Carpal bones - structure, function, movement - Samarpan Physio (2023)

introduction

The carpal bones are a group of eight small bones located in the wrist between the radius and ulna (forearm bones) and the metacarpals (bones of the hand). These bones are arranged in two rows, with four bones in each row.

The names of the carpal bones, from lateral (thumb) to medial (pinky), in the proximal row are:

• scaphoid (navicular bone).
• Mondbein
• Triquetral (triangular) bone
• the pisiform

The names of the carpal bones in the distal row are, from lateral to medial:

• trapezoid bones
• trapezoid bones
• head bones
• hamate bones

These bones are connected by strong ligaments that provide stability to the wrist. They also have numerous joints with other bones of the wrist and hand, allowing for a wide range of movements such as flexion, extension, abduction, adduction, and circumduction of the wrist.

proximal row
Bone is a navicular bone, lunate bone, triquetrum bone, os pisiforme.

distal row
Bone is a trapezium bone, trapezium bone, head bone, hamate bone.

mnemonic

• SIs -scaphoid
• Li like it -Crazy
• TÖ -Triquetrum
• Plie down -pea shaped
• Try –trapeze
• TÖ -trapeze
• Catch -you happen
• HIs -Hamat

The carpal bones are eight irregularly shaped bones located in the wrist area. These bones connect the distal part of the long forearm bones (radius and ulna) to the proximal parts of the metacarpal bones.

The carpal bones are divided into two columns: proximal and distal. The proximal column of the carpal bones (radial to ulnar) has the pisiform, scaphoid, lunate, and triquetrum bones. The distal column is comfortable for the trapezius, trapezius, capitulum and hamate. The unique carpal bone is fantastically shaped and diverse, suggesting that it can communicate with multiple wrap bones, muscles, and ligaments in the forearm and hand. In this way, the carpal bones provide flexibility and various types of movement to the soft tissues of the hand. They supply the skeletal framework of the wrist, which supports the development of the various neurovascular structures in the hand.

Structure

The eight carpal bones could be controlled as either two transverse columns. When evaluated as paired rows, each row produces a curve that is convex proximally and concave distally. On the palmar side, the carpus is concave and encloses the carpal tunnel, which is protected by the flexor retinaculum.

The proximal row (consisting of the scaphoid, lunate, triquetrum and pisiform bone) articulates with the surfaces of the radius and distal carpal row and therefore always conforms to these mobile surfaces. Within the proximal row, each carpal bone has little independent mobility. e.g., the scaphoid provides bone strength at the center of the carpal bone through distal articulation with the trapezius and trapezium. In contrast, the distal row is more difficult because its transverse arch interacts with the metacarpal bones.

Clinically and biomechanically, the carpal bones are well conceptualized3 longitudinal columns:

Radial navicular column: scaphoid, trapezium and trapezium.

Lunar Pillar: Lunar Bone and Capitol Bone.

Ulnar triquetrum column: triquetrum bone and hamate boneIn this context, the Os pisiforme means a sesamoid bone that is implanted in the tendon of the Musculus flexor carpi ulnaris.

The ulnar column has an opening between the ulna and the triquetrum; Consequently, only the radial or scaphoid bone and the prominent bone columns or head bone columns are transferred with the radius. Because of the strength of additional capsules and ligaments than the interlocking areas of the skeleton, the wrist is more useful and stable in flexion than in extension. Virtually all carpal bones have six surfaces (except for the pisiform bone). The palmar or anterior surfaces and the dorsal or posterior surfaces are irregular and serve for ligament attachment; The dorsal surfaces are wider, except on the belly.

The superior or proximal and the inferior or distal texture are articular, the superior being naturally convex and the inferior concave; The medial and lateral surfaces are again articulated where they touch the adjacent bones, otherwise they are rough and tuberculous.

The structure is generally comparable: spongy tissue surrounded by a layer of compact bone.

scaphoid

The scaphoid is the most prominent carpal bone in the proximal row. The scaphoid is a boat-shaped bone (“scaphoid” in Greek “tool boat,” hence its name) that lies slightly below the anatomical snuff-box. It meets the radius proximally and the trapezius and trapezius distally. In addition, the scaphoid communicates with the lunate and capitate bones.

