<p begin="00:00:07.599" end="00:00:09.331" style="s2">- [Voiceover] A linear array transducer</p>
<p begin="00:00:09.331" end="00:00:11.503" style="s2">with a musculoskeletal exam type</p>
<p begin="00:00:11.503" end="00:00:14.034" style="s2">is used to perform an<br />ultrasound examination</p>
<p begin="00:00:14.034" end="00:00:15.740" style="s2">of the volar wrist.</p>
<p begin="00:00:15.740" end="00:00:17.893" style="s2">The patient is placed<br />in a sitting position</p>
<p begin="00:00:17.893" end="00:00:21.453" style="s2">with the dorsal hand placed<br />on an examination table.</p>
<p begin="00:00:21.453" end="00:00:23.830" style="s2">The transducer is placed<br />over the wrist crease</p>
<p begin="00:00:23.830" end="00:00:26.575" style="s2">in a transverse fashion<br />with the orientation marker</p>
<p begin="00:00:26.575" end="00:00:28.882" style="s2">directed towards the patient's right.</p>
<p begin="00:00:28.882" end="00:00:30.670" style="s2">The transducer should be oriented</p>
<p begin="00:00:30.670" end="00:00:33.465" style="s2">to see the scaphoid tubercle and pisiform</p>
<p begin="00:00:33.465" end="00:00:36.259" style="s2">as bright, hyperechoic structures.</p>
<p begin="00:00:36.259" end="00:00:38.517" style="s2">The flexor carpi radialis tendon</p>
<p begin="00:00:38.517" end="00:00:40.845" style="s2">and flexor pollicis longus tendons</p>
<p begin="00:00:40.845" end="00:00:43.504" style="s2">can be seen as round,<br />hyperechoic structures</p>
<p begin="00:00:43.504" end="00:00:46.106" style="s2">superficial to the scaphoid bone.</p>
<p begin="00:00:46.106" end="00:00:48.993" style="s2">The superficial and deep<br />flexor tendons of the hand</p>
<p begin="00:00:48.993" end="00:00:51.782" style="s2">are seen as bundled,<br />hyperechoic structures</p>
<p begin="00:00:51.782" end="00:00:54.486" style="s2">below the thin flexor retinaculum.</p>
<p begin="00:00:54.486" end="00:00:56.795" style="s2">The median nerve appears<br />as a fasciculated,</p>
<p begin="00:00:56.795" end="00:01:00.772" style="s2">hyperechoic structure superficial<br />to the flexor tendons.</p>
<p begin="00:01:00.772" end="00:01:03.096" style="s2">It can be readily<br />distinguished from the tendons</p>
<p begin="00:01:03.096" end="00:01:04.959" style="s2">by its lack of anisotropy,</p>
<p begin="00:01:04.959" end="00:01:07.600" style="s2">with slight rocking of the transducer.</p>
<p begin="00:01:07.600" end="00:01:11.039" style="s2">The ulnar artery is seen as<br />a round, pulsatile structure</p>
<p begin="00:01:11.039" end="00:01:15.206" style="s2">next to the ulnar nerve,<br />lateral to the pisiform bone.</p>

<p begin="00:00:07.633" end="00:00:09.278" style="s2">- [Voiceover] A linear array transducer</p>
<p begin="00:00:09.278" end="00:00:11.397" style="s2">with a musculoskeletal exam type</p>
<p begin="00:00:11.397" end="00:00:13.874" style="s2">is used to perform an<br />ultrasound examination</p>
<p begin="00:00:13.874" end="00:00:16.046" style="s2">of Guyon's canal.</p>
<p begin="00:00:16.046" end="00:00:18.047" style="s2">The patient is placed<br />in a sitting position</p>
<p begin="00:00:18.047" end="00:00:21.467" style="s2">with the dorsal hand placed<br />on an examination table.</p>
<p begin="00:00:21.467" end="00:00:23.801" style="s2">The transducer is placed<br />over the wrist crease</p>
<p begin="00:00:23.801" end="00:00:26.357" style="s2">in a transverse fashion,<br />with the orientation marker</p>
<p begin="00:00:26.357" end="00:00:28.779" style="s2">directed towards the patient's right.</p>
<p begin="00:00:28.779" end="00:00:31.123" style="s2">The pisiform bone is seen as a bright,</p>
