What is the Anvil
Anvil, also referred to as the incus, is one of the three middle ear bones, along with the malleus and stapes. In Latin, the term ‘incus’ means ‘anvil’, which relates to its similarity to the metalworking tool in shape.
Where Can the Anvil be Found
This bone is located in the middle of the chain of three small bones in the middle ear.
Key Points
| Type | Irregular Bone |
| How many are there in the human body | 2 (1 in each ear) |
| Articulates with | Malleus and stapes |
Roles
The anvil conveys vibrations from the outer to the inner ear through the malleus and stapes. When sound waves strike the eardrum, it initiates a vibration that travels through all three bones, malleus, anvil, and stapes, reaching the inner ear.
Structure
The anvil consists of a body, two crura (singular: crus), short and long, that diverge nearly at right angles, and a lenticular process.
1. Body: It is somewhat cubical but compressed transversely. The body also features a deep concavo-convex facet on its anterior surface, which articulates with the head of the malleus.
2. Short crus: Also called short limb or process, it is somewhat conical in shape, projecting almost horizontally backward. The posterior ligament of the anvil attaches here.
3. Long crus: Alternatively known as the long limb or process, it descends inferiorly from the body and runs parallel to the malleus.
4. Lenticular process: The lower end of the long crus bends at a right angle to form this hooked-shaped part. It articulates with the head of the stapes.
Ligament Attachment
The two ligaments that suspend the anvil in place are:
- Superior ligament of the anvil – Attaches the body to the tympanic cavity roof.
- Posterior ligament of the anvil – Attaches the short limb to the tympanic cavity’s posterior wall (mastoid).
Connections
i. Anvilmalleolar connection: It is a synovial connection between the body of the anvil and the head of the malleus.
ii. Anvil-stapes connection: It is another synovial connection formed between the lenticular process of the long limb of the anvil and the head of the stapes.
References
- Anvil – Radiopaedia.org
- Anatomy of the Distal Anvil in Humans – Ncbi.nlm.nih.gov
- Auditory ossicles – Kenhub.com
- Anvil – Sciencedirect.com
