The Brainstem, Cranial Nerves And The Visual Pathway Flashcards
(184 cards)
1
Q
Location of midbrain
A
Most superior part of brainstem
2
Q
2 parts of the midbrain
A
Tectum
Tegmentum
3
Q
Location of Tectum
A
Smaller part of the midbrain located dorsal of the cerebral aqueduct
4
Q
Tectum
A
Contains 2 pairs of rounded bumps = colliculi
5
Q
Role of superior colliculi
A
Involved in regulating eye movements and reflexes associated with visual stimuli, such as turning or moving the head quickly when something quickly enters our field of vision
6
Q
Role of inferior colliculi
A
Involved sound location, pitch discrimination and reflexes associated with auditory stimuli, such as turning our head on hearing a loud noise
7
Q
Location of tegmentum
A
Larger part of midbrain located ventrally of cerebral aqueduct
8
Q
What separates the tegmentum and Tectum
A
Cerebral aqueduct
9
Q
Which colliculi are involved with visual stimuli
A
Superior colliculi
10
Q
Which colliculi are involved with auditory stimuli
A
Inferior colliculi
11
Q
Substantia nigra
A
Important in motor control by producing dopamine
12
Q
Cerebral peduncles
A
On most ventral surface of tegmentum
Large white matter bundles that connect the midbrain to the thalami
13
Q
Red nuclei
A
Support motor control of limbs
14
Q
What 3 structures does the tegmentum contain
A
Substantia nigra
Cerebral peduncles
Red nuclei
15
Q
Which nuclei does the midbrain contain
A
Nuclei of the oculomotor (CN III) and trochlear (CN IV) nerves
Edinger-Westphal nuclei (involved in pupillary light reflex)
16
Q
Pons
A
Large, rounded middle part of the brainstem
Contains the Pneumotaxic and aponeustic centres involved in regulation of breathing
17
Q
Which artery lies on the ventral surface of the pons
A
Basilar artery
18
Q
Middle cerebellar peduncles
A
Large white matter connections to the cerebellum on the dorsal surface of the pons
19
Q
What is located on the ventral surface of the pons
A
Basilar artery
20
Q
What is located on the dorsal surface of the pons
A
Middle cerebellar peduncles
21
Q
Where is the fourth ventricle situated
A
Dorsal surface of pons between 2 middle cerebellar peduncles
22
Q
Which nuclei are in the pons
A
Nuclei of the trigeminal (CN V), abducens (CN VI), facial (CN VII), vestibulocochlear (CN VIII) nerves
23
Q
Which centres are involved in the regulation of breathing
A
Pneumotaxic and Apneustic
24
Q
Where are the Pneumotaxic and apeneustic centres located
A
Pons
25
Location of medulla oblongata
Connects pons to spinal cord
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Anterior median fissure
Groove on ventral surface of medulla oblongata that separates the 2 medullary pyramids
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Medullary pyramids
2 distinct lumps on ventral surface of medulla separated by anterior median fissure
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Which tracts run through the medullary pyramids
Corticospinal tracts
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Medullary olives
Prominent ridges immediately lateral to the medullary pyramids
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2 nuclei in the dorsal column medial lemniscus
Fasciculus gracilis
Fasciculus cuneatus
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Dorsal column medial lemniscus
Sensory nerve pathway in dorsal part of medulla
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Which fibres decussate in the medulla
Corticospinal
Dorsal column medial lemniscus
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Where do the corticospinal tracts decussate
Medulla
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Where do the dorsal column medial lemniscus decussate
Medulla
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Which nuclei are in the medulla
Nuclei of the Glossopharyngeal (CN IV), vagus (CN X), accessory (CN XI) and Hypoglossal (CN XII) nerves
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Medulla
Contains vital centres responsible for regulating respiration, heart rate, blood pressure and initiating vomiting
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Where are the centres responsible for regulating respiration, heart rate, blood pressure and initiating vomiting located
Medulla
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Bulbar palsy
This term refers to dysfunction of the cranial nerves that arise from the medulla (glossopharyngeal, vagus, accessory and hypoglossal). Symptoms include difficulty speaking and swallowing, excessive saliva production, wasting and fasciculations of the tongue and an absent gag reflex. Causes include diseases which affect peripheral nerves such as motor neurone disease and Guillain-Barré syndrome.
