What is the location of the modiolus?

Location of the Modiolus in Facial Anatomy

The modiolus is a dense, compact, mobile fibromuscular structure located at the corner of the mouth (oral commissure), serving as a convergence point for several facial muscles involved in facial expression.

Anatomical Position and Structure

• The modiolus is positioned at the lateral angle of the mouth, approximately 11.0±2.6 mm lateral and 8.9±2.8 mm inferior to the cheilion (corner of the mouth where the upper and lower lips meet) 1
• It appears as a tortuous, blunt cone-like structure that extends vertically from the buccal mucosa to the dermis of the skin, with the base of the cone adjacent to the mucosa 2
• The facial artery typically passes approximately 1 mm lateral to the lateral border of the modiolus (in 80% of cases) or anterior to it (in 20% of cases) 3, 4

Histological Composition

• In the central region of the modiolus, there is a convergence of muscle fibers forming a dense irregular collagenous connective tissue structure 3
• A tendinous tissue nodule within the modiolus was found in 21.4% of examined cases, which could act as an anchor for the converging facial muscles 3
• The middle layer between the skin and oral mucosa appears particularly dense, compact, and prominent horizontally 3

Functional Significance

• The modiolus serves as a critical anchor point for multiple facial muscles involved in facial expression 3, 4
• It plays an essential role in facial animation, beauty, and aging, making it a key facial landmark both functionally and aesthetically 3
• Proper function of the modiolus is crucial for normal mouth movements, including speaking and eating 5

Clinical Relevance

• The modiolus is a critical structure in reconstructive and aesthetic facial surgery, particularly for procedures involving the oral commissure 5, 4
• Reconstruction techniques for defects involving the modiolus often require careful consideration of both functional and aesthetic outcomes 5
• In botulinum toxin injections targeting muscles around the mouth corner (such as depressor anguli oris), understanding the precise location of the modiolus is essential for optimal results 1

Three-Dimensional Structure

• Three-dimensional reconstruction studies reveal that the modiolus has a complex architecture extending from the buccal mucosa to the skin 2
• Understanding this three-dimensional structure is vital for surgeons to achieve satisfactory aesthetic and functional results during operations related to the oral commissure 2