Medial longitudinal fasciculus

Brain: Medial longitudinal fasciculus
Gray711.png
Transverse section of mid-brain at level of inferior colliculi. (Medial longitudinal fasciculus labeled at center right.)
Gray710.png
Axial section through mid-brain.
1. Corpora quadrigemina.
2. Cerebral aqueduct.
3. Central gray stratum.
4. Interpeduncular space.
5. Sulcus lateralis.
6. Substantia nigra.
7. Red nucleus of tegmentum.
8. Oculomotor nerve, with 8’, its nucleus of origin. a. Lemniscus (in blue) with a’ the medial lemniscus and a" the lateral lemniscus. b. Medial longitudinal fasciculus. c. Raphé. d. Temporopontine fibers. e. Portion of medial lemniscus, which runs to the lentiform nucleus and insula. f. Cerebrospinal fibers. g. Frontopontine fibers.
Latin fasciculus longitudinalis medialis
Gray's subject #188 803
NeuroNames ancil-743

The medial longitudinal fasciculus (MLF) is a pair of crossed fiber tracts (group of axons), one on each side of the brainstem. These bundles of axons are situated near the midline of the brainstem and are composed of both ascending and descending fibers that arise from a number of sources and terminate in different areas.

Contents

Function

The MLF carries information about the direction that the eyes should move.

It yokes the cranial nerve nuclei III (Oculomotor nerve), IV (Trochlear nerve) and VI (Abducens nerve) together, and integrates movements directed by the gaze centers (frontal eye field) and information about head movement (from cranial nerve VIII, Vestibulocochlear nerve). It is an integral component of saccadic eye movements as well as vestibulo-ocular and optokinetic reflexes.

It also carries the descending tectospinal tract and medial vestibulospinal tracts into the cervical spinal cord, and innervates some muscles of the neck and upper limbs.

Inputs

The descending MLF mainly arises from the medial Vestibular nucleus (VN) and is thought to be involved in the maintenance of gaze. This is achieved by inputs to the VN from

  1. the Vestibulocochlear (8th cranial) nerve about head movements,
  2. gain adjustments from the flocculus of the cerebellum,
  3. head and neck propioceptors and foot and ankle muscle spindle, via the fastigial nucleus.

Descending fibers can also arise from the superior colliculus in the rostral midbrain for visual reflexes, the accessory occulomotor nuclei in the rostral midbrain for visual tracking, and the pontine reticular formation, which facilitates extensor muscle tone. Ascending tracts arise from the Vestibular nucleus (VN) and terminate in the III, IV and VI nuclei, which are important for visual tracking.

Pathology

Lesions of the MLF produce internuclear ophthalmoplegia and can be a presenting symptom of multiple sclerosis,[1] where it presents as nystagmus and occasionally diplopia.[2] These lesions cause damage to the ipsilateral (same side) eye, but nystagmus on the contralateral (opposite side) eye.

History

In 1846 neurologist Benedict Stilling first referred to what is now known as the MLF as the acusticus, followed by Theodor Meynert in 1872 calling it posterior. But in 1891, Heinrich Schutz chose the name dorsal to describe the longitudinal bundle, "for brevity's sake". This name stuck despite other authors attempting further renaming (Ramon y Cajal's periependymal in 1904, Theodor Ziehen's nubecula dorsalis in 1913). But finally, it was Wilhelm His, Sr. who changed the name to medial for the sake of the Basle nomenclature to end the confusion.

Additional images

References

  1. ^ Multiple Sclerosis Encyclopaedia
  2. ^ Internuclear Ophthalmoplegia

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • medial longitudinal fasciculus — n any of four longitudinal bundles of white matter of which there are two on each side that extend from the midbrain to the upper parts of the spinal cord where they are located close to the midline ventral to the gray commissure and that are… …   Medical dictionary

  • Rostral interstitial nucleus of medial longitudinal fasciculus — Infobox Brain Name = PAGENAME Latin = nucleus interstitialis GraySubject = GrayPage = Caption = Coronal section through mid brain. (Nucleus is not labeled, but MLF is b , in red.) Caption2 = IsPartOf = Components = Artery = Vein = BrainInfoType …   Wikipedia

  • longitudinal fasciculus medial — f. longitudinalis medialis …   Medical dictionary

  • longitudinal fasciculus of medulla oblongata medial — f. longitudinalis medialis medullae oblongatae …   Medical dictionary

  • Dorsal longitudinal fasciculus — Brain: Dorsal longitudinal fasciculus Latin fasciculus longitudinalis posterior; fasciculus longitudinalis dorsalis NeuroLex ID birnlex 986 The dorsal longitudinal fasciculus (DLF) (not to be confused with the medial longitudinal fasciculus, nor… …   Wikipedia

  • Superior longitudinal fasciculus — Infobox Brain Name = PAGENAME Latin = fasciculus longitudinalis superior cerebri GraySubject = 189 GrayPage = 844 Caption = Diagram showing principal systems of association fibers in the cerebrum. (Sup. longitudinal fasc. labeled at center top.)… …   Wikipedia

  • Fasciculus — can refer to: * nervous tissue ** Superior longitudinal fasciculus *** Arcuate fasciculus ** Dorsal longitudinal fasciculus ** Medial longitudinal fasciculus ** Flechsig s fasciculus * A structure in the wrist * Fasciculus Chemicus * Fasciculus… …   Wikipedia

  • Medial vestibular nucleus — Brain: Medial vestibular nucleus A cross section of the lower pons showing the medial vestibular nucleus (#3) labeled at the top left …   Wikipedia

  • fasciculus longitudinalis posterior — [TA] posterior longitudinal fasciculus: a lightly myelinated fiber bundle that runs in the periventricular gray substance throughout the extent of the mesencephalon, near the medial longitudinal fasciculus; called also SchÑŒtz bundle or tract, f …   Medical dictionary

  • fasciculus longitudinalis medialis — [TA] medial longitudinal fasciculus: a fiber tract extending between the mesencephalon and the upper part of the spinal cord; it lies close to the median plane, just ventral to the central gray matter, and interconnects the vestibular nuclei with …   Medical dictionary


Share the article and excerpts

Direct link
Do a right-click on the link above
and select “Copy Link”

We are using cookies for the best presentation of our site. Continuing to use this site, you agree with this.