WRISTAna
tomy:
Upp
er L
imb
I186
TERMINOLOGYDefinitions Articulation complex comprising distal radioulnar,
radiocarpal, ulnocarpal, pisotriquetral, midcarpal, andcarpometacarpal joints
IMAGING ANATOMYOsseous Structures Distal radius: Lister tubercle on dorsal surface Distal ulna: Ulnar variance refers to length of ulnar
head relative to distal radius: Ulnar minus or ulnar plus Proximal carpal row: Scaphoid, lunate, triquetrum,
pisiform Scaphoid: Proximal and distal pole separated by waist
Tuberosity = volar prominence of distal pole Lunate: Half-moon-shaped Triquetrum: Triangular-shaped Pisiform: Pea-shaped sesamoid-type bone to which
flexor carpi ulnaris attaches and continues distally aspisohamate and pisometacarpal ligaments
Distal carpal row: Trapezium, trapezoid, capitate,hamate Trapezium: Saddle-shaped bone linking carpus and
thumb Trapezoid: Wedge-shaped bone Capitate: Head (proximal), neck (midportion), and
body (bulky distal portion) Hamate: Hook (hamulus) arises from palmar surface
Ligaments Extrinsic (on palmar or volar aspects of wrist) or
intrinsic (between carpal bones) Major wrist stabilizers: Volar ligaments Extrinsic ligaments
Palmar: Radioscaphocapitate, radiolunotriquetral,radioscapholunate, ulnotriquetral, ulnolunate,scaphotriquetral
Dorsal: Scaphotriquetral, radiotriquetral,ulnotriquetral, radial collateral
Intrinsic ligaments Proximal interosseous: Scapholunate, lunotriquetral Distal interosseous: Trapeziotrapezoid,
trapeziocapitate, capitohamate
Muscles and Tendons Flexors, deep
Flexor digitorum profundus: Originated from ulna;inserted to index, middle, ring, and little finger distalphalangeal bases
Flexor pollicis longus: Originated from radius,interosseous membrane and coronoid process ofulna; inserted to distal phalangeal base of thumb
Flexors, superficial Flexor carpi radialis: Originated from medial
epicondyle; inserted to 2nd metacarpal base Palmaris longus: Originated from medial epicondyle;
inserted to palmar aponeurosis Flexor carpi ulnaris: Originated from medial
epicondyle and medial olecranon/proximal ulna;inserted to pisiform
Flexor digitorum superficialis: Originated frommedial epicondyle and coronoid process of ulna andanterior radius; inserted to middle phalangeal basesof digits 2-5
Extensors, deep Abductor pollicis longus: Originated from ulna;
inserted to radial aspect 1st metacarpal base Extensor pollicis brevis: Originated from radius;
inserted to proximal phalangeal base of thumb Extensor pollicis longus: Originated from midulna;
inserted to distal phalangeal base of thumb Extensor indicis: Originated from midulna; joins
ulnar side of extensor digitorum tendon insertinginto 2nd digit extensor hood
Extensors, superficial Extensor carpi radialis longus: Originated from lateral
supracondylar ridge of humerus; inserted to dorsalradial 2nd metacarpal base
Extensor carpi radialis brevis: Originated from lateralhumeral epicondyle; inserted to dorsal radial 3rdmetacarpal base
Extensor digitorum: Originated from lateral humeralepicondyle; inserted to distal phalangeal bases ofdigits of 2-5
Extensor digiti minimi: Originated from lateralhumeral epicondyle; inserted to extensor hood oflittle finger
Extensor carpi ulnaris: Originated from lateralhumeral epicondyle; inserted to 5th metacarpal base
Retinacula Flexor retinaculum
