Tensor tympani

The middle ear begins on the inner side of the ear drum. The middle ear is an air-filled chamber that vents to the throat through the Eustachian tube. It contains three small bones (ossicles) and two suspensory muscles for them. The three bones are the maleus (hammer), the incus (anvil), and the stapes (stirrup). Sound energy travels across the three bones from the tympanic membrane of the outer ear to the oval window of the inner ear. The action of these three bones produces an amplification of about 2.5 dB. The suspensory muscles are the tensor tympani and the stapedius. When there is a loud sound, these muscles contract and provide some attenuation of energy transmitted across the three bones. 

Fig. 4 Photomicrographs of hematoxylin and eosin-stained sections of the middle ear from a guinea pig. 1 external auditory canal, 2 tympanic membrane, 3 junction of the tympanic membrane and malleus, 4 cochlea, 5 malleus, 6 incus, 7 stapes, 8 round window, 9 tensor tympani, 70 middle ear mucosa, 11 entrance to the eustachian tube...

Fig. Il.la-h. Anatomy. Coronal (a-d) and axial (e-h) high-resolution MPR of the temporal bone from ventral to dorsal (a-d) and cranial to caudal (e-h). Spaces A Epitympanum, B mesotympamrm, C hypotympamrm, D mastoid antrum, E Prussak s space, F sinus tympani. 1 Scutum, 2 promontory, 3 malleus, 4 incus, 5 stapes, 6 incudomalleolar joint, 7 tensor...

---