III,IV & VI Cranial Nerves By. Dr Rakesh Kumar Verma Assistant Professor Anatomy KGMU,UP, Lucknow

Oculomotor (III) cranial nerve (nervus oculomotorius)

Functional Component General Somatic Efferent (GSE) General Visceral Efferent (GVE) General Somatic Afferent (GSE)

Oculomotor nerve (nervus oculomotorius) contains motor and vegetative (parasympathetic) fibers Type of fibers Beginning End 1. Motor fibers Neurons contained in the oculomotor nerve nucleus (situated in the midbrain) Innervated extraocular muscles Neurons contained in the central nucleus of Perlia (situated in the midbrain) 2. Parasympathetic nucleus Neurons contained in the accessory oculomotor nerve nucleus (of Edinger-Westphal) (situated in the midbrain) Innervated intraocular muscles

Topography of the oculomotor nerve nuclei and root

Location of oculomotor nerve nuclei Oculomotor nerve nucleus (nucleus nervi oculomotorii) Accessory oculomotor nerve nucleus (nucleus acceccorius nervi oculomotorii) (nucleus of Edinger-Westphal)

Location of oculomotor nerve nuclei in midbrain cross-section Central nucleus of Perlia (nucleus centralis impar) Oculomotor nerve nucleus (nucleus nervi oculomotorii) Accessory nucleus (nucleus acceccorius nervi oculomotorii) (of Edinger-Westphal)

Oculomotor nerve emerges in the oculomotor sulcus at the region of the interpeduncular fossa

Course of oculomotor nerve

The course of the oculomotor nerve before the entrance the orbit Superior orbital fissure (fissura orbitalis superior) Central nucleus of Perlia (nucleus centralis impar) Superior branch (motor) (ramus superior) Parasympathetic fibers of oculomotor nerve Motor fibers to the medial rectus Accessory nucleus (nucleus accessorius nervi oculomotori) (of Edinger-Westphal) Motor fibers to other extraocular muscles Oculomotor nerve nucleus (nucleus nervi oculomotori) Inferior branch (mixed) (ramus inferior) Cavernous sinus (sinus cavernosus)

The course of the motor fibres of the oculomotor nerve in the orbit Levator palpebrae superioris Superior branch of oculomotor nerve (ramus superior) Superior rectus Medial rectus Inferior branch of oculomotor nerve (ramus inferior) Inferior rectus Inferior obliquus

Location of oculomotor nerve in the orbit Superior orbital fissure (fissura orbitalis superior) Superior branch of oculomotor nerve (ramus superior) Levator palpebrae superioris Superior rectus Medial rectus Inferior rectus Inferior obliquus Inferior branch of oculomotor nerve (ramus inferior)

The course of the parasympathetic fibres in the orbit Ciliary muscle (musculus ciliaris) Preganglionic fibers Musculus sphincter pupillae Ciliary ganglion (ganglion ciliare) Postganglionic fibers (short ciliary nerves) (nervi ciliares breves)

The ocular muscles innervated by the oculomotor nerve I. Motor fibers innervate: 1. Levator palpebrae superioris 2. Superior rectus 3. Medial rectus 4. Inferior rectus 5. Inferior obliquus II. Parasympathetic fibers innervate: 1. Ciliary muscle 2. Sphincter of pupil

Symptoms of oculomotor nerve injury

The damage to the nucleus, root or trunk of the oculomotor nerve leads to the following symptoms : Ptosis (falling) of the upper eyelid because of paralysis or paresis of the levator palpebrae superioris

2. Divergent strobismus – the eyeball is inclined outwards and slightly downwards due to predominance of the functioning of the superior oblique and lateral rectus muscle 3. Mydriasis (dilation of pupil) on the injured side due to predominance of the pupillary sphincter functioning; the pupillary light reflex is absent on the injured side

4. Horizontal diplopia – appearance of two images in the horizontal plane; it increases if to look to the side of the injured medial rectus and disappears if look only with one eye. 5. The movements of the eye upwards and inwards are limited; the eyeball can not converge 7. Paralysis of accomodation due to the damage to the ciliary muscle 8. Small exophthalmos due to the decrease of the muscle tone

Trochlear (IV) cranial nerve (nervus trochlearis)

Functional Component General Somatic Efferent (GSE) General Somatic Afferent (GSE)

Trochlear nerve (nervus trochlearis) is fully motor Type of fibers Beginning End Motor fibers Neurons contained in the trochlear nerve nucleus (situated in the midbrain) Superior oblique muscle of eyeball

Topography of the trochlear nerve nucleus and root

Location of the trochlear nerve nucleus (nucleus nervi trochlearis)