The scaphoid has a bony growth on its palmar surface called the scaphoid tubercle. Since it lies subcutaneously, the tubercle is easy to feel on the palm of the hand. The scaphoid is the numerous, continuously fractured bones in the wrist. Fractures of the scaphoid usually occur when a person slips on an outstretched hand.

Mondbein

The lunate is the next bone in the proximal row and is located between the navicular and triquetrum bones. The lunate communicates with the radial head (carpal articular surface) and the articular disc of the distal radius.

A triquetra bone

The triquetrum is one of eight carpal bones that comprise the wrist area. It is a pyramidal bone that can be placed on the medial side of the wrist. The name triquetrum bone comes from the Latin word triquetrous, which means "triangular". It lies laterally on the lunate bone and distally on the hamate. Upon accumulation, the triquetrum picks up an isolated oval element on its distal palm for presentation with the pisiform bone.

the pisiform

The pisiform is a small, pea-shaped bone located on the distal palm of the triquetrum. It has a dorsal joint part for connection with the triquetrum bone. The pisiform bone is a sesamoid bone, which means that it is completely embedded in a tendon, more precisely in the tendon of the flexor carpi ulnaris muscle. This bone also lies superficially in the palm of the hand and is easy to feel.

trapezoid bones

The trapezium of the hand is a wrist bone with an odd shape. The thumb metacarpal is directly adjacent to the trapezium, which is within the distal row of carpal bones. The trapezius and the scaphoid are located on their lunar surface.[1] 708 The surface faces medially and upwards; It articulates with the scaphoid and is smooth on the medial side; It merges into the side surface and is rough on the side.

For connection with the base of the first metacarpal, the underside is oval, concave side-to-side, and convex front-to-back. The opposing movement of the thumb is due in part to this saddle-shaped articulation.

trapezoid bones

The trapezium lies wedge-shaped in the distal line of the carpal bones of the wrist. It may look extremely small compared to the other bones in a palmar region, but it is much wider on the back. It articulates proximally with the scaphoid, laterally with the trapezium, and medially with the capitate and its distal facet to articulate with the two metacarpals.

head bones

The skull is the largest of all the carpal bones. It communicates mainly distally with the 3rd metacarpal. In addition, it forms joints with the surrounding carpal bones; with trapezoid, scaphoid, lunate bone and hamate.

hamate bones

The hamate is wedge-shaped and the numerous medial bones in the distal row. The hamate formations articulate distally with the fourth and fifth metacarpals, with the capitate laterally, and the triquetrum proximally.

The hamulus contributes to the formation of the medial border of the carpal tunnel and the lateral border of the ulnar canal (i.e. Guyon's canal). The hamulus also serves as a tender point for many different ligaments and muscles in the hand and forearm, including the flexor retinaculum.

You are concerned about how you will determine all the wrist bones. Then our interactive carpal bone studies and labeling activities are for you – they help you consolidate information quickly and efficiently.

Work

ribbons

Four groups of ligaments in the wrist area. There are four groups of ligaments in the wrist area. The ligaments of the wrist connect the ulna or radius to the carpus: the ulnar and radial collateral ligaments; the palmar and dorsal radiocarpal ligaments; and the palmar ulnocarpal ligament.

The ligaments in the intercarpal joints connect the carpal bones together:

The radiating carpal ligament
palm band
The back straps
The interosseous intercarpal ligaments
Das Pisohamatband

The ligaments of the carpometacarpal accents connect the carpal bones to the metacarpals: the metacarpal ligament and the palmar and dorsal carpometacarpal ligaments. The ligaments of the intermetacarpal joints connect the metacarpals: the dorsal, interosseous, and palmar metacarpals.

blood supply and lymphatic diseases

The radial artery, ulnar artery, and anastomoses provide blood supply to the wrist. The radial artery mainly supplies the thumb and the lateral side of the index finger, while the ulnar artery supplies the rest of the fingers and the medial side of the index finger. In individuals, vascular supply occurs via the anastomotic network, which consists of three dorsal and three palmar arches arising from both the radial and ulnar artery and overlapping the carpal bones.

The scaphoid, calcaneus, and a small portion of the lunate (20%) all involve an intraosseous vascular mass. or not, the scaphoid has a single radial artery which supplies blood from the distal part of the bone to the proximal part, rendering its proximal pole extremely helpless to avascular necrosis. Both the trapezius and the hamate have two provinces for blood collection without intraosseous anastomoses.

