The wrist joint also called the radiocarpal joint, is a crucial transition point and connection between the forearm and hand within the distal upper limb. Functioning as a synovial joint of the condyloid type, it possesses a unique modification resembling a ball and socket joint, enabling various movements, including flexion, extension, abduction, and adduction. The wrist is a remarkably intricate joint that is a sophisticated bridge, seamlessly linking the hand to the forearm. Wrist anatomy comprising of bones, muscles, ligaments, tendons, and joints. Its overall anatomical structure encompasses the carpus or carpal bones—a fascinating complex consisting of eight bones that shape the proximal skeletal segment of the hand. The wrist joint, the radiocarpal joint, denotes the connection established between the radius and the carpus.
Surrounding the carpal region, the wrist’s anatomical domain encompasses the distal portions of the forearm bones, the proximal segments of the metacarpus or the five metacarpal bones, and a sequence of joints interconnecting these intricate skeletal components.
Table of Contents
Wrist Anatomy Diagram
Parts of a Wrist
Carpal Bone Names
- Proximal row (closest to the forearm)
- Distal row (closest to the hand)
- Radiocarpal Joint
- Intercarpal Joints
- Midcarpal Joint
- Carpometacarpal Joints
- Intercarpometacarpal Joints
- Distal Radioulnar Joint
- Flexor carpi radialis
- Palmaris longus
- Flexor carpi ulnaris
- Extensor carpi radialis longus
- Extensor carpi radialis brevis
- Extensor carpi ulnaris
- Radial collateral ligament
- Ulnar collateral ligament
- Palmar radiocarpal ligament
- Dorsal radiocarpal ligament
- Scapholunate ligament
- Triangular fibrocartilage complex (TFCC)
- Flexor pollicis longus tendon
- Flexor digitorum superficialis tendons
- Flexor digitorum profundus tendons
- Extensor pollicis longus tendon
- Extensor digitorum tendons
- Extensor digiti minimi tendon
Wrist Anatomy: Parts & Functions
Wrist Bone Anatomy
It consists of a proximal and Distal row. We will see the function of each wrist bone in detail.
Proximal Row (closest to the forearm)
The proximal row of carpal bones is situated closest to the forearm. It presents an extraordinary ensemble of four remarkable bones. These bones demonstrate captivating features and contribute to the intricate mechanics of wrist movement, stability, and overall hand function.
Prepare to be astonished by the scaphoid, the largest and most prominent bone in the proximal row. Nestled on the radial side of the wrist, the scaphoid forms an essential connection with the radius bone of the forearm.
This bone showcases extraordinary versatility, facilitating the intricate movements of wrist flexion, extension, and radial and ulnar deviation. It excellently transmits forces from the hand to the forearm, ensuring seamless coordination.
However, the scaphoid’s uniqueness comes with a price. Its location and structure make it susceptible to fractures. This demands meticulous care and specialized medical attention for proper healing.
The lunate is a bone-enchanting crescent shape reminiscent of a half-moon. The lunate occupies the center of the wrist and is positioned next to the scaphoid.
It preserves the stability of the wrist. This bone takes center stage, flawlessly accommodating the demands of wrist extension and flexion with impeccable precision.
It expertly disperses the forces transmitted through the hand during various activities. It ensures smooth and coordinated execution. Yet, the lunate’s splendor is not impervious to challenges.
A triquetrum is a three-sided pyramid shape that immediately captivates the observer. It elegantly resides alongside the lunate, adorning the ulnar side of the wrist.
This bone experiences wrist flexion, extension, ulnar, and radial deviation. The triquetrum is pivotal in providing necessary support and stability to the wrist joint, ensuring harmonious and coordinated movements.
However, even the triquetrum’s elegance cannot shield it from adversity. Traumatic incidents, such as falls or direct trauma, can disrupt its delicate balance. This necessitates thorough medical evaluation and precise treatment to restore its magnificence.
The pisiform is the smallest bone within the proximal row. Nestled on the ulnar side of the wrist, just below the triquetrum.
The pisiform diligently contributes to the orchestration of wrist flexion. It provides additional support to the carpal bones, reinforcing the structural integrity of the wrist.
Furthermore, this bone is a remarkable flexor carpi ulnaris tendon pulley. It amplifies its mechanical advantage and ensures the seamless execution of wrist movements.
Distal Row (closest to the hand)
Nestled closest to the hand, these four great bones—the trapezium, trapezoid, capitate, and hamate—emerge as nature’s masterpieces, each possessing indispensable contributions to wrist motion and stability.
