Hammer (Ear Bone)
Malleus
location_on Middle ear cavity within the temporal bone, attached to the tympanic membrane
The malleus is the largest of the three auditory ossicles and the most laterally positioned, with its handle (manubrium) embedded in the tympanic membrane. It receives sound vibrations from the eardrum and transmits them to the incus. Together with the incus and stapes, it forms a lever system that amplifies sound pressure by approximately 20 times between the tympanic membrane and the oval window.
Key Anatomical Features
- Head articulates with the body of the incus in the incudomalleolar joint
- Manubrium (handle) is embedded in the tympanic membrane
- Neck is a constricted region between the head and manubrium
- Anterior process is connected to the anterior wall of the middle ear by a ligament
- Lateral process creates a small bump on the external surface of the tympanic membrane
Muscle Attachments
| Muscle | Attachment | Action |
|---|---|---|
| Tensor tympani | Manubrium of malleus | Pulls the malleus medially, tensing the tympanic membrane to dampen loud sounds |
| Superior malleolar ligament | Head to roof of epitympanum | Suspends the malleus in the middle ear cavity |
| Anterior malleolar ligament | Anterior process to petrotympanic fissure | Limits anterior displacement of the malleus |
| Lateral malleolar ligament | Neck to tympanic bone | Suspends the malleus laterally |
Joints and Articulations
| Joint | Type | Connects to |
|---|---|---|
| Incudomalleolar joint | Synovial saddle | Incus (body) |
| Tympanomalleolar attachment | Fibrous (embedded in tympanic membrane) | Tympanic membrane |
Common Pathologies
Ossicular chain disruption
Dislocation of the incudomalleolar joint from head trauma or chronic ear infection, causing conductive hearing loss of up to 60 dB.
Cholesteatoma erosion
Chronic cholesteatoma can erode the malleus and other ossicles, progressively worsening conductive hearing loss.
Malleus fixation
Congenital or acquired fixation of the malleus head in the epitympanum causing conductive hearing loss. May mimic otosclerosis clinically.
Clinical Relevance
The manubrium of the malleus is visible through the intact tympanic membrane during otoscopy and serves as the key landmark for identifying the light reflex, pars tensa, and pars flaccida. A conductive hearing loss with a normal-appearing tympanic membrane should raise suspicion for ossicular chain disruption. Ossiculoplasty using prosthetic or autograft materials can restore the ossicular chain after damage.
Development and Ossification
The malleus develops from the cartilage of the first pharyngeal arch (Meckel's cartilage), the same arch that gives rise to the mandible. Ossification begins around the 4th fetal month. The malleus is fully ossified and adult-sized at birth.
Did You Know?
- Malleus means hammer in Latin, named for its shape resembling a mallet
- The malleus, incus, and stapes are the three smallest bones in the body and are fully formed at birth
- The malleus develops from the same embryonic structure (first pharyngeal arch) as the mandible
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