Malleus
Encyclopedia
The malleus or hammer is a hammer
-shaped small bone
or ossicle
of the middle ear
which connects with the incus
and is attached to the inner surface of the eardrum
. The word is Latin
for hammer.
It transmits the sound vibrations from the eardrum
to the incus
.
The malleus is unique to mammals, and evolved from a lower jaw bone
in basal amniotes called the articular
, which still forms part of the jaw joint in reptiles and birds. Embryologically it is derived from the first pharyngeal arch along with the rest of the bones of mastication, such as the maxilla
and mandible.
Hammer
A hammer is a tool meant to deliver an impact to an object. The most common uses are for driving nails, fitting parts, forging metal and breaking up objects. Hammers are often designed for a specific purpose, and vary widely in their shape and structure. The usual features are a handle and a head,...
-shaped small bone
Bone
Bones are rigid organs that constitute part of the endoskeleton of vertebrates. They support, and protect the various organs of the body, produce red and white blood cells and store minerals. Bone tissue is a type of dense connective tissue...
or ossicle
Ossicles
The ossicles are the three smallest bones in the human body. They are contained within the middle ear space and serve to transmit sounds from the air to the fluid-filled labyrinth . The absence of the auditory ossicles would constitute a moderate-to-severe hearing loss...
of the middle ear
Middle ear
The middle ear is the portion of the ear internal to the eardrum, and external to the oval window of the cochlea. The mammalian middle ear contains three ossicles, which couple vibration of the eardrum into waves in the fluid and membranes of the inner ear. The hollow space of the middle ear has...
which connects with the incus
Incus
The incus or anvil is the anvil-shaped small bone or ossicle in themiddle ear. It connects the malleus to the stapes. It was first described by Alessandro Achillini of Bologna.The incus transmits sound vibrations from the malleus to the stapes....
and is attached to the inner surface of the eardrum
Eardrum
The eardrum, or tympanic membrane, is a thin membrane that separates the external ear from the middle ear in humans and other tetrapods. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...
. The word is Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for hammer.
It transmits the sound vibrations from the eardrum
Eardrum
The eardrum, or tympanic membrane, is a thin membrane that separates the external ear from the middle ear in humans and other tetrapods. Its function is to transmit sound from the air to the ossicles inside the middle ear. The malleus bone bridges the gap between the eardrum and the other ossicles...
to the incus
Incus
The incus or anvil is the anvil-shaped small bone or ossicle in themiddle ear. It connects the malleus to the stapes. It was first described by Alessandro Achillini of Bologna.The incus transmits sound vibrations from the malleus to the stapes....
.
The malleus is unique to mammals, and evolved from a lower jaw bone
Evolution of mammalian auditory ossicles
The evolution of mammalian auditory ossicles is one of the most well-documented and important evolutionary events, demonstrating both numerous transitional forms as well as an excellent example of exaptation, the re-purposing of existing structures during evolution.In reptiles, the eardrum is...
in basal amniotes called the articular
Articular
The articular bone is part of the lower jaw of most tetrapods, including amphibians, sauropsids and early synapsids. In these animals it is connected to two other lower jaw bones, the suprangular and the angular...
, which still forms part of the jaw joint in reptiles and birds. Embryologically it is derived from the first pharyngeal arch along with the rest of the bones of mastication, such as the maxilla
Maxilla
The maxilla is a fusion of two bones along the palatal fissure that form the upper jaw. This is similar to the mandible , which is also a fusion of two halves at the mental symphysis. Sometimes The maxilla (plural: maxillae) is a fusion of two bones along the palatal fissure that form the upper...
and mandible.
See also
- Bone terminology
- Evolution of mammalian auditory ossiclesEvolution of mammalian auditory ossiclesThe evolution of mammalian auditory ossicles is one of the most well-documented and important evolutionary events, demonstrating both numerous transitional forms as well as an excellent example of exaptation, the re-purposing of existing structures during evolution.In reptiles, the eardrum is...
- Terms for anatomical location
- Neck of malleusNeck of malleusThe neck of malleus is the narrow contracted section of the bone in the middle ear called the malleus. It lies just beneath the head of the malleus; below it is a prominence to which the various processes are attached....
- Superior ligament of malleusSuperior ligament of malleusThe Superior ligament of the malleus is a delicate fibrous strand that crosses from the roof of the tympanic cavity to the head of the malleus....
- Lateral ligament of malleusLateral ligament of malleusThe Lateral ligament of the malleus is a triangular fibrous band that crosses from the posterior aspect of the tympanic notch to the head or neck of the malleus....
- Anterior ligament of malleusAnterior ligament of malleusThe Anterior ligament of the malleus is a fibrous band that extends from the neck of the malleus just above its anterior process to the anterior wall of the tympanic cavity close to the petrotympanic fissure. Some of the fibers also pass through the fissure to the spine of sphenoid bone....
External links
- The Anatomy Wiz Malleus