Normal Sonographic Anatomy of the Wrist and Hand

doi:10.1148/rg.256055028

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Normal Sonographic Anatomy of the Wrist and Hand¹

Justin C. Lee, FRCR and Jeremiah C. Healy, FRCR

¹ From the Department of Radiology, Chelsea and Westminster Hospital, 369 Fulham Rd, London SW10 9NH, England. Recipient of a Certificate of Merit award for an education exhibit at the 2004 RSNA Annual Meeting. Received February 11, 2005; revision requested March 10 and received May 18; accepted May 23. Both authors have no financial relationships to disclose.

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Figure 1a. Normal sonographic appearance of tendons in the wrist. (a) Longitudinal sonogram of the flexor surface of the wrist depicts the flexor digitorum superficialis (FDS) tendon at its junction with the muscle. Note the typical linear fibrillar appearance of the tendon. (b) Transverse sonogram at the same level as a shows the musculotendinous junctions of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP). The tendons appear as hypoechoic fibrils in echogenic fascicles surrounded by an echogenic epitendineum.

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Figure 1b. Normal sonographic appearance of tendons in the wrist. (a) Longitudinal sonogram of the flexor surface of the wrist depicts the flexor digitorum superficialis (FDS) tendon at its junction with the muscle. Note the typical linear fibrillar appearance of the tendon. (b) Transverse sonogram at the same level as a shows the musculotendinous junctions of the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP). The tendons appear as hypoechoic fibrils in echogenic fascicles surrounded by an echogenic epitendineum.

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Figure 2. Transverse sonogram shows the extensor surface of the wrist at the level of the distal carpal row, with a normal small volume of anechoic synovial fluid in the tendon sheath between the extensor tendons.

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Figure 3a. Anisotropy artifact. Transverse sonograms of the extensor surface of the wrist show the extensor digitorum (ED) and extensor pollicis longus (EPL) tendons, clearly and without artifact on the image obtained with the probe held exactly perpendicular to the tendons (a), but with a significant loss of echogenicity on the image obtained with the probe held at an oblique angle to the tendons (b).

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Figure 3b. Anisotropy artifact. Transverse sonograms of the extensor surface of the wrist show the extensor digitorum (ED) and extensor pollicis longus (EPL) tendons, clearly and without artifact on the image obtained with the probe held exactly perpendicular to the tendons (a), but with a significant loss of echogenicity on the image obtained with the probe held at an oblique angle to the tendons (b).

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Figure 4a. Normal sonographic appearance of nerves. (a) Transverse sonogram of the median nerve in the distal forearm shows multiple hypoechoic groups of fascicles surrounded by the echogenic perineurium and epineurium, as well as an unusually prominent but normal median artery. (b) Longitudinal sonogram of the median nerve shows parallel hypoechoic groups of nerve fascicles and the median nerve, which lies deep to the flexor digitorum superficialis (FDS) muscle in the distal forearm.

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Figure 4b. Normal sonographic appearance of nerves. (a) Transverse sonogram of the median nerve in the distal forearm shows multiple hypoechoic groups of fascicles surrounded by the echogenic perineurium and epineurium, as well as an unusually prominent but normal median artery. (b) Longitudinal sonogram of the median nerve shows parallel hypoechoic groups of nerve fascicles and the median nerve, which lies deep to the flexor digitorum superficialis (FDS) muscle in the distal forearm.

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Figure 5. Transverse sonogram through the anatomic snuffbox shows the tendons of the first extensor compartment: the extensor pollicis brevis (EPB) and the abductor pollicis longus (APL). The slip from the extensor pollicis brevis to the extensor pollicis longus (slip to EPL) is an uncommon but normal variant. Note the location of the radial artery (radial a.) and the accompanying veins (*), deep to the tendons.

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Figure 6. Transverse sonogram shows the second extensor compartment, which contains the extensor carpi radialis brevis (ECRB) and longus (ECRL) tendons.

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Figure 7. Transverse sonogram shows the third extensor compartment, which contains the extensor pollicis longus (EPL) tendon, and its location between the neighboring extensor digitorum (ED) and extensor carpi radialis brevis (ECRB) tendons.

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Figure 8. Transverse sonogram shows the fourth extensor compartment. The extensor retinaculum (ER) is identified as a thick hypoechoic band (arrowheads) above the extensor digitorum (ED) and extensor pollicis longus (EPL) tendons. Note the slip from the extensor retinaculum to the distal radius, which forms the radial border of the fourth compartment.