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Which part of the brainstem do nerves affected by bulbar palsy originate in
Medulla
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Is the olfactory nerve sensory or motor
Sensory
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Is the optic nerve sensory or motor
Sensory
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Is the oculomotor nerve sensory or motor
Motor + parasympathetic
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Is the trochlear nerve sensory or motor
Motor
44
Is the trigeminal nerve sensory or motor
Both
45
Is the abducens nerve sensory or motor
Motor
46
CNS origin of the olfactory nerve
Cerebrum
47
CNS origin of the optic nerve
Diencephalon
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CNS origin of the oculomotor nerve
Midbrain
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CNS origin of the trochlear nerve
Midbrain
50
CNS origin of the trigeminal nerve
Pons
51
CNS origin of the abducens nerve
Pons
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Which skull base Foramen does the olfactory nerve exit
Cribriform plate
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Which skull base Foramen does the optic nerve exit
Optic canal
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Which skull base Foramen does the oculomotor nerve exit
Superior orbital fissure
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Which skull base Foramen does the trochlear nerve exit
Superior orbital fissure
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Which skull base Foramen does the abducens nerve exit
Superior orbital fissure
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Which skull base Foramen does the ophthalmic branch of the trigeminal nerve exit
Superior orbital fossue
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Which skull base Foramen does the maxillary branch of the trigeminal nerve exit
Foramen rotundum
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Which skull base Foramen does the mandibular branch of the trigeminal nerve exit
Foramen ovale
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3 branches of trigeminal nerve
Ophthalmic
Maxillary
Mandibular
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Function of the olfactory nerve
Olfaction (smell)
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Function of the optic nerve
Sight
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Function of the oculomotor nerve
Eye movements (SR, IR, MR, IO)
Eyelid opening (LPS_
Pupillary constriction
Accommodation
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Function of the trochlear nerve
Eye movement (SO)
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Function of the abducens nerve
Eye movements (LR)
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Function of the ophthalmic branch of the trigeminal nerve
Sensation from upper 1/3 of face - as far as top of head to anterior surface of the eye
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Function of the maxillary branch of the trigeminal nerve
Sensation from the middle 1/3 of face - including most of the internal nasal cavity, upper teeth and palate
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Function of the mandibular branch of the trigeminal nerve
Sensation from the lower 1/3 of face - including general sensation to anterior 2/3 of the tongue, mandibular teeth and gums
Motor to the muscles of mastication
Motor to tensor tympani muscle
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Where are the olfactory bulbs located
Superior surface of the Cribriform plate either side of the crista galli
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Where are the olfactory cortices
Temporal lobes
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V1 branch of trigeminal nerve
Ophthalmic
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V2 branch of trigeminal nerve
Maxillary
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V3 branch of trigeminal nerve
Mandibular
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Muscles of mastication supplied by the mandibular nerve (V3)
Temporalis
Masseter
Medial pterygoid
Lateral pterygoid
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5 branches of the facial nerve
Temporal
Zygomatic
Buccal
Marginal mandibular
Cervical
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Where does the facial nerve branch into 5
Within the parotid salivary glands
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Chorda tympani
Branch of the facial nerve
Supplies taste to anterior 2/3 tongue
Parasympathetic secretomotor function to the submandibular and sublingual salivary glands
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Which Foramen does the facial nerve leave the skull by
Stylomastoid Foramen in the temporal bone
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Where is the Stylomastoid Foramen
Temporal bone
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Pathway of facial nerve
Passes through internal auditory meatus alongside vestibulocochlear nerve
Gives off a branch to the lacrimal glands
Progresses through middle ear cavity - branch to Stapedius muscle and Chorda tympani
Leaves skull via Stylomastoid foramen
