What is innervated by the third cranial nerve?
What is innervated by the third cranial nerve?
The oculomotor nerve is the third cranial nerve (CN III). It enters the orbit through the superior orbital fissure and innervates extrinsic eye muscles that enable most movements of the eye and that raise the eyelid. The oculomotor nerve is derived from the basal plate of the embryonic midbrain.
Do cranial nerves innervate muscles?
Cranial nerves innervate the muscles of the jaw, face, pharynx, larynx, tongue, and neck. Unlike the spinal nerves, which attach to the cord at regular intervals, the cranial nerves are attached to the brain at irregular intervals. They do not all have dorsal (sensory) and ventral (motor) roots.
What is the function of cranial nerve 3?
The oculomotor nerve is the third cranial nerve (CN III). It allows movement of the eye muscles, constriction of the pupil, focusing the eyes and the position of the upper eyelid. Cranial nerve III works with other cranial nerves to control eye movements and support sensory functioning.
What muscles does oculomotor innervate?
The oculomotor nerve innervates all the extraocular muscles except the superior oblique (trochlear nerve) and lateral rectus (abducens nerve). The extraocular muscles are the inferior oblique and the superior, medial, and inferior rectus muscles.
Is the levator Palpebrae Superioris in extraocular muscle?
Six of the extraocular muscles control movement of the eye and the other muscle the levator palpebrae controls eyelid elevation….Movements.
| Muscle | Levator palpebrae superioris |
|---|---|
| Innervation | Oculomotor nerve |
| Origin | Sphenoid bone |
| Insertion | Tarsal plate of upper eyelid |
| Primary action | Elevation/retraction of the upper eyelid |
What does the Abducens nerve innervate?
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).
Are cranial nerves myelinated?
All the cranial nerves, except the optic and olfactory nerves, which are considered to be more a direct expansion of the central nervous system, have a transitional zone between central myelin (coming from oligodendrocytes) and peripheral myelin (produced by Schwann cells).
Which muscles is innervated by CN VII?
The principal muscles are the frontalis, orbicularis oculi, buccinator, orbicularis oris, platysma, the posterior belly of the digastric, and the stapedius muscle.
What 3 cranial nerves directly control the eye muscles?
The extraocular muscles are innervated by lower motor neurons that form three cranial nerves: the abducens, the trochlear, and the oculomotor (Figure 20.3).
What muscles does the Abducens nerve innervate?
Which cranial nerves innervate extraocular muscles?
Which extraocular eye muscles are innervated by which cranial nerve?
The muscles of the eye are innervated by three cranial nerves. Most of the muscles of the eye are innervated by the oculomotor nerve (cranial nerve III). The lateral rectus is innervated by the abducens nerve, CN IV, which causes abduction of the eye. The trochlear nerve, CN VI, innervates the superior oblique.
