The nucleus of the trochlear nerve () is located in the
midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', " ...
, at an intercollicular level between the
superior colliculus
In neuroanatomy, the superior colliculus () is a structure lying on the roof of the mammalian midbrain. In non-mammalian vertebrates, the homologous structure is known as the optic tectum, or optic lobe. The adjective form ''tectal'' is commonly ...
and
inferior colliculus
The inferior colliculus (IC) (Latin for ''lower hill'') is the principal midbrain nucleus of the auditory pathway and receives input from several peripheral brainstem nuclei in the auditory pathway, as well as inputs from the auditory cortex. The ...
.
It is a motor nucleus, and so is located near the midline, embedded within the
medial longitudinal fasciculus
The medial longitudinal fasciculus (MLF) is an area of crossed over tracts, on each side of the brainstem. These bundles of axons are situated near the midline of the brainstem. They are made up of both ascending and descending fibers that ari ...
(see diagram at right). The
oculomotor nerve
The oculomotor nerve, also known as the third cranial nerve, cranial nerve III, or simply CN III, is a cranial nerve that enters the orbit through the superior orbital fissure and innervates extraocular muscles that enable most movements of ...
and
trochlear nerve
The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pul ...
are the only two cranial nerves with nuclei in the
midbrain
The midbrain or mesencephalon is the forward-most portion of the brainstem and is associated with vision, hearing, motor control, sleep and wakefulness, arousal (alertness), and temperature regulation. The name comes from the Greek ''mesos'', " ...
, other than the trigeminal nerve, which has a midbrain nucleus called the
mesencephalic nucleus of trigeminal nerve, which functions in preserving dentition.
Oddly, fibers from the trochlear nucleus cross over in the trochlear decussation of the midbrain, located in the
superior medullary velum to exit dorsally, the only cranial nerve to do so. The
trochlear nerve
The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pul ...
then goes around the midbrain, and is visible coming out of the sides.
See also
*
Trochlear nerve
The trochlear nerve (), ( lit. ''pulley-like'' nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates just one muscle: the superior oblique muscle of the eye, which operates through the pul ...
Additional images
File:Gray697.png, Nuclei of origin of cranial motor nerves schematically represented; lateral view.
File:Gray774.png, Scheme showing central connections of the optic nerves and optic tracts.
File:Brain stem sagittal section.svg, Brain stem sagittal section
References
External links
* - "Brainstem, Cranial Nerve Nuclei, Sagittal Section, Medial View"
Midbrain
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