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Figure 9. Transverse sonogram shows the third through the fifth extensor compartments. Note the position of the extensor digiti minimi (EDM) tendon, above the distal radioulnar (RU) joint. ED = extensor digitorum tendon, EI = extensor indicis tendon, EPL = extensor pollicis longus tendon.

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Figure 10. Transverse sonogram shows the sixth extensor compartment, which contains the extensor carpi ulnaris (ECU) tendon and sheath.

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Figure 11. Transverse sonogram shows the dorsal aspect of the proximal carpal row, just distal to the level of the Lister tubercle. Note the echogenic fibrillar appearance of the dorsal scapholunate ligament, which underlies the extensor digitorum (ED) tendons.

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Figure 12. Transverse sonogram at the same level as Figure 11 but on the ulnar side of the dorsal carpus shows the echogenic dorsal aspect of the lunatotriquetral ligament and, above it, the extensor digiti minimi (EDM) tendon. ECU = extensor carpi ulnaris tendon, ED = extensor digitorum tendon.

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Figure 13a. Sonographic examination of the ulnar surface of the wrist. (a) Photograph shows the correct position of the transducer. (b) Longitudinal sonogram shows the echogenic triangular fibrocartilage deep to the extensor carpi ulnaris (ECU) tendon.

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Figure 13b. Sonographic examination of the ulnar surface of the wrist. (a) Photograph shows the correct position of the transducer. (b) Longitudinal sonogram shows the echogenic triangular fibrocartilage deep to the extensor carpi ulnaris (ECU) tendon.

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Figure 14. Longitudinal sonogram of the ulnar aspect of the metacarpophalangeal joint of the thumb shows the convex echolucent ulnar collateral ligament (arrows) with the overlying echogenic adductor aponeurosis (AA).

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Figure 15a. Sonographic appearance of the dorsal extensor hood of the finger. (a) Line drawing shows the finger extensor hood and its attachments from the radial side. (b) Transverse sonogram depicts the lateral extent of the dorsal extensor expansion or hood (arrows) between its sites of attachment to the proximal phalanx, as well as the extensor digitorum (ED) tendon, which courses through the middle of the hypoechoic hood. (c) Longitudinal sonogram over the dorsum of the proximal phalanx of the middle finger shows hypoechoic thickening over the extensor digitorum (ED) tendon, a finding that represents the extensor hood. MCP jt = metacarpophalangeal joint.

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Figure 15b. Sonographic appearance of the dorsal extensor hood of the finger. (a) Line drawing shows the finger extensor hood and its attachments from the radial side. (b) Transverse sonogram depicts the lateral extent of the dorsal extensor expansion or hood (arrows) between its sites of attachment to the proximal phalanx, as well as the extensor digitorum (ED) tendon, which courses through the middle of the hypoechoic hood. (c) Longitudinal sonogram over the dorsum of the proximal phalanx of the middle finger shows hypoechoic thickening over the extensor digitorum (ED) tendon, a finding that represents the extensor hood. MCP jt = metacarpophalangeal joint.

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Figure 15c. Sonographic appearance of the dorsal extensor hood of the finger. (a) Line drawing shows the finger extensor hood and its attachments from the radial side. (b) Transverse sonogram depicts the lateral extent of the dorsal extensor expansion or hood (arrows) between its sites of attachment to the proximal phalanx, as well as the extensor digitorum (ED) tendon, which courses through the middle of the hypoechoic hood. (c) Longitudinal sonogram over the dorsum of the proximal phalanx of the middle finger shows hypoechoic thickening over the extensor digitorum (ED) tendon, a finding that represents the extensor hood. MCP jt = metacarpophalangeal joint.

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Figure 16a. Normal sonographic appearances of the carpal tunnel. (a) Transverse sonogram over the carpal tunnel shows the hypoechoic flexor retinaculum (arrowheads) with the median nerve immediately beneath it. The long flexor tendons of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are located deep to the nerve. Note the presence of a normal variant median artery (curved arrow) alongside the median nerve. (b) Extended-field-of-view transverse sonogram of the carpal tunnel shows the bones that mark its boundaries. FCR = flexor carpi radialis tendon, FPL = flexor pollicis longus tendon.

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Figure 16b. Normal sonographic appearances of the carpal tunnel. (a) Transverse sonogram over the carpal tunnel shows the hypoechoic flexor retinaculum (arrowheads) with the median nerve immediately beneath it. The long flexor tendons of flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP) are located deep to the nerve. Note the presence of a normal variant median artery (curved arrow) alongside the median nerve. (b) Extended-field-of-view transverse sonogram of the carpal tunnel shows the bones that mark its boundaries. FCR = flexor carpi radialis tendon, FPL = flexor pollicis longus tendon.

