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Carpal tunnel

Patient Positioning

Patient seated in front of the examiner, hand palm up resting on the examination table.

Probe Positioning

Place the transducer on transverse plane over the palmar wrist. First move the transducer cranially to identify the bony landmarks of the proximal carpal tunnel: radial sided the scaphoid tubercle, ulnarly the pisiform. To identify the distal carpal tunnel, muve the transducer distally over the radial sided trapezium tubercle and the hamate hook ulnarly.

Dynamic scanning of the carpal tunnel during acitve flexion and extension of the fingers.
Hand wrist palmar carpal tunnel proximal transverse
Hand wrist palmar distal transverse

mn: median nerve

fpl: flexor pollicis longus tendon

ua: ulnar artery

fds: flexor digitorum superficialis tendons

fcr: flexor carpi radialis tendon

fdp: flexor digitorum profundus tendons

mbun: main branch of ulnar nerve

note: tilting the probe helps to avoid anisotropy and to check the structures within the carpal tunnel. Use dynamic scanning (flexion and extension of the fingers) to assess the nine long flexor tendons (flexor digitorum superficialis, flexor digitorum profundus and flexor pollicis longus radially).

Hand wrist palmar carpal tunnel proximal longitudinal
Hand wrist palmar carpal tunnel proximal longitudinal

note: long axis view of the carpal tunnel