Also called transverse carpal ligament: Attachedto pisiform and hook of hamate, scaphoid, andtrapezium
Extensor retinaculum Attaches to ulnar styloid process, triquetrum, and
pisiform medially; crosses obliquely to attach to Listertubercle and radial styloid process laterally Sends septa to radius, creating 6 compartments for
extensor tendons Compartment contents
1st: Abductor pollicis longus (APL) and extensorpollicis brevis (EPB)
2nd: Extensor carpi radialis, longus (ECRL) andbrevis (ECRB)
3rd: Extensor pollicis longus (EPL) 4th: Extensor digitorum (ED) and extensor indicis
(EI) 5th: Extensor digiti minimi (EDM) 6th: Extensor carpi ulnaris (ECU)
Anatomic Spaces Carpal tunnel
Margins: Carpal bones (dorsal margin); flexorretinaculum (volar margin); pisiform and hook ofhamate (ulnar margin); scaphoid and trapezium(radial margin); radiocarpal joint (proximal margin);and metacarpal base (distal margin) Contents: Flexor digitorum superficialis, flexor
digitorum profundus, flexor pollicis longus,median nerve
Guyon canal Margins: Fascial extension from flexor retinaculum,
volar carpal ligament (volar margin), pisiformand flexor carpi ulnaris (ulnar margin), flexorretinaculum (radial and dorsal margins) Contents: Ulnar artery and vein, ulnar nerve
WRISTAnatom
y: Upper Lim
b
I187
GRAPHICS, CARPAL BONES AND WRIST COMPARTMENTS
Capitate
Hamate
Pisiform
Lunate
Triquetrum
Ulna
Distal radioulnar joint
1st metacarpal
1st carpometacarpal joint
Trapezium
Scaphoid
Radial styloid process
Trapezoid
Common carpometacarpalcompartment
Pisotriquetral compartment
Distal radioulnarcompartment
Radiocarpal compartment
Midcarpal compartment
1st carpometacarpalcompartment
(Top) Graphic shows the bones of the wrist joint. (Bottom) Graphic shows the 5 different wrist compartments: Distal radioulnar compartmentis separated from the radiocarpal compartment by the triangular fibrocartilage complex (TFCC). Pisotriquetral compartment is separated fromthe radiocarpal compartment in 20%. Midcarpal compartment is separated from the radiocarpal compartment by the scapholunate andlunotriquetral ligaments and typically communicates with the carpometacarpal joints. First carpometacarpal compartment is separated from thecommon carpometacarpal compartment by the trapeziometacarpal ligament.
WRISTAna
tomy:
Upp
er L
imb
I188
GRAPHICS, DORSAL TENDONS AND TENDON SHEATHS
Abductor pollicis longustendon
Extensor pollicis longustendon
Extensor pollicis brevistendon
Extensor carpi radialis brevistendon
Extensor carpi radialislongus tendon
Extensor carpi ulnaristendonExtensor digiti minimitendon
Extensor retinaculum
Extensor digitorum tendon
Extensor indicis tendon
Compartment 1: APL, EPB
Compartment 2: ECRL,ECRB
Compartment 3: EPL
Compartment 6: ECU
Compartment 5: EDM
Compartment 4: ED, EI
(Top) Dorsal extensor tendons pass deep to the extensor retinaculum, separated into 6 compartments by fibrous attachments of the retinaculumto underlying bone. Compartment contents include abductor pollicis longus (APL) and extensor pollicis brevis (EPB), extensor carpi radialislongus (ECRL) and brevis (ECRB), extensor pollicis longus (EPL), extensor digitorum (ED) and extensor indicis (EI), extensor digiti minimi (EDM),and extensor carpi ulnaris (ECU). (Bottom) Separate tendon sheaths enclose dorsal extensor tendons in compartments 1-6 individually.
