# Surgical anatomy of the pectoralis major, pectoralis minor, latissimus dorsi and teres major for tendon transfer in irreparable subscapularis tendon tears

## TL;DR

This study maps the anatomy of four muscles and their surrounding nerves and blood vessels to guide tendon transfer surgery for severe shoulder injuries.

## Contribution

The study provides detailed anatomical measurements for safe tendon transfer in irreparable subscapularis tears.

## Key findings

- The medial pectoralis nerve is on average 6.5 cm from the pectoralis minor's coracoid insertion.
- Neurovascular structures cross posterior to the LD and TM at specific distances from their humeral insertions.
- The radial nerve lies medial to the humerus at defined locations relative to the LD and TM.

## Abstract

Tendon transfer of the pectoralis major (PM), pectoralis minor (Pm), latissimus dorsi (LD) and teras major (TM) is recommended for irreparable subscapularis (SSC) tears. This study aimed to describe the landmarks and neurovascular structures in the regions of the four muscles to facilitate their transfer to irreparable SSC tears.

Descriptive laboratory study.

Twelve fresh‐frozen adult specimens were dissected and important neurovascular structures around the four tendons were identified. The relationships between the tendons and neurovascular structures were quantitatively investigated during tendon transfer procedures.

The average distance of medial pectoralis nerve (MPN) to the insertion of Pm on the coracoid was 6.5 cm (5.4–8.1 cm). The MPN travelled with the lateral thoracic artery (LTA) to pierce the PM with an average of 9.7 cm (8.3–12.1 cm) medial to the humeral insertion. Axillary nerve and posterior humeral circumflex vessels were above the superior margin of TM muscle with average of 0.8 cm (0.5–1.2 cm). These neurovascular structures crossed posterior to the plane of the LD and TM at 2.6 cm (1.9–3.3 cm) from the humeral insertion of these two muscles. The radial nerve (RN) and its motor branch to triceps were found to lie an average of 2.7 cm (2.0–4.3 cm) medial to the humerus at the superior border of the LD, and an average of 2.4 cm (1.8–3.5 cm) medial to the humerus at the inferior border of the TM. The neurovascular pedicles to the LD and TM were at an average of 12.7 cm (10.2–15.6 cm) and 7.0 cm (5.6–8.5 cm) to the humeral insertions, respectively.

Our results clarify the complex local anatomic structures of the PM, Pm, LD and TM for tendon transfer to treat irreparable SSC tears and provide potentially useful references for tendon transfer.

Not applicable.