What is the route of cranial nerve IV?
The trochlear nerve emerges from the back (dorsal) brainstem, just below the inferior colliculus. It circles from behind around the brainstem and runs forward toward the eye in the subarachnoid space.
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.
What does cranial nerve 4 control?
The fourth cranial nerve controls the actions of one of the external eye muscles, the superior oblique muscle. This muscle runs from the back of the eye socket to the top of the eye. It passes through a loop of tissue near the nose known as the trochlea. It turns the eye inward and downward.
What cranial nerve sends odor messages to the brain?
Also known as CN1, the olfactory nerve is the first of 12 cranial nerves located within the head. It relays sensory data to the brain, and it is responsible for the sense of smell.
Which is the most slender nerve?
Trochlear Nerve
Trochlear Nerve Pathway Of the cranial nerves, the trochlear nerve is the only one that leaves the dorsal aspect of the CNS. It is the most slender of the cranial nerves, and its attachment is very delicate.
Is Trochlear 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).
Does 4th nerve palsy go away?
Treatment of fourth nerve palsy depends on its cause. Idiopathic fourth nerve palsies tend to go away on their own. Palsies caused by injury can also get better with time. If something is pressing on the fourth cranial nerve, you may need surgery to ease the pressure.
What does it mean when the cranial nerve does not decussate?
Cranial Nerve Decussation. The cranial nerves do not decussate generally with exceptions being CN2, CN4, CN7 and CN12. That means if a lesion affects Cranial Nerve 1, 5, 8, 9 and 11 or the respective nucleus there is either sensation loss or atrophy of the muscle (dependent on what the nerve does) of the ipsilateral side.
Is the trochlear nerve the smallest of the cranial nerves?
The trochlear nerve is the fourth cranial nerve (CN IV) and one of the ocular motor nerves that controls eye movement. 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.
Which is affected by nerve decussation in CN7?
Cranial Nerve Decussation. If the nerve is affected, it is typically the ipsilateral side. The same I imagine is true for CN12. In CN7, the forehead is bilaterally innervated so if the upper motor neurone is affected eyebrows can be raised but the lower side of the face is affected ipsilaterally.
What kind of damage does cranial nerve XII cause?
Considering cranial nerve XII we should speak about nuclear-infranuclear and supranuclear damage and with this notion supranuclear damage will cause contralateral transient tongue paresis. Nuclear-infranuclear damage will cause more permanent palsy, which is mostly bilateral because the nuclei are close to each other.