The trapezium occupies a place at the base of the thumb. Its unique structure, resembling an irregular quadrilateral, showcases nature’s ingenuity.
The trapezium and the thumb’s metacarpal bone weave the tapestry of the thumb’s carpometacarpal joint. It allows humans to execute delicate pinching gestures and precisely manipulate objects.
The trapezoid establishes a harmonious connection with the second metacarpal bone, forging the second carpometacarpal joint.
This ethereal fusion endows the wrist with stability and flexibility. It allows for a seamless orchestration of intricate hand movements. These movements both astound and delight.
Its regal stature and commanding presence set it apart from its counterparts. The capitate joins forces with the third metacarpal bone, creating the awe-inspiring third carpometacarpal joint.
The capitate wields its unparalleled size and structure to channel the forces from the forearm, empowering the wrist with the strength and finesse necessary for gripping, rotating, and flexing movements.
A supernatural allure bone emerges on the wrist’s ulnar side—the hamate. Its presence is highlighted by a captivating hook-like projection known as the hamulus, an adornment unseen in any other bone.
The hamate builds the fourth and fifth carpometacarpal joints by forming a good connection with the fourth and fifth metacarpal bones, cementing its role as a protector of stability.
The hamulus anchors vital structures like the revered flexor retinaculum and the esteemed ulnar nerve.
Wrist Joint Anatomy
This joint serves as the gateway to interesting wrist movements. Together, they create flexion, extension, adduction, abduction, and circumduction.
The radiocarpal joint, wrapped in a cushion of smooth cartilage, ensures that every motion is executed with remarkable fluidity and finesse.
Deep within the inner workings of the wrist lie the intercarpal joints, a network of interconnected joints that bring stability to the wrist’s movements.
These joints are like master sculptors, collaborating to enable subtle gliding and sliding motions between the carpal bones. With each joint playing its unique role, they work together in perfect synchrony, transforming flexibility and control.
Step into the extraordinary mid-carpal joint, a hidden gem between the proximal and distal rows of carpal bones. This joint possesses a charisma that adds an extra touch of wonder to the wrist’s capabilities.
The midcarpal joint unlocks a mesmerizing flexion, extension, adduction, and abduction combination. The wrist possesses a secret chamber where these intricate movements are refined and perfected.
The mid-carpal joint’s contribution to the wrist’s fluidity and versatility elevates it to a true wrist virtuoso.
The carpometacarpal (CMC) joints the bridge between the wrist and the hand. Each CMC joint possesses its distinctive charm, showing the hand its remarkable capabilities.
The remaining CMC joints work perfectly, providing stability and coordination to the fingers, allowing them to execute intricate manipulations and expressiveness with precision.
These joints are like conductors in an orchestra, guiding the fingers’ movements to control the motion.
Inter Carpometacarpal Joints
Deep within the wrist’s hidden sanctum lie the inter carpometacarpal (ICMC) joints, the secret agents that unite the carpal and metacarpal realms. These joints lend strength and fluidity to the hand’s movements.
With subtle gliding and sliding motions, the fingers can execute precise and controlled gestures, transforming the hand into a mesmerizing instrument of dexterity.
Distal Radioulnar Joint
This joint is the axis of rotational movements, allowing the forearm to perform astonishing twists and turns.
It’s like having a built-in compass within the wrist, guiding the hand’s graceful navigation through the world. With its intricate interplay between the radius and ulna bones, the DRUJ adds the final touch to the wrist’s motion.
It’s a testament to the wonders of nature, ensuring that our wrists possess the flexibility and versatility to tackle the most intricate tasks with finesse and precision.
Wrist Muscle Anatomy
Flexor Carpi Radialis
The flexor carpi radialis muscle, nestled within the forearm, can facilitate wrist and hand movement. This muscle begins from the medial epicondyle of the humerus, a prominent bony protrusion on the inside of the elbow. It ends at the base of the second metacarpal bone.
The flexor carpi radialis plays a crucial part in flexing and abducting the wrist joint, displaying its innate ability. This awe-inspiring ability allows for the graceful curvature of the hand toward the palm. It also indulges in an elegant lateral movement away from the body’s midline.
This muscle facilitates gripping and enables tasks that demand a robust grasp. Examples include lifting objects or wielding tools.
A biologically enigmatic muscle, the palmaris longus resides within the forearm, nestled between the esteemed flexor carpi radialis and the venerable flexor carpi ulnaris.
It must be acknowledged that the palmaris longus boasts a variable existence. It remains absent in approximately 14% of the population, shrouding itself in intrigue and individuality.