The trapezium, triquetrum, pisiform bone, or most lunate bone (80%) have two areas of blood pooling and smooth intraosseous anastomoses. Consequently, the remaining carpal bones, with the exception of the scaphoid, capitate, and a small portion of the lunate bone, are at less risk of progressive avascular necrosis after fracture.

Annoy

The wrist is innervated by the anterior interosseous branch of the median nerve. posterior interosseous branch of the radial nerve. the dorsal and deep branches of the ulnar nerve. The lateral antebrachial cutaneous nerve, the posterior interosseous nerve, the dorsal branch and perforating branches of the ulnar nerve, and the external branch of the radial nerve innervate the wrist from the back. The palmar cutaneous component of the median nerve, the anterior interosseous nerve, and the great trunk and deep component of the ulnar nerve innervate the wrist from the palm.

attachment of muscles

The muscles of the hand are made up of two types of muscles: external muscles and intrinsic muscles.

Intrinsic muscles grow in the hand itself and also contribute to wrist strength by canceling flexion and extension forces via their sensitivity to the metacarpal bases. Some carpal bones serve as origins or insertion sites for the external and internal muscles of the hand. The flexor carpi ulnaris is the most prominent external muscle, penetrating the carpal bones, particularly the pisiform and hook of the hamate, and the base of the fifth metacarpal, allowing it to flex and adduct the wrist.

All internal muscles originate in the carpal bones. The thenar muscles, which include the antagonist pollicis, abductor pollicis brevis, and flexor pollicis brevis, have sites of origin that involve the scaphoid and trapezius carpus. The adductor pollicis muscle has its origin in the metacarpal and in the second metacarpal and in the third metacarpal. The hypothenar muscles, such as the opponens digiti minimi, the abductor digiti minimi, and the flexor digiti minimi brevis, arise from the pisiform bone and the curvature of the hamate.

Physiological variants

Although unique, in reality the finger's carpal bones may change due to accessory bones, separate bones, anatomical variants, or genetic abnormalities. Over twenty accessory carpal bones have been reported, with numerous common variants inhabiting the central carpi, external radial bone, triangular bone, and stylus bone.

Various instances of other carpal bones can be interesting cleft bones of the navicular, lunate, and even hamate. Anatomical variants lead to the creation of additional carpal bones because the fusion of the ossification centers of the carpal bones fails. More recent hereditary anomalies that produce fewer carpal bones can occur either because of the hereditary absence of normal bone (which originates primarily from the scaphoid, lunate, or triquetrum bone) or because of a connection between two carpal bones, most commonly involving the lunate and triquetrum bones.

movements

Anatomical terms for movement and special movements of the hands and feet. The hand is said to be in a straight position when the third finger passes over the skull bone and is in a straight line with the forearm. This should not be complicated by the middle position of the hand, which corresponds to about 12 degrees of ulnar variation. From the straight position, two sets of actions of the hand are possible: abduction (movement in the direction of the radius, so-called radial deviation or abduction) by 15 degrees and adduction (movement in the direction of the ulna, so-called ulna deviation or adduction) of 40 degrees with strong supination of the arm and scarcely larger in severe pronation. Flexion and extension can be achieved with a full range of 170 degrees. Radial abduction/ulnar adduction.

Left: ulnar adduction
Right: Radial Abduction

Links: Dorsalflexion
Right: palmar flexion

In radial abduction, the scaphoid tilts toward the palm, allowing the trapezius and trapezius to close the radius. Since the trapezium is intimately connected to the second metacarpal, which is also attached to the flexor carpi radialis and extensor carpi radialis muscles, radial abduction effectively pulls this combined system radially. During radial abduction, the pisiform bone crosses the most important pathway of all carpal bones.

Die radiale Abduktion erfött (in der Riehnehlung ihrer Wichtigkeit) durch den Musculus extensor carpi radialis longus, den Musculus abductor pollicis longus, den Musculus extensor pollicis longus, den Musculus flexor carpi radialis und den Musculus flexor pollicis longus.

Ulnar adduction forces a tilt or dorsal movement of the proximal carpal bone row. It is formed by the extensor carpi ulnaris muscle, the flexor carpi ulnaris muscle, the extensor digitorum muscle, and the extensor digiti minimi muscle. Both radial abduction and ulnar adduction occur about a dorsopalmar axis that runs across the skull head.

