Mnemonics and Metaphorical Videos for Teaching/Learning Musculoskeletal Sonoanatomy : American Journal of Physical Medicine & Rehabilitation

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Mnemonics and Metaphorical Videos for Teaching/Learning Musculoskeletal Sonoanatomy

Jačisko, Jakub MD; Mezian, Kamal MD, PhD; Güvener, Orhan MD; Ricci, Vincenzo MD; Kobesová, Alena MD, PhD; Özçakar, Levent MD

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American Journal of Physical Medicine & Rehabilitation: December 2022 - Volume 101 - Issue 12 - p e189-e193
doi: 10.1097/PHM.0000000000002084

Abstract

This feature is a unique combination of text (voice) and video that more clearly presents and explains procedures in musculoskeletal medicine. These videos will be available on the journal’s Website. We hope that this feature will change and enhance the learning experience.

Walter R. Frontera, MD, PhD

Editor-in-Chief

Because of its numerous advantages and various applications in musculoskeletal (MSK) medicine, ultrasonography (US) has become a routine examination tool in the clinical practice of physical and rehabilitation medicine specialists.1 On the other hand, because of its user dependency, MSK US remains a complex discipline that requires knowledge of (sono)anatomy, appropriate/lengthy training, experience, and interpretation capabilities. To cover these needs as well as to shorten the learning curve, several resources (books, courses, etc.) also including new technologies, for example, artificial intelligence, applications, (online) courses, or standardized protocols, are yet available.2–7

Among several classical/modern teaching methods,8 the use of mnemonic aids has been shown to improve information retention and better understanding.9–11 In addition, it has been confirmed that pictures and characteristic sounds are associated with significantly better recall than verbal labels alone.12 Herein, an essential approach in modern pedagogy is “entertainment education,” which can be defined as the intentional placement of educational messages within an entertaining content.13,14 Likewise, we have tried to incorporate all the previously mentioned techniques in this comprehensive, expert-, and consensus-based set of images, schematic drawings, and multimedia videos. Our primary/eventual aim was to facilitate the learning in MSK US.

In this sense, we have gathered (as many as possible) the characteristic appearances in daily MSK US images. Using metaphoric nomenclature and the pertinent/typical sounds, several normal structures (N = 26) are being illustrated. We believe that the used names/signs will help the novice sonographers easily imagine/recall the relevant standard scans. While the text exemplifies only 5 of the 26 structures, to avoid repetition, the rest is given in the video gallery. Of note, the second article of this series will comprise US of different MSK pathologies.

HONEYCOMB (Video 1, https://links.lww.com/PHM/B749)

Peripheral nerves contain many nerve fibers grouped into fascicular bundles. Transverse scan of a nerve shows several hypoechoic “bubbles”—representing these nerve fascicles—inside the hyperechoic epineurium. This highly organized structure looks like a delicious honeycomb where nerve fascicles represent the tunnels for the bees. Its recognition might prompt the distinction from a tendon which is fibrillar instead.

FEATHER (Video 2, https://links.lww.com/PHM/B750)

Muscle fascicles run parallel to the length of the muscle (fusiform muscles) or attach at an angle to the aponeurosis (pennate muscles). Longitudinal scan of a bipennate muscle shows its hyperechoic fibroadipose component branching within the hypoechoic muscular tissue. This pattern is very similar to the esthetic structure of a feather with its central beam and multiple peripheral ramifications. Its recognition might facilitate accurate measurements of the muscle architecture.

STARRY SKY (Video 3, https://links.lww.com/PHM/B751)

The internal structure of a muscle consists of hypoechoic fascicles and hyperechoic perimysium. Transverse scan of muscles shows the physiological alternation of these two compartments. While the former corresponds to the dark sky, the latter forms the stars. Accordingly, the relaxing starry sky is commonly used to recognize a transverse scan of a muscle tissue wherever present/needed. Its recognition might prompt the differential diagnosis of normal versus pathological muscle.

