Cranial Nerves PDF

1. Motor: ❑ Hypoglossal nucleus. ❑ Nucleus ambiguous. 2. Sensory: ❑ Spinal trigeminal nucleus. ❑ Solitary nucleus. 3. Parasympathetic: ❑ Dorsal vagal nucleus. ❑ Inferior salivatory nucleus. 4. Vestibular nuclei: ❑ Medial and inferior nuclei 1. Hypoglossal nerve. 2. Accessory nerve. 3. Vagus ne...

1. Motor: ❑ Hypoglossal nucleus. ❑ Nucleus ambiguous. 2. Sensory: ❑ Spinal trigeminal nucleus. ❑ Solitary nucleus. 3. Parasympathetic: ❑ Dorsal vagal nucleus. ❑ Inferior salivatory nucleus. 4. Vestibular nuclei: ❑ Medial and inferior nuclei 1. Hypoglossal nerve. 2. Accessory nerve. 3. Vagus nerve 4. Glossopharyngeal nerve. ❑ Pure motor nerve. ❑ Arises from the hypoglossal nucleus in the open medulla. ❑ Leaves the medulla from the antero-lateral sulcus. ❑ Leaves the cranial cavity through the hypoglossal foramen. ❑ Supply all extrinsic and intrinsic muscles of the tongue except palatoglossus. LMNL: Damage to hypoglossal nucleus. The tongue, when protruded, deviates towards the damaged nerve because of the overaction of the strong genioglossus muscles. Atrophy Fasciculations. UMNL: Supranuclear lesions cause the tongue to protrude away from the nerve because of predominant neural crossing for upper motor neurons. Mild weakness.  Purely motor. Has a double origin: 1- Cranial division: ❑ Arises from nucleus ambiguus (SVE). ❑ Leaves the medulla from the postero- lateral sulcus and joins the vagus. ❑ Innervates the intrinsic muscles of the larynx (via the recurrent laryngeal nerve) with the exception of the cricothyroid muscle. 2- Spinal division: (GSE) ❑ Arises from the ventral horns of cervical segments C1 - C6. ❑ Supplies: Sternomastoid muscle and Trapezius muscle. ❑ Mixed nerve. ❑ Arises from : 1. Nucleus ambiguous (SVE) 2. Dorsal nucleus of vagus (GVE) 3. Solitary tract and nucleus (GVA & SVA) 4. Spinal tract and nucleus of trigeminal nerve (GSA) ❑ Leaves the medulla from the postero-lateral sulcus. Vagus nerve functional components ❑ Motor: From nucleus ambiguus, supply muscles of the larynx and pharynx. ❑ Parasympathetic : o From the dorsal nucleus of vagus. o Carry parasympathetic innervation to neck, thorax and abdominal viscera. ❑ Visceral sensation: ❑ Ends in the medial part of the solitary tract and nucleus. ❑ Carry general sensation from the pharynx, larynx, esophagus, thoracic and abdominal viscera. ❑ Taste sensation: - Ends in the lateral part of the solitary nucleus. - Carry taste sensation from the epiglottis. ❑ General somatic sensation: - Ends in the spinal tract and nucleus of the trigeminal nerve. - Carry general sensation from the external ear. Vasovagal syncope The medical term for passing out is syncope. When the vagus nerve that connects the brain and heart overreacts in response to environmental cues such severe heat, anxiety, hunger, pain, or stress, the result is vasovagal syncope. An abrupt drop in blood pressure, often known as orthostatic hypotension, can lead to symptoms such as dizziness and fainting. 1. Nucleus ambiguous (SVE) 2. Inferior salivatory nucleus (GVE) 3. Solitary tract and nucleus (GVA & SVA) 4. Spinal tract and nucleus of trigeminal nerve (GSA) - Leaves the medulla from the postero-lateral sulcus. - Mediates: Taste, salivation & swallowing. Its functional components: ❑ Motor : Arises from nucleus ambiguous. - Supplies the stylopharyngeus muscle. ❑ Parasympathetic: Arises from the inferior salivatory nucleus. - supply the parotid gland. ❑ Visceral sensation: Ends in the soliatary tract and nucleus. - Carries general sensation from the posterior third of the tongue and auditory tube. Its functional components: ❑ Taste sensation: - Ends in the lateral part of the solitary tract and nucleus. - Carry taste sensation from the posterior 1/3 of the tongue. ❑ General somatic sensation: - Ends in the spinal tract and nucleus of the trigeminal nerve. - Carries general sensation from the external auditory meatus. 1. Motor: ❑ Abducent nucleus. ❑ Motor nucleus of trigeminal N. ❑ Facial motor nucleus. 2. Sensory: ❑ Spinal trigeminal nucleus ❑ Solitary nucleus ❑ Main sensory N. of trigeminal N. ❑ Mesencephalic N. ❑ Cochlear N. 3. Parasympathetic: ❑ Superior salivatory N. 4. Vestibular nuclei: ❑ Superior and lateral nuclei 1. Vestibulocochlear nerve. 2. Facial nerve. 3. Abducent nerve. 4. Trigeminal nerve. ❑ It consists of two components: 1- Cochlear nerve: :from ventral and dorsal cochlear nuclei. 2- Vestibular nerve: :from 4 vestibular nuclei. ❑ Both nerves leave the brain stem at the lower border of pons, together with the facial nerve at the cerebello-pontine angle lateral to the olive. ❑ Both nerves, together with the facial nerve, enter the internal auditory meatus.  Abducent nerve (CN, VI): ❑pure GSE nerve, arises from abducent nucleus ❑Leaves the brain stem at the inferior border of pons. ❑Enters the superior orbital fissure to reach the orbit to supply the lateral rectus muscle. Sixth nerve palsy is a condition where damage to a specific nerve disrupts eye movement and alignment. It’s usually unilateral and affects one eye only A malignant tumour is damaging the patient's glossopharyngeal nerve. They will experience: a) loss of taste over the anterior two-thirds of the tongue. b) loss of somaesthetic sensation over the anterior two thirds of the tongue. c) loss of taste and somaesthetic sensation over the posterior third of the tongue. d) paralysis of the muscles of the tongue. A patient is stabbed in the neck. You suspect damage to the accessory nerve in the posterior triangle. You would test nerve function by asking the patient to a) extend their neck against resistance. b) extend their neck without impairment. c) lift their shoulders against resistance. d) lift their shoulders without impairment.