WRISTAnatom
y: Upper Lim
b
I189
GRAPHICS, TENDONS: RELATIONS TO DORSAL & VOLAR WRIST
Flexor carpi ulnaris
Flexor digitorumsuperficialis tendon
Flexor digitorum profundustendon
Extensor carpi ulnaristendon
Extensor digiti minimitendon
Extensor indicis tendon
Extensor digitorum tendonslips
Ulnar nerve
Palmaris longus tendon
Flexor carpi radialis tendon
Flexor pollicis longustendon
Abductor pollicis longustendon
Extensor pollicis brevistendon
Extensor carpi radialislongus tendon
Extensor carpi radialis brevistendon
Median nerve
Extensor pollicis longustendon
Extensor digitorum tendonslips
Extensor indicis tendon
Extensor digiti minimitendon
Extensor carpi ulnaristendon
Flexor digitorum tendon
Volar carpal ligament
Abductor digiti minimitendon
Ulnar nerve
Flexor retinaculum
Flexor pollicis longustendon
Extensor pollicis brevistendon
Extensor carpi radialis brevis& longus tendon
Extensor pollicis longustendon
Abductor pollicis longustendon
Median nerve
Flexor carpi radialis tendon
(Top) Graphic representation shows tendons in the proximal wrist. Extensor tendons are deep to the extensor retinaculum, whereas flexortendons are proximal to the flexor retinaculum at this level in the wrist. (Bottom) Midcarpal tunnel is shown. Median nerve is slightly flattenedas it passes deep to the flexor retinaculum and remains superficial to the flexor pollicis longus. Ulnar nerve, artery, and veins lie lateral to thepisiform and may divide near the pisiform into deep and superficial branches.
WRISTAna
tomy:
Upp
er L
imb
I190
TRANSVERSE US, RADIAL ASPECT
2nd compartment tendons
Distal end of radius
Cephalic vein
1st compartment tendons
Extensor pollicis brevis tendon
Abductor pollicis tendon
Radius
Scaphoid
Cephalic vein
Extensor pollicis brevis tendon
Radial veins
Radial artery, superficial and deepbranch
Abductor pollicis longus tendon
(Top) Transverse grayscale US shows the 1st extensor compartment proximal to the distal radius. The 1st compartment contains the extensorpollicis brevis (EPB) and the larger abductor pollicis longus (APL) tendons. The 1st compartment tendons run obliquely over 2nd compartmenttendons a few centimeters proximal to the wrist. Pain may occur at this intersection (intersection syndrome). (Middle) Transverse grayscale USshows the 1st extensor compartment at the distal radius. EPB extends to the base of the proximal phalanx of the thumb, whereas APL insertsonto the base of the 1st metacarpal bone. They form the radial aspect of the anatomical snuff box. These tendons are swollen in patients with deQuervain disease. (Bottom) Transverse grayscale US shows the 1st extensor compartment at the level of the scaphoid. Dorsal branch of the radialartery passes deep to the tendons of the 1st extensor compartment to enter the dorsum of the hand.
WRISTAnatom
y: Upper Lim
b
I191
TRANSVERSE US, DORSAL WRIST
Extensor pollicis longus tendon
Extensor carpi radialis brevis tendon
Lister tubercle Extensor carpi radialis longus tendon
Cephalic vein
Radius
Extensor pollicis longus tendon
Extensor carpi radialis brevis tendon
Radius
Extensor carpi radialis brevis tendon
Extensor carpi radialis longus tendon
Scaphoid Extensor pollicis longus tendon
(Top) Transverse grayscale US shows the 2nd & 3rd extensor compartments at the distal radius level. The 2nd extensor compartment comprisesthe extensor carpi radialis longus (ECRL) and extensor carpi radialis brevis (ECRB). ECRL inserts into the base of the index finger metacarpal,whereas ECRB inserts into the middle finger metacarpal. The 2nd compartment is separated from the 3rd compartment, containing the extensorpollicis longus (EPL), by the Lister tubercle. (Middle) Transverse grayscale US shows the 2nd and 3rd extensor compartments at the distal radiuslevel. The 2nd compartment forms the dorsal aspect of the anatomical snuff box. (Bottom) Transverse grayscale US shows the 2nd extensorcompartment at the scaphoid level. The EPL tendon hooks around the Lister tubercle and crosses superficial to the 1st compartment tendons asit runs toward its insertion on the base of the distal phalanx of the thumb. It is prone to rupture in inflammatory arthropathies and distal radialfractures.