SPAGHETTI (Video 4, https://links.lww.com/PHM/B752)

Tendons are highly organized structures made of overlapping collagen fascicles and septa planes. Longitudinal scan of a tendon shows the (physiological) fibrillar pattern, that is, regularly aligned multiple hyperechoic lines. Multiple collagen fibers arranged parallel to each other look like a bunch of spaghetti—savory with the right sauce. Its recognition might facilitate the distinction from other tubular structures. In addition, because of fibrous or fibrocartilaginous tissue, their attachment sites (entheses) can also appear in the shape of free spaghetti ends giving anisotropy.

MICKEY MOUSE (Video 5, https://links.lww.com/PHM/B753)

Neurovascular structures run together. Transverse scan of a vascular bundle shows three anechoic “bubbles”—similar to the sympathetic face and ears of Mickey Mouse. Of note, gentle compression can be performed with the probe to collapse the “venous ears” and distinguish the artery (A). Another simple way would be to use the Doppler for visualizing different (steady vs. pulsatile) vascular flow patterns. The recognition of Mickey mouse might avoid possible injury during neuromusculoskeletal interventions.

BIRD BEAK (Video 6, https://links.lww.com/PHM/B754)

The supraspinatus tendon passes under the acromioclavicular joint and attaches to the greater tuberosity of the humerus. With the shoulder in neutral position, longitudinal scan of the supraspinatus tendon looks like the bird beak whereby the acromion also corresponds to its head. The strong beak avoids the (pathological) cranial subluxation of the humeral head toward the acromion. Its recognition might indicate the presence of a normal tendon (supraspinatus critical zone).

TIRE (Video 7, https://links.lww.com/PHM/B755)

The modified crass position is a maneuver used to better view the superior/posterior parts of the supraspinatus tendon (Fig. 1). The patient is asked to place the volar surface of the hand on the ipsilateral hip, and the anterior transverse scan shows the intact rotator cuff as a tire. When “inflated” (i.e., intact covering the humeral head), it absorbs the shocks and avoids subluxation. Its examination is paramount for describing the width and thickness of a possible rotator cuff tear.

F1
FIGURE 1:
Shoulder rotator cuff. Normal, ridiculoUS, and schematic (from left to right) images show the shoulder rotator cuff in its shorts axis. Its ring shape resembles a tire surrounding a wheel’s rim.

HAMBURGER (Video 8, https://links.lww.com/PHM/B756)

At the elbow, the median nerve passes between the pronator teres and the brachialis muscle. When the probe is placed in a transverse-oblique plane, the median nerve appears like an essential ingredient (cucumber) of a hamburger. Another cucumber represents the brachial vessels. The ‘cheese’ resembles the intermuscular fascia. Recognition of the hamburger might be contributory when targeting spastic muscles with botulinum toxin injections.

MOON OVER A HOUSE (Video 9, https://links.lww.com/PHM/B757)

The interosseous transverse septum between the bones of the forearm divides the muscles into superficial and deep layers. Flexor digitorum superficialis, pronator teres, palmaris longus, flexor carpi radialis, and flexor carpi ulnaris (the most medial one) form the superficial layer. During transverse sonotracking of the forearm, the ulna typically acquires a quadrangular shape resembling a house. At the same level, the flexor carpi ulnaris muscle resides superficially—like a moon illuminating it. Again, its recognition might be contributory during specific muscle targeting.

FULL MOON (Video 10, https://links.lww.com/PHM/B758)

The flexor pollicis longus tendon passes between the superficial and deep layers of the flexor pollicis brevis muscle. Transverse oblique scan on the volar aspect of the thenar eminence shows a hyperechoic round structure, that is, the flexor pollicis longus tendon. Among the surrounding hypoechoic muscles, it looks like the terrifying “full moon.” Its recognition—especially via testing anisotropy—might be noteworthy to assess the tendon morphology and vascularity.

