Cranial Nerves Flashcards
What is cranial nerve I?
Olfactory - olfactory sense/smell
What is cranial nerve II?
Optic - optic sense/vision
What is cranial nerve III?
Oculomotor - motor to muscles that move eye
What is cranial nerve IV?
Trochlear - innervates one eyeball muscle whose tendon turns around a pulley (trochlea)
What is cranial nerve V?
Trigeminal nerve - has three major branches of “twin” nerves
What is cranial nerve VI?
Abducens - innervates the muscle that abducts the eyeball/pupil
What is cranial nerve VII?
Facial - innervates muscles of facial expression
What is cranial nerve VIII?
Vestibulocochlear - balance/sensing acceleration and hearing
What is cranial nerve IX?
Glossopharyngeal - mainly sensory to back of tongue and pharynx
What is cranial nerve X?
Vagus nerve - wide distribution in neck, thorax, and abdomen
What is cranial nerve XI?
Spinal accessory
What is cranial nerve XII?
Hypoglossal - motor to tongue (enters tongue from below)
What is the route of parasympathetic neurons through the cranial nerves?
They exit the brain and travel with cranial nerves III, VII, and IX (and also X), synapse in the parasympathetic ganglia, and then follow the trigeminal nerve (V) branches to their effector glands/tissues
What is the embryonic primordium of the olfactory nerve (I)?
Ectoderm of olfactory placode
What are the neuron components and function of the olfactory nerve (I)?
Special sensory neurons for smell (special visceral afferents)
What are the bony relations of the olfactory nerve (I)?
It lies on the cribiform plate of the ethmoid bone in the anterior cranial fossa
What is unique about the neuron cell bodies of the olfactory nerve (I)?
There are two sets of neuron cell bodies.
First set (olfactory nerve proper) sit at the top of the nasal cavity and pass through the cribiform plate to synapse in the olfactory bulb.
The second set (olfactory tract) meet the nerve proper synapses in the olfactory bulb and are surrounded by meninges and CSF
What is A?
Olfactory tract
What is B?
Olfactory Bulb
What is C?
Cribiform plate of ethmoid bone
What is D?
Olfactory nerves
What is E?
Frontal sinus
What is F?
Olfactory bulb
What is G?
Olfactory nerves
What is H?
Olfactory tract
What is I?
Sphenoid sinus
What is J?
Middle concha
What is the primordium of the optic nerve (II)?
Ectodermal optic cup (extension of the neural tube)
What are the neuron components/function of the optic nerve (II)?
Special sensory neurons for vision
What are the bony relations of the optic nerve (II)?
Passes through the optic canal in the lesser wing of the sphenoid bone (along side the ophthalmic artery) to enter the middl ecranial fossa where the optic chiasma is located
What eyeball structure is the optic nerve continuous with?
The retina lining the eyeball
What surrounds the optic nerve (II)?
CSF and meninges
What is a detached retina?
An injury that can be caused if a blow to the head causes the visual retina to fall away from the pigmented retina (they are not tightly fused)
What effect does a unilateral lesion anterior to the optic chiasma have on vision?
It causes vision loss in the eye on the side of the lesion
What effect does a unilateral lesion posterior to the optic chiasma have on vision?
It causes loss of vision in the left or right visual field that is sensed by the lateral retina of one eye and the medial retina of the opposite eye (each optic tract contributes to the field of vision of both eyes)
What is A?
Optic nerve
What is B?
Optic tract
What is C?
Optic chiasma
What is the primordium of the oculomotor nerve (III)?
Pre-otic somite
What are the neuron components of the oculomotor nerve (III)?
Somatomotor, presynaptic parasympathetic
What are the bony relations of the oculomotor nerve (III)?
Superior orbital fissure of the sphenoid bone
What are the functions of the somatomotor fibers of the oculomotor nerve (III)?
Eye movements and elevation of the upper eyelid (levator palpebrae superioris)
All extra-ocular eye movements except for two (lateral rectus - VI, superior oblique - IV)
What are the functions of the postsynaptic parasympathetic fibers of the oculomotor nerve (III)?
Controls smooth muscle in the cilliary body for close up vision and in the iris for pupil constriction
Where do the presynaptic parasympathetic fibers of the oculomotor nerve (III) synapse?
Ciliary ganglion
What is the primordium that the trochlear nerve (IV) is derived from?
Pre-otic somite
What are the neuron components of the trochlear nerve (IV)?
Somatomotor
What are the bony relations of the trochlear nerve (IV)?
Superior orbital fissure of sphenoid bone
What is the function of the trochlear nerve (IV)?
Help move the pupil down and out via the superior oblique muscle
What muscle is innervated by the trochlear nerve (IV)?
Superior oblique extraocular muscle
What is the primordium of the trigeminal nerve (V)?
Branchial arch 1 with maxillary and mandibular parts
Pretrematic branch relates to the ectoderm and head mesenchyme (from neural crest) of the frontonasal process
What are the neuron components of the trigeminal nerve (V)?
General sensory, branchiomotor, and parasympathetics (mostly postsynaptic)
Where are the general sensory cell bodies of the trigeminal nerve (V) located?
What is the relationship of parasympathetics to the trigeminal nerve (V)?
They travel to the ganglia via other cranial nerves, but they synapse in ganglia that are related to terminal branches of the trigeminal and then join the branches to the target tissues
What are the functions of the trigeminal nerve (V)?
General sensory (forehad, face, orbit, nasal cavity, oral cavity)
Branchiomotor (muscles of mastication)
Second half of parasympathetic pathway to lacrimal gland, nasal mucosa, and salivary glands (first half from nerve VII, then follows V2)
What are the three main divisions of the trigeminal?
Ophthalmic division (V1)
Maxillary division (V2)
Mandibular division (V3)
What is the pathway of V1?
The ophthalmic division (V1) passes through the superior orbital fissure and provides general sensory neurons to the derivatives of the frontonasal process (it is the pre-trematic branch of V)