Week 5 - Cranial Nerves

Which cranial nerves come from the telencephalon?

1 - Olfactory

What are the three basic neuronal cell layers of the retina?

1. Photoreceptor cell layer (rods and cones) 2. Interneuron cell layer (horizontal, bipolar, and amacrine) 3. Ganglionic layer

How many cranial nerves are there?

12

Which cranial nerves come from the Diencephalon?

2 - Optic

Which four cranial nerves contain parasympathetic nuclei?

3 - Oculomotor 7 - Facial 9 - glossopharyngeal 10 - Vagus

Which cranial nerves come from the mesencephalon?

3 - Oculomotor and 4 - Trochlear

What motor innervation does the recurrent laryngeal nerve supply?

All muscles of larynx EXCEPT for cricothyroid muscle.

What do the semicicular ducts register?

Angular acceleration.

With regards to the Glossopharyngeal nerve, where do fibers arise, and which structure do they exit by?

Arise from medulla, and exit via jugular foramen.

Where do the fibers of the hypoglossal nerve arise, and by which structure do they exit?

Arise from the medulla, and exit the skull via hypoglossal canal.

Where does the olfactory nerve arise from and where does it pass through?

Arises from the olfactory epithelium, and passes through the cribriform plate of the ethmoid bone.

What type of nerves does the glossopharyngeal nerve carry?

Both sensory and motor

Is the mandibular nerve motor or sensory?

Both. sensory wise -skin of lower face, teeth of lower jaw, general sensation to the anterior 2/3 tongue. NOT TASTE - pain temp etc. Motor - All the muscles the trigeminal nerve innervates. Mastication, tensor tympani, digastric, mylohyoid, tensor veli pallatini.

What are the five major branches of the facial nerve that supply facial expression?

Buccal, cervical, marginal mandibular, temporal, and zygomatic.

In cranial and spinal nerves, where are the parasympathetic nerves located?

Cranial - 3, 7, 9 and 10 Spinal - thoraco-lumbar and sacral regions

What are the locations of the sensory nuclei in both the cranial and spinal nerves on the brainstem?

Cranial - Lateral part of the brainstem Spinal - Dorsal horn of the grey matter

What are the locations of the motor nuclei in both cranial and spinal nerves on the brainstem?

Cranial - Medial part of the brainstem Spinal - Ventral part of the grey matter

The peripheral nervous system consists of which two types of nerves?

Cranial and Spinal

What are the three major things the trigeminal nerve is responsible for in terms of sensory innervation?

Face - including orbital, nasal and oral cavities. Teeth and bony skull. Most part of the dura mater - meniges.

With regards to the vestibulocochlear nerve... What two places do the fibers arise from? What structure do they travel through, and where do they enter brainstem?

Fibers arise from vestibular apparatus and the cochlea. Travel through the internal acoustic meatus. Enter brainstem at the pons-medulla border.

What are considered first and second order neurons?

First order are bipolar neurons. Second order are retinal ganglion cells.

What are the ophthalmic nerves major branches?

Frontal, nasociliary, and lacrimal

Explain the pupillary light reflex.

Light enters one pupil, optic nerve/tract transports light signal which synapse on neurons of the pretectal area. Pretectal neurons project bilaterally to the Edinget-Westphal nuclei. These parasympathetic fibers innervate the sphincter pupillae muscle.

What is the sensory organ of the utricle and saccule?

Macula

Where does the oculomotor nerve originate from? What structure does it pass through?

Midbrain. Superior Orbital Fissure.

Where is the trigeminal (semilunar) ganglion located?

Middle cranial fossa.

What is the function of the abducens cranial nerve?

Motor innervation of the lateral rectus extrinsic eye muscle.

Which two cranial DO NOT arise from the brainstem?

Olfactory and Optic.

Where do the olfactory nerves terminate?

Olfactory bulb, where they synapse with interneurons and mitral nerve cells.

Oh, Oh, Oh, To Touch And Feel Virgin Girls Vagina And Heiney - What are the 12 nerves?

Olfactory, Optic, Oculomotor, Trochlear, Trigeminal, Abducens, Facial, Vestibulocochlear, Glossopharyngeal, Vagus, Accessory, Hypoglossal.

Which set of nerves (cranial vs. spinal) innervate special senses?

Only cranial nerves - more specifically 1, 2, 7, 8, 9 and 10.

