Scaphoid bone

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Scaphoid bone
Scaphoid bone (left hand) 01 palmar view.png
Left hand anterior view (palmar view). Scaphoid bone shown in red.
Gray221.png
The left scaphoid bone
Details
Pronunciation /ˈskæfɔɪd/
Articulationsarticulates with five bones
radius proximally
trapezoid bone and trapezium bone distally
capitate and lunate medially
Identifiers
Latin os scaphoideum,
os naviculare manus
MeSH D021361
TA98 A02.4.08.003
TA2 1250
FMA 23709
Anatomical terms of bone

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 is the largest bone of the proximal row of wrist bones, its long axis being from above downward, lateralward, and forward. It is approximately the size and shape of a medium cashew nut.

Contents

Structure

The scaphoid is situated between the proximal and distal rows of carpal bones. It is located on the radial side of the wrist, [1] :176 adjacent to the styloid process of the radius. [2] It articulates with the radius, lunate, trapezoid, trapezium, and capitate. [1] :176 Over 80% of the bone is covered in articular cartilage. [3]

Bone

The palmar surface of the scaphoid is concave, and forming a distal tubercle, giving attachment to the transverse carpal ligament. The proximal surface is triangular, smooth and convex. [3] The lateral surface is narrow and gives attachment to the radial collateral ligament. The medial surface has two facets, a flattened semi-lunar facet articulating with the lunate bone, and an inferior concave facet, articulating alongside the lunate with the head of the capitate bone. [4]

The dorsal surface of the bone is narrow, with a groove running the length of the bone and allowing ligaments to attach, and the surface facing the fingers (anatomically inferior) is smooth and convex, also triangular, and divided into two parts by a slight ridge. [4]

Blood supply

It receives its blood supply primarily from lateral and distal branches of the radial artery, via palmar and dorsal branches. These provide an "abundant" supply to middle and distal portions of the bone, but neglect the proximal portion, which relies on retrograde flow. [1] :189 The dorsal branch supplies the majority of the middle and distal portions, with the palmar branch supplying only the distal third of the bone. [3]

Variation

The dorsal blood supply, particularly of the proximal portion, is highly variable. [1] :189 Sometimes the fibers of the abductor pollicis brevis emerge from the tubercle. [4]

In animals

In reptiles, birds, and amphibians, the scaphoid is instead commonly referred to as the radiale because of its articulation with the radius.

Function

The carpal bones function as a unit to provide a bony superstructure for the hand. [5] :708 The scaphoid is also involved in movement of the wrist. [1] :6 It, along with the lunate, articulates with the radius and ulna to form the major bones involved in movement of the wrist. [5] The scaphoid serves as a link between the two rows of carpal bones. With wrist movement, the scaphoid may flex from its position in the same plane as the forearm to perpendicular. [1] :176–177

Clinical significance

Fracture

Scaphoidfraktur 1 pfeil.jpg
Scaphoidfraktur 2 postoperativ.jpg
Scaphoid fracture before and after operation

Fractures of the scaphoid are the most common of the carpal bone injuries, because of its connections with the two rows of carpal bones. [1] :177

The scaphoid can be slow to heal because of the limited circulation to the bone. Fractures of the scaphoid must be recognized and treated quickly, as prompt treatment by immobilization or surgical fixation increases the likelihood of the bone healing in anatomic alignment, thus avoiding mal-union or non-union. [6] Delays may compromise healing. Failure of the fracture to heal ("non-union") will lead to post-traumatic osteoarthritis of the carpus. [1] :189 One reason for this is because of the "tenuous" blood supply to the proximal segment. [3] Even rapidly immobilized fractures may require surgical treatment, including use of a headless compression screw such as the Herbert screw to bind the two halves together.

Healing of the fracture with a non-anatomic deformity (frequently, a volar flexed "humpback") can also lead to post-traumatic arthritis. Non-unions can result in loss of blood supply to the proximal pole, which can result in avascular necrosis of the proximal segment.

Scaphoid fractures may be difficult to diagnose via plain x-ray. A repeat x-ray may be required at a later date, as might cross-sectional imaging via MRI or CT scan. [6]

Other diseases

A condition called scapholunate instability can occur when the scapholunate ligament (connecting the scaphoid to the lunate bone) and other surrounding ligaments are disrupted. In this state, the distance between the scaphoid and lunate bones is increased. [1] :180

One rare disease of the scaphoid is called Preiser's Disease.

Palpation

The scaphoid can be palpated at the base of the anatomical snuff box. It can also be palpated in the volar (palmar) hand/wrist. Its position is the intersections of the long axes of the four fingers while in a fist, or the base of the thenar eminence. When palpated in this position, the bone will be felt to slide forward during radial deviation (wrist abduction) and flexion.

