Cranial Nerves Flashcards
(42 cards)
Name all the Cranial Nerves.
- CN I - Olfactory
- CN II - Optic
- CN III - Oculomotor
- CN IV - Trochlear
- CN V - Trigenminal (Opthalmic, Maxillary, Mandibular)
- CN VI - Abducens
- CN VII - Facial
- CN VIII - Vestibulocochlear
- CN IV - Glossopharyngeal
- CN X - Vagus
- CN XI - Accessory
- CN XII - Hypoglossal
Name Cranial Nerve I and describe its innervation. How does it exit the cranium?
Olfactory
- Special Sensory - Olfaction (smell)
- through Cribiform Plate of Ethmoid Bone
Name Cranial Nerve I and describe its innervation. How does it exit the cranium?
Olfactory
- Special Sensory - Olfaction (smell)
- through Cribiform Plate of Ethmoid Bone
What may be the complications of fractured Cribiform Plate of the Ethmoid Bone?
- Ansomnia
- Rhinorrhea
Name Cranial Nerve II and describe its innervation. How does it exit the cranium?
Optic
- Special sensory - Vision
- through Optic Canal
How may increased cranial pressure lead to blindness?
- Optic nerve is a brain tract e.g. wrapped around with meninges
- Raised ICP -> Swollen Optic Nerve
Name Cranial Nerve III and describe its innervation. How does it exit the cranium?
Oculomotor
- Somatic Motor - Extraocular muscles (except Superior Oblique & Lateral Rectus) & Levator Palpebrae Superioris
- PNS Motor - Constrictor Pupillae
- through Superior Oribital Fissure
How may a Cranial Nerve III palsy represent?
- Out and down eyeball
- Complete Ptosis
- Dilated Pupil
Name Cranial Nerve IV and describe its innervation. How does it exit the cranium?
Trochlear
- Somatic Motor - Superior Oblique
- through Superior Orbital Fissure
How do you test a Cranial Nerve IV palsy represent?
- Extorted eyeball
- Patient unable to look medially when looked down e.g. unable to read book
Name Cranial Nerve V and describe its innervation. How does it exit the cranium?
Trigeminal
- Opthalmic Br. leaves via Superior Orbital Fissure
- Opthalmic Br. - general sensory - Upper Conjunctive & Cornea & Scalp & forehead & anteriosuperior nose & Frontal + Ethmoid sinuses
- Maxillary Br. leaves via Foramen Rotundum
- Maxillary Br. - general sensory - Maxillary sinuses & Posteroinferior nose & Palate & Upper teeth & upper lip
- Mandibular Br. leaves via Forman Ovale
- Mandibular Br. - general sensory - Auricles & External Acoustic Canal & External Eardrum membrane & skin of Temples & Cheeks & Lower Teeth & Anterior 2/3 tongue
- Mandibular Br. - somatic motor - muscles of Mastication
A patient comes to you with rashes on his Upper forehead and complains about severe pain in of his eyes. What may be the diagnosis?
Varicella Zoster infection of Opthalmic Nerve (CN Vi)
What is the Corneal reflex?
irritation of cornea -> Opthalmic (CN Vi) efferent -> brain -> Facial (CN VII) afferent -> Orbicularis Oculi -> blinking
How do you test the Mandibular Nerve?
Palpate Temporalis and Masseter when patient clenches the teeth
Name Cranial Nerve VI and describe its innervation. How does it exit the cranium?
Abducens
- Somatic Motor - Lateral Rectus
- through Superior Orbital Fissure
How may an infection of Oculomotor Nerve spread to other nerves? Which nerves may be affected?
- CN IV - Trochlear
- CN Vi - Opthalmic
- CN Vii - Maxillary
- CN VI - Abducens
- all these nerves are surrounded by Cavernous Sinus
What is the Corneal reflex?
irritation of cornea -> Opthalmic (CN Vi) Afferent -> brain -> Facial (CN VII) Efferent -> Orbicularis Oculi -> blinking
Name Cranial Nerve VII and describe its innervation.
Facial Neve
- General sensory - via CN Viii, Auricle & External Acoustic Meatus
- Special sensory - Taste of anterior 2/3 of tongue
- Somatic motor - muscles of Facial Expression
- PNS - Greater Petrosal Br. - Mucous glands of oral cavity, nose, pharynx & Lacrimal glands
- PNS - Chorda Tympani Br. - Submandibular & Sublingual salivary glands
Name Cranial Nerve VIII and describe its innervation. How does it exit the cranium?
Vestibulocochlear
- Vestibular Br. - special sensory - Balance
- Cochlear Br. - special sensory - Hearing
- through Internal Acoustic Canal
Describe the course of Cranial Nerve VII.
Arise from brain with 3 nuclei:
- Facial Nucleus - motor
- Nucleus Salitarius PNS
3 roots travel within Temporal Bone first via Internal Acoustic Canal
- close to the inner ear
- also the Trochlear Nerve
Enter Facial Canal then:
- motor & sensory roots fuse to form Facial Nerve Proper
- Facial Nerve Proper & PNS fibres form the Geniculate Ganglion
They branch to give rise:
- Greater Petrosal Nerve -> PNS fibres to mucous glands
- Nerve to Stapedius
- Chorda Tympani PNS to Submandibular & Sublingual glands
Rest of fibres as Cranial Nerve exits cranium via Stylomastoid Foramen then
- 3 motor branches run posterior to the ear and neck
- main motor trunk travels through Parotid gland without innervating it, splits into 5 motor fibres to muscles of Facial expression
Compare and contrast Lower Motor Neurone Facial Nerve Palsy and Bell’s Palsy.
- Loss facial expression - Occipitofrontalis spared (caused by BILATERAL UPPER motor neurone Facial N palsy)
- Complete Ptosis
- Loss of lacrimation & secremotor function in oral and nasal mucosa
- Changes in taste & hearing
- Facial Nerve Palsy: often permanent & known causes
- Bell’s Palsy: will recover & idiopathic causes
Name Cranial Nerve IX and describe its innervation. How does it exit the cranium?
Glossopharyngeal
- General sensory - Pharynx & Middle Ear & internal surface of Tympanic Membrane & posterior 1/3 Tongue
- Special sensory - Taste of posterior 1/3 tongue
- Visceral sensory - Carotid Body & Sinus
- Somatic motor - Stylopharyngeus
- PNS - Parotid Gland
- through Jugular Foramen
Name Cranial Nerve X and describe its innervation. How does it exit the cranium?
Vagus
- General sensory - External Acoustic Canal & external surface of Tympanic Membrane
- Motor - muscles of Pharynx, Larynx & Palate
- PNS - smooth muscles & glands of Thorax (including bronchi) & Abdomen
How may the Vagus Nerve be damaged? What complication may it cause?
- Left Recurrent Laryngeal Br. is more vulnerable
- Mitral Stenosis -> enlarged LA -> lifted L. Pulmonary A. -> push L. Recurrent Laryngeal N. against Aortic Arch
- Paralysis of Vocal Cords -> hoarseness in voice