Introduction The use of the botulinum neurotoxin injection is a growing area of research and clinical activity, with a focus on its role in facilitating postoperative pain management after reconstructive breast surgery. The study aimed to find out the standard injection points for botulinum neurotoxin injection by revealing the intramuscular nerve arborization of the pectoralis major.

Methods Sihler’s technique was conducted on the pectoralis major muscles (16 cadaveric specimens). The intramuscular nerve arborization was documented relative to the inferior border of the clavicle bone and lateral border of the sternum.

Results After the staining, the pectoralis major was divided into fifths transversely from the inferior border of the clavicle and vertically into fifths from the lateral border of the sternum. Intramuscular nerve arborization of the pectoralis major muscle was the largest in the middle sections of the muscle belly.

Discussion The results indicate that botulinum neurotoxin should be applied to the pectoralis major in certain regions. The regions of major arborization are optimal as the most effective and most reliable points for injecting botulinum neurotoxin.