Enters parotid gland where branches into 5
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Which nerve supplies a branch to the lacrimal gland
Facial nerve- parasympathetic
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Which nerve gives off a branch to the Stapedius muscle in the middle ear cavity
Facial nerve
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2 branches of facial nerve in middle ear cavity
Chorda tympani
Branch to Stapedius
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Is the facial nerve sensory or motor
Both + parasympathetic
85
Is the vestibulocochlear nerve sensory or motor
Sensory
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Is the Glossopharyngeal nerve sensory or motor
Both + parasympathetic
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Is the vagus nerve sensory or motor
Both + parasympathetic
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Is the accessory nerve sensory or motor
Motor
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Is the Hypoglossal nerve sensory or motoru
Motor
90
CNS origin of the facial nerve
Poms
91
CNS origin of the vestibulocochlear nerve
Pons
92
CNS origin of the Glossopharyngeal nerve
Medulla
93
CNS origin of the vagus nerve
Medulla
94
CNS origin of the accessory nerve
Spinal cord C1-C5
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CNS origin of the Hypoglossal nerve
Medulla
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Which cranial nerve originates from the spinal cord C1-C5
Accessory nerve (CN XI)
97
Which skull base foramen does the facial nerve exit
Internal auditory meatus
Then Stylomastoid foramen
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Which skull base foramen does the vestibulocochlear nerve exit
Internal auditory meatus
99
Which skull base foramen does the Glossopharyngeal nerve exit
Jugular foramen
100
Which skull base foramen does the vagus nerve exit
Jugular foramen
101
Which skull base foramen does the accessory nerve exit
Jugular foramen
102
Which skull base foramen does the Hypoglossal nerve exit
Hypoglossal canal
103
Which skull base foramen does the accessory nerve enter the skull
Foramen magnum
104
Function of the facial nerve
Motor to muscles of facial expression
Motor to Stapedius muscle
Sensation to the ear canal
Secretomotor function to the submandibular and sublingual salivary glands, and lacrimal glands
Taste to anterior 2/3 tongue
105
Function of the vestibulocochlear nerve
Balance and hearing
106
Function of the Glossopharyngeal nerve
Motor to the stylopharyngeus muscle
Sensation from the pharynx
Taste and sensation for posterior 1/3 tongue
Sensation from carotid baroreceptors
Secretomotor function to parotid gland
107
Function of the vagus nerve
Motor to muscles of soft palate, pharyngeal muscles and internal laryngeal muscles
Sensation from the external ear and ear canal
Taste from the epiglottis
Parasympathetic to thoracic and abdominal organs
108
Function of the accessory nerve
Motor to trapezius and sternocleidomastoid muscles
109
Function of the Hypoglossal nerve
Motor to muscles of the tongue
110
Function of stylopharyngeus muscle
Assists with facilitating swallowing
111
Which nerve carries unconscious sensory information from carotid chemoreceptors and baroreceptors to medulla
Glossopharyngeal
112
Function of sternocleidomastoid muscle
Turning the head and nodding
113
Function of trapezius muscle
Responsible for shrugging and numerous movements of the scapula
114
Which muscle of the tongue is not supplied by the Hypoglossal nerve
Palatoglossus (vagus nerve)
115
Which nerve supplies the palatoglossus muscle
Vagus
116
Unilateral Hypoglossal nerve damage
cause that side of the tongue to be paralysed and atrophy, meaning the other side will overpower it. This leads to a characteristic finding of the tongue pointing towards the side of the lesion.
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Which nerve supplies motor innervation the the intrinsic and extrinsic muscles of the tongue
Hypoglossal
118
Which nerve supplies motor innervation to the soft palate, palatine folds and pharyngeal constrictors
Vagus
119
Which nerve supplies general sensation to the ear canal and Pinna
Vagus
120
Which nerve carries taste sensation from the epiglottis
Vagus
121
How to test for the olfactory nerve
the clinician can simply ask the patient if their sense of smell has changed, or they can ensure the patient is able to identify certain strong-smelling compounds, such as coffee, chocolate, vanilla, or cinnamon.
122
How to test for the optic nerve
this nerve is tested in several ways. Firstly, visual acuity is tested using a Snellen chart (a chart with letters of decreasing sizes). Visual fields (peripheral vision), accommodation to near and far objects, colour vision, and the pupillary light reflex also test the optic nerve.
123
How to test for the oculomotor and trochlear and abducens nerve
this nerve is tested alongside CN IV (trochlear) and CN VI (abducens) by a clinician asking a patient to follow their finger as they move it across the patient’s field of vision. The clinician can observe the movements of the patient’s eyes to ensure they are moving as they should. The pupillary light reflex also tests the oculomotor nerve.