PYRAMID (Video 11, https://links.lww.com/PHM/B759)

The greater trochanter is an important landmark when evaluating the lateral hip. Transverse scan shows the triangular hyperechoic shape of the greater trochanter—similar to the ancient Egyptian pyramid (Fig. 2). Its recognition might guide while navigating for its different facets as well as for ensuring the transition from the femoral shaft (rather round in shape) to the trochanter (triangular).

F2
FIGURE 2:
The greater trochanter. Normal, ridiculoUS, and schematic (from left to right) images show the greater trochanter’s bony surface in the lateral short-axis view of the thigh. Its triangular shape converging to a single step at the top resembles an ancient Egyptian pyramid. FL, fascia lata; M, muscle; T, rotator cuff of the hip.

WINDMILL (Video 12, https://links.lww.com/PHM/B760)

Transverse scan of the dorsal thigh at the proximal third shows the “famous” windmill formed by the conjoined tendon of semitendinosus-biceps femoris, sciatic nerve, and the adductor magnus muscle (Fig. 3). Similar to the windmill blades (metaphorically), these anatomical structures are pivotal to guaranteeing the “energy” for lower limb movements. Practically, their recognition might help physicians better locate the sciatic nerve and avoid an otherwise detrimental injury. This appearance had also been mentioned in the literature as the Mercedes-Benz sign, but in the near/green future, we hope/believe that the windmills will rather “overwhelm.”

F3
FIGURE 3:
The sciatic nerve. Normal, ridiculoUS, and schematic (from left to right) images represent short-axis view of the posterior thigh at the proximal third. The biceps femoris and semitendinosus muscles (all together with their conjoined tendon) form a superficial layer, while the adductor magnus is situated deeply. The connective tissues appear like a windmill with the sciatic nerve in the middle. N, sciatic nerve.

RAILWAY (Video 13, https://links.lww.com/PHM/B761)

The biceps femoris is a long muscle—also named as the lateral hamstring muscle in the posterior thigh. As the name suggests, it has two different heads, one of which extends deeply. Transverse scan of the posterior thigh (distally) shows the short head of the biceps femoris muscle appearing like a hopeful railway in between the long head of the biceps femoris and vastus lateralis muscles. Its recognition might facilitate guided electromyography or interventions.

CHERRY ON THE CAKE (Video 14, https://links.lww.com/PHM/B762)

Semimembranosus and semitendinosus are the medial hamstring muscles in the posterior thigh. Transverse scan (distal third) shows the semitendinosus tendon progressively shifting over the semimembranosus muscle—like the attractive cherry on the cake. Again, recognizing these structures is helpful for better/local orientation.

SUNGLASSES (Video 15, https://links.lww.com/PHM/B763)

The gastrocnemius is the most superficial calf muscle with two (medial and lateral) heads separated from the femur. Transverse scan of the proximal calf shows these two heads like a pair of fashionable sunglasses. Their recognition would be important for several diagnostic/interventional procedures (e.g., tennis leg, spasticity).

SEAL WITH A BALL (Video 16, https://links.lww.com/PHM/B764)

Tibialis posterior is a deep muscle covered by flexor hallucis longus and flexor digitorum longus muscles located on the posteromedial side of the leg. Transverse scan shows the tibialis posterior muscle, posterior tibial artery, and the tibial nerve, which altogether picture the sweet seal with a ball. Identifying these structures is important in daily practice to target the right muscle and avoid the nerve/artery during botulinum toxin injections.

HAMMOCK (Video 17, https://links.lww.com/PHM/B765)

The calcaneofibular ligament is one of the three parts of the ankle lateral ligament complex (Fig. 4). It extends from the lateral malleolus to the tubercle on the lateral aspect of the calcaneus. Longitudinal (oblique) scan can be performed to visualize the calcaneofibular ligament—appearing like a comfortable hammock on which the fibularis brevis and longus tendons swing. In case the ligament cannot be easily imaged, the outward movement of the tendons from the joint (during active ankle dorsiflexion) would indirectly confirm the presence of an intact ligament.

