Biomedical Engineering Reference
In-Depth Information
right maxillary bones. It supports a prominent partition that
forms part of the nasal septum.
• Middle ear (6)
• The middle ear contains the auditory ossicles—tiny bones in the
middle ear of vertebrates that connect the eardrum to the inner
ear. They transmit vibrations of the eardrum caused by sound
waves in the air to the fluid of the inner ear via the oval window.
Three ossicles—the malleus (hammer), incus (anvil), and stapes
(stirrup)—are present in the mammalian ear. They form a lever
system, diminishing the force of sound waves and increasing the
force on the inner ear. A single ossicle occurs in the ear of birds,
amphibians, and reptiles.
• The malleus (2) is the largest ossicle and has a head, a neck, a long
process or handle, an anterior process, and a lateral process. The
head is rounded and lies within the epitympanic recess. It artic-
ulates posteriorly with the incus. The neck is the restricted part
below the head. The handle passes downward and backward and
is firmly attached to the medial surface of the tympanic membrane
(eardrum). It can be seen through the tympanic membrane on oto-
scopic examination. The anterior process is a spicule of bone that
is connected to the anterior wall of the tympanic cavity by a liga-
ment. The lateral process projects laterally and is attached to the
anterior and posterior malleolar folds of the tympanic membrane.
• The incus (2) is the anvil-shaped small bone or ossicle in the
middle ear. It attaches the malleus to the inner bone (stapes). The
incus transmits sound vibrations from the malleus to the stapes.
• The stape (2) is the stirrup-shaped small bone or ossicle in the
middle ear that is attached through the incudostapedial joint to
the incus laterally and to the fenestra ovalis, the “oval window,
” medially.
A.2.1.2 Hyoid Bone (1)
The hyoid bone is a U-shaped bone that hangs below the skull, suspended by
ligaments from the styloid processes of the temporal bones, and serves as a
base for muscles associated with the tongue and larynx. At rest, it lies at the
level of the base of the mandible in the front and the third cervical vertebra
behind. Unlike other bones, the hyoid is only distantly articulated to other
bones by muscles or ligaments.
A.2.1.3 Vertebral Column (26)
The vertebral column forms the central part of the skeleton. It supports the
skull and protects the spinal cord. It also serves as attachment for the ribs
