Targeted muscle reinnervation in the upper arm: A functional anatomical study

Area of Science:

• Neuroscience
• Anatomy
• Surgical Research

Background:

• Targeted muscle reinnervation (TMR) aims to restore motor function after nerve injury.
• Accurate identification of specific nerve fascicles controlling hand movement is crucial for TMR success.

Purpose of the Study:

• To precisely map the anatomical location and diameter of neural fascicles controlling hand movement within the median, ulnar, and radial nerves.
• To provide detailed data for enhancing motor intention expression following TMR procedures.

Main Methods:

• Dissection of the median, ulnar, and radial nerves in 6 fresh cadaver specimens.
• Measurement of fascicle location (o'clock position) and diameter at 10 and 20 cm below the acromion.
• Measurement of diameters of muscle branches for target reinnervation muscles.

Main Results:

• Median nerve fascicles for finger/wrist flexion located at 9-12 o'clock (10cm) and 10-20cm below acromion, with diameters ~2.0 mm.
• Ulnar nerve fascicles for flexion located at 8-12 o'clock, with diameters ~1.8-2.0 mm.
• Radial nerve fascicles for extension located at 10-2 o'clock (10cm) and 6-12 o'clock (20cm), with diameters ~2.5-3.0 mm.

Conclusions:

• Nerve fascicles for finger flexion/extension occupy relatively consistent regions within major arm nerves.
• Fascicle diameters correlate with the size of their target muscle reinnervation branches.
• This anatomical data is vital for optimizing surgical planning in TMR.