the thumb side of the wrist (also called the lateral or radial side). It forms the radial border of the carpal tunnel. The scaphoid bone ...
. 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 likely to be the weak link .
Scaphoid fracture
A scaphoid fracture is a break of the scaphoid bone in the wrist. Symptoms generally includes pain at the base of the thumb which is worse with use of the hand. The anatomic snuffbox is generally tender and swelling may occur. Complications may ...
is one of the most frequent causes of medico-legal issues.
An 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
Necrosis () is a form of cell injury which results in the premature death of cells in living tissue by autolysis. Necrosis is caused by factors external to the cell or tissue, such as infection, or trauma which result in the unregulated dige ...
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.
Additional images
File:Gray416.png, Tendons of forefinger and vincula tendina.
File:Gray573.png, The veins on the dorsum of the hand.
File:Gray1237.svg, Palm of left hand, showing position of skin creases and bones, and surface markings for the volar arches.
File:Anatomical snuff box2.jpg, A particularly cavernous anatomical snuff box.
See also
*
Anatomical terminology
Anatomical terminology is a form of scientific terminology used by anatomists, zoologists, and health professionals such as doctors.
Anatomical terminology uses many unique terms, suffixes, and prefixes deriving from Ancient Greek and Latin. The ...
*
Anatomical terms of bone
Many anatomical terms descriptive of bone are defined in anatomical terminology, and are often derived from Greek and Latin. Bone in the human body is categorized into long bone, short bone, flat bone, irregular bone and sesamoid bone.
Types of ...
References
External links
"Instant Anatomy"
{{DEFAULTSORT:Anatomical Snuff Box
Hand
Anatomy