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.
What is the smallest 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.
Which is the longest cranial nerve?
The vagus nerve (cranial nerve [CN] X) is the longest cranial nerve in the body, containing both motor and sensory functions in both the afferent and efferent regards.
What does the 4th cranial nerve 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.
Which is the thickest cranial nerve?
The largest cranial nerve is trigeminal nerve. The smallest cranial nerve is abducens nerve. The thinnest cranial nerve is trochlear nerve.
What’s the biggest nerve in your body?
The sciatic nerve is the largest nerve in the human body.
Which side of the neck is the vagus nerve on?
On the right side, it arises from the trunk of the vagus as it lies beside the trachea. On the left side, it originates from the recurrent laryngeal nerve only.
What is the difference between cranial nerves and spinal nerves?
Cranial nerves are the nerves that emerge directly from the brain (including the brainstem). In contrast, spinal nerves emerge from segments of the spinal cord. Cranial nerves relay information between the brain and parts of the body, primarily to and from regions of the head and neck.
What cranial nerve goes to the heart?
The vagus nerve, historically cited as the pneumogastric nerve, is the tenth cranial nerve or CN X, and interfaces with the parasympathetic control of the heart, lungs, and digestive tract. The vagus nerves are normally referred to in the singular.
How do you test cranial nerve 4?
Trochlear nerve (CN IV)
Cranial nerve IV acts as a pulley to move the eyes down—toward the tip of the nose. To assess the trochlear nerve, instruct the patient to follow your finger while you move it down toward his nose.
What is the fourth cranial nerve called?
The trochlear nerve is the fourth paired cranial nerve. It is the smallest cranial nerve (by number of axons), yet has the longest intracranial course. It has a purely somatic motor function.
How do you test for 4th nerve palsy?
Features suggestive of a bilateral fourth nerve palsy include:
- Alternating hypertropia on horizontal gaze or tilt.
- Positive Bielschowsky head tilt test to either shoulder.
- Large degree of excyclotorsion (> 10 degrees)
- Absent or small hypertropia in primary gaze.
- Underaction of both superior obliques on duction testing.
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What is the fattest cranial nerve?
The trigeminal nerve is the largest cranial nerve and is the great sensory nerve of the head and face, and the motor nerve of the muscles of mastication.
Which cranial nerve has longest Intradural course?
CN III, IV & VI: Oculomotor, Trochlear & Abducent Nerves
It is also the only cranial nerve to emerge from the dorsal side of the brainstem and, consequently, has the longest intradural (intracranial) course of any cranial nerve.
Which cranial nerve has highest number of branches?
Vagus nerve has the highest number of branches.