Intrinsic auricular muscles and auricular form

Area of Science:

• Anatomy
• Developmental Biology
• Otolaryngology

Background:

• The external ear's complex shape, specifically the antihelical fold, is formed by the intricate interplay of numerous intrinsic and extrinsic auricular muscles.
• Understanding the muscular influence on auricular cartilage development is crucial for diagnosing congenital ear deformities.

Purpose of the Study:

• To investigate the role of the transversus and obliquus auricular muscles in the formation of the antihelical fold.
• To determine if the presence and typical insertion of these muscles correlate with normal ear cartilage folding.

Main Methods:

• Dissection of ten external auricles from anencephalic fetuses (gestation ≥ 6 months).
• Evaluation of the transversus and obliquus auricular muscles and their insertions in relation to the antihelical fold.
• Comparison of auricular form with the presence and insertion patterns of these specific muscles.

Main Results:

• Four auricles exhibited normal form with typical insertions of the transversus and obliquus auricular muscles.
• Six auricles presented with simplified forms, lacking antihelical folding (five) or having minimal development (one).
• Absence of identified transversus or obliquus auricular muscle fibers in the six simplified auricles.

Conclusions:

• The presence and functioning of the transversus and obliquus auriculae muscles are strongly suggested to determine antihelical folding.
• Normal auricular cartilage folding appears dependent on functioning auricular muscles.
• Abnormal ear shape in children may indicate abnormal muscle placement/function, potentially signaling neuromuscular weakness or absence of muscle.