<p begin="00:00:31.123" end="00:00:33.492" style="s2">hyperechoic, prominent structure.</p>
<p begin="00:00:33.492" end="00:00:36.599" style="s2">The ulnar artery is a<br />round, pulsatile structure</p>
<p begin="00:00:36.599" end="00:00:38.669" style="s2">above the flexor retinaculum,</p>
<p begin="00:00:38.669" end="00:00:41.274" style="s2">which appears as a hyperechoic line.</p>
<p begin="00:00:41.274" end="00:00:43.185" style="s2">The ulnar nerve is located between</p>
<p begin="00:00:43.185" end="00:00:45.424" style="s2">the ulnar artery and the pisiform,</p>
<p begin="00:00:45.424" end="00:00:48.849" style="s2">and can be seen as a darker,<br />fasciculated structure.</p>
<p begin="00:00:48.849" end="00:00:50.715" style="s2">The transducer should be slowly moved</p>
<p begin="00:00:50.715" end="00:00:53.447" style="s2">distal to the wrist crease<br />to follow the ulnar nerve</p>
<p begin="00:00:53.447" end="00:00:56.339" style="s2">until it splits into a<br />superficial sensory branch</p>
<p begin="00:00:56.339" end="00:00:58.674" style="s2">and a deeper motor branch which courses</p>
<p begin="00:00:58.674" end="00:01:00.885" style="s2">alongside the hamate hook.</p>
<p begin="00:01:00.885" end="00:01:03.924" style="s2">The arcade of the flexor<br />brevis can be seen in this view</p>
<p begin="00:01:03.924" end="00:01:06.163" style="s2">as an oval, hyperechoic structure</p>
<p begin="00:01:06.163" end="00:01:09.913" style="s2">just between the branches<br />of the ulnar nerve.</p>

<p begin="00:00:07.243" end="00:00:09.095" style="s2">- [Voiceover] A linear array transducer</p>
<p begin="00:00:09.095" end="00:00:11.275" style="s2">with a musculoskeletal exam type</p>
<p begin="00:00:11.275" end="00:00:13.852" style="s2">is used to perform an<br />ultrasound examination</p>
<p begin="00:00:13.852" end="00:00:16.319" style="s2">of median nerve entrapment.</p>
<p begin="00:00:16.319" end="00:00:18.503" style="s2">The patient is in a sitting position</p>
<p begin="00:00:18.503" end="00:00:22.215" style="s2">with the arm flexed and the<br />hand externally rotated.</p>
<p begin="00:00:22.215" end="00:00:24.654" style="s2">The transducer is placed transversely</p>
<p begin="00:00:24.654" end="00:00:26.535" style="s2">over the proximal wrist crease,</p>
<p begin="00:00:26.535" end="00:00:30.067" style="s2">with the orientation marker<br />directed to the patient's right.</p>
<p begin="00:00:30.067" end="00:00:33.060" style="s2">The flexor retinaculum<br />spans the wrist structures,</p>
<p begin="00:00:33.060" end="00:00:36.004" style="s2">and is seen as a band-like structure.</p>
<p begin="00:00:36.004" end="00:00:38.844" style="s2">The bright, hyperechoic<br />surface of the lunate</p>
<p begin="00:00:38.844" end="00:00:42.500" style="s2">forms the most posterior<br />boundary of the volar wrist.</p>
<p begin="00:00:42.500" end="00:00:45.318" style="s2">The superficial and deep<br />tendons of the wrist</p>
<p begin="00:00:45.318" end="00:00:48.142" style="s2">can be seen as light gray oval structures,</p>
<p begin="00:00:48.142" end="00:00:51.306" style="s2">which are highly subject to anisotropy.</p>
<p begin="00:00:51.306" end="00:00:54.871" style="s2">The ulnar artery and nerve<br />can be seen in Guyon's canal</p>
<p begin="00:00:54.871" end="00:00:58.516" style="s2">superficially and on the<br />medial surface of the wrist.</p>
<p begin="00:00:58.516" end="00:01:00.908" style="s2">The median nerve is a dark, hyperechoic,</p>
<p begin="00:01:00.908" end="00:01:04.292" style="s2">elliptical shaped, honeycombed,<br />fascicular structure</p>
<p begin="00:01:04.292" end="00:01:07.821" style="s2">just ulnar to the flexor<br />carpi radialis tendon,</p>
