Neuro & Opthal - Intro Flashcards
How many paired Cranial Nerves are there
12
Functions of cranial nerves
Sensory (general or special)
Motor
Parasympathetic
CN I
Olfactory
CN II
Optic
CN III
Oculomotor
CN IV
Trochlear
CN V
Trigeminal
CN VI
Abducens
CN VII
Facial
CN VIII
Vestibulocochlear
CN IX
Glossopharyngeal
CN X
Vagus
CN XI
Accessory
CN XII
Hypoglossal
Which CNs have a motor function
III
IV
V
VI
VII
IX
X
XI
XII
Which CNs have a sensory function
CN I
CN II
CN V
CN VII
CN VIII
CN IX
CN X
How do CNs communicate
Via reflex arc for integrated function
Do CNs generally decussate
No except VI which crosses before exiting brainstem and CN II partially
Basic concepts of CN
Motor info from CNS is carried in EFFERENT nerve fibres
Sensory info form internal and external environment is carried to CNS in AFFERENT nerve fibres - ‘general and special senses’
General vs special senses
General sense - pain, pressure, touch, temp, proprioception
Special sense - all carried in CN - olfaction, vision, taste, hearing and vestibular function
Organisation of CN based on functional components of each nerve
General Somatic Afferent (GSA) fibres
General Visceral Afferent (GVA) fibres
General Visceral Efferent (GVE) fibres
General Somatic Efferent (GSE) fibres
What are GSA fibres related to
Receptors for pain, temp, touch, proprioceptive receptors, in the skin, muscles, tendons and joints
What are GVA fibres related to
Receptors in visceral structures
What are GVE fibres
Preganglionic autonomic fibres
What do GSE fibres do
Innervate skeletal muscle (axons of alpha and gamma motor neurons)
Sequences of neurons in conscious sensation
3rd order neurones
Peripheral receptor (1st order)–> CNS (2nd order) –> thalamus (3rd order) –> sensory cortex
Perception of sensation occurs in cerebral cortex
What’s the exception to three order neurons in conscious sensation
Olfactory projections
Only have 2 neurons between receptor and cerebral cortex and doesn’t primarily project via thalamus
Sequences of autonomic efferent fibres
Two order neurones
Cell bodies of first order neurone (preganglionic neurone) are located in brain/ brainstem
Cell bodies of second order neurone (post-ganglionic neurone) are located in periphery in autonomic ganglion
What does brainstem consist of
Mid-brain
Pons
Medulla oblongata
Which CNs exit at mid-brain
III
IV
Which CNs exit at pons
V
Which CNs exit at ponto-medulaary junctions
VI
VII
VIII
Which CNs exit at medulla oblongata
IX
X
XI (cranial part)
XII
Which CNs leave at C1-C5
XI (spinal part)
Where do CNs leave the brainstem relationally
Anterior: CN III, VI and XII
Lateral: CN V and vII-XI (cranial root)
Posterior: CN IV
CN and their nuclei
Each CN is associated w/ one or more nuclei in the brain and brainstem
CN I and II are from nuclei compartments of the forebrain
CN III - XII are from CN nuclei in the brainstem
How are CN nuclei arranged
In columns according to their embryological origin
What do CN nuclei found in the midbrain deal with
Discrimination of tone and recognition of sound
Vision and light reflex
Movement of eyes
What do CN nuclei found in the pons deal with
Maintenance of awake state
Connection between cerebrum and cerebellum
Muscle movements of the face
Hearing and spatial orientation
Sensation from head and neck area
What do CN nuclei found in the medulla oblongata deal with
Balance
Movement of tongue
Sensation from head and neck area
General rule of thumb about location of CN nuclei
Sensory nerve nuclei tend to be located in the lateral brainstem, while motor nuclei tend to be located more medially
Nuclei of mixed CN
Nerves w/ mixed sensory and motor fibres have more than one nucleus of origin - at least sensory (afferent) and one motor (efferent)
Sometimes more than one nerve will originate form a single nucleus e.g. taste
Where do sensory CN nuclei receive input from
Periphery
Are sensory receptors cell bodies of sensory CN nuclei found in the nucleus itself
No, they are located outside the CNS in the dorsal root ganglion or trigeminal ganglion
Types of sensory afferent CN nuclei
General: trigeminal nucleus
Auditory and motion: vestibular and cochlear nuclei
Tase: nucleus solitarius
How many sensory efferent columns are there for CN nuclei
Somatic efferent
Branchiomotor
Parasympathetic efferent
Which CN nuclei are found in the somatic efferent column
CN III
CN IV
CN VI
CN XII
Which CN nuclei are found in the branchiomotor column
CN V
CN VII
CN IX
CN X
CN XI
Trigeminal motor & facial nuclei and nucleus ambiguus
Which CN nuclei are found in the parasympathetic column
CN III
CN VII
IX
X
Edinger-Westphal, salivary and motor vagus nuclei
Pathway of olfactory nerve
Olfactory epithelium
Olfactory nerve
Olfactory bulb
Olfactory tract
Olfactory cortex - frontal lobe (forebrain)