The trigeminal nerve has three major branches, which are...

Ophthalmic nerve (V1), Maxillary (V2) and Mandibular (V3).

What is the organ that contains auditory sensory signals?

Organ of Corti

Where does the abducens cranial nerve originate from, and what structure does it pass through?

Originates from the pons (anterior border), and it passes through the superior orbital fissure.

What is the parasympathetic component of the glossopharyngeal nerve?

Paortid salivary gland via otic ganglion. Supplies carotid sinus.

Lesion of the facial nerve leads to which 5 characteristic occurrences? AKA Bell's Palsy

Paralysis of fascial expression. Loss of anterior 2/3 taste. Dry eyes. Dry mouth OR hyposalivation. Hyperacusis - lack of stapedius muscle innervation.

What structure does the mandibular nerve pass through and which structure does it enter?

Passes through the foramen ovale, ends up in infratemporal fossa.

Axons of the mitral cells run through the olfactory tract and terminate where?

Primary olfactory cortex, which is the basal and medial part of the temporal cortex.

What type of nerve is the accessory nerve?

Pure motor nerve.

What type of nerve is the hypoglossal?

Purely motor.

The retina contains two types of photoreceptors, rods and cones. What is the difference between the two?

Rods - Night vision - high quantity 120 million Cones - Day and colour vision - 6 million

Which two structures detect gravity and linear acceleration?

Saccule and Utricle

What is the function of the olfactory cranial nerve?

Sense of smell.

What does the internal branch of the superior laryngeal nerve supply?

Sensory information to the supraglottic region of larynx.

What does the maxillary nerve supply?

Sensory only. Skin of upper face. Upper nasal cavity, and palate. Teeth of upper jaw and maxillary sinus.

What mnenomic helps you remember what the function of each cranial nerve is?

Some Say Marry Money But My Brother Says Big Brains Matter More. S = Sensory, M = Motor, B = Both

With regards to sensation, the glossopharyngeal nerve is responsible for what?

Special sense of taste for the dorsal 1/3 of the tongue. General sensation of the pharynx and dorsal 1/3 of the tongue.

What muscle does the glossopharyngeal nerve innervate?

Stylopharyngeus muscle

What sensory innervation does the recurrent laryngeal nerve supply?

Subglottic region of larynx.

Where does the ophthalmic nerve pass through?

Superior Orbital fissure.

Axons of the optic cross over to the contralateral side at which structure?

The Optic Chiasm.

With regards to cranial and spinal nerves, what makes up the component fibers?

The cranial nerves can be motor, sensory or both. Whereas spinal nerves are always both - Only C1 is a purely motor nerve.

What is the sensory organ of rotation located in the semi-circular canals?

The crista ampullaris

Which branch of the vagus nerve supplies motor innervation to the cricothyroid muscle?

The external branch of the superior laryngeal nerve

Which cranial nerve exits anteriorly between the olives and pyramids?

The hypoglossal nerve.

Which is the largest of all the cranial nerves?

The trigeminal nerve - it is part of the pons

What is the only cranial nerve that extends beyond the head and neck?

The vagus nerve.

True or false, sensory neurons of the trigeminal nerve are NOT located in the CNS.

True - They are in the terminal ganglion, which is a part of the peripheral nervous system. They are unipolar neurons.

How is a failed pupillary light reflex indicitive of high intracranial pressure?

Uncal herniation puts pressure on the third cranial nerve, causing pupil to dilates, and compresses the nerve preventing the reflex. Could also lose motor commands.

What are the vestibular and cochlear nerves concerned with?

Vestibular nerve carries information concerned with the position of the head in relation to movement of the head and gravity. Cochlear nerve is concerned with hearing.

What is the pupillary light reflex?

When bright light enters one eye, the pupils of BOTH eyes become smaller due to the reflex.

Which structures do the spinal nerves innervate?

Whole body apart from the head. (cranial nerves innervate that.

Is the vagus nerve a mixed nerve?

Yes - it has three components - sensory, motor and parasympathetic.

The vestibular and tympanic duct contains which kind of fluid?

perilymph fluid

Axons of the optic nerve (second order neurons) synapse on the neurons of the..,.

thalamus (lateral geniculate nucleus (3rd order neurons))

What is the motor, sensory, and parasympathetic innervation of the facial nerve?

