which cranial nerve has the longest intracranial course

Which nerve has the second longest intracranial course?

Of all the cranial nerves, the abducens nerve has the second longest intracranial course. It is located in the pons at the floor of the fourth ventricle, at the same level as the facial colliculus.

Which cranial nerve has the longest area of supply?

Vagus (Xth) Cranial nerve has the longest and varied area of supply, right from oral cavity to heart, eye, posterior part of tongue, palate, larynx , muscles for respiration to GIT, all are supplied by Vagus or it's associates. The name Vagus is derived by the word Vagrant, Vague or Vagabond ( a person who moves around here and there).

What does the fourth cranial nerve innervate?

The fourth cranial nerve is a purely efferent or pure motor nerve and it innervates a single muscle, the superior oblique.

What does the cranial nerve six do?

Cranial nerve six (CN VI), also known as the abducens nerve, is one of the nerves responsible for the extraocular motor functions of the eye, along with the oculomotor nerve (CN III) and the trochlear nerve (CN IV). NCBI Skip to main content Skip to navigation Resources

Which cranial nerve has the longest intracranial course in contact with bone?

Description. The trochlear nerve is the fourth Cranial Nerve (CNIV) with the longest intracranial course, but also the thinnest. It has a general somatic efferent (somatic motor) nerve, which innervates a single muscle (superior oblique muscle) on the contralateral side of its origin.

Which cranial nerve has shortest intracranial course?

The trochlear nerveCN IV is a motor nerve only (a somatic efferent nerve), unlike most other CNs. 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.

Which of the following cranial nerves has the longest course in the body?

The longest cranial nerve is the vagus nerve. Your vagus nerve has both sensory and motor functions. It runs through many parts of your body, including your tongue, throat, heart and digestive system.

What is the shortest cranial nerve?

The trochlear nerveThe 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.

Which is the largest and the shortest cranial nerve?

Largest Cranial Nerve – Trigeminal nerve (5th Cranial nerve) Smallest cranial nerve – Trochlear Nerve (4th Cranial nerve)

What is the shortest nerve in the body?

The trochlear nerveDetailed Solution. Option 1 is correct: The trochlear nerve is the fourth cranial nerve (CN IV) and one of the ocular motor nerves that control eye movement. The trochlear nerve is the smallest nerve of the human body.

Which is the longest nerve?

Sciatic NerveSciatic Nerve and Sciatica. The sciatic nerve is the longest, largest nerve in your body. Your sciatic nerve roots start in your lower back and run down the back of each leg.

What is the second longest cranial nerve?

the abducens nerveOf all the cranial nerves, the abducens nerve has the second longest intracranial course. It is located in the pons at the floor of the fourth ventricle, at the same level as the facial colliculus. In fact, the axons of the facial nerve loop around the posterior aspect of the abducens nucleus.

Is the vagus nerve the longest nerve in the body?

The vagus nerve is the longest nerve of the autonomic nervous system and is one of the most important nerves in the body. The vagus nerve helps to regulate many critical aspects of human physiology, including the heart rate, blood pressure, sweating, digestion, and even speaking.

Which is the thickest cranial nerve?

Thickest Cranial Nerve---> Trigeminal.

Which is smallest and thinnest nerve?

Expert-verified answer The smallest cranial nerve is abducens nerve. The thinnest cranial nerve is trochlear nerve.

Which is the thinnest and the smallest cranial nerve?

Trigeminal is the smallest cranial nerve while Vagus is the longest cranial nerve.

Which nerve innervates the Recti medialis and lateralis of the eye?

The Abducens Nerve, the mode of innervation of the Recti medialis and lateralis of the eye, Rhomboid Fossa, Rectus Medialis. Contributed by Gray's Anatomy Plates

Which nerve is responsible for the extraocular motor function of the eye?

Cranial nerve six (CN VI), also known as the abducens nerve, is one of the nerves responsible for the extraocular motor functions of the eye, along with the oculomotor nerve (CN III) and the trochlear nerve (CN IV).

What nerve innervates the ipsilateral lateral rectus muscle?

The abducens nerve functions to innervate the ipsilateral lateral rectus muscle and partially innervate the contralateral medial rectus muscle (at the level of the nucleus - via the medial longitudinal fasciculus). Physiologic Variants. A few physiologic variants of abducens nerve anatomy have been documented.

What is the abducens nerve?

Unlike the oculomotor nerve and the trochlear nerve, the abducens nerve is a purely motor nerve, meaning the nerve has no sensory function. Its main function is to carry general somatic efferent nerve axons to innervate the lateral rectus muscle, which then abducts the eye on the ipsilateral side. It is also secondarily involved in innervation ...

What is the CN VI?

Last Update: November 19, 2020. Introduction. Cranial nerve six (CN VI), also known as the abducens nerve, is one of the nerves responsible for the extraocular motor functions of the eye, along with the oculomotor nerve (CN III) and the trochlear nerve (CN IV). Structure and Function. Unlike the oculomotor nerve and the trochlear nerve, ...

How many variants of the abducens nerve were found?

A few physiologic variants of abducens nerve anatomy have been documented.  In a study of 20 cadaveric heads (40 nerves), three variants were found. Variation I was found in 70% of cases, which was where the abducens nerve was found to be a single trunk. Twenty percent of cases had variation II, branching of the nerve exclusively within the cavernous sinus. Lastly, 10% of cases had variation III, duplication of the abducens nerve. [4]

How are the abducens nerves formed?

Embryology. The abducens nerve is formed embryologically from the derivatives of the somatic efferent column of the basal plates of embryonic pons. Nerves. The nerve can be divided into four distinct portions: the nucleus, the cisternal portion, the cavernous sinus portion, and the orbital portion.

Which nerve has the longest intracranial course?

