What is the trochlear?

The trochlear nerve is one of 12 sets of cranial nerves. It enables movement in the eye’s superior oblique muscle. This makes it possible to look down. The nerve also enables you to move your eyes toward your nose or away from it.

What does the trochlear control?

The primary function of the trochlear nerves (IV) is also motor, controlling eye movements. These nerves originate in the midbrain, passing through the superior orbital fissures of the sphenoid bone, to reach the superior oblique muscles. The trochlear nerves are the smallest of the cranial nerves.

What is trochlear nucleus?

The trochlear nucleus is a small, ovoid group of neurons nestled in the medial longitudinal fasciculus of the caudal midbrain (Fig. 28.8; see p. 420). These motor neurons supply the contralateral superior oblique muscle.

Is trochlear nerve in midbrain?

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.

How common is Trochlear nerve palsy?

Trochlear nerve palsy was less common than abducens or oculomotor palsies. Of 4,373 acquired cases of extraocular muscle palsy in adults, there were only 657 cases of isolated fourth nerve disease. Fourth nerve palsy was also the least frequent in pediatric population.

What happens if the trochlear nerve is damaged?

Injury to the trochlear nerve can cause weakness in the ability to move the eyeball downward. This effects the vertical alignment of images resulting in double vision known formally as diplopia. To fix this, patients learn to lower their head (tuck in their chin) to bring the two eyes back to a single visual field.

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).

Is Trochlear sensory or motor?

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.

What would happens if the trochlear nerve is damaged?

Patients with trochlear nerve palsy complain of double vision vertically (vertical diplopia) or the images being tilted or rotated (torsional diplopia). The diplopia is binocular and may worsen or improve in different gazes.

How is trochlear nerve palsy diagnosed?

The diagnosis of unilateral trochlear nerve palsy is based on acute onset vertical deviation which increases in contralateral side gaze, down gaze and ipsilateral head-tilt together with excyclodeviation which also increases in both down gaze and ipsilateral head-tilt.

Where does the trochlear nerve come from?

The rest of the nerves in your body emerge from the spinal cord but all the cranial nerves, including the trochlear nerve, come from your brain. Ten of the cranial nerves emerge from the brainstem, which sits at the back of the skull and attaches the brain to the spinal cord.

Where is the trochlea tendon located?

The tendon extends between the orbital roof and passes through a fibrous loop (known as the trochlea) located on the frontal bone. The tendon then reaches laterally and posteriorly prior to its insertion point on the posterior half of the eye.

What is the trochlear angle in radiography?

The trochlear angle refers to the opening angle of the trochlea as visualized on a 30° flexion axial radiograph. In the study of Henri Dejour et al., a threshold of 145° successfully excluded all normal patients.

What is the importance of the proximal trochlea?

Importance of the Proximal Trochlea. When the human knee is fully extended, especially if the quadriceps muscle is contracted, the patella does not articulate with the femoral trochlea; instead, it lies just superolateral to the most superior portion of the trochlea.