<p begin="00:01:07.821" end="00:01:10.415" style="s2">in line with the three carpal bones.</p>
<p begin="00:01:10.415" end="00:01:12.711" style="s2">The nerve can be<br />distinguished from the tendons</p>
<p begin="00:01:12.711" end="00:01:15.351" style="s2">by the fact it is less<br />subject to anisotropy,</p>
<p begin="00:01:15.351" end="00:01:17.120" style="s2">and it remains in constant position</p>
<p begin="00:01:17.120" end="00:01:19.478" style="s2">with transducer translation.</p>
<p begin="00:01:19.478" end="00:01:21.803" style="s2">The nerve should remain<br />a constant diameter</p>
<p begin="00:01:21.803" end="00:01:25.059" style="s2">with movement of the transducer<br />distally in the hand.</p>
<p begin="00:01:25.059" end="00:01:27.714" style="s2">The transducer should be<br />centered over the median nerve</p>
<p begin="00:01:27.714" end="00:01:30.909" style="s2">and rotated 90 degrees clockwise.</p>
<p begin="00:01:30.909" end="00:01:34.020" style="s2">The median nerve will appear<br />as a fascicular structure</p>
<p begin="00:01:34.020" end="00:01:37.893" style="s2">which lies on top of the<br />similar-appearing flexor tendons.</p>
<p begin="00:01:37.893" end="00:01:39.670" style="s2">The patient can be instructed to flex</p>
<p begin="00:01:39.670" end="00:01:41.494" style="s2">their third and fourth finger</p>
<p begin="00:01:41.494" end="00:01:43.197" style="s2">to cause movement in the tendons,</p>
<p begin="00:01:43.197" end="00:01:46.058" style="s2">to distinguish them from<br />the overlying nerve.</p>
<p begin="00:01:46.058" end="00:01:49.049" style="s2">The median nerve should be<br />evaluated for any edema,</p>
<p begin="00:01:49.049" end="00:01:51.426" style="s2">which will make the<br />nerve more hyperechoic,</p>
<p begin="00:01:51.426" end="00:01:55.593" style="s2">or swelling, which may<br />occur distal to entrapment.</p>

<p begin="00:00:04.763" end="00:00:06.755" style="s2">- [Voiceover] The<br />following are case studies</p>
<p begin="00:00:06.755" end="00:00:10.133" style="s2">of carpal tunnel, also<br />including a bifid median nerve,</p>
<p begin="00:00:10.133" end="00:00:13.560" style="s2">as well as median nerve compression.</p>
<p begin="00:00:13.560" end="00:00:16.828" style="s2">The bony anatomy associated<br />with carpal tunnel</p>
<p begin="00:00:16.828" end="00:00:19.534" style="s2">is complex, but not difficult to learn.</p>
<p begin="00:00:19.534" end="00:00:22.476" style="s2">Highlighted in blue is the distal radius.</p>
<p begin="00:00:22.476" end="00:00:25.305" style="s2">Highlighted in green<br />would be the distal ulna.</p>
<p begin="00:00:25.305" end="00:00:29.405" style="s2">Highlighted in light blue<br />would be the volar lunate.</p>
<p begin="00:00:29.405" end="00:00:32.276" style="s2">Highlighted in purple would<br />be the volar scaphoid.</p>
<p begin="00:00:32.276" end="00:00:35.693" style="s2">Highlighted in red is the volar pisiform.</p>
<p begin="00:00:37.832" end="00:00:41.915" style="s2">In orange, we have the<br />bell-shaped capitate bone.</p>
<p begin="00:00:43.140" end="00:00:46.082" style="s2">Blue is the volar trapezium bone,</p>
<p begin="00:00:46.082" end="00:00:50.803" style="s2">and orange is the volar<br />hamate and hamulus landmarks.</p>
<p begin="00:00:50.803" end="00:00:53.761" style="s2">The white areas are the<br />actual insertion points</p>
<p begin="00:00:53.761" end="00:00:56.337" style="s2">of the carpal tunnel landmarks.</p>
<p begin="00:00:56.337" end="00:01:00.504" style="s2">From the red pisiform,<br />attaches to the purple scaphoid</p>
<p begin="00:01:01.785" end="00:01:05.544" style="s2">and the orange hook of<br />the hamate crosses over</p>