How many cranial nerves leave the cranial cavity
One - CN II
Decussation of CN II
Semi-dec sustain in optic chiasm and project to thalamus
Motor function of CN III
Innervates all but two extra ocular muscles of the eye and muscles of upper eyelid (SO, LR)
What movements are caused by CN III
Gaze fixation and eye tracking
Raises eyelid
Parasympathetic function of CN III
Contracts smooth intrinsic muscle fo pupil and accommodates lens - pupil constriction
What does the superior branch of the motor nerve fibres of CN III innervate
Superior rectus
Levator palpebrare
What does the inferior branch of the motor nerve fibres of CN III innervate
Medial rectus
Inferior rectus
Inferior oblique
Motor function of CN IV
Innervates superior oblique on contralateral side, turns eyeball down & out
Route of CN IV
Emerges from posterior aspect of midbrain
Fibres cross as they leave brainstem
Runs w/ CN III through cavernous sinus
Leaves skull via superior orbital fissure
Divisions of CN V
Ophthalmic nerve
Maxillary nerve
Mandibular nerve - motor fibres only travel in this direction
Sensory component of CN V
Touch, pain, temp of face
Motor component of CN V
Mastication - tensor tympani and tensor veli palatini
Sensory areas of body supplied by CN V
Face
Scalp
Cornea
Nasal and oral cavities
Teeth and gums
Cranial dura mater
Role of mesenphalic nucleus in CNV
Proprioception form muscles of mastication and temporomandibular joint
Sub-nuclei of sensory nuclei of CN V
Chief
Mesenphalic
Spinal
Motor function of CN VI
Innervate lateral rectus - responsible for EOM w/ CN III (abduct eye)
Nerve roots of CN VII
Lateral nervus intermedius (sensory and parasympathetic)
Medial facial nucleus (motor)
Branches of CN VII
Temporal (forntal)
Zygomatic
Buccal
Marginal mandibular
Cervical
Where does CN VII terminate at
Parotid gland
How can we divide the facial nerve
Intracranial
Extracranial
Role of special sensory fibres in CN VII
Taste to ant 2/3rd of tongue
Cutaneous sensation from external ear
Where do the parasympathetic preganglionic fibres of CN VII go to
Lacrimal, submandibular, lingual glands
Nasal and oral mucosa
Where do the parasympathetic preganglionic fibres of CN VI originate from
Superior salivary nucleus
Components of CN VIII
Vestibular nerve carries info regarding position and movement of head
Cochlear nerve carries auditory info
Where does CN IX originate from
4 nuclei - pair of sneery and motor each located in medulla oblongata
What do the afferent fibres of CN IX innervate
General sensation - oropharynx, posterior 1/3rd of tongue, middle ear, carotid body, Eustachian tube
Chemo and baroreceptors
Where do fibres of general sensation in CN IX end
Trigeminal sensory nucleus
Somatic motor function of CN IX
Efferent fibres innervate stylopharyngeus
Visceral motor function of CN IX
Innervate parotid gland
What branches come off the general somatic sensory of CN IX
Tympanic
Carotid sinus
Pharyngeal
Tonsillar
Lingual
Special sensory function of CN IX
Taste fibres from posterior 1/3 of tongue
Structure of CN X
Pair of nerves emerging from L and R side of medulla oblongata
Sensory function of CN X
Innervates skin of external acoustic meatus, laryngopharynx, larynx, visceral sensation to heart and abdo viscera
Special sensory function of CN X
Taste sensation to epiglottis and root of tongue
Motor function of CN X
Innervates majority of muscles of the pharynx, soft palate and larynx
Parasympathetic branches of CN X
Cardiac
Bronchial
Oesophageal
Role of cardiac parasympathetic branch of CN X
Slow HR
Role of bronchial parasympathetic branch of CN X
Constricts bronchi
Role of oesophageal parasympathetic branch of CN X
Control involuntary muscle in digestive system, stimulating peristalsis and GI secretions
Components of CN XI
Spinal and cranial root
Where does the spinal component of CN IX originate from
C1-C5/6
Role of spinal component of CN XI
Innervates trapezius and SCM - allows head movement
Where does the cranial component of CN XI originate from
Medulla oblongata and fibres distribute w/ vagus nerve fibres
Motor function of CN XII
Innervates intrinsic and extrinsic muscles of tongue
Reflex movements of CN XII
Chewing, sucking and swallowing
Basic functional unit of brain
Neurone
Basic structural unit of brain
Neuroglia
Which cell bodies form groups
Those w/ similar functions
CNS: nucleus
PNS: ganglion (exception is basal ganglia inside brain)
What is the CNS made up of
Cerebral hemisphere - L & R, covered in gyri and sulci
Diencephalon deep to hemispheres (gateway to brainstem)
Cerebellum
Brainstem
Spinal cord (continuation of brainstem)
Where is thalamic lateral found
Diencephalon
What does the brainstem consist of
Mid-brain
Pons
Medulla oblongata
Ventricles in the brain
Two lateral ventricles Bothe drain into 3rd
