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Human posterior cricoarytenoid muscle compartments. Anatomy and mechanics
N J Bryant1, G E Woodson, K Kaufman
1Division of Otolaryngology, Yale University School of Medicine, New Haven, Conn, USA.
Objective:
To document the presence and functional significance of distinct anatomical compartments in the human posterior cricoarytenoid muscle (PCA).
Design:
Anatomic study of human cadaver larynges.
Subjects:
Seventeen fresh larynges, harvested at autopsy from 8 men and 9 women, with no history of laryngeal disease or surgery.
Interventions:
Twenty-three PCA muscles from 12 human cadaver larynges were dissected. Computed tomographic scanning and rigid body mechanical analysis were used to compute 3-dimensional motion with simulated individual contraction of PCA compartments in 5 fresh larynges.
Results:
Discrete medial and lateral bellies with different orientations of muscle fibers were found in every muscle. The 2 bellies insert on opposing aspects of the muscular process of the arytenoid. Very little linear translation was effected by either muscle. The axes of rotation attributable to the 2 bellies differed significantly, with the medial belly effecting rotation about a more vertical axis. The axis of rotation for the lateral muscle belly was nearer the anterior posterior axis than that of the medial belly.
Conclusions:
These data indicate that PCA muscle contraction results in arytenoid rotation about a variable oblique axis without significant lateral gliding. There are 2 bellies within the human PCA muscle with differing mechanical actions on the cricoarytenoid joint.