Wrist and Hand

Original Editors - Rachael Lowe

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Introduction

The upper limb has sacrificed locomotor function and stability for mobility, dexterity and precision.  The hand sits at the end of the upper limb and is a combination of complex joints whose function is to manipulate, grip and grasp- this is made possible by the opposing movement of the thumb.  

Bony Anatomy

The hand and wrist have a total of 27 bones arranged to roll, spin and slide; allowing the hand to explore and control the environment and objects. The hand is divided into three regions:

• Proximal region of the hand is the carpus (wrist)
• The middle region the metacarpus (palm)
• The distal region the phalanges (fingers).

The Carpus

The carpus consists of eight bones, sitting in two rows, with four bones in each row (figure 1).  The carpus controls length-tension relationships in the multiarticular hand muscles and to allow fine adjustment of grip. 

Three of the bones in the proximal row articulate with the radius forming the radiocarpal joint and distally with the distal carpal forming the midcarpal joint.  The four carpal bones in the distal row articulate with the bases of the five metacarpal bones forming the carpometacarpal joints.  The joints formed between the carpal bones are known as the intercarpal joints and most are of the plane synovial type, as the bones interlock with each other the rows are sometimes referred to as two single synovial joints.   

Figure 1 - Bones of the Hands

Bones - Dorsum of Left Hand		Bones - Volar of Left Hand

The arrangement of the bones and ligaments allows very little movement between bones, but they do slide contributing to the finer movements of the wrist.  The exception to this is the capitate which has a larger range of movement.  The small bones are named after the shape they resemble.

Proximal Row

• Scaphoid – (boat like)– anterior surface palpable tubercle. Articulates proximally with radius, medially with lunate and distally with the head of the capitate.  It is a common site of fracture- 70% of all carpal fractures, often injured by a fall onto an outstretched limb

• Lunate – (moon shaped) – Its palmar surface is smooth and convex and is larger than its dorsal surface.  Proximally it articulates with the radius and articular disc, medially with the triquetrum, laterally with the scaphoid and distally with the head of the capitate

• Triquetrum – (three cornered) – Nestles in the space between the lunate and hamate.  When the hand is adducted it enters the radiocarpal joint.

• Pisiform – (pea shaped) = a small round bone found in the tendon of flexor carpi ulnaris.  It articulates with the palmar surface of the triquetrum.   The anterior surface projects distally and laterally forming the medial part of the carpal tunnel. 

Distal Row

• Trapezium – four sided figures with no two sides parallel – the most irregular, with a palpable tubercle and groove anterior medially. It articulates proximally with the scaphoid and medially with the trapezoid.  Its articular surface is saddle-shaped and contributes to the mobility of the carpometacarpal joint of the thumb

• Trapezoid – four sided figure with two parallel sides – Articulates distally with the second metacarpal, laterally with the trapezium, proximally with the scaphoid and medially with the capitate

• Capitate - head shaped – The largest of all the carpal bones sitting centrally and articulating with the lunate and scaphoid, medially with the hamate and laterally with the trapezoid.  The distal surface articulates mainly with the base of the third metacarpal but also by narrow surfaces with the bases of the second and fourth metacarpals.

• Hamate – hooked – This is wedge shaped with a curved palpable hook projecting from the palmar surface near the base of the fifth metacarpal.

The following pneumonic makes it easy to remember the position of each bone:    

Carpal mneumonic

The Carpal Tunnel – formed by the anterior concave space formed by the pisiform and hamate – on the ulnar side and the scaphoid and trapezium – on the radial side, with a roof like covering of the flexor retinaculum (strong fibrous bands of connective tissue).  The long flexor tendons of the digits and thumb and the median nerve pass through the carpal tunnel

The Metacarpus

The metacarpus, the palm of the hand, which is made up of five bones – the metacarpals.  The bones are numbered laterally, from the thumb, 1 – 5.  Each bone is long with a proximal quadrilateral base, a shaft (body) and a distal rounded head.  The base of the first metacarpal is saddle-shaped and articulates with he trapezium.  The base of the second metacarpal articulates with the trapezium, trapezoid and capitate. The base of the third metacarpal articulates with the capitate.  The bases of the fourth and fifth metacarpal articulate with the hamate.  The bases of the second to fifth metacarpals also articulate with each other.

