The annular ligament of the stapes, also known as the ligamentum anulare stapedis, attaches the rim of the footplate of the stapes to the rim of the oval window. This forms the stapediovestibular joint; a fully-functional articulation is vital for transmission of sound vibrations in the middle ear to the fluid in the vestibule, and thence in the cochlea 2.
The annular ligament is formed from fibrous tissue. Recent measurements of cadaveric specimens using micro-CT show that the thickness of the annular ligament varied from 0.26 mm to 0.64 mm, with a mean of 0.38 mm 1. In clinical work the small size of these structures is below the spatial resolution of even high resolution CT of the petrous bone to resolve. However cone-beam CT might be able to in the future.
The stapediovestibular joint shows the typical development of a syndesmosis. The annular ligament forms as a cartilaginous precursor from the adjacent footplate and the otic capsule. The joint attains its normal developed form by the 12th gestation week.
- 1. Mohammadi A, Jufas N, Sale P, Lee K, Patel N, O'Leary S. Micro-CT analysis of the anatomical characteristics of the stapedial annular ligament. (2017) Anatomical science international. 92 (2): 262-266. doi:10.1007/s12565-016-0331-4 - Pubmed
- 2. Kwacz M, Rymuza Z, Michałowski M, Wysocki J. Elastic Properties of the Annular Ligament of the Human Stapes--AFM Measurement. (2015) Journal of the Association for Research in Otolaryngology : JARO. 16 (4): 433-46. doi:10.1007/s10162-015-0525-9 - Pubmed
- 3. Whyte JR, González L, Cisneros AI, Yus C, Torres A, Sarrat R. Fetal development of the human tympanic ossicular chain articulations. (2002) Cells, tissues, organs. 171 (4): 241-9. doi:10.1159/000063124 - Pubmed