Indirect traumatic musculocutaneous nerve injury confused with static line injury: A case report

The musculocutaneous nerve is rarely injured because it is short and is located deep in the shoulder and arm. Damage is usually caused by direct injuries, including stabbing, explosion, and surgery in a war setting. Although indirect injury of the musculocutaneous nerve is extremely rare, it occurs in various situations. In military parachuting-related activities, musculoskeletal injury occurs most commonly, and static line injury is known as rupture of the biceps brachii tendon. However, musculocutaneous neuropathy can also result from secondary injury by the static line. The musculocutaneous nerve goes together with the biceps brachii muscle, and the musculocutaneous nerve could overstretch and compress within the coracobrachialis muscle where the nerve is relatively fixed due to the overloading of the upper arm with shoulder extension. This report focuses on the indirect musculocutaneous nerve injury with axonotmesis following an overloading event by the static line during military parachuting. In this case, some physicians may confuse nerve injury with static line injury, leading to delays in the diagnosis of neuropathy. If the biceps brachii muscle is damaged due to trauma, checking for the accompanying musculocutaneous nerve injury is necessary.

Postsynaptic cleft density changes with combined exercise protocols in an experimental model of muscular hypertrophy

The vertical ladder-based protocols contribute to the NMJ junction's adaptations, and when combined with and without load, can be potentiated. The present study aimed to investigate postsynaptic regions of the biceps brachii muscle in adult male Wistar rats submitted to different vertical ladder-based protocols (Sedentary - S; Climbing - C; Climbing with Load - LC and Combined Climbing - CC). The protocols (C, LC, CC) were performed in 24 sessions, 3 x/week, for 8 weeks. The myofibrillar ATPase analysis showed an increase in cross-sectional area (CSA) of the muscle fibers Type I in all trained Groups; Type II in C and LC and reduction in CC; Type IIx higher in all trained Groups. In the postsynaptic cleft, the stained area presents smaller in Groups C, LC, and CC; the total area showed smaller than LC and higher in C and CC. The stained and total perimeter, and dispersion showed a reduction in C, LC, and CC, higher maximum diameter in Groups C and CC, and decreased in LC. Regarding the postsynaptic cleft distribution, the stained area presented a decrease in all trained Groups. The integrated density presented higher principally in CC. The NMJ count showed an increase in all trained Groups. We concluded that the vertical ladder-based protocols combined contributed to the postsynaptic region adaptations.

Is it the coracobrachialis superior muscle, or is it an unidentified rare variant of coracobrachialis muscle?

The coracobrachialis muscle (CBM) originates from the apex of the coracoid process, in common with the short head of the biceps brachii muscle, and from the intermuscular septum. The CBM demonstrates variability in both the proximal and distal attachment, with some extremely rare varieties, such as the coracobrachialis superior, coracobrachialis longus and coracocapsularis muscle. This case report describes an extremely rare variant of the coracobrachialis superior muscle, or a very rare variant of the CBM. Our findings highlight the importance of muscle variants in the shoulder region, especially the coracoid region, and are significant for radiologists, anatomists, physiotherapists and surgeons specializing in the shoulder joint.

Dynamics of Сhanges in the Power Characteristics of the Biceps Brachii Muscle under the Influence of Different Vibration Effects

Aim. To determine the effects of vibration therapy devices exposure with a constant and aperiodic frequency of vibrations on the tissue of the biceps muscle of the shoulder. Material and methods. The study was conducted on 10 volunteers aged 24-35 years. the program Adobe Audition CC 2020, the device for vibration therapy with a constant vibration frequency “Charm 1-t”, the device for vibration therapy with an aperiodic vibration frequency “Individual massager with a pseudo-boiling layer” (MI EPS), the robotic biomechanical diagnostic and training complex with biological feedback CON-TREX were used. The measurement of the maximum strength of the biceps brachii muscle was carried out once to detect sensitivity to vibration, and then during 7 days for the dynamics of power characteristics. The maximum force was measured before exposure to vibrotherapy devices and immediately after exposure using the isokinetic classical mode of operation of the diagnostic system. Results. In a single measurement of biceps strength on one shoulder in a group of women, the average increase in muscle strength after using the Charm 1-T device was 0.8 N (2.3%), after using MI EPS – 1.9 N (6.4%). In the group of men, the average increase in muscle strength after using the device “Charm 1-T” was 1.9 N (3.2%), after using “MI EPS” – 4.6 N (7.2%). At the seven-day follow-up, the average increase in strength in the group of women on the right hand after using the Charm 1-T device was 21.8% (5.6 N), on the left hand after using MI EPS, the increase was 23.2% (6.1 N). In the group of men, the average increase in strength on the right hand after using “Charm 1-T” was 53% (30.7 N), on the left hand after using “MI EPS” – 15.5% (11.5 N). Conclusion. All participants in the study groups were determined to be sensitive to both types of vibration exposure. The study participants demonstrated an increase in strength indicators when testing the biceps muscle of the shoulder, and there was also an improvement in the tolerability of the procedure itself.