Lecture 8: Cranial Nerve Flashcards
Name all of the Cranial Nerves
1) Olfactory Nerve 2) Optic Nerve 3) Oculomotor Nerve 4) Trochelar nerve 5) Trigeminal nerve 6) Abducent nerve 7) Facial nerve 8) Vestibulocochlear nerve 9) Glossopharyngeal nerve 10) Vagus nerve 11) Accessory nerve 12) Hypoglossal nerve
Which nerves are sensory, which are motor and which are both?
Where does the olfactory nerve exit from the skull/
Cribiform of the ethmoid bone
Describe the Olfactory Nerve
CNI
Sensory
Allocortex/limbus
Found in the Olfactory space. It projects up from the cribriform plate of the ehtmoid muscle to form the olfatory bulb, and this olfactory bulb forms the olfactory tract which projects to the Primary olfactory cortex in the brain. (note that the olfactory tract is part of the limbic system- why smells trigger memories/emotions).
Involved in smell
Describe the Optic Nerve
CII
Sensory
Allocortex/Limbus
Exits: Optic Canal
Connect to the back of the retina, pass through the optic canal to the optic chiasma. These fibres then get mixed then form the optic tract then synapse with the Lateral geniculate nucleus of the thalamus which sends info to the cortex.
Vision
Describe the Occulomotor Nerve
CNIII
Motor
Midbrain
Exit: Superior Orbital fissure
Controls majority of the muscles that control the movement in the eye (1) Levator Palpebrae Superioris (elevates the superior (upper) eyelid), 2) Superior rectus, 3) Inferior rectus, 4) medial rectus, 5) inferior olique muscles)
Also Innervates a number of the extraocular muscles as well as parasympathetic innervation on the 6) sphincter pupillae and the 7) ciliary muscles (responsible for accommodation fo the lesne for near vision)
Elevates, abducts, adducts and depresses the eye.
If this is damaged, the patient’s ability to depress the eye is often damaged (their eyes will move upwards)
Describe the Trochlear nerve
CN IV
Motor
Midbrain
Exit: Superior Orbital fissure
Motor nerve (a somatic efferent nerve) that innervates only a single muscle: the superior oblique muscle of the eye, which operates through the pulley-liketrochlea. (abducts, depresses and tortes/internally rotates the eye)
Describe the Trigeminal Nerve
CNV
Both sensory and motor
Pons
Exit: Superior Orbital fissure
The three major branches of the trigeminal nerve—the ophthalmic nerve (V1), the maxillary nerve (V2) and the mandibular nerve (V3)—converge on the trigeminal ganglion. These exit the cranium at different points because they divide before they exit
It supplies sensations to the face, mucous membranes, and other structures of the head.
- Opthalmic nerve is involved in sensory innnervation of forehead, eyelid and top of nose. It is also involved in cornear, lacrimal glands
- Maxillary get sensation from the lower part of the ye and upper lip. It also synapses with a ganglion that receives info from a lot of nerves from nose and mouth.
- Mandibular gland also receives info from anterior 2/3 of tongue (pain and temp etc.), and also involved in getting info from the sweat glands and other structues in the mouth. It also synapses with the Otic ganglion which is involved in the regulation of the carotid glands (salivary glands).
It is the motor nerve for the muscles of mastication (chewing) and contains proprioceptive fibers.
Describe the Abducent Nerve
CNVI
Motor
Pons
Exit: Superior Orbital Fissure
Innervates lateral rectus muscle (The lateral rectus muscle is a muscle on the lateral side of the eyeball in the orbit. It is one of six extraocular musclesthat control the movements of the eye. The lateral rectus muscle is responsible for lateral movement of the eyeball, specifically abduction)
Describe the Facial Nerve
CN VII
Both sensory and motor
Pons/Medulla
Exit: Stylomastoid foramen
Controls the muscles of facial expression, and functions in the conveyance of taste sensations from the anterior two-thirds of the tongue and oral cavity.
(learn below)
Motor: Innervates the muscles of f_acial expression_, the posterior belly of the digastric, the stylohyoid and the stapedius muscles (control fo the eyelid, closing of the eyes, pouting of the mouth, movement of the cheek etc.)
Sensory: A small area around the concha of the auricle.