P. S. The nerve with the longest intracranial course is the VIth nerve - Trochlear.

How many cranial nerves are there in the human body?

Cranial nerves, like the spinal nerves, supply the sensory and motor functions of the face, and autonomic functions f the body. There are 12 pairs of cranial nerves, only 10 pairs exit the brain stem. Cranial nerves I and II do not communicate with the CNS via the brain stem.

What nerve is responsible for headaches?

Vagus nerve, is a mixed nerve, having both sensory and motor functions. It also has ,sympathetic components which regulates tracheo-bronchial secretions and g.i.secretions. Vagus can be headache for an anaesthetist due to its effect on heart (inhibitory effect), secretions in respiratory and gastrointestinal tract etc, during surgery.

What nerve is X vagus?

X Vagus is also a mixed nerve, predominantly autonomic. It transmits visceral sensation from the respiratory, cardiovascular and GI organs down to the colon. Vagus innervates voluntary muscles of the larynx, pharynx

Which nerve runs from the medulla oblongata in the base of the brain to as far?

If you asked me which is the longest cranial nerve, I'd tell you in a wink, it's the Xth nerve - The mighty vagus, running from the medulla oblongata in the base of the brain to as far as our stomach.

Which nerve has the longest supply?

Vagus (Xth) Cranial nerve has the longest and varied area of supply, right from oral cavity to heart, eye, posterior part of tongue, palate, larynx , muscles for respiration to GIT, all are supplied by Vagus or it's associates.

Which olfactory nerve carries information from the nose directly to the brain?

I Olfactory nerve carries information from the nose directly to the brain. It does not project first to the brain stem or the thalamus as other cranial nerves do. The sensory neurons have their cell bodies in the sensory epithelium in the nose, their axons form the first cranial nerve or the olfactory nerve.

Which cranial 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 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 ...

Which cranial nerve is the only one to have a dorsal exit from the brainstem?

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. It originates in the midbrain and extends laterally and anteriorly to the superior oblique muscle.

Which cranial nerve has the longest intracranial course?

ANATOMY. The fourth cranial nerve (trochlear nerve) has the longest intracranial course; it is the only cranial nerve that has a dorsal exit from the brainstem ( figure 1 ). It begins in the midbrain at the level of the inferior colliculus as fascicles extending from the fourth nerve nuclei.

Where does the fourth nerve go?

The fourth nerve passes between the superior cerebellar artery and the posterior cerebral artery and runs in the subarachnoid space. It travels within the lateral wall of the cavernous sinus and enters the orbit via the superior orbital fissure to innervate the superior oblique muscle [ 1-10 ].

What nerve is prone to injury?

The long course of the fourth cranial nerve renders it particularly prone to injury from blunt head trauma or compression from changes in intracranial pressure, brain tumors, or swelling anywhere along its course.

Which nerve innervates the ipsilateral lateral rectus muscle?

The abducens nerve functions to innervate the ipsilateral lateral rectus muscle and partially innervate the contralateral medial rectus muscle (at the level of the nucleus - via the medial longitudinal fasciculus).

Which nerve is responsible for the extraocular motor function of the eye?

Cranial nerve six (CN VI), also known as the abducens nerve, is one of the nerves responsible for the extraocular motor functions of the eye, along with the oculomotor nerve (CN III) and the trochlear nerve (CN IV).

What nerves are affected by infarcts of the ventral pons?

Similarly, infarcts of the ventral pons can affect the fibers of the abducens nerve as it exits the pontomedullary junction near the corticospinal tract. This produces a contralateral hemiparesis (remember that the fibers of the corticospinal tract cross at the level of the medulla).

What causes the abducens nerve to be damaged?

Damage to the abducens nerve can be caused by anything that compresses or stretches the nerve, such as tumors, aneurysms, fractures, or increased intracranial pressure (ICP). Other general causes include damage to the blood supply of the nerve (strokes), demyelinating syndromes, or infectious processes such as meningitis, or various neuropathies.

What is unilateral abducens nerve palsy?

The incidence of unilateral abducens nerve palsy in head trauma ranges from 1% to 3%. Compromise of the abducens nerve results in the inability to abduct the ipsilateral eye and a partial decrease in the ability to adduct the contralateral eye. This manifests in the patient as diplopia or double vision due to the unopposed action of the medial rectus. This vision is worse at a distance, and the patient will have an esotropia on the primary gaze. Patients may also present with a head turn and/or strabismus to maintain binocularity and binocular fusion to minimize diplopia. Since some fibers cross as described above, the lack of a contralateral adduction defect makes it easy to differentiate a lesion in the abducens nucleus and before the medial longitudinal fasciculus from a lesion beyond the medial longitudinal fasciculus. On physical exam, the patient will not be able to abduct the affected eye past midline. They will also complain of worsening diplopia on attempted lateral gaze. [6] [7] [8]

What is the abducens nerve?

Unlike the oculomotor nerve and the trochlear nerve, the abducens nerve is a purely motor nerve, meaning the nerve has no sensory function. Its main function is to carry general somatic efferent nerve axons to innervate the lateral rectus muscle, which then abducts the eye on the ipsilateral side. It is also secondarily involved in innervation of the contralateral medial rectus muscle by way of the medial longitudinal fasciculus so that both eyes move laterally in a coordinated manner. [1] [2] [3]

How many variants of the abducens nerve were found?

A few physiologic variants of abducens nerve anatomy have been documented. In a study of 20 cadaveric heads (40 nerves), three variants were found. Variation I was found in 70% of cases, which was where the abducens nerve was found to be a single trunk. Twenty percent of cases had variation II, branching of the nerve exclusively within the cavernous sinus. Lastly, 10% of cases had variation III, duplication of the abducens nerve. [4]