Guidelines for Removal of Temporal Bones for Pathological Study

Temporal bone specimens should fit the following criteria:

  1. The entire middle ear and inner ears must be intact.

  2. Most of the mastoid should be present.

  3. Some external auditory canal should be present.

  4. The trunks of the seventh and eighth cranial nerves should be visible at the entrance of the internal auditory canal (indicating that the nerve trunks are intact within the temporal bone)

If you have any questions, please contact the Registry, 24 hours a day at (800) 822-1327.

Removal details:

A. Necessary instruments
Instruments video
B. Removal of the Brain
The brain is elevated from the floor of the skull sufficiently to expose the trunks of cranial nerves VII and VIII. These must be cut at the meatus of the internal auditory canal.
Note: Failure to do this will frequently result in avulsion of these nerves from the canal, which detracts from the value of the specimens.

Removal of Brainstem
If the auditory brain has been donated, the auditory brain stem should also be removed.
Note: If unsure of how to separate the brain stem from the cerebellum, it is better to send the entire brain intact to avoid destroying the cochlear nucleus when removing the cerebellum.

Storage of Brain and Brainstem
Brain tissue should be placed in cold 10% neutral buffered formalin (fully submerge and cover the specimen).

Brain and brainstem removal video

Methods of Temporal Bone Removal
The right and left temporal bones can be removed by either the block or bone plug method. The block method can be done with mallet and osteatome or with the motor-driven oscillating, rocker-type saws, both of which are standard equipment in autopsy rooms.

C. Bone plug method
This method consists of using the bone plug cutter in the oscillating motor driven saw. For the adult body, the proper saw diameter is 1- 1/2 inches.

Plug removal method video

D. Block method

Four cuts are made in the bone of the skull base on both the right and left side.

Part 1 - Making the Cuts

Part 2 - Removing blocks

Block removal method video