It arises from the prestigious medial epicondyle of the humerus, mirroring the origin of the flexor carpi radialis.
Flexor Carpi Ulnaris
Originating from the sacred medial epicondyle of the humerus, akin to its esteemed counterpart, the flexor carpi radialis, this magnificent muscle embarks on an exquisite journey, culminating in its ethereal insertion into the pisiform bone—an elegant carpal entity—and the base of the fifth metacarpal bone.
The flexor carpi ulnaris rules the stage of motion and orchestrates the majestic act of flexing and adducting the wrist joint, displaying its regal grandeur. This sublime dance enables the hand to tenderly caress the palm and approach the body’s illustrious midline.
The flexor carpi ulnaris rises to prominence in activities requiring gripping and stabilizing. It also commands a potent grip and the prodigious ulnar deviation of the wrist.
Extensor Carpi Radialis Longus
Emblazoned upon the canvas of the forearm, the extensor carpi radialis longus manifests as a compelling force.
This extraordinary muscle emanates from the famous lateral supracondylar ridge of the humerus, an ethereal bony ridge embellishing the outside of the elbow and descending to its termination, gently integrating into the base of the second metacarpal bone.
The extensor carpi radialis longus emerges as a stalwart guardian, bestowing the gift of extension and abduction upon the wrist joint. With a sweeping gesture, the hand gracefully parts ways with the palm, traversing toward the bright radial side of the forearm.
This resilient muscle is a bastion of stability. It shines during tasks demanding unwavering wrist extension. It also excels in resisting the siren call of radial deviation. For instance, it supports the elegant strokes of a painter’s brush. Similarly, it aids in the melodic dance of fingers on musical instruments.
Extensor Carpi Radialis Brevis
In the majestic realm of the forearm, the extensor carpi radialis brevis emerges as an illustrious companion to its counterpart, the extensor carpi radialis longus.
This remarkable muscle originates from the revered lateral epicondyle of the humerus. It is a well-known bony protrusion gracing the outside of the elbow. The muscle reaches its apex when it wraps around the third metacarpal bone.
In harmony with its counterpart, the extensor carpi radialis brevis partakes in the ballet of extension and abduction, coaxing the hand away from the gentle cradle of the palm and propelling it toward the bright radial side of the forearm.
Like a guardian sentinel, this persistent muscle ensures stability during endeavours demanding repetitive or forceful wrist extension and radial deviation. It supports those who lift burdens or yield hammers with unwavering determination.
Extensor Carpi Ulnaris
The extensor carpi ulnaris is a powerful muscle from the lovely forearm artwork. It traces its origins to the prestigious lateral epicondyle of the humerus, with its gaze fixed upon the illustrious base of the fifth metacarpal bone—a testament to its unwavering commitment.
The extensor carpi ulnaris, a champion of extension and adduction, guides the hand away from the tender embrace of the palm, steering it firmly toward the ulnar side of the forearm.
Activities demanding strength and grace, such as wielding a tennis racket or launching a ball into the vast expanse. It fortifies the wrist during forceful or repetitive wrist extension and ulnar deviation.
Wrist Ligament Anatomy
Radial Collateral Ligament
The radial collateral ligament, which connects the radius bone to the scaphoid and trapezium bones, is a powerful protector nestled inside the complex structure of the wrist.
Its continued presence ensures steadfast stability, preventing audacious attempts of excessive thumb-side deviation. This ligament’s remarkable strength fortifies the wrist joint, preserving its integrity and functionality.
Injuries to the radial collateral ligament often result from forceful impacts or extreme stretching. The consequences are not to be trifled with, as pain, swelling, and a disturbing sense of instability seize the wrist joint.
Ulnar Collateral Ligament
The ulnar collateral ligament commands the outer echelons of the wrist’s defence. It forms an unyielding bond, connecting the ulna bone to the triquetrum and pisiform bones, warding off any ill-fated lateral wrist wanderings towards the little finger side.
Much like its radial counterpart, the ulnar collateral ligament is weak to the perils of traumatic events and the wearisome strain of repetitive motions.
When this valiant ligament suffers, the consequences are anything but inconspicuous—pain, swelling, and an unsettling sense of instability lay claim to the wrist joint.
Palmar Radiocarpal Ligament
The palmar radiocarpal ligament, concealed beneath the palm’s layers, sets out on an unwavering quest to connect the radius bone to the lunate, capitate, and hamate bones. This indomitable ligament erects an impenetrable fortress, guarding against the insidious forces of excessive flexion and hyperextension, preserving the wrist joint’s delicate equilibrium.