<p begin="00:01:05.544" end="00:01:08.794" style="s2">and attaches to the trapezium tubercle.</p>
<p begin="00:01:10.596" end="00:01:13.752" style="s2">Contained within the<br />carpal tunnel are four</p>
<p begin="00:01:13.752" end="00:01:17.080" style="s2">deep flexor profundus tendons,</p>
<p begin="00:01:17.080" end="00:01:19.747" style="s2">four superficial flexor tendons,</p>
<p begin="00:01:21.328" end="00:01:25.027" style="s2">as well as the flexor<br />policis longus tendon</p>
<p begin="00:01:25.027" end="00:01:29.194" style="s2">on the radial aspect and the<br />median nerve, here in yellow.</p>
<p begin="00:01:30.583" end="00:01:32.426" style="s2">Crossing over all of these structures,</p>
<p begin="00:01:32.426" end="00:01:34.175" style="s2">creating the roof of the carpal tunnel,</p>
<p begin="00:01:34.175" end="00:01:36.474" style="s2">is the flexor retinaculum.</p>
<p begin="00:01:36.474" end="00:01:39.403" style="s2">Probe placement for the proximal<br />carpal tunnel examination</p>
<p begin="00:01:39.403" end="00:01:40.320" style="s2">is in blue.</p>
<p begin="00:01:41.385" end="00:01:43.270" style="s2">Here is the corresponding image.</p>
<p begin="00:01:43.270" end="00:01:47.437" style="s2">Highlighted here in white is<br />the actual flexor retinaculum.</p>
<p begin="00:01:48.510" end="00:01:51.068" style="s2">Highlighted in purple is<br />the scaphoid insertion</p>
<p begin="00:01:51.068" end="00:01:53.452" style="s2">and red is the pisaform.</p>
<p begin="00:01:53.452" end="00:01:56.035" style="s2">The blue is the lunate surface.</p>
<p begin="00:01:57.507" end="00:02:00.697" style="s2">In gray are the deep flexor tendons.</p>
<p begin="00:02:00.697" end="00:02:04.038" style="s2">The light gray are the<br />superficial flexor tendons.</p>
<p begin="00:02:04.038" end="00:02:06.621" style="s2">The yellow is the median nerve.</p>
<p begin="00:02:07.731" end="00:02:10.693" style="s2">And in blue, on the far radial aspect,</p>
<p begin="00:02:10.693" end="00:02:11.914" style="s2">bordering the scaphoid,</p>
<p begin="00:02:11.914" end="00:02:16.081" style="s2">is the flexor pollicus longus<br />tendon, flexor carpi radialis,</p>
<p begin="00:02:18.889" end="00:02:21.581" style="s2">and the ulnar nerve and ulnar artery,</p>
<p begin="00:02:21.581" end="00:02:23.498" style="s2">creating Guyon's Canal.</p>
<p begin="00:02:26.198" end="00:02:28.809" style="s2">It is also important to wiggle the fingers</p>
<p begin="00:02:28.809" end="00:02:32.142" style="s2">to test for laxity in the carpal tunnel.</p>
<p begin="00:02:34.174" end="00:02:37.508" style="s2">Now scanning from the<br />proximal carpal tunnel</p>
<p begin="00:02:37.508" end="00:02:39.841" style="s2">to the distal carpal tunnel.</p>
<p begin="00:02:42.343" end="00:02:44.570" style="s2">Here is the correct probe placement</p>
<p begin="00:02:44.570" end="00:02:47.231" style="s2">for distal carpal tunnel.</p>
<p begin="00:02:47.231" end="00:02:50.981" style="s2">Here we have, as landmark,<br />the capitate bone.</p>
<p begin="00:02:54.111" end="00:02:58.221" style="s2">The bony trapezium and trapezium tubercle</p>
<p begin="00:02:58.221" end="00:03:01.638" style="s2">and bony prominent, as well as the hamate</p>
<p begin="00:03:03.881" end="00:03:06.381" style="s2">and hook of the hamate in red.</p>
<p begin="00:03:07.621" end="00:03:10.454" style="s2">And the distal flexor retinaculum.</p>
<p begin="00:03:13.244" end="00:03:17.285" style="s2">Shown in light gray here<br />are the deep flexor tendons.</p>
<p begin="00:03:17.285" end="00:03:21.182" style="s2">In gray would be the<br />superficial flexor tendons.</p>