The heads of the metacarpals, commonly known as knuckles, are smooth and rounded and extend onto the palmar surface – these become visible when the fist is clenched.  The head of the first metacarpal is wider than the others, having two sesamoid bones, usually found in the short tendons crossing the joint, which articulate with the palmar part of the joint surface.  The heads fit into a concavity on the base of the proximal phalanx at the metacarapophlangeal joints.

The Phalanges

The phalanges, the fingers, consist of 14 long bones.  Apart from the thumb (the pollex) each phalanx has three bones, the distal, middle and proximal phalanx – the thumb has only two distal and proximal.  As with the metacarpals the phalanges are numbered 1-5 starting at the thumb.  The proximal phalanx is large and is concave for articulation with the head of the metacarpal.  The shaft is curved along its length being convex dorsally.  It is convex from side to side on its dorsal surface and flat on the palmar surface.  The distal end, the head, is smaller and convex to articulate with the next bone in sequence.  In order from the thumb digits are also known as the index finger, middle finger, ring finger and little finger.  

Joints of the Wrist and Hand

The wrist has two degrees of freedom, although some say three degrees of freedom because they include the movements of pronation and supination, which occur at the the radioulnar joint. The radioulnar joint is often referred to as a joint of the forearm but it is this articulation that gives the wrist more freedom of movement.  The true joints of the wrist and hand are listed in the table below.

Articulating surfaces /Joints of the wrist and hand

Joint	Proximal articulation	Distal Articulation	Type	Movement
Radiocarpal joint	Radius and articular disc/ concave	Scaphoid, lunate, triquetrum / – convex	Ellipsoid	Flexion-extension; Abduction-adduction
Midcarpal joint	Scaphoid. Lunate, Triquetrum	Trapezium, Trapezoid, Capitate, Hamate	Gliding	Flexion-extension; Abduction-adduction
Carpometacarpal joint (thumb)	1st metacarpal	trapezium	Saddle	Flexion-extension; Abduction-adduction; circumduction; opposition
Carpometacarpal joint (fingers)	2nd metacarpal 3rd metacarpal 4th metacarpal 5th metacarpal	trapezoid, trapezium capitate capitate, hamate hamate	Ellipsoidal	Flexion-extension
Metacarpophalangeal joints	Carpals	phalangeal	Ellipsoidal	Flexion, extension, abduction, adduction, circumduction
Interphalangeal	Distal phlangeal	Proximal phalangeal	Hinge	Flexion (lots) Extension (minimal)

Ligaments of the Wrist and Hand

The stability of the wrist is provided by ligaments (see table); on the palmar aspect is the flexor retinaculum which together with the carpal bones forms a canal – the carpal tunnel - which nerves, muscles and blood vessels run through, it is this area that is involved in carpal tunnel syndrome.

Ligaments of the Wrist and Hand

Ligament	Location	Function
Posterior radiocarpal ligament	runs diagonally across the posterior aspect of the wrist from the distal end of the radius to the triquetral and hamate carpal bones (on the ulnar side of the wrist	limits flexion of the wrist
Anterior radiocarpal ligament	runs from the anterior aspect of the distal end of the radius to the scaphoid, lunate and capitate bones of the wrist	Limits extension of the wrist
Radial collateral ligament	from the styloid process of radius to the scaphoid bone	limits adduction of wrist (frontal plane)
Ulnar collateral ligament	from the styloid process of the ulna to the triquetral	limits abduction (front plane)
Anterior, posterior and interosseous carpal ligaments	Between the carpal bones	holds carpal bones together - reinforced by the shape and interlocking structure of the bones
Transverse carpal ligament	flexor retinaculum	The roof of the carpal tunnel which the median nerve and flexor tendons pass through
Ligaments of the fingers	To be added

