Calyx of held
Encyclopedia
The Calyx of Held is a particularly large synapse
in the mammalian
auditory
central nervous system, named by H. Held in his 1893 article Die centrale Gehörleitung, due to its flower-petal
-like shape.
Globular bushy cells in the Ventral Cochlear Nucleus (VCN)
send axons
to the contralateral Medial Nucleus of the Trapezoid body
(MNTB), where they synapse via these calyces on MNTB principal cells.
These principal cells then project to the ipsilateral Lateral Superior Olive (LSO)
,
where they inhibit postsynaptic neurons and provide a basis for interaural level detection (ILD), required for high frequency sound localization.
This synapse has been described as the largest in the brain,
which hints at its importance. This structure is specially designed for fast, efficient transportation of information from one cell to the next.
The related end bulb of Held is a smaller synapse found in other auditory brainstem structures. As with the calyx, these synapses promote fast, efficient information transfer.
Synapse
In the nervous system, a synapse is a structure that permits a neuron to pass an electrical or chemical signal to another cell...
in the mammalian
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
auditory
Auditory system
The auditory system is the sensory system for the sense of hearing.- Outer ear :The folds of cartilage surrounding the ear canal are called the pinna...
central nervous system, named by H. Held in his 1893 article Die centrale Gehörleitung, due to its flower-petal
Flower
A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants . The biological function of a flower is to effect reproduction, usually by providing a mechanism for the union of sperm with eggs...
-like shape.
Globular bushy cells in the Ventral Cochlear Nucleus (VCN)
Cochlear nuclei
The cochlear nuclei are two heterogeneous collections of neurons in the mammalian brainstem that receive input from the cochlear nerve, which carry sound information from the cochleae...
send axons
Axon
An axon is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neuron's cell body or soma....
to the contralateral Medial Nucleus of the Trapezoid body
Trapezoid body
The trapezoid body is part of the acoustic pathway. It is a bundle of fibers and cells in the pontine tegmentum. It consists of fibers arising from the ventral cochlear nucleus. A collection of nerve cells inside forms a trapezoid nucleus. The superior olivary nucleus is situated on the dorsal...
(MNTB), where they synapse via these calyces on MNTB principal cells.
These principal cells then project to the ipsilateral Lateral Superior Olive (LSO)
Superior olivary nucleus
The superior olivary complex is a collection of brainstem nuclei that functions in multiple aspects of hearing and is an important component of the ascending and descending auditory pathways...
,
where they inhibit postsynaptic neurons and provide a basis for interaural level detection (ILD), required for high frequency sound localization.
This synapse has been described as the largest in the brain,
which hints at its importance. This structure is specially designed for fast, efficient transportation of information from one cell to the next.
The related end bulb of Held is a smaller synapse found in other auditory brainstem structures. As with the calyx, these synapses promote fast, efficient information transfer.