WRISTAna
tomy:
Upp
er L
imb
I192
TRANSVERSE US, EXTENSOR DIGITORUM
Extensor digiti minimi tendon
Ulna
Extensor pollicis longus tendon
Lister tubercle
Extensor digitorum tendon
Extensor retinaculum
Radius
Lunate
Extensor digiti minimi tendon
Extensor digitorum tendon
Extensor retinaculum
Scaphoid
Lunate
Extensor digitorum tendonsScapholunate ligament (dorsalcomponent)
Scaphoid
Extensor retinaculum
(Top) Transverse grayscale ultrasound shows the 4th extensor compartment at the distal radius. The 4th extensor compartment contains the 4extensor digitorum tendons and the extensor indicis tendon, which lies radial to the extensor digitorum tendons. The extensor digiti minimi hasa separate compartment. (Middle) Transverse grayscale ultrasound shows the 4th extensor compartment at the level of the proximal carpal row.The extensor retinaculum is a thickened continuation of the antebrachial fascia. It is attached to the anterior aspect of the distal radius, styloidprocess of the ulna, and the triquetral and pisiform bones. (Bottom) Transverse grayscale ultrasound shows the 4th extensor compartment atthe level of the proximal carpal row. The extensor retinaculum holds the extensor tendons in place. Because it is closely applied to the extensortendons, with anisotropy, it may appear hypoechoic and be confused with tenosynovitis.
WRISTAnatom
y: Upper Lim
b
I193
TRANSVERSE US, EXTENSOR CARPI ULNARIS
Extensor carpi ulnaris tendon
Ulna Extensor digiti minimi tendon
Radius
Extensor carpi ulnaris tendon
Articular disc
Radius
Extensor digiti minimi tendon
Extensor carpi ulnaris tendon
Hamate
Capitate
(Top) Transverse grayscale ultrasound shows the 5th and 6th extensor compartments. The 5th compartment contains the extensor digiti minimi(EDM) tendon. This tendon is joined by the extensor digitorum (ED) tendon to the little finger just proximal to the metacarpophalangeal (MCP)joint. The 6th compartment contains the extensor carpi ulnaris (ECU) tendon, which runs in a groove in the distal ulna. Its position in the groovewill change with pronation and supination. (Middle) Transverse grayscale ultrasound shows the 5th and 6th extensor compartments. The ECUtendon often has a midline irregular hypoechoic line within its substance close to the insertion. This should not be mistaken for a longitudinaltear. (Bottom) Transverse grayscale ultrasound at insertion of the ECU tendon is shown. The ECU tendon widens as it passes the lunate bone onits way to insert into the base of the 5th metacarpal.
WRISTAna
tomy:
Upp
er L
imb
I194
GRAPHICS, VOLAR WRIST
Hypothenar eminence
Flexor retinaculum
Flexor digitorum profundustendons
Flexor digitorumsuperificialis tendons
Flexor carpi ulnaris tendon
Pronator quadratus muscleFlexor pollicis longusmuscle and tendon
Flexor carpi radialis tendon
Abductor pollicis longustendon
Extensor pollicis brevistendon
Thenar eminence
Opponens digiti minimimuscle
Flexor digiti minimi brevismuscle
Abductor digiti minimimuscle
Flexor digitorumsuperficialis tendons
Pronator quadratus muscle
Flexor carpi ulnaris tendon
Flexor digitorum profundustendons
Flexor carpi radialis tendon
Flexor pollicis longustendon
Abductor pollicis longustendon
Flexor retinaculum
Abductor pollicis brevismuscle
Flexor pollicis brevis muscle
Flexor pollicis longustendon
Extensor pollicis brevistendon
(Top) Graphic shows tendons and retinaculum of the volar wrist. The flexor retinaculum spans the palmar arch, attaching to the to the tubercleof the scaphoid, the pisiform, the hook of hamate, and the ridge of the trapezium. The thenar eminence musculature includes abductor pollicisbrevis, opponens pollicis, flexor pollicis brevis, and adductor pollicis. The hypothenar eminence musculature includes palmaris brevis, adductordigiti minimi, flexor digiti minimi brevis, and opponens digiti minimi. (Bottom) Volar muscles and tendons are displayed with their relation tothe flexor retinaculum. Note the muscles of thenar and hypothenar eminences arise from the retinaculum itself. The flexor digitorum and flexorpollicis longus tendons pass deep to the retinaculum. On the radial side, the retinaculum splits to accommodate the flexor carpi radialis tendon.