When the palmar radiocarpal ligament falls to the sudden impacts, the repercussions reverberate through the wrist’s corridors. Pain becomes a steadfast companion. Swelling takes hold.
Dorsal Radiocarpal Ligament
The dorsal radiocarpal ligament wraps its arms around the wrist’s dorsal breadth, connecting the radius bone with the scaphoid, lunate, and triquetrum bones.
This intrepid ligament stands as a stalwart sentinel, staunchly averting the difficult path of dorsal bending and hyperextension. Its resolute stance ensures the wrist’s stability and unrestrained movement.
Injuries beset the dorsal radiocarpal ligament stem from the tumultuous realms of forceful impacts or ceaseless bouts of wearisome strain. Pain becomes an unwelcome guest, swelling emerges, and the once-effortless range of motion dwindles.
A luminary amidst the wrist’s vast array of ligaments, the scapholunate ligament forms an elegant bridge connecting the scaphoid and lunate bones. This ethereal bond ensures seamless alignment and steadfast stability, allowing the wrist to navigate its intricate motions carefully.
Sprains or tears that afflict the scapholunate ligament emerge from the treacherous precipice of falls upon outstretched hands or the ceaseless onslaught of repetitive stress. These injuries leave an indelible mark as pain grips the wrist, swelling engulfs its delicate contours, and instability takes hold.
Triangular Fibrocartilage Complex (TFCC)
Hidden away along the ulnar side of the wrist joint, the enigmatic triangular fibrocartilage complex (TFCC) reveals its wondrous tapestry. Comprised of an intricate interweaving of ligaments, cartilage, and tendons, this complex confers unwavering support and stability to the joint.
The TFCC’s remarkable architecture bears the weight of the wrist’s burdens, distributing forces evenly and preserving the delicate balance.
Injuries that assail the TFCC arise from the fickle hands of gravity, repetitive activities, or the relentless march of degenerative changes. The repercussions are far from inconspicuous—of pain, swelling, clicks, or pops, and the once-fluid movements of the wrist yield a disheartening chorus of limitation.
Wrist Tendon Anatomy
Flexor Pollicis Longus Tendon
The flexor pollicis longus tendon resides within the wrist. It originates from the midsection of the radius bone in the forearm and embarks through the carpal tunnel. At its destination, it firmly attaches to the distal phalanx of the thumb, securing its critical role.
This extraordinary tendon possesses an evolutionary advantage, enabling the flexion of the thumb. It empowers us to grasp objects with exceptional precision and finesse.
Flexor Digitorum Superficialis Tendons
The flexor digitorum superficialis tendons on the palm side of the wrist represent the perfect balance between muscle and bone. These tendons transform at the medial epicondyle of the humerus bone and go deep into the forearm.
With their strength and grace, these tendons enable the flexion of our fingers at the proximal interphalangeal joints. They endow us with the ability to grab objects, write, and embrace the artistry of craftsmanship.
Flexor Digitorum Profundus Tendons
The flexor digitorum profundus tendons represent subtle energy tightly woven into our hands’ fabric and concealed behind their superficial counterparts. These tendons leave the ulna and interosseous membrane and go into the forearm, demonstrating their tenacity.
Through their tenacity, these tendons facilitate the flexion of the distal interphalangeal joints. Their harmonious collaboration with other tendons and muscles grants us the power of delicate finger movements, allowing us to articulate our thoughts through the strokes of a pen or the strings of an instrument.
Extensor Pollicis Longus Tendon
Unyielding and steadfast, the extensor pollicis longus tendon commands attention to the forearm’s dorsal aspect, dictating our thumbs’ movement.
Originating from the ulna gliding through a bony groove etched into the radius. Its final destination rests at the base of the distal phalanx of the thumb.
This tendon empowers the extension of the thumb, enabling it to move away from the palm and oppose the other fingers. It bestows us the ability to grasp objects, create, and shape the world around us.
Extensor Digitorum Tendons
The extensor digitorum tendons are located on the dorsal side of the wrist. Originating from the lateral epicondyle of the humerus, they traverse the expanse of the forearm, gracefully passing through the intricate confines of the wrist.
These tendons orchestrate the extension of our fingers at the proximal and distal interphalangeal joints. Their strength and coordination empower us to open our fingers gracefully, imbuing our actions with purpose and precision.
Extensor Digiti Minimi Tendon
The extensor digiti minimi tendon adds a touch of uniqueness to the wrist’s repertoire. Originating from the ulna, it traces a parallel path to the extensor digitorum tendons. Its journey culminates at the base of the distal phalanx of the little finger, bearing witness to the subtleties of fine motor control.
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