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Encyclopedia > Lateral lemniscus
Brain: Lateral lemniscus
Figure 1: Arrangement of the lateral lemniscus, showing the tract and nuclei. Dorsal nucleus of the lateral lemniscus (DNLL), Intermediate nucleus of the lateral lemniscus (INLL), ventral nucleus of the lateral lemniscus (VNLL).
Latin lemniscus lateralis
Gray's subject #188 805
NeuroNames hier-605
Dorlands/Elsevier l_06/12483107

The lateral lemniscus is a tract of axons in the brainstem that carries information about sound from the cochlear nucleus to various brainstem nuclei and ultimately the contralateral inferior colliculus of the midbrain. Image File history File links No higher resolution available. ... Latin is an ancient Indo-European language originally spoken in Latium, the region immediately surrounding Rome. ... NeuroNames is a system of nomenclature for the brain and related structures. ... Elseviers logo. ... An axon or nerve fiber, is a long, slender projection of a nerve cell, or neuron, that conducts electrical impulses away from the neurons cell body or soma. ... The brain stem is the stalk of the brain below the cerebral hemispheres. ... The cochlear nuclei consist of: (a) the lateral cochlear nucleus, corresponding to the tuberculum acusticum on the dorso-lateral surface of the inferior peduncle; and (b) the ventral or accessory cochlear nucleus, placed between the two divisions of the nerve, on the ventral aspect of the inferior peduncle. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ... In biological anatomy, the mesencephalon (or midbrain) is the middle of three vesicles that arise from the neural tube that forms the brain of developing animals. ...

Contents

Connections

The brainstem nuclei include:

Fibers leaving these brainstem nuclei ascending to the inferior colliculus rejoin the lateral lemniscus. In that sense, this is not a 'lemniscus' in the true sense of the word (second order, decussated sensory axons), as there is third (and out of the lateral superior olive, fourth) order information coming out of some of these brainstem nuclei. For the cerebellar structure, see Dentate nucleus. ... This does not cite any references or sources. ...


The lateral lemniscus is located where the cochlear nuclei and the pontine reticular formation (PRF) crossover. The PRF descends the reticulospinal tract where it innervates motor neurons and spinal interneurons. It is the main auditory tract in the brainstem which connects the superior olivary complex (SOC) with the inferior colliculus (IC). The Dorsal Cochlear Nucleus (DCN) has input from the LL and output to the contralateral LL via the ipsilateral and contralateral Dorsal Acoustic Stria. The cochlear nuclei consist of: (a) the lateral cochlear nucleus, corresponding to the tuberculum acusticum on the dorso-lateral surface of the inferior peduncle; and (b) the ventral or accessory cochlear nucleus, placed between the two divisions of the nerve, on the ventral aspect of the inferior peduncle. ... For the cerebellar structure, see Dentate nucleus. ... The paired inferior colliculi together with the superior colliculi form the eminences of the corpora quadrigemina. ...


There are three small nuclei on each of the lateral lemnisci; the ventral, dorsal and the intermediate. The two lemnisci communicate via the commissural fibres of Probst.


Function of this part of the brain

This part of the brain also funcions in identifying the onset of the sound, the duration of the sound and also with mono aural volume.


The function of the lateral lemniscus is not known; however it has good temporal resolution compared to other cells higher than the cochlear nuclei and is sensitive to both timing and amplitude changes in sound. It is also involved in the acoustic startls reflex; the most likely region for this being the VNLL.


The cells of the DNLL respond best to bilateral inputs. Sound in the contralateral ear leads to the strongest responses in the VNLL which deals with some temporary processing. The VNLL may also be essential to the IC’s decoding of amplitude modulated sounds.


DNLL cells have onset and complexity tuned sustained responses. VNLL cells have little spontaneous activinty, broad and moderately complex tuning curves; they have both phasic and tonic responses and are involved in temporal processing.


INLL also has little spontaneous activity and broad tuning curves. The temporal responses are significantly different to cells of the VNLL.


Inputs and outputs to nuclei

The table below shows that each of the nuclei have a complicated arrangement of ipsilateral and contralateral afferent inputs and outputs.

Nucleus Input Output
  Contralateral Ipsilateral Contralateral Ipsilateral
VNLL Anterior and posterior ventral cochlear nuclei Medial nucleus of the trapezoid body   Inferior Colliculus

DNLL

INLL Anterior and posterior Ventral Cochlear Nucleus Medial nucleus of the trapezoid body   Medial Geniculate body

Inferior Colliculus

DNLL Anterior Ventral

Cochlear nucleus (and Bilateral)

Medial superior Olivary Nucleus

Lateral Superior Olivary Nucleus (and Bilateral)

DNLL

Inferior Colliculus

Mid brain reticular formation

Superior Olivary Complex

Inferior Colliculus

 Medial Geniculate Body

Mid brain reticular formation

Superior Olivary Complex

Additional images


  Results from FactBites:
 
IX. Neurology. 5h. The Acoustic Nerve. Gray, Henry. 1918. Anatomy of the Human Body. (540 words)
If the further connections of the cochlear nerve of one side, say the left, be considered, it is found that they lie lateral to the main sensory tract, the lemniscus, and are therefore termed the lateral lemniscus.
In the upper part of the lateral lemniscus there is a collection of nerve cells, the nucleus of the lateral lemniscus, around the cells of which some of the fibers arborize and from the cells of which axons originate to continue upward the tract of the lateral lemniscus.
The ultimate ending of the left lateral lemniscus is partly in the opposite medial geniculate body, and partly in the inferior colliculi.
ICP monitors (3416 words)
• Flocculus and choroid plexus of the fourth ventricle lie beside the lower border of the pons laterally, in the CP angle.
The lateral recesses extend around the inferior cerebellar peduncle around side of the medulla and open ventrally as the foraminae of Luschka (found at the CP angle at the junction of the medulla, cerebellum and pons.
Hypoglossal nucleus, nucleus solitarius, and nucleus of the spinal trigeminal tract from medial to lateral.
  More results at FactBites »

 
 

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