WRISTAnatom
y: Upper Lim
b
I195
TRANSVERSE US, VOLAR WRIST
Radial artery
Palmaris longus tendon
Median nerve
Flexor digitorum superficialis muscle
Radius
Flexor carpi radialis tendon
Flexor pollicis longus tendon Flexor digitorum profundus muscle
Pronator quadratus muscle
Anterior interosseous artery, vein, &nerve
Interosseous membrane
Ulna
Flexor carpi radialis tendon
Median nerve
ScaphoidFlexor tendons
Lunate
Triquetrum
ScaphoidFlexor tendons
Capitate
Flexor carpi radialis tendon
Flexor retinaculum
Extrinsic carpal ligamentUlnar artery, vein, & nerve
Median nerve
Pisiform
(Top) Transverse grayscale ultrasound shows the volar aspect of the distal forearm just proximal to the wrist. In addition to the tendons thatpass through the carpal tunnel, the flexor carpi ulnaris, flexor carpi radialis, and palmaris longus tendons also traverse the wrist joint. (Middle)Transverse grayscale ultrasound shows the volar aspect of the wrist just proximal to the carpal tunnel. The 4 tendons of flexor digitorumsuperficialis (FDS), 4 tendons of flexor digitorum profundus (FDP), and flexor pollicis longus (FPL) tendons pass through the carpal tunnel.The median nerve dips deeply as it enters the carpal tunnel. (Bottom) Transverse grayscale ultrasound shows the volar aspect of the wrist atthe tunnel inlet. The inlet (and outlet) of the carpal tunnel can be best recognized by identifying the proximal and distal margins of the flexorretinaculum. In evaluating carpal tunnel syndrome, the caliber of the nerve should be measured proximal to the tunnel, at the tunnel inlet, and atthe tunnel outlet.
WRISTAna
tomy:
Upp
er L
imb
I196
US, VOLAR WRIST
Abductor pollicis brevis muscle
Trapezium
Flexor tendons
Median nerve
Ulnar artery
Opponens pollicis muscle
Capitate
Ulnar nerve & vein
Flexor retinaculum
Base of 3rd metacarpal
Trapezium
Opponens pollicis muscle
Hook of hamate
Flexor tendons
Capitate
Abductor pollicis brevis muscle
Flexor retinaculum
Median nerve
Flexor pollicis longus tendon
Metacarpal of index finger
Flexor pollicis brevis muscle
Opponens pollicis muscle Metacarpal of ring finger
Flexor tendons
Adductor pollicis muscle
Abductor pollicis brevis muscle
Metacarpal of 3rd finger
Ulnar artery
Branch of median nerve
(Top) Transverse grayscale ultrasound shows the volar aspect at midcarpal tunnel. The median nerve lies in the carpal tunnel just deep to theretinaculum. You may need to use anisotropy to clearly identify the margins of the median nerve separate from the adjacent flexor tendons.(Middle) Transverse grayscale ultrasound shows the volar aspect of the wrist at the tunnel outlet. The tunnel outlet is considered to be thenarrowest part of the carpal tunnel. (Bottom) Transverse grayscale ultrasound shows the volar aspect of the wrist just beyond the tunnel outlet.The median nerve divides into its terminal branches just beyond the tunnel outlet.
