Stapes

The stapes is the stirrup-shaped small bone or ossicle in the middle ear which is attached through the incudostapedial joint to the incus laterally and to the fenestra ovalis, the "oval window", medially. Stapes means stirrup in Latin. The oval window is adjacent to the vestibule of the inner ear. The stapes is the smallest and lightest bone in the human body. It was described by the professor Giovanni Filippo Ingrassia in 1546 at the University of Naples.

Function

The stapes transmits the sound vibrations from the incus to the membrane of the inner ear inside the fenestra ovalis. The stapes is also stabilized by the stapedius muscle, which is innervated by the facial nerve.^[2]

Evolutionary variation

In non-mammalian tetrapods, the bone homologous to the stapes is usually called the columella; however, in reptiles, either term may be used. In fish, the homologous bone is called the hyomandibular, and is part of the gill arch supporting either the spiracle or the jaw, depending on species.^[3]

Development

As the stapes first develops embryologically from the 6th to 8th week of life, it surrounds the stapedial artery, which supplies the majority of the vasculature of the embryonic head. After that period, the external carotid artery is generated and takes over for the stapedial artery, which subsequently involutes, leaving the stapes with a windowframe-like structure.

See also

• Bone terminology
• Terms for anatomical location
• Evolution of mammalian auditory ossicles

Notes

References

• Vallejo-Valdezate LA, Martín-Gil J, José-Yacamán M, Martín-Gil FJ, Gil-Carcedo LM. (2000 Sep). Scanning electron microscopy images and energy-dispersive X-ray microanalysis of the stapes in otosclerosis and van der Hoeve syndrome. 110. 1505–10. 

External links

• "Development of mammal skull from primitive reptile skull". archive.org. Archived from the original on 2006-11-11. http://web.archive.org/web/20061111030032/http://webpages.marshall.edu/~hurlburt/310lec13.html. Retrieved January 2010. 
• "Reptilia Lab". Juniata Collage. http://faculty.juniata.edu/yohn/reptilialab.htm. Retrieved January 2010. 
• "3-D Virtual Models of the Human Temporal Bone and Related Structures". Eaton Peabody Laboratory of Auditory Physiology. http://research.meei.harvard.edu/otopathology/3dmodels/. Retrieved January 2010.