124
How to test for the trigeminal nerve
the motor and sensory parts of the trigeminal nerve are tested separately. Firstly, sensation is tested by simply ensuring the patient can feel a brush of cotton wool against their skin in the three regions of the face (forehead, cheek, jaw) on both sides. Sensation may be further tested by ensuring the patient is able to tell the difference between sharp and crude touch, or by testing the blink reflex when the cornea of the eye is touched. Motor function is tested by palpating a patient’s jaw muscles as they clench their teeth or asking the patient to forcibly open their mouth against resistance.
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How to test for the facial nerve
the motor function of the facial nerve is its only function that is routinely tested. This is achieved by asking the patient to perform a series of facial movements, such a raising their eyebrows, closing their eyes tightly, blowing their cheeks out or showing all their teeth. The clinician looks for any asymmetry in their movements.
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How to test for the vestibulocochlear nerve
the simplest way this nerve is tested is by blocking the one of the patient’s ears and whispering a number or word in the other ear and asking the patient to repeat it to check their hearing. The test is repeated with the other ear. The function of the ear, cochlear and vestibular system can be tested more thoroughly with other tests using tuning forks and dedicated equipment in specialist clinics.
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How to test for the Glossopharyngeal nerve
this nerve is tested by assessing the patient’s gag reflex. A tongue-depressor (a blunt wooden ‘lolly-stick’) is pressed against the oropharynx and a normal finding would be the patient ‘gagging’ or looking like they will vomit. This tests the sensory function of this nerve.
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How to test for the vagus nerve
there are several ways to test the vagus nerve. The gag reflex above tests the motor function of the vagus nerve, but it can be further tested by asking the patient to open their mouth and say ‘ahhh’. This should cause elevation of the soft palate by muscles which are supplied by the vagus nerve. Coughing and swallowing also both require function of the vagus nerve.
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How to test for the accessory nerve
to test the trapezius muscle, a clinician can ask the patient to shrug their shoulders, and to test the sternocleidomastoid, a clinician asks the patient to turn their head against resistance.
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How to test for the Hypoglossal nerve
finally, the hypoglossal nerve is tested by asking the patient to protrude their tongue. Deviation of the tongue to one side or the other may imply damage to one of the hypoglossal nerves.
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Pituitary tumour
A tumour of the pituitary gland may cause it to enlarge. As it sits immediately beneath the optic chiasm, it can enlarge enough to compress the optic chiasm. This will cause the characteristic bitemporal hemianopia.
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Monocular vision loss
defect is caused by damage to an optic nerve, meaning all vision is lost from the ipsilateral eye.
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Damage to which nerve causes monocular vision loss
Optic nerve
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Visual fields
The areas we can see with each eye
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How are visual fields divided
Into a temporal field and nasal field
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Temporal field
Lateral half of the visual field
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Nasal field
Medial half of visual field
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Which part of the retina provides temporal visual field
Nasal retina
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Which part of the retina is provides nasal visual field
Temporal retina
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Location of optic chiasm
Immediately anterior to midbrain
Superior to pituitary gland
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Which visual information decussates at the optic chiasm
Information from the temporal visual fields (nasal retina) … so left eye information goes to right side of brain
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Pathway of optic tracts after optic chiasm
Travel to thalamus where synapse at the lateral geniculate nucleus
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Which nucleus do the optic tracts synapse at
Lateral geniculate nucleus
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Optic radiations
Superior and inferior pathways of optic fibres from lateral geniculate nucleus to primary visual cortex
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Parietal radiation
Superior optic radiation travels in the parietal lobe
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Temporal radiation/ Meyer’s loop
Inferior optic radiation travels in the temporal lobe
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What receives input from the optic tracts
Edinger-Westphal nucleus
Superior colliculi
Primary visual cortex
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What constitutes inferior fields of vision
Parietal radiations
Superior as-ears of the retina
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What constitutes superior fields of vision
Temporal radiation
Inferior parts of retina
150
Bitemporal hemianopia is caused by damage to
Optic chiasm
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Bitemporal hemianopia
Vision loss of temporal visual fields due to damage to fibres that carry nasal retinal information
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Homogenous hemianopia is caused by damage to
An optic tract between the optic chiasm and the lateral geniculate nucleus
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Homogenous hemianopia
If left optic tract is damaged, information from the left temporal retina and right nasal retina is lost, so the left nasal visual field and right temporal visual field are lost (right side of vision in both eyes)
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Homonymous quadrantanopia
If the left parietal optic radiation is damaged, information from the left superior temporal retina and right superior nasal retina is lost, meaning the left inferior nasal visual field and the right inferior temporal visual field are lost. This would mean the patient has lost the bottom-right corner of their vision in both eyes, so would be termed a right inferior homonymous hemianopia.
