FoundationalConceptsNeuroscience

connected bones, collectively called the ossicles. Individually, they are
called the hammer, anvil, and stirrup (Latin: malleus, incus, and stapes)
because their shapes are reminiscent of those various items. As the
eardrum vibrates, the hammer, which is attached to the eardrum, also
vibrates. This vibration is then transferred to the anvil and thence to
the stirrup, which is attached to another drumskin-like tissue called
the oval window. The oval window defines the boundary between the
middle ear and the inner ear, which consists of the cochlea and semi-
circular canals, collectively called the bony labyrinth (Fig. 15.11).

Pinna Semicircular canals

Ossicles

External

ear Canal

Eustachian tube

Figure 15.10. The human ear. The external ear is the pinna, ear canal, and

eardrum; the middle ear is the chamber containing the ossicles; the inner ear

is the cochlea and semicircular canals. The cochlear and vestibular nerves

form cranial nerve 8. The Eustachian tube connects the middle ear with the

nasopharynx and allows for equalization of air pressure between the middle-

ear chamber and the external atmosphere. The Eustachian tube is named

after sixteenth-century Italian anatomist Bartolomeo Eustachi, a contempo-

rary of Vesalius.