Third ventricle in centre of diencephalon
Aqueduct passes through diencephalon into brainstem
Fourth ventricles has apertures which acts as outlets so CSF flows in subarachnoid space
Functions of CSF
Supports and cushions structure
Provide nutrition
Removes waste products
What are the two cerebral hemispheres divided by
Great longitudinal fissure (gap)
What are cerebral hemispheres joined y
Corpus callosum
What is white matter divided into
Fibre groups - association fibres, commissural fibres, projection fibres
Where do the sensory fibres of the internal capsule pass through
Anterior limb - prefrontal cortex
Posterior limb - somatomotor
Retro-lentiform - visual
Sub-lentiform - auditory
Where do the motor fibres of the internal capsule pass through
Genu - head and neck
Post limb (anterior) - truck and limbs
What are hemispheres broken down into
Lobes that relate to cortical functional areas, separated by sulci
Sulci of the brain
Central (separates frontal and parietal)
Lateral (separates frontal, parietal and lateral)
Parieto-occipital (separates parietal and occipital)
What is the frontal lobe associated w/
Movement and higher order functions
Motor speech (Broca’s area)
Smell link to limbic system
What is prefrontal area involved in
Personality and behaviour
Role of parietal lobe
Integrates sensory info from various parts of body - associated w/ movement, orientation, lang, reading & taste
Role of temporal lobes
Primary auditory area - auditory perception
Secondary auditory area - interpreting sounds
Balance and coordination
Wernicke’s area - understanding info
What is the limbic system also known as
Primitive brain - coordinates instinctive behaviours w/ higher critical functioning
Role of basal ganglion
Important in stabilising & coordinating slow and fine movements
What is basal ganglion made of
Caudate nucleus
Lentiform nucleus
Amygdaloid body
Substantia Nigra
Basal ganglia pathways
Direct - initials movements
Indirect - suppresses movement
Role of thalamus
Transmits sensory info to cerebral cortex & areas controlling movement
What is the thalamus involved in
Conscious awareness
Sleep-wake area
Emotions and behaviour through limbic system
How many sensory systems have a thalamic nucleus
All (except olfactory system) incl a thalamic nucleus that receives sensory signals —> associated primary cortical area
What is the hypothalamus involved in
Instinctive desires and behaviours
Functions of hypothalamus
Regulation of body temp
Emotion and behaviour
Hunger & thirst
Sexual activity & procreation
Autonomic and endocrine activities and biorhythms
Largest part of hindbrain
Cerebellum
Where does the cerebellum originate
From the dorsal aspect of the brainstem overlies 4th ventricle
How is the cerebellum connected to the brainstem
By three cerebellar peduncles - superior, middle and inferior
What is the reticular formation
Cluster of nuclei that regulate sleep/wake cycle
Number of nerves originating from spinal cord
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal
Regions of white and grey matter in spinal cord
Dorsal (posterior) horns - sensory neurons
Ventral (anterior) horns - motor neurons
Lateral horns - autonomic (motor neurons), thoracic regions - T1-L2
Columns - ascending (sensory) and descending (motor) tracts
Features of hyperopia
Long sighted, smaller eyes, image focuses at back of retina
Features of myopia
Short sighted, bigger eyes, image focuses in front of retina
Significance of loss of colour vision
First thing lost in optic neuropathy or compressive lesion
Measuring colour vision
Ishihara colour plates
Red desaturation
Muscles involved in oculumotility
Superior oblique
Inferior oblique
Superior rectus
Inferior rectus
Lateral rectus
Medial rectus
Muscles and ocular movements
Superior rectus - up & out
Lateral rectus - outwards
Medial rectus - inwards
Inferior oblique - up and in
Inferior rectus - down & out
Superior oblique - down & in
Relative Afferent Pupillary Defect
Both pupils should constrict when performing swinging light test
Issue when only one constricts
Aniscoria (R is constricted, L is dilated)
In dim light, pt’s R is abnormal
In bright light, pt’s L is abnormal
Testing for Adie’s tonic pupil
Abnormal pupil constricts w/ pilocarpine eye drops, normal does not
Testing for Horner’s syn
4% cocaine ye drops - cocaine blocks reuptake of noradrenaline in synapse
Normal pupil dilates, Horner’s does NOT (either pre- or post-ganglionic)
Confirming Horner’s syn
Test w/ 1% hydroxyamphetamine - post-ganglionic lesion causes both pupils to dilate, pre- does NOT
Can also use weak once of adrenaline - post dilates
Apraclinidine - alpha2 agonist has not effect on normal pupils but Horner’s dilates
Features of Horner’s syn
Ptosis
Anhidrosis
Miosis
Enopthalmos
Loss of ciliospinal reflex