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Figure 17. Transverse sonogram of the carpal tunnel shows the location of the flexor carpi radialis (FCR) tendon within the lateral part of the flexor retinaculum.

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Figure 18a. Sonographic appearance of the long flexor tendons in the palm. Transverse (a) and longitudinal (b) sonograms of the long flexor tendons in the palm show the flexor digitorum superficialis (FDS) tendon, which lies above the flexor digitorum profundus (FDP) tendon.

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Figure 18b. Sonographic appearance of the long flexor tendons in the palm. Transverse (a) and longitudinal (b) sonograms of the long flexor tendons in the palm show the flexor digitorum superficialis (FDS) tendon, which lies above the flexor digitorum profundus (FDP) tendon.

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Figure 19a. Sonographic appearances of the long tendons of the finger, the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP). (a) Transverse sonogram through the finger flexor tendons at the midpoint of the proximal phalanx shows the division of the superficialis tendon into two slips to surround the profundus tendon, which cannot be seen because of anisotropy. (b) Transverse sonogram in exactly the same position as a but with the transducer held perpendicular to the profundus tendon shows hypoechogenicity in the superficialis tendon slips because of an anisotropy artifact. (c) Transverse sonogram at a more distal location along the proximal phalanx depicts the reunion of the superficialis tendon slips deep to the profundus tendon.

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Figure 19b. Sonographic appearances of the long tendons of the finger, the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP). (a) Transverse sonogram through the finger flexor tendons at the midpoint of the proximal phalanx shows the division of the superficialis tendon into two slips to surround the profundus tendon, which cannot be seen because of anisotropy. (b) Transverse sonogram in exactly the same position as a but with the transducer held perpendicular to the profundus tendon shows hypoechogenicity in the superficialis tendon slips because of an anisotropy artifact. (c) Transverse sonogram at a more distal location along the proximal phalanx depicts the reunion of the superficialis tendon slips deep to the profundus tendon.

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Figure 19c. Sonographic appearances of the long tendons of the finger, the flexor digitorum superficialis (FDS) and flexor digitorum profundus (FDP). (a) Transverse sonogram through the finger flexor tendons at the midpoint of the proximal phalanx shows the division of the superficialis tendon into two slips to surround the profundus tendon, which cannot be seen because of anisotropy. (b) Transverse sonogram in exactly the same position as a but with the transducer held perpendicular to the profundus tendon shows hypoechogenicity in the superficialis tendon slips because of an anisotropy artifact. (c) Transverse sonogram at a more distal location along the proximal phalanx depicts the reunion of the superficialis tendon slips deep to the profundus tendon.

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Figure 20. Longitudinal sonogram shows the insertion site of the flexor digitorum superficialis tendon at the base of the middle phalanx. Note the thickening of the joint capsule on the volar aspect of the proximal interphalangeal joint, which is also known as the volar plate.

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Figure 21a. (a) Longitudinal sonogram shows the insertion of the flexor digitorum profundus (FDP) tendon onto the base of the terminal phalanx. Note the thickening of the distal interphalangeal joint capsule at the volar plate. (b) Extended-field-of-view image of the distal part of the flexor digitorum profundus tendon shows hypoechoic artifacts (*) caused by tendinous anisotropy.

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Figure 21b. (a) Longitudinal sonogram shows the insertion of the flexor digitorum profundus (FDP) tendon onto the base of the terminal phalanx. Note the thickening of the distal interphalangeal joint capsule at the volar plate. (b) Extended-field-of-view image of the distal part of the flexor digitorum profundus tendon shows hypoechoic artifacts (*) caused by tendinous anisotropy.

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Figure 22a. Transverse (a) and longitudinal (b) sonograms through the thenar eminence show the relationship of the echogenic flexor pollicis longus tendon to the short muscles of the thumb.

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Figure 22b. Transverse (a) and longitudinal (b) sonograms through the thenar eminence show the relationship of the echogenic flexor pollicis longus tendon to the short muscles of the thumb.

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Figure 23. Transverse sonogram of the Guyon canal, obtained by using the linear-array transducer in sector mode for a wider field of view, shows the presence of a normal variant accessory muscle that may be associated with compression of the adjacent ulnar nerve.

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Figure 24. Transverse sonogram at the level of the proximal part of the proximal phalanx shows the second annular pulley as a hypoechoic thickening of the flexor sheath that extends to the sides of the base of the proximal phalanx.

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Figure 25. Longitudinal sonogram of the finger at the level of the proximal phalanx shows the second annular pulley as a thin hyperechoic line (arrows) superficial to the long flexor tendons.