Intramuscular Neural Distribution of Rhomboid Muscles: Evaluation for Botulinum Toxin Injection Using Modified...

Area of Science:

• Anatomy
• Neuroscience
• Medical Imaging

Background:

• Accurate anatomical knowledge of the rhomboid major and minor muscles is crucial for effective clinical interventions.
• Existing data on the precise intramuscular nerve branching patterns is limited.
• Understanding nerve distribution aids in optimizing procedures like botulinum toxin injections and electromyography.

Purpose of the Study:

• To precisely map the nerve entry point and intramuscular nerve branching of the rhomboid major and minor muscles.
• To provide anatomical guidance for safer and more effective botulinum toxin injections and electromyography procedures.
• To identify optimal and critical zones for needle insertion to avoid nerve injury.

Main Methods:

• A modified Sihler method was applied to 10 specimens each of the rhomboid major and minor muscles.
• Nerve entry points and intramuscular arborization areas were identified relative to anatomical landmarks (spinous processes, scapular angles).
• Detailed mapping of neural distribution within the muscles was performed.

Main Results:

• The nerve entry point for both rhomboid muscles was consistently found in the middle muscular area between cervical (C) 7 and thoracic (T) 1 vertebral levels.
• The rhomboid minor exhibited its largest arborization in the medial and lateral sections between C7 and T1.
• The rhomboid major displayed its largest arborization area in the middle section between T1 and T5.

Conclusions:

• Botulinum neurotoxin injections and electromyography for the rhomboid minor should target the medial and lateral sections between C7-T1.
• For the rhomboid major, the middle section between T1-T7 is recommended for these procedures.
• Avoidance of the middle C7-T1 section is advised to prevent mechanical nerve trunk injury, ensuring safer clinical practice.