Clicking of the scaphoid or no anterior translation can indicate scapholunate instability.

Etymology

The word scaphoid (Greek : σκαφοειδές) is derived from the Greek skaphos, which means "a boat", and the Greek eidos, which means "kind". [7] The name refers to the shape of the bone, supposedly reminiscent of a boat. In older literature about human anatomy, [4] the scaphoid is referred to as the navicular bone of the hand (this time from the Latin navis for boat); there is also a bone in a similar position in the foot, which is called the navicular. The modern term for the bone in the hand is scaphoid; in human anatomy the term navicular is reserved for the bone in the foot.

Additional images

Related Research Articles

<span class="mw-page-title-main">Carpal bones</span> Eight small bones that make up the wrist (or carpus) that connects the hand to the forearm

The carpal bones are the eight small bones that make up the wrist 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, the main role of the wrist is to facilitate effective positioning of the hand and powerful use of the extensors and flexors of the forearm, and the mobility of individual carpal bones increase the freedom of movements at the wrist.

<span class="mw-page-title-main">Wrist</span> Part of the arm between the lower arm and the hand

In human anatomy, the wrist is variously defined as (1) the carpus or carpal bones, the complex of eight bones forming the proximal skeletal segment of the hand; (2) the wrist joint or radiocarpal joint, the joint between the radius and the carpus and; (3) the anatomical region surrounding the carpus including the distal parts of the bones of the forearm and the proximal parts of the metacarpus or five metacarpal bones and the series of joints between these bones, thus referred to as wrist joints. This region also includes the carpal tunnel, the anatomical snuff box, bracelet lines, the flexor retinaculum, and the extensor retinaculum.

<span class="mw-page-title-main">Anatomical snuffbox</span> Indent on back of hand between tendons

The anatomical snuff box or snuffbox or foveola radialis is a triangular deepening on the radial, dorsal aspect of the hand—at the level of the carpal bones, specifically, the scaphoid and trapezium bones forming the floor. The name originates from the use of this surface for placing and then sniffing powdered tobacco, or "snuff." It is sometimes referred to by its French name tabatière.

<span class="mw-page-title-main">Trapezoid bone</span> Carpal (wrist) bone

The trapezoid bone is a carpal bone in tetrapods, including humans. It is the smallest bone in the distal row of carpal bones that give structure to the palm of the hand. It may be known by its wedge-shaped form, the broad end of the wedge constituting the dorsal, the narrow end the palmar surface; and by its having four articular facets touching each other, and separated by sharp edges. It is homologous with the "second distal carpal" of reptiles and amphibians.

<span class="mw-page-title-main">Trapezium (bone)</span> Bone of the wrist

The trapezium bone is a carpal bone in the hand. It forms the radial border of the carpal tunnel.

<span class="mw-page-title-main">Metacarpal bones</span> Bones of hand

In human anatomy, the metacarpal bones or metacarpus form the intermediate part of the skeletal hand located between the phalanges of the fingers and the carpal bones of the wrist, which forms the connection to the forearm. The metacarpal bones are analogous to the metatarsal bones in the foot.

<span class="mw-page-title-main">Capitate bone</span> Carpal bone in the wrist

The capitate bone is a bone in the human wrist found in the center of the carpal bone region, located at the distal end of the radius and ulna bones. It articulates with the third metacarpal bone and forms the third carpometacarpal joint. The capitate bone is the largest of the carpal bones in the human hand. It presents, above, a rounded portion or head, which is received into the concavity formed by the scaphoid and lunate bones; a constricted portion or neck; and below this, the body. The bone is also found in many other mammals, and is homologous with the "third distal carpal" of reptiles and amphibians.

<span class="mw-page-title-main">Hamate bone</span> Carpal bone in the wrist

The hamate bone, or unciform bone, Latin os hamatum and occasionally abbreviated as just hamatum, is a bone in the human wrist readily distinguishable by its wedge shape and a hook-like process ("hamulus") projecting from its palmar surface.

<span class="mw-page-title-main">Lunate bone</span> Carpal bone in the human hand

The lunate bone is a carpal bone in the human hand. It is distinguished by its deep concavity and crescentic outline. It is situated in the center of the proximal row carpal bones, which lie between the ulna and radius and the hand. The lunate carpal bone is situated between the lateral scaphoid bone and medial triquetral bone.

<span class="mw-page-title-main">Radius (bone)</span> One of the two long bones of the forearm

The radius or radial bone is one of the two large bones of the forearm, the other being the ulna. It extends from the lateral side of the elbow to the thumb side of the wrist and runs parallel to the ulna. The ulna is usually slightly longer than the radius, but the radius is thicker. Therefore the radius is considered to be the larger of the two. It is a long bone, prism-shaped and slightly curved longitudinally.