Movements of the Wrist and Hand

Movements of the Wrist

Movement	Muscles	Range	Origin	Insertion	Innervation	Joint
Flexion	Flexor carpi radialis	0-80	Medial Epicondyle of humerus	2nd and 3rd metacarpals	Median nerve (C6,7)	Radiocarpal Jt
	Flexor carpi ulnaris		Medial epicondyle of humerus and sup.post. border of ulna	Pisiform, hamate and base 5th metacarpal	Ulnar nerve (C7,8)
	Palmaris longus		Medial epicondyle of humerus	Flexor reinaculum and palmar aponeurosis	Median nerve (C8)
	Flexor digitorum superficialis		Medial epicondyle of humerus, coronoid process of ulna, and a ridge along lateral margin of anterior surface of radius	Middle phalanges of each finger	Median nerve (C7,8 T1)
	Flexor digitorum profundus		Anterior medial surface of body of ulna	Base of distal phalanx of thumb	Median nerve (C7,8, T1) Ulnar nerve (C8, T1)
	Flexor pollicis longus		Anterior surface of radius and interosseous membrane	Base of distal phalanx of thumb	Median nerve (C8, T1)
Extension	Extensor carpi radialis longus	0-70			Radial nerve (C6,7)	Radiocarpal Jt
	Extensor carpi radialis brevis				Radial nerve (C6,7)
	Extensor carpi ulnaris				Radial nerve (C7,8)
	Extensor digitorum				Radial nerve (C7,8)
	Extensor indicis				Radial nerve (C7, 8)
	Extensor digiti minimi				Radial nerve (C7,8)
	Extensor pollicis longus				Radial nerve (C7,8)
	Extensor pollicis brevis				Radial nerve (C7,8)
Radial deviation		30				Radiocarpal Jt
Ulnar deviation		20				Radiocarpal Jt
Supination (of forearm)	Supinator	60			Radial nerve (C5,6)	Sup. and inf.radioulnar jt
	Biceps brachii				Musculocutaneous nerve (C5,6)
	Brachioradialis				Radial Nerve (C5,6)
Pronation (of forearm)	Pronator teres	40			Median nerve (C6,7)	Sup.and inf.radioulnar jt
	Pronator quadratus				Median nerve (C8, T1)
	Brachioradialis				Radial nerve (C5,6)

Clinical Examination

• Wrist & Hand Examination
• Special Tests
  • Allen Test
  • Bunnell-Littler Test
  • CPR for Carpal Tunnel Syndrome
  • Finkelstein Test
  • Fovea Sign
  • Froment’s Sign
  • Kaltenborn of Hand
  • Phalen’s Sign
  • Scaphoid (Watson) Shift Test
  • Supination Lift Test
  • Sweater finger Sign
  • Thumb CMC Grind
  • Tinel’s Test
  • Valgus Stress to UCL
• Outcome Measures
  • DASH Outcome Measure
  • PRWE Score
  • Brigham and Women's Carpal Tunnel Questionnaire
  • Gartland and Werley Score

Conditions

• Carpel Tunnel Syndrome
  
• De Quervains
• Wrist Sprain
• Carpel Instability
• Colles Fracture
• Smiths Fracture
  
• Scaphoid Fracture
• Wrist & Hand Osteoarthritis
  
• Rheumatoid Arthritis
  
• Complex Regional Pain Syndrome
• Triangular Fibrocartilage Complex Injuries
• Gamekeeper’s Thumb
• Blackberry Thumb
• Lunate Instability
• Hamate Fracture
• Ape Hand
• Benediction Hand
• Claw Hand
• Dupuytren’s Contracture
• Metacarpal Fractures
• Extensor Mechanism Injuries
• Flexor Tendon Injuries
• Ulnocarpal Impaction Syndrome
  
• Lunotriquetral Ligament Tears
  

Procedures

• Total Wrist Replacement