The rostral interstitial nucleus of medial longitudinal fasciculus (riMLF) is a collection of neurons in the

medial longitudinal fasciculus The medial longitudinal fasciculus (MLF) is a prominent bundle of nerve fibres which pass within the ventral/anterior portion of periaqueductal gray of the mesencephalon (midbrain). It contains the interstitial nucleus of Cajal, responsible ...

in the

midbrain The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

. It is responsible for mediating vertical conjugate eye movements (vertical

gaze In critical theory, philosophy, sociology, and psychoanalysis, the gaze (French: ''le regard''), in the figurative sense, is an individual's (or a group's) awareness and perception of other individuals, other groups, or oneself. Since the 20th ...

) and vertical

saccade In vision science, a saccade ( ; ; ) is a quick, simultaneous movement of both Eye movement (sensory), eyes between two or more phases of focal points in the same direction. In contrast, in Smooth pursuit, smooth-pursuit movements, the eyes mov ...

s. It mostly projects efferents to the ipsilateral oculomotor and trochlear nuclei. To mediate downgaze, it projects efferents to the ipsilateral

oculomotor nucleus The fibers of the oculomotor nerve arise from a nucleus in the midbrain, which lies in the gray substance of the floor of the cerebral aqueduct and extends in front of the aqueduct for a short distance into the floor of the third ventricle. F ...

and

trochlear nucleus The trochlear nucleus () is the motor nucleus of the trochlear nerve ( cranial nerve IV). It is located in the medial midbrain. Structure The trochlear nucleus is located in the midbrain, at an intercollicular level between the superior collic ...

; mediate upgaze, it projects efferents to the contralateral aforementioned nuclei through the

posterior commissure The posterior commissure (also known as the epithalamic commissure) is a rounded band of white fibers crossing the middle line on the dorsal aspect of the rostral end of the cerebral aqueduct. It is important in the bilateral pupillary light re ...

. It is one of the accessory oculomotor nuclei.

Anatomy

Structure

The riMLF is a wing-shaped nucleus. The riMLF contains two populations of neurons: excitatory burst neurons mediating vertical gaze/saccades, as well as omnipause neurons which are functionally similar to those mediating horizontal gaze.

Relations

It is situated at the caudal extremity of the

mesencephalon The midbrain or mesencephalon is the uppermost portion of the brainstem connecting the diencephalon and cerebrum with the pons. It consists of the cerebral peduncles, tegmentum, and tectum. It is functionally associated with vision, hearing, mo ...

at its junction with the

telencephalon The cerebrum (: cerebra), telencephalon or endbrain is the largest part of the brain, containing the cerebral cortex (of the two cerebral hemispheres) as well as several subcortical structures, including the hippocampus, basal ganglia, and olf ...

, at the level of the

superior colliculus In neuroanatomy, the superior colliculus () is a structure lying on the tectum, roof of the mammalian midbrain. In non-mammalian vertebrates, the Homology (biology), homologous structure is known as the optic tectum or optic lobe. The adjective f ...

. It is situated dorsal to the rostral extremity of the

red nucleus The red nucleus or nucleus ruber is a structure in the rostral midbrain involved in motor coordination. The red nucleus is pale pink, which is believed to be due to the presence of iron in at least two different forms: hemoglobin and ferritin. ...

, and rostral to the

interstitial nucleus of Cajal The interstitial nucleus of Cajal is a collection of neurons in the mesencephalon (midbrain) which are involved in integrating eye position-velocity information in order to coordinate head-eye movements - especially those related to vertical and ...

Clinical significance

Lesions of the riMLF may impair vertical gaze completely, or predominately impair downgaze. Lesions of the posterior commissure meanwhile disrupt upgaze.

References

Brainstem nuclei {{Neuroanatomy-stub

Anatomy

Structure

Relations

Clinical significance

See also

References