<span class="mw-page-title-main">Navicular bone</span> Small bone found in the feet of most mammals

The navicular bone is a small bone found in the feet of most mammals.

<span class="mw-page-title-main">Triquetral bone</span> Bone in the wrist

The triquetral bone is located in the wrist on the medial side of the proximal row of the carpus between the lunate and pisiform bones. It is on the ulnar side of the hand, but does not directly articulate with the ulna. Instead, it is connected to and articulates with the ulna through the Triangular fibrocartilage disc and ligament, which forms part of the ulnocarpal joint capsule. It connects with the pisiform, hamate, and lunate bones. It is the 2nd most commonly fractured carpal bone.

<span class="mw-page-title-main">Distal radius fracture</span> Fracture of the radius bone near the wrist

A distal radius fracture, also known as wrist fracture, is a break of the part of the radius bone which is close to the wrist. Symptoms include pain, bruising, and rapid-onset swelling. The ulna bone may also be broken.

<span class="mw-page-title-main">Carpometacarpal joint</span>

The carpometacarpal (CMC) joints are five joints in the wrist that articulate the distal row of carpal bones and the proximal bases of the five metacarpal bones.

<span class="mw-page-title-main">Intercarpal joints</span> Joints of the carpal bones of the wrist

The intercarpal joints can be subdivided into three sets of joints : Those of the proximal row of carpal bones, those of the distal row of carpal bones, and those of the two rows with each other.

<span class="mw-page-title-main">Triangular fibrocartilage</span> Anatomical feature in the wrist

The triangular fibrocartilage complex (TFCC) is formed by the triangular fibrocartilage discus (TFC), the radioulnar ligaments (RULs) and the ulnocarpal ligaments (UCLs).

<span class="mw-page-title-main">Midcarpal joint</span>

The midcarpal joint is formed by the scaphoid, lunate, and triquetral bones in the proximal row, and the trapezium, trapezoid, capitate, and hamate bones in the distal row. The distal pole of the scaphoid articulates with two trapezial bones as a gliding type of joint. The proximal end of the scaphoid combines with the lunate and triquetrum to form a deep concavity that articulates with the convexity of the combined capitate and hamate in a form of diarthrodial, almost condyloid joint.

<span class="mw-page-title-main">Scaphoid fracture</span> Fracture of the scaphoid bone in the wrist

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 include nonunion of the fracture, avascular necrosis of the proximal part of the bone, and arthritis.

<span class="mw-page-title-main">Hand</span> Extremity at the end of an arm or forelimb

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 are often described as having "hands" instead of paws on their front limbs. The raccoon is usually described as having "hands" though opposable thumbs are lacking.

<span class="mw-page-title-main">Wrist osteoarthritis</span> Medical condition

Wrist osteoarthritis is a group of mechanical abnormalities resulting in joint destruction, which can occur in the wrist. These abnormalities include degeneration of cartilage and hypertrophic bone changes, which can lead to pain, swelling and loss of function. Osteoarthritis of the wrist is one of the most common conditions seen by hand surgeons.

References

  1. 1 2 3 4 5 6 7 8 9 Beasley RW (2003). Beasley's Surgery of the Hand. New York: Thieme. ISBN   978-1-282-95002-3. OCLC   657589090.
  2. Martini, Frederic; Tallitsch, Robert B.; Nath, Judi L. (2017). Human Anatomy (9th ed.). Pearson. p. 182. ISBN   9780134320762.
  3. 1 2 3 4 Eathorne SW (March 2005). "The wrist: clinical anatomy and physical examination--an update". Primary Care. 32 (1): 17–33. doi:10.1016/j.pop.2004.11.009. PMID   15831311.
  4. 1 2 3 4 Gray H (1918). "6b. The Hand. 1. The Carpus". Anatomy of the Human Body. 4 via Bartleby.com.
  5. 1 2 Drake RL, Vogl W, Mitchell AW (2005). Gray's anatomy for students. Illustrated by Richard Tibbitts and Paul Richardson. Philadelphia: Elsevier/Churchill Livingstone. ISBN   978-0-8089-2306-0. OCLC   646533128.
  6. 1 2 Wijetunga AR, Tsang VH, Giuffre B (March 2019). "The utility of cross-sectional imaging in the management of suspected scaphoid fractures". Journal of Medical Radiation Sciences. 66 (1): 30–37. doi:10.1002/jmrs.302. PMC   6399186 . PMID   30160062.
  7. Anderson K, Anderson LE, Glanze WD (1994). Mosby's Medical, Nursing & Allied Health Dictionary (4th ed.). St. Louis: Mosby. p. 1396. ISBN   978-0-8016-7225-5. OCLC   461378724.