Location of the trochlear nerve nucleus in the cross-section of the midbrain Trochlear nerve nucleus (nucleus nervi trochlearis)

Trochlear nerve (nervus trochlearis) emerges on the dorsal surface of the midbrain, lateral to the frenulum of the superior medullary velum; then the nerve skirts the cerebral peduncle from the lateral side and appears on the cerebral base (the trochlear nerve is a single cranial nerve which emerges on the dorsal surface of the brain steam)

The course of the trochlear nerve

The course of the trochlear nerve before entering the orbit Superior orbital fissure (fissura orbitalis superior) Trochlear nerve Trochlear nerve nucleus (nucleus nervi trochlearis) Cavernous sinus (sinus cavernosus)

The course of the trochlear nerve in the orbit Superior oblique muslce (nervus trochlearis)

Location of the trochlear nerve in the orbit Superior orbital fissure (fissura orbitalis superior) Trochlear nerve (nervus trochlearis) Levator palpebrae superioris Supeior rectus muscle Superior oblique muscle Medial rectus muscle Inferior rectus muscle Inferior oblique muscle

The trochlear nerve innervates Superior oblique muscle of eye

Symptoms of the trochlear nerve injury

The damage to the nucleus, root or trunk of the trochlear nerve leads to the following symptoms : 1. Convergent strabismus - the eyeball is turned inwards and slightly upwards due to the disorder of the superior oblique muscle innervation; it increases if to look down. 2. Vertical diplopia – appearance of two images in the vertical plane, especially if to look down. During bending of the head to the side of the injured muscle, diplopia increases; to the opposite side – decreases.

Abducent (VI) cranial nerve (nervus abducens)

Functional Component General Somatic Efferent (GSE) General Somatic Afferent (GSE)

Abducent nerve (nervus abducens) is fully motor Type of fibers Beginning End Motor fibers Neurons contained in the abducent nerve nucleus (situated in the pons) Lateral rectus muscle of eye

Topography of the abducent nerve nucleus and root

Location of the abducent nerve nucleus (nucleus nervi abducentis) is arched by the curve of the facial nerve fibers (genu nervi facialis) in the facial colliculus of the rhomboid fossa

Location of the abducent nerve nucleus in the cross-section of the pons Abducent nerve nucleus (nucleus nervi abducentis)

Abducent nerve (nervus abducens) Emerges in a transverse pontomedullary groove between the pons and pyramids of the medulla oblongata

The course of the abducent nerve

The course of the abducent nerve before the entering the orbit Superior orbital fissure (fissura orbitalis superior) Abducent nerve Abducent nerve nucleus (nucleus nervi abducentis) Cavernous sinus (sinus cavernosus)

The course of the abducent nerve in the orbit (nervus abducens) Lateral rectus muscle (has been cut)

Location of the abducent nerve in the orbit Superior orbital fissure (fissura orbitalis superior) Levator palpebrae superioris Superior rectus muscle Superior oblique muscle Abducent nerve (nervus abducens) Lateral rectus muscle Medial rectus muscle Inferior rectus muscle Inferior oblique muscle

The abducent nerve innervates Lateral rectus muscle of the eye

Symptoms of the abducent nerve injury

The damage to the nucleus, root or trunk of the abducent nerve leads to the following symptoms : 1. Convergent strabismus - the eyeball is turned inwards due to disorder of the lateral rectus muscle innervation. 2. Horizontal diplopia – appearance of two images in the horizontal plane if to look to the injured side.

the III, IV, VI cranial nerves Topography of the III, IV, VI cranial nerves

Location of the nuclei of the III, IV and VI cranial nerves Trochlear nerve nucleus (nucleus nervi trochlearis) Accessory nucleus of oculomotor nerve (nucleus accessorius nervi oculomotorii) (of Edinger-Westphal) Abducent nerve nucleus (nucleus nervi abducentis) Oculomotor nerve nucleus (nucleus nervi oculomotorii)

Location of the branches of the III, IV and VI cranial nerves in the orbit Trochlear nerve (nervus trochlearis) Superior branch of oculomotor nerve (ramus superior) Short ciliary nerves (nervi ciliares breves) Abducent nerve (nervus abducens) Inferior branch of oculomotor nerve (ramus inferior) Ciliary ganglion (ganglion ciliare)

Location of the branches of the III, IV and VI cranial nerves in the orbit Superior branch of oculomotor nerve (ramus superior) Trochlear nerve (nervus trochlearis) Inferior branch of oculomotor nerve (ramus inferior) Abducent nerve (nervus abducens)