Transverse humeral ligament: does it exist?

Area of Science:

• Orthopedics
• Anatomy
• Surgical Anatomy

Background:

• The transverse humeral ligament (THL) is traditionally described as a distinct anatomical structure.
• Its precise anatomical nature and relationship with surrounding tendons, particularly the subscapularis tendon, remain subjects of investigation.

Purpose of the Study:

• To clarify the anatomical existence and composition of the transverse humeral ligament (THL).
• To investigate variations in the insertion of the subscapularis tendon in relation to the long head of the biceps tendon.

Main Methods:

• Dissection of 85 embalmed adult shoulders.
• Detailed examination of the structures overlying the long head of the biceps tendon as it exits the shoulder joint capsule.

Main Results:

• No distinct transverse humeral ligament (THL) was identified in any specimen.
• A fibrous expansion, originating from the pectoralis major tendon, consistently covered the long head of the biceps tendon.
• In 86% of shoulders, subscapularis tendon fibers were incorporated into this expansion, inserting onto the greater tubercle.
• Variations in subscapularis tendon insertion deep to the biceps tendon were observed in 33% of cases.
• Exclusive insertion of the subscapularis tendon onto the lesser tubercle occurred in only 8% of shoulders.

Conclusions:

• The transverse humeral ligament (THL) likely does not exist as a separate anatomical entity.
• The structure typically identified as the THL is composed of subscapularis tendon fibers within a fibrous expansion from the pectoralis major tendon.
• This complex may function as a retinaculum, stabilizing the long head of the biceps tendon, especially when the subscapularis tendon has a typical lesser tubercle insertion.