F4
FIGURE 4:
The calcaneofibular ligament. Normal, ridiculoUS, and schematic (from left to right) images show the lateral ankle scan along the calcaneofibular ligament with the overlying fibular tendons. The hammock, representing the calcaneofibular ligament, relates to an indirect dynamic test commonly used to assess ligamentous injuries. CFL, calcaneofibular ligament; FB, fibularis brevis; FL, fibularis longus.

PAC-MAN (Video 18, https://links.lww.com/PHM/B766)

Plantar intrinsic muscles of the foot are adjacent to the tendons of the extrinsic muscles of the foot. Transverse scan of the plantar surface shows the hungry Pac-Man and the nearby flexor digitorum longus and flexor hallucis longus tendons. When tracking the two previously mentioned tendons proximally, their crossover—known as the knot of Henry—can easily be visualized. Henry’s knot identification can be important during the examination of plantar intersection syndrome.

TRAFFIC LIGHTS (Video 19, https://links.lww.com/PHM/B767)

After the cervical nerve roots exit the neural foramina, they course between the scalene muscles. Transverse scan of the lateral neck (from proximal to distal) shows the C5, C6, and C7 nerve roots position between the anterior and middle scalene muscles—reminiscent of the classical traffic lights. Their recognition would indisputably be crucial during a broad range of neck interventions.

GRAPES (Video 20, https://links.lww.com/PHM/B768)

In the suprascapular region, the cervical roots form the trunks, which then divide into upper and lower divisions. Transverse scan of the lateral neck shows the brachial plexus coursing between the anterior and middle scalene muscles. Recognition of this juicy bunch of grapes is the mainstay of several neck procedures from different perspectives.

SAW TEETH (Video 21, https://links.lww.com/PHM/B769)

Facet joints are angled approximately 45 degrees at the upper cervical level, and they are more vertical in the lower cervical region. Posterior parasagittal scan of the cervical vertebrae shows the regularly aligned facet joints that appear like the dangerous saw teeth. Their recognition aids for better targeting the joints or the neighboring anatomical structures (e.g., medial branches).

TRIDENT (Video 22, https://links.lww.com/PHM/B770)

Longitudinal paramedian scan of the lumbar spine shows the three transverse processes giving sharp shadowings. Recognizing this frightening trident can ensure the interventional physician that the imaging pertains to a far lateral view—for a potential use during lumbar root targeting.

CAMEL HUMPS AND HORSE HEADS (Videos 23 and 24, https://links.lww.com/PHM/B771, https://links.lww.com/PHM/B772)

The typical lumbar vertebra consists of a body, arch (two laminae and two pedicles), and two transverse and one spinous processes. Longitudinal paramedian scans of the lumbar spine show the facet joints and the laminae that look like camel humps and horse heads, respectively. Both structures are targeted during pertinent interventions.

BAT AND BUTTERFLY (Video 25, https://links.lww.com/PHM/B773)

Transverse scan of the lumbar vertebra shows the deep bony lining and the erector spinae muscles, which respectively look like a bat and a butterfly (Fig. 5). Bony structures serve as important landmarks during pertinent interventions. Imaging the erector spinae can also be important during exercise therapy when using “sono-feedback.”

F5
FIGURE 5:
The lumbar vertebra and erector spinae muscle. On transverse scan of the lumbar spine, the shape of the vertebral bony surface resembles a bat, while the muscles appear like a butterfly. ES, erector spinae; F, facet joint; TP, transverse process.

FROG EYES (Video 26, https://links.lww.com/PHM/B774)

Sacrum (formed by the fusion of sacral vertebrae) is the continuation of the vertebral canal. The 5th sacral laminae do not fuse, resulting in a bony defect, that is, the sacral hiatus. Lateral walls of the sacral hiatus are formed by the tubercles of the inferior articular processes of the 5th sacral vertebrae (sacral cornua). Transverse scan shows the sacral cornua, which appear as the overwhelming frog eyes. Recognizing the hyperechoic band between the eyes (i.e., the sacrococcygeal ligament) would be important while planning for US-guided procedures in this region.

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Keywords:

Ultrasonography; Musculoskeletal; Education; Funny; Multimedia

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