WRISTAnatom
y: Upper Lim
b
I197
US, SCAPHOID
Distal part of scaphoid
Waist of scaphoid
Flexor carpi radialis tendon
Joint
Proximal part of scaphoid
Radius
Trapezium
Radial artery
Articular cartilage
Scaphoid
Radius
Trapezium
Scaphoid
Articular cartilage
Radial artery
(Top) Grayscale ultrasound longitudinal to palmar aspect of the scaphoid bone is shown. Ultrasound is a useful means of diagnosing a scaphoidfracture. Angulation of the transducer along the long axis of the scaphoid allows the palmar cortical outline to be appreciated. (Middle)Grayscale ultrasound longitudinal to dorsal aspect of the scaphoid bone is shown. There is often mild cortical irregularity of the scaphoid surface,particularly on the dorsal side. The absence of surrounding edema, hematoma, periosteal thickening, and cortical discontinuity allows one todifferentiate this normal appearance from a fracture. (Bottom) Grayscale ultrasound transverse to dorsal aspect of the scaphoid bone is shown.
WRISTAna
tomy:
Upp
er L
imb
I198
GRAPHICS AND US, TRIANGULAR FIBROCARTILAGE
Ulnar collateral ligament
Extensor carpi ulnaris
Ulnar styloid process
Ulnocarpal ligament
Dorsal radioulnar ligament
Volar radioulnar ligament
Extensor carpi ulnaris tendonDorsal radioulnar ligament
Articular disc
Extensor carpi ulnaris tendon
Triquetrum
Articular cartilage
Articular disc (fibrocartilage)
Ulnar head
(Top) Graphic shows supporting structures of triangular fibrocartilage (TFCC). The ulnocarpal ligaments and the volar radioulnar ligament are onthe volar side. At the ulnar border, there is the ulnar collateral ligament. On the dorsal surface, there is the extensor carpi ulnaris (ECU) tendonand its subsheath as well as the dorsal radioulnar ligament. (Middle) Graphic depicts the axial view of the articular disc of TFCC. The articulardisc is inseparable from supporting dorsal and volar radioulnar ligaments. The disc is widest at its radial attachment. Central tears are morecommon, while peripheral tears, being better vascularized, have the capacity to heal. (Bottom) Longitudinal grayscale ultrasound shows the ulnaraspect of TFCC. The fibrocartilaginous articular disc is of different echotexture to hypoechoic hyaline cartilage. US is not as sensitive at depictingTFCC tears as MRI. The ECU tendon provides an acoustic window though which to see the articular disc of the TFCC.
WRISTAnatom
y: Upper Lim
b
I199
GRAPHICS, VOLAR AND DORSAL LIGAMENTS
Carpometacarpal ligaments
Capitohamate ligament
Triquetrocapitate ligament
Ulnotriquetral ligament
Lunotriquetral ligament,volar portion
Ulnocapitate ligament
Ulnolunate ligament
Volar radioulnar ligament
Trapeziocapitate ligament
Scaphotrapezium-trapezoidligament
Interligamentous sulcus
Radial collateral ligament
RadioscaphocapitateligamentLong radiolunate ligament
RadioscapholunateligamentShort radiolunate ligament
Dorsal scaphotriquetralligament
Dorsal intercarpal ligament
Trapeziotrapezoid ligament
Dorsal radioulnar ligament
Dorsal radiocarpal ligament
Carpometacarpal ligaments
Capitohamate ligament
Triquetrohamate ligament
(Top) Graphic shows volar intrinsic and extrinsic ligaments. The extrinsic ligaments connect the bones of the forearm (radius and ulna) and thoseof the carpus. The intrinsic ligaments connect carpal bones to carpal bones. (Bottom) Dorsal ligaments stabilize and restrict motion but are lesscritical to the stability of the wrist structures than the volar ligaments. On the volar aspect of the wrist, there is a triangular area of weakness(called the space of Poirier) between the lunate and capitate, which is not covered by any ligaments.