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The trochlear nerve (/ ˈ t r ɒ k l ɪər /), [1] (lit. pulley-like nerve) also known as the fourth cranial nerve, cranial nerve IV, or CN IV, is a cranial nerve that innervates a single muscle - the superior oblique muscle of the eye (which operates through the pulley-like trochlea).
This nerve is involved (together with nerve IX) in the pharyngeal reflex or gag reflex. XI Accessory. Sometimes: cranial accessory, spinal accessory. Mainly motor Cranial and Spinal Roots Located in the jugular foramen. Controls the sternocleidomastoid and trapezius muscles, and overlaps with functions of the vagus nerve (CN X). Symptoms of ...
Nerves may be compressed because of increased intracranial pressure, a mass effect of an intracerebral haemorrhage, or tumour that presses against the nerves and interferes with the transmission of impulses along the nerve. [22] Loss of function of a cranial nerve may sometimes be the first symptom of an intracranial or skull base cancer. [23]
Then, it courses posteriorly toward the nuclei of the oculomotor nerve (III), trochlear nerve (IV) and abducens nerve (VI), the three cranial nerves that mediate eye movements. [3] At the level of the caudal midbrain, corticomesencephalic fibers descend through the tegmentum in the medial lemniscus toward the oculomotor (III) and the trochlear ...
Cranial nerves: They are the nerve fibers that carry information into and out of the brain stem. [4] They include smell, eye muscles, mouth, taste, ear, neck, shoulders, and tongue. [6] Partially innervating the head and neck structures are the cranial nerves, which supply afferent and efferent functions.
Two of the cranial nerves show chiasmas: (1) the chiasma of the optic tract (i.e., cranial nerve II), which originates from the eyes and inserts on the optic tectum of the midbrain; and (2) the trochlear nerve (i.e., cranial nerve IV), which originates in the ventral midbrain and innervates one of the six muscles that rotate the eye (i.e., the ...
Winter brings less daylight and colder temperatures, which can disrupt sleep. Seasonal Affective Disorder (SAD) is more common in winter due to the lack of sunlight, causing sleep disturbances.
The oculomotor nerve originates from the third nerve nucleus at the level of the superior colliculus (in non-mammalian vertebrates this is the optic tectum) in the midbrain. The rostral part of the nerve crosses the midline to merge with the part of the contralateral nerve that does not cross. Since the midline crossing occurs inside the brain ...