<p begin="00:03:21.182" end="00:03:24.893" style="s2">In blue would be the<br />flexor pollicus longus.</p>
<p begin="00:03:24.893" end="00:03:27.893" style="s2">In yellow would be the median nerve.</p>
<p begin="00:03:29.454" end="00:03:33.414" style="s2">Probe position, long axis carpal tunnel.</p>
<p begin="00:03:33.414" end="00:03:36.509" style="s2">In long axis, nerves and<br />tendons can look similar,</p>
<p begin="00:03:36.509" end="00:03:41.014" style="s2">so dynamic flexion will<br />determine nerve from tendon,</p>
<p begin="00:03:41.014" end="00:03:43.748" style="s2">as the tendon will side beneath the nerve</p>
<p begin="00:03:43.748" end="00:03:47.915" style="s2">while the nerve stays in a<br />relatively stationary position.</p>
<p begin="00:03:49.211" end="00:03:52.574" style="s2">Highlighted is the volar lunate surface,</p>
<p begin="00:03:52.574" end="00:03:54.859" style="s2">followed by the volar capitate surface,</p>
<p begin="00:03:54.859" end="00:03:57.005" style="s2">which is bell-shaped.</p>
<p begin="00:03:57.005" end="00:03:59.471" style="s2">The deep and superficial flexor tendons,</p>
<p begin="00:03:59.471" end="00:04:02.082" style="s2">highlighted in white, and yellow,</p>
<p begin="00:04:02.082" end="00:04:05.225" style="s2">representing the median nerve.</p>
<p begin="00:04:05.225" end="00:04:08.910" style="s2">Seen here is the proximal carpal tunnel.</p>
<p begin="00:04:08.910" end="00:04:12.948" style="s2">Highlighted is the<br />proximal capitate surface,</p>
<p begin="00:04:12.948" end="00:04:16.448" style="s2">lunate surface, and distal radius in blue.</p>
<p begin="00:04:18.747" end="00:04:20.736" style="s2">As seen before, we have the deep</p>
<p begin="00:04:20.736" end="00:04:22.438" style="s2">and superficial flexor tendons,</p>
<p begin="00:04:22.438" end="00:04:26.851" style="s2">followed by the yellow,<br />representing the median nerve.</p>
<p begin="00:04:26.851" end="00:04:29.994" style="s2">To confirm position within<br />the true carpal tunnel,</p>
<p begin="00:04:29.994" end="00:04:32.748" style="s2">Scan medial to lateral<br />for the bony prominence,</p>
<p begin="00:04:32.748" end="00:04:35.999" style="s2">such as the scaphoid surface or pisiform.</p>
<p begin="00:04:35.999" end="00:04:39.556" style="s2">Here is a case study involving<br />a bifid median nerve,</p>
<p begin="00:04:39.556" end="00:04:42.316" style="s2">with comparison to the other hand,</p>
<p begin="00:04:42.316" end="00:04:44.816" style="s2">showing no bifid median nerve.</p>
<p begin="00:04:46.937" end="00:04:50.426" style="s2">When scanning from the<br />carpal tunnel proximally,</p>
<p begin="00:04:50.426" end="00:04:53.704" style="s2">it is easy to identify where<br />the bifurcation takes place</p>
<p begin="00:04:53.704" end="00:04:57.621" style="s2">in the forearm, showing<br />this becomes one nerve.</p>
<p begin="00:04:58.959" end="00:05:02.452" style="s2">The image on the left shows<br />a characteristic flattening</p>
<p begin="00:05:02.452" end="00:05:04.617" style="s2">of the median nerve.</p>
<p begin="00:05:04.617" end="00:05:07.557" style="s2">On this image, there<br />is a fusiform swelling,</p>
<p begin="00:05:07.557" end="00:05:11.671" style="s2">or bulging, just proximal<br />to the carpal tunnel.</p>
<p begin="00:05:11.671" end="00:05:14.178" style="s2">Although not quite four millimeters,</p>
<p begin="00:05:14.178" end="00:05:16.508" style="s2">there is slight bulging<br />to the symptomatic side</p>
<p begin="00:05:16.508" end="00:05:19.847" style="s2">in this wrist, where the<br />asymptomatic side stays</p>
<p begin="00:05:19.847" end="00:05:23.430" style="s2">completely beneath the<br />carpal tunnel level.</p>