The pterygostapedius is a rare accessory muscle of the middle ear, variably connecting the pterygoid region to the stapedius or stapedial tendon. It represents a phylogenetic remnant and is of minimal functional significance. It is encountered as an unexpected finding during middle ear surgery and tympanoplasty.
| Origin | Variable; minor slip from the medial pterygoid plate or lateral pterygoid muscle |
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| Insertion | Stapedial tendon or stapedius muscle; variable in its relationship to the stapedius |
| Nerve Supply | Branch of the nerve to the medial pterygoid (V3) |
| Blood Supply | Inferior tympanic artery variant |
| Actions | Minor accessory function to the stapedius; damps ossicular chain vibrations; present in approximately 5-10% of individuals and functionally insignificant in most |
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The pterygostapedius is a surgical curiosity encountered during ossicular chain reconstruction and stapedectomy. Its presence must be recognised to avoid inadvertent division producing further conductive hearing loss. Preoperative CT of the middle ear may occasionally identify soft tissue in the oval window region that represents this anomalous muscle. It has been implicated anecdotally in cases of unusual conductive hearing loss not explained by standard ossicular pathology.
An anomalous pterygostapedius encountered during stapedectomy for otosclerosis crosses the oval window region and must be carefully dissected or divided before stapedial footplate fenestration; its inadvertent division produces no additional hearing loss but its misidentification as the stapedius tendon can lead to premature stapedectomy at an incorrect level.