Palmarflexion/Dorsalflexion

In palmar flexion, dorsiflexion replaces the proximal carpal bones with the dorsal and palmar sides. While flexion and extension consist of activities about a team of transverse axes, they occur primarily in the radiocarpal joint and dorsiflexion in the midcarpal joint, which passes through the lunate bone for the proximal row and the capitate bone for distal columnar-palmar flexion.

Die Dorsalflexion wird (in der Rehnehlung ihrer Bedeutung) durch den Extensor digitorum muscle, den Extensor carpi radialis longus, den Extensor carpi radialis brevis, den Extensor index muscle, den Extensor pollicis longus und den Musculus extensor digiti minimi ergott Die Palmarflexion wird (in der Rehnehlung ihrer Bedeutung) durch den Musculus Flexor Digitorum Superficialis, den Musculus Flexor Digitorum Profundus, den Musculus Flexor Carpi Ulnaris, den Musculus Flexor Pollicis Longus, den Musculus Flexor Pollicis Radialis und den Musculus Abductor Pollicis Longus ergott.

Combined movements

Combined with movements at both the elbow joint and the shoulder joint, intermediate or related movements at the wrist correspond to movements at the ball joint, with the need for some rules, such as: B. Maximum palmar flexion blocking abduction.

side movements

Anteroposterior sliding movements between impacting carpal bones or along the metacarpal joint can be achieved by stabilizing certain bones while squeezing another (e.g., sponging the bone between thumb and forefinger).

The ossification of the metacarpal starts at the heel bone and ends at the pisiform bone.
The carpal bones do not ossify at birth. Although there is a great deal of individual variability, the approximate ossification words are as follows:

• Head: 1-3 months
• Hamat: 2-4 Sweet
• Triquetrum: 2-3 years
• crazy: 2-4 years
• Scaphoid: 4-6 years
• Trapeze: 4-6 years
• Trapeze: 4-6 years
• Os pisiform: 8-12 years

Aside from the pisiform bone, one way to remember the invocation of ossification is to start at the head bone and then proceed counterclockwise on the volar character of the right carpal bone.
Distal radius and ulna ossification commands.

Clinical Significance

Fracture of the scaphoid bone

The most typical fracture of the wrist is a fracture of the scaphoid. It usually occurs when someone slacks off at lengthy writing while trying to control the incident. Symptoms include pain and swelling in the parts called the anatomical snuff box. Difficulties arise from a lack of blood supply at the site of the palmar-carpal component of the radial artery. This lack of blood and the associated lack of nutrients can lead to avascular osteonecrosis.

Carpal tunnel syndrome

Carpal tunnel syndromeis the basic term for a condition understood as median nerve reduction and is the most common standard condition of compression neuropathy. It is most often induced by occupational preferences such as repeated flexion and extension of the wrist and leads to overuse of the anatomical structures directly involved in these movements. As a result, an additional force in the carpal tunnel presses on the median nerve, which leads to sensory and motor disturbances in its innervation areas. Chronic contractions can lead to permanent nerve damage and atrophy of the thenar muscles, which appear as weakness in the thumb and forefinger. Therapy involves resting the wrist and not using it for a period of time. Bandages and splints can support and stabilize the region, in extreme cases anti-inflammatory drugs and painkillers can be prescribed.

Hamate Quarry Hook

These fractures result from natural accidents, usually from "touching down" a golf club or "checking" a baseball bat. They often present with pain in the hypothenar area and paresthesia in the area of ​​the ulnar nerve. They are analyzed radiologically and verified by CT if the radiological findings are negative. Standard daily care continues to unhook the hamate component, which has yielded successful results with a return to sport at 6 weeks.

Lunate dislocation

Due to the proximity of the lunate bone to the median nerve, anterior removal of the bone can result in mechanical reduction of the median nerve in the carpal tunnel, and even with median nerve neuropathy, signs and symptoms such as paresthesia of the front three fingers and the radius half of the fourth finger can be produced and deficiency and atrophy of the thenar eminence. Again, the anatomical connection of the carpal bones can be compromised by ligament damage, giving rise to two classifications of instability: dorsal intercalated segmental instability (DISI) and volar intercalated segmental instability (VISI).

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