Ultrasound Imaging of Brachial and Antebrachial Fasciae

Knowledge about fasciae has become increasingly relevant in connection to regional anesthesiology, given the growing interest in fascial plane, interfascial, and nerve blocks. Ultrasound (US) imaging, thanks to high definition, provides the possibility to visualize and measure their thickness. The purpose of this study was to measure and compare, by US imaging, the thickness of deep/muscular fasciae in different points of the arm and forearm. An observational study has been performed using US imaging to measure brachial and antebrachial fasciae thickness at anterior and posterior regions, respectively, of the arm and forearm at different levels with a new protocol in a sample of 25 healthy volunteers. Results of fascial thickness revealed statistically significant differences (p < 0.0001) in the brachial fascia between the anterior and the posterior regions; in terms of the antebrachial fascia, no statistically significant difference was present (p > 0.05) between the regions/levels. Moreover, regarding the posterior region/levels, the brachial fascia had a greater thickness (mean 0.81 ± 0.20 mm) than the antebrachial fascia (mean 0.71 ± 0.20 mm); regarding the anterior region/levels, the antebrachial fascia was thicker (mean 0.70 ± 0.2 mm) than the brachial fascia (mean 0.61 ± 0.11 mm). In addition, the intra-rater reliability reported good reliability (ICC2,k: 0.88). US imaging helps to improve grading of fascial dysfunction or disease by revealing subclinical lesions, clinically invisible fascial changes, and one of the US parameters to reliably evaluate is the thickness in the different regions and levels.

That Tendon is the Median Nerve: Perils of a Palmaris Longus Deficient Wrist

Background: To document the course of the median nerve in the distal forearm in palmaris longus (PL) deficient forearms and elucidate features that help distinguish it from the PL. Methods: In the cadaveric study, 56 cadaveric forearms were dissected and the location and course of the median nerve were documented. In the clinical study, 20 healthy subjects with absent PL were examined with provocative tests to elucidate the PL (Schaeffer’s test and Thompson’s test), and modified Durkan’s and Phalen’s tests. In the imaging study, one subject with a clearly visible and palpable median nerve was further evaluated with MRI with a superficial fiducial marker. Results: Cadaveric dissection revealed that the median nerve was deep to the antebrachial fascia and superficial to the FDS tendons in the distal forearm. In 9 specimens without a PL, the median nerve was the most superficial structure deep and lay draped over the FDS tendons. In the clinical study, PL absence was bilateral in 4 subjects and unilateral in 16. The nerve was visible and palpable in 4 forearms and palpable but not visible in 20 forearms. In all 24 forearms, the nerve was palpable as a lax, mobile, cord-like structure that could be rolled over the taut FDS tendons. Tinel’s and Durkan’s signs were positive in 11 subjects. In the imaging study, MRI confirmed that the palpable structure was the median nerve. Conclusions: Unlike the PL, the nerve is non-contractile and remains flaccid on provocative testing. It is usually palpable and may also be visible in thin forearms. Careful scrutiny may reveal it to be distinct from, and draped over underlying FDS tendons. These findings may help avoid inadvertent median nerve harvest in place of a PL tendon graft.

Morphological study of the proximal boundary of the flexor retinaculum and of its constituent parts

The proximal boundary of the flexor retinaculum is not readily demarcated, and previous reports of three distinct regions of the flexor retinaculum were not consistent with the authors’ experience. This study was undertaken to clarify the proximal boundary and the constituent parts of the flexor retinaculum. A total of 56 cadaveric wrists were used in the study. The proximal boundary of the flexor retinaculum was identified by a change in thickness and colour of the longitudinally sectioned surface of the continuous membranous sheet of the flexor retinaculum and antebrachial fascia. Steel wires were placed on the proximal and distal boundaries, and anteroposterior radiographic images were taken. MRI was carried out before dissection or serial section. The locations of the proximal and distal boundaries of the flexor retinaculum varied. The flexor retinaculum was comprised of two parts, which were distinguishable by thickness and transparency. These two parts were also identified on MR images and by light microscopy.

The Concomitant Presence of Two Anomalous Muscles in the Forearm

This article describes the concomitant presence of two anomalous forearm muscles in a 20-year-old man, discovered accidentally during an operation for a forearm injury. The first one was similar to a reverse palmaris longus muscle except for its direction to the Guyon's canal. The second one originated from the radial antebrachial fascia, superficial to all other forearm muscles in the lower half of the forearm, then diverged medially and extended into the Guyon's canal and was innervated by the ulnar nerve. The patient had no symptoms related to overcrowding of the Guyon's canal before the injury. A hand surgeon should be well informed about the anatomic variations of the hand to be comfortable during surgical practice.

Compression Neuropathy of the Palmar Cutaneous Branch of the Median Nerve by the Antebrachial Fascia

An isolated compression neuropathy of the palmar cutaneous branch of the median nerve is described in a woman who presented with a small tender mass over the anterior aspect of her distal forearm and complete numbness over the thenar eminence. Surgical exploration revealed thickening of the palmar cutaneous nerve as it passed upwards through the antebrachial fascia on the ulnar aspect of the flexor carpi radialis tendon. Neurolysis of two separate fascicles of the palmar cutaneous branch of the median nerve and excision of a window of antebrachial fascia resulted in complete return of sensation over the thenar eminence.

Intermittent Occlusion of the Ulnar Artery

Intermittent occlusion of the ulnar artery developed in a patient causing cramp in her right hand. Both flexion and extension of the wrist completely obstructed bloodflow in the ulnar artery, a level just proximal to the wrist. At operation, a tight hand of antebrachial fascia was found to the cause of this intermittent arterial occlusion. Surgical release of this fascial ban reduced complete relief of her symptoms.