Table of Contents
- 1 What is unique about the origin of the trochlear nerve?
- 2 Where is trochlear nerve originate from?
- 3 Why does trochlear nerve cross?
- 4 Where does the Trochlear nerve travel?
- 5 Why is trochlear nerve called pathetic nerve?
- 6 Where does the trochlear nerve Decussate?
- 7 Where does the trochlear nerve originate and end?
- 8 Which cranial nerves arise from the brain stem?
- 9 What are the lesions of trochlear nerve palsy?
What is unique about the origin of the trochlear nerve?
The trochlear nerve is unique among the cranial nerves in several respects: It is the smallest nerve in terms of the number of axons it contains. It has the greatest intracranial length. It is the only cranial nerve that exits from the dorsal (rear) aspect of the brainstem.
Where is trochlear nerve originate from?
The trochlear nerve pair originates from a pair of symmetrical trochlear nuclei within the medial midbrain at the level of the inferior colliculus. The left and right nerves then travel dorsally surrounded by the periaqueductal gray matter, decussating before their exit in the dorsal midbrain.
Why does trochlear nerve cross?
The trochlear nerve supplies one muscle: the superior oblique. The trochlear nucleus gives rise to nerves that cross (decussate) to the other side of the brainstem just prior to exiting the brainstem. Thus, each superior oblique muscle is supplied by nerve fibers from the trochlear nucleus of the opposite side.
Which cranial nerves do not originate in the brain stem?
The olfactory nerve is the shortest of the 12 cranial nerves and only one of two cranial nerves (the other being the optic nerve) that do not join with the brainstem. The specialized olfactory receptor neurons of the olfactory nerve are located in the olfactory mucosa of the upper parts of the nasal cavity.
Why is Trochlear nerve called pathetic nerve?
the fourth cranial, or trochlear, nerve, which supplies the superior oblique, or pathetic, muscle of the eye. …
Where does the Trochlear nerve travel?
midbrain
Trochlear Nucleus (Fourth Cranial Nerve) The trochlear nerve then travels around the midbrain in the ambient cistern. It passes between the superior cerebellar and posterior cerebral arteries and courses toward the lateral wall of the cavernous sinus and the superior orbital fissure to ultimately enter the orbit.
Why is trochlear nerve called pathetic nerve?
Where does the trochlear nerve Decussate?
The Trochlear Nerve (IV) It decussates at the anterior medullary velum in the roof of the aqueduct before exiting from dorsal midbrain below the inferior colliculus (Fig. 4.7). The nerve is the only motor cranial nerve that leaves from the dorsal side of the brainstem. Figure 4.7.
Is the Trochlear nerve sensory or motor?
The trochlear, abducens, accessory, and hypoglossal nerves are only motor nerves; the trigeminal nerve is both sensory and motor; the oculomotor nerve is both motor and parasympathetic; the facial glossopharyngeal, and vagus nerves have sensory, motor, and parasympathetic components (Standring, 2008).
Which cranial nerves originate in the brain stem?
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem), in contrast to spinal nerves (which emerge from segments of the spinal cord)….Gov’t Insurance.
| Forebrain | ||
|---|---|---|
| II. | Optic nerve | Mostly Afferent |
| Midbrain | ||
| III. | Oculomotor nerve | Mostly Efferent |
| IV. | Trochlear nerve | Mostly Efferent |
Where does the trochlear nerve originate and end?
It originates in the midbrain and extends laterally and anteriorly to the superior oblique muscle.[1] The trochlear nerve is the fourth cranial nerve (CN IV) and one of the ocular motor nerves that controls eye movement.
Which cranial nerves arise from the brain stem?
Cranial nerves III – XII arise from the brain stem (Figure 1). They can arise from a specific part of the brain stem (midbrain, pons or medulla), or from a junction between two parts: Midbrain – the trochlear nerve (IV) comes from the posterior side of the midbrain. It has the longest intracranial length of all the cranial nerves.
What are the lesions of trochlear nerve palsy?
Trochlear nerve palsy can occur in lesions involving the nucleus, central segment, cisternal segment, cavernous segment, and orbital segment. The nerve is most susceptible to pressure in the cisternal segment. The oculomotor, trochlear, and abducens nerves control actions of the intraocular (pupillary sphincter) and extraocular muscles.
Which nerve has the longest intracranial course?
The trochlear nerve, while the smallest of the cranial nerves, has the longest intracranial course as it is the only nerve to have a dorsal exit from the brainstem. It originates in the midbrain and extends laterally and anteriorly to the superior oblique muscle.[1]