Special Sensory: Provides special taste sensation to the anterior 2/3 of the tongue. (Cauda tympani nerve)
Parasympathetic: Supplies many of the glands of the head and neck, including:
Submandibular and sublingual salivary glands, Nasal, palatine and pharyngeal mucous glands and the Lacrimal glands.
Describe the Vestibulocochlear Nerve
CN VIII
Sensory
Medulla
Exit: Leave cranial cavity through the internal acoustic meatus
Damage to this nerve can result in vertigo (sensation of movement when you’re not), nausea, vommiting etc.
Vestibular division = balance
Cochlear division = hearing
Describe the glossopharyngeal nerve
CN IX
Both sensory and motor
Medulla
Exit: Jugula foramen
It exits the brainstem out from the sides of the upper medulla, just rostral (closer to the nose) to the vagus nerve.
Control and receive info from the tongue (_parotid gland)_and parts of the throat. Mainly sensory but some control functions.
Sensory: Innervates the oropharynx, carotid body (info about pressure), and carotid sinus (structure in the carotid that senses changes in pH, CO2, O2 etc.), posterior 1/3 of the tongue, middle ear cavity and Eustachian tube.
Special Sensory: Provides taste sensation to the posterior 1/3 of the tongue.
Parasympathetic: Provides parasympathetic innervation to the parotid gland (production of saliva).
Motor: Innervates the stylopharyngeus muscle of the pharynx.
Describe the Vagus Nerve
CNX
Both sensory and motor
Medulla
Exit: Jugular Foramen
Interfaces with parasympathetic control of the heart, lungs, and digestive tract.
Lots of nuclei and lots of branches that control exterior parts of the inner ear and oracle. Also receive sensory info from the meninges.
1) Pharyngeal branch (motor control of muscles in the pharynx)
2) Superior laryngeal branch (2 parts = internal which is involved in sensory from the larynx and external branch that is involved in motor)
3a) Right nerve travels back up from under the subclavian artery to control the muscles
3b) The left nerve passes under the aorta, then comes back up again (recurrent laryngeal nerve)
Works with the sympathetic nervous system to regulate bodily function.
Describe the Acessory Nerve
CN XI
Motor
Medulla
Exit: Jugular foramen
Innervates the sternocleidomastoid and trapezius muscles (rotation of the head and shrugging of the shoulders). Start in the Spinal cord and goes up into the cranium. The cranial portion joins with the vagus nerve very quickly.
Describe the Hypoglossal Nerve
CN XII
Motor
Medulla
Exit: Hypoglossal canal
Innervates the hypoglossus, genioglossus and styloglossus muscles and all intrinsic muscles of the tongue.
(innervates all the extrinsic and intrinsic muscles of the tongue, except for the palatoglossus which is innervated by the vagusnerve. It is a nerve with a solely motor function.)
How are the types of nerves organised in the spinal cord?
All of the different types are organised differently (e.g. Special somatic sensory is grouped together and is separated from Special visceral sensory nerves)
If you damage your optic nerve prior to the optic chiasma, what sort of symptoms would you get?
Complete blindness in 1 eye
If you damage your optic nerve POST the optic chiasma, what sort of symptoms would you get?
You get partial blindness in both eyes.
Describe the 3 branches of the trigeminal nerve
- Opthalmic nerve is involved in sensory innnervation of forehead, eyelid and top of nose. It is also involved in cornear, lacrimal glands
- Maxillary get sensation from the lower part of the ye and upper lip. It also synapses with a ganglion that receives info from a lot of nerves from nose and mouth.
- Mandibular gland also receives info from anterior 2/3 of tongue (pain and temp etc.), and also involved in getting info from the sweat glands and other structues in the mouth. It also synapses with the Otic ganglion which is involved in the regulation of the carotid glands (salivary glands).
What is Bell’s palsy?
Bell’s palsy is a condition in which the muscles on one side of your face become weak or paralyzed.
It affects only one side of the face at a time, causing it to droop or become stiff on that side. It’s caused by some kind of trauma to the seventh cranial nerve.
This is also called the “facial nerve.”
Due to inflammation of the facial nerve. Can be due to herpes.
What is the nerve associated with the disorder where on one side of your face become weak or paralyzed.
Bell’s Palsy