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Homonymous quadrantanopia is caused by damage to
Either the parietal or temporal optic radiation
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1. Which structure divides the midbrain into the tectum and tegmentum?
Cerebral aqueduct
157
2. Where are the nuclei of the following cranial nerves?
a. Oculomotor
Midbrain
158
2. Where are the nuclei of the following cranial nerves?
b. Trigeminal
Pons
159
2. Where are the nuclei of the following cranial nerves?
c. Facial
Pons
160
2. Where are the nuclei of the following cranial nerves?
d. Vagus
Medulla
161
2. Where are the nuclei of the following cranial nerves?
e. Hypoglossal.
Medulla
162
3. What are the functions of the superior and inferior colliculi?
The superior colliculi are involved in regulating eye movements and reflexes associated with visual stimuli, such as turning or moving the head quickly when something quickly enters our field of vision. The inferior colliculi are involved sound location, pitch discrimination and reflexes associated with auditory stimuli, such as turning our head on hearing a loud noise.
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4. How many cranial nerves are sensory, motor, or both? How many contain parasympathetic fibres?
4. Purely sensory: 3, purely motor: 5, both: 4, contain parasympathetics: 4.
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5. Which cranial nerves are responsible for:
a. Constriction of the pupil in response to bright light.
Oculomotor III
165
5. Which cranial nerves are responsible for:
b. Motor control to the tongue.
Hypoglossal XII
166
5. Which cranial nerves are responsible for:
c. Motor control to the muscles of mastication.
Trigeminal - mandibular division V3
167
5. Which cranial nerves are responsible for:
d. Taste from the posterior 1/3 of the tongue.
Glossopharyngeal IX
168
5. Which cranial nerves are responsible for:
e. Secretomotor function to the parotid salivary gland.
Glossopharyngeal IX
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6. How can you test the following cranial nerves?
a. Facial.
a. Ask the patient to make certain facial movements like raising their eyebrows, closing their eyes tightly, showing their teeth and blowing their cheeks out.
170
6. How can you test the following cranial nerves?
b. Glossopharyngeal.
b. Stimulate the oropharynx with a tongue depressor to elicit the gag reflex.
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6. How can you test the following cranial nerves?
c. Hypoglossal.
c. Ask the patient to protrude their tongue and move it side to side.
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6. How can you test the following cranial nerves?
d. Trigeminal.
d. Test sensation in three on each side of the face (forehead, cheek, jaw). Also test tone in temporalis by palpating the sides of the head during teeth clenching and testing the lateral pterygoid by asking the patient to open their moth against resistance.
173
6. How can you test the following cranial nerves?
e. Accessory.
e. Ask the patient to turn their head and shrug their shoulders against resistance to test the sternocleidomastoid and trapezius, respectively.
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8. Enlargement of which structure may cause a bitemporal hemianopia?
8. Pituitary gland. It will begin to compress the optic chiasm as it enlarges.
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9. Which cranial nerves pass through the cavernous sinus
Oculomotor (III), Trochlear (IV), Ophthalmic (V1), Maxillary (V2) and Abducens (VI).
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What symptoms and signs might a patient display if there is disease of the cavernous sinus?
Symptoms: headache, bulging eyeball (exophthalmos), double vision (diplopia), paralysis of eye muscles (ophthalmoplegia) and sensory deficit on the face.
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Exophthalmos
Bulging eyeball
178
Diplopia
Double vision
179
Ophthalmoplegia
Paralysis of eye muscles
180
Bulbopontine sulcus
Line between pons and midbrain
181
Which fibres cross in the optic chiasm
Nasal retina fibres
182
Superior retinal fibres form which radiation
Parietal
183
Inferior retinal fibres form which radiation
Temporal
184
To work out homonymous quadrantanopia
Opposite
Eg if lesion in left parietal radiation
Right inferior homonymous quadrantanopia