Motor = facial expression + scalp, posterior belly of digastric, stylohyoid and stapedius muscle. Sensory = Taste sensation from anterior 2/3 tongue Parasympathetic = tear gland, submandibular and lingual glands, and nasal glands.

What does the vestibular nerve receive input from?

3 semicicular canals, utricle, and the saccule

What are the TWO exceptions that revolve around the olfactory nerve?

It is the only nerve whose fibers do NOT pass through the thalamus. It is the only nerve capable of regeneration.

What is the sensory component of the vagus nerve?

Larynx and external ear

Rods and cones synapse on a single bipolar neuron. How many of each?

Many rods synapse, whereas only a few cones will synapse.

Which eye muscles does the oculomotor nerve innervate? There are 7 in total.

4 extrinsic eye muscles: Superior Rectus, Inferior Rectus, Medial Rectus, and Inferior Oblique. Levatator Palpebrae Superioris. 2 Intrinsic eye muscles: Ciliary Muscle and Sphincter pupillae (These are the parasympathetic innervation for CN3)

Which cranial nerves come from the Rhombencephalon?

5 - 12 Trigeminal, abducens, facial, vestibulocochlear, glossopharyngeal, vagus, accessory and hypoglossal

Where do the fibers of the vagus nerve emerge, and what structure do they exit by?

Emerge from the medulla and exit via the jugular foramen.

The cochlear duct contains which type of fluid?

Endolymph fluid

Where does the maxillary nerve branch enter, and through which structure?

Enters the pterygopalatine fossa, via the foramen rotundum. Once in the pterygopalatine fossa it gives off several branches. BUT major nerve continues as the infraorbital nerve.

What is the function of the pigment cells?

Absorb stray light and prevent scatter of light.

What motor components is the trigeminal nerve responsible for?

All muscles of mastication. Anterior belly of the digastric muscle. Mylohyoid muscle. Tensor Tympani and tensor veli palatini muscles.

What is the motor component of the vagus nerve?

All muscles of the pharynx and larynx, palatoglossus and levatoator veli palatini.

Which muscles does the hypoglossal nerve innervate?

All muscles of the tongue (intrinsic and extrinsic), apart from the palatoglossus muscle.

What is the parasympathetic component of the vagus nerve?

All visceral organs of the neck, thorax and upper abdomen. And the parts of the intestine that are derived from the foregut and midgut.

The superior root of which nerve travels for a short distance through the hypoglossal nerve?

Ansa cervicalis nerve

What are the two parts of the accessory nerve and where do they travek?

Cranial part originates from brainstem and merges with the vagus nerve. Spinal part emerges from the spinal cord, enters the skull via foramen magnum, and merges with the cranial counterpart, which leave the skull at the jugular foramen.

Fill in the (blank)s. The optic nerve is a part of the (blank). It is responsible for the sense of (blank). It passes through the (blank) canal into the (blank) cavity.

Diencephalon. Vision. Optic. Cranial.

Which structure does the trochlear nerve pass through? And what does it innervate?

Passes through the superior orbital fissure, and innervates the superior oblique extrinsic eye muscle.

What is the branch of the vagus nerve that wraps around the aortic arch (left) and subclavian artery (right)?

Recurrent laryngeal nerves.

Axons of which cells form the optic nerve?

Retinal ganglion cells

Does the ophthalmic nerve carry sensory, motor or both types of fibers? What does it supply?

Sensory ONLY. Skin of forehead, eyelid, eyebrow and nose. Eye sensory - pain sensation of the cornea and conjuctiva. Mucous membrane of the upper nasal cavity.

The trochlear nerve is the only nerve to arise from which part of the midbrain?

The dorsal part

What else is in the petrous part of the temporal bone (borders the middle ear) with the facial nerve?

The geniculate ganglion

Which two muscles of the neck does the accessory nerve innervate?

Trapezius and sternocleidomastoid

What does the facial nerve travel through and where does it end up?

Travels through internal acoustic meatus, travels through the facial canal and ends up in the stylomastoid foramen.

The tendon of the superior oblique muscle passes through a cartilaginous pulley known as the...

Trochlea - hence the name trochlear nerve.

Which cranial nerve DOES NOT arise from the anterior / basal surface of the brain?

Trochlear nerve

True or false: Light passes through all layers of the retina before reaching the photoreceptors?

True