A mimic of first dorsal interosseus atrophy revealed by ultrasound study

International Journal of Morphology, 2007

2005

Journal of Clinical Neurophysiology, 2007

Journal of Electromyography and Kinesiology, 2006

During the routine anatomical dissection in the hypothenar region of the left hand of a 67-year-old female cadaver, a number of variant structures were observed. The most prominent finding in our case was a supernumerary muscle hitherto unknown in the anatomical literature. This variant muscle had a muscular body formed by the connection of two deeply situated muscular bellies - medial and lateral. The lateral belly originated from the flexor retinaculum, the medial one - from the hamate bone. The common muscular body inserted to the antero-lateral surface of the base of the fifth proximal phalanx. Due to its location and possible function, we named the variant muscle as “deep abductor-flexor” of the little finger. The flexor digiti minimi brevis muscle showed two proximal tendons – the medial tendon was attached to the hamulus of the hamate bone while the aberrant lateral tendon originated from the lateral part of the flexor retinaculum. Both, the aberrant lateral tendon of the flexor digiti minimi brevis and the lateral belly of the “deep abductor-flexor”, passed over the palmar branch of the ulnar nerve, which define their possible clinical significance in ulnar nerve compression. Therefore, the variations of the hypothenar muscles are reviewed and their relation to the compression of the ulnar nerve is discussed.

Journal of Electrodiagnosis and Neuromuscular Diseases

An isolated musculocutaneous nerve (MCN) injury is a rare condition that can be easily missed if it presents late. A 28-year-old man reported painless and progressive wasting of the right arm for 6 months. On examination, there was visible wasting of the right biceps brachii muscle along with its slight weakness, depressed biceps jerk, and an impaired pinprick sensation in the lateral antebrachial cutaneous nerve distribution. He described a history of a road traffic accident 14 months beforehand. Based on the history and clinical examination, the differential diagnosis included an isolated MCN injury, upper trunk plexopathy, lateral cord plexopathy, C5/6 radiculopathy, and monomelic amyotrophy involving the C5/6 myotomes on the right side. The results of nerve conduction studies and electromyography were consistent with chronic proximal MCN neuropathy (right). In cases of arm wasting without pain or numbness, MCN injury should be included in the differential diagnosis, even in the ...

Background: The motor innervation of the thumb muscles though important for the hand surgeon, yet it is still a subject of debate since median and ulnar nerves play variable roles. Objectives: To describe the innervation of the short muscles of the thumb and the possible presence of a 1st palmar interosseous muscle. To correlate the variations of innervation to prognostic values in nerve diseases and injuries. Methods: A dissection of 15 adult embalmed hands was performed. An EMG study on 42 hands of healthy volunteers was done in which the compound muscle action potential and the interference pattern were studied by sampling separate muscles. Results: In (86.6%) of the dissections the muscular branch of the median nerve was the first branch in the palm. A median-ulnar anastomosis was found in (53.3%) of the dissected hands, demonstrated at different levels. In spite of special attention to reveal a first palmar interosseous muscle, it was not detected as a separate entity. In the EMG study, innervation showed considerable variations. Adductor pollicis did not receive pure median innervation, it received the ulnar nerve in (90.5%) of the cases. Abductor pollicis brevis did not show a pure ulnar supply, it was mainly supplied by median nerve (66.7%). The highest percentage (66.7%) of a mixed innervation was shown in opponens pollicis. Conclusions: The palmar median-ulnar anastomosis at different levels makes it vulnerable in surgical interventions. The absence of significant laterality in the mode of innervation of specific muscles may help the prognosis of the affected hand from an EMG study done on the contralateral side. The conventional EMG method does not specify the exact innervation of each muscle. From the prognostic point of view if the method used in this study is applied conventionally, the severity of the injury can be expressed in terms of muscles involved. Many muscles received mixed innervation and will retain their function on the long run.

2010

Cureus, 2021

The Journal of hand surgery, European volume, 2008