L1: Introduction to Neurology Flashcards
Def of Neurology
The branch of medicine that deals with diseases of the nervous system & diseases of the muscles & myoneural junction.
What is the structural & Functional unit of Nervous System?
Neuron
Neurons Grey & White Matters
Classifications of Nervous System
Anatomical & Physiological
Anatomical Classification of Nervous System
Two cerebral hemispheres connected to
- Each other → …..
- The brain stem → ……
- by corpus callosum
- by cerebral peduncles.
The surface of each hemisphere is divided into 4 LOBES ……
1) Frontal.
2) Parietal.
3) Temporal.
4) Occipital.
Cerebral Lobes Histology
Basal Nuclei
What is Brainstem Formed of?
What is Brainstem Connected to?
- Cerebral hemispheres → by cerebral beduncles
- Cerebellum → by cerebellar peduncles.
Site of Cerebellum
lies at the BACK & the BOTTOM of the cranium behind the brain stem, in the posterior cranial fossa.
What is Cerebellum formed of?
Two cerebellar hemispheres connected to each other by the ‘vermis’
Composition of Cerebellum
Connection of Cerebellum
Connected to brain stem by superior, middle & inferior cerebellar peduncles.
Site of Spinal Cord
It lies in the spinal canal.
End of Spinal Cord
It ends at the lower border of the 1st lumbar vertebra (L1).
Segments of Spinal Cord
Def of Conus medullaris
The lowermost 3 segments of the spinal cord (53, 4, 5).
Def of Epiconus
The 4 segments above the conus medullaris (L4, 5, S1, 2).
what does a section in spinal cord show?
Grey matter (cells) surrounded by white matter (fibers).
Spinal Cord Grey Matter
Spinal Cord white Matter
Def of Cauda Equina
Collection of Lumbosacral roots
Functional Classification of Nervous System
Site of Cauda Equina
- It fills the lower part of the spinal canal.
- It starts at the lower border of the 1st lumbar vertebra (L1).
Compare Between Cranial Nerves & Spinal Nerves in terms of:
- Number
- Origin
- Exit
- Supply
- Course
What are cortical senstations?
the ability of the cortical sensory area to LOCALIZE the sensations perceived by the thalamus.
Parts of Voluntary Motor System
- Pyramidal System (UMN)
- Extrapyramidal System
- Cerebellar System
- LMN
Origin of Pyramidal System (UMN)
the cerebral cortex (motor area “4” & premotor area “6”).
Termination of Pyramidal System (UMN)
At the AHCs of the different levels of the spinal cord.
Control by Pyramidal System (UMN)
controls the opposite side
Functions of Pyramidal System (UMN)
Origin of Extrapyramidal System
Termination of Extrapyramidal System
Control of Extrapyramidal System
It controls the opposite side of the body.
Functions of Extrapyramidal System
- REGULATION et the voluntary motor activity.
- Regulation of the emotional & associated movements.
- Inbibition of muscle tone.
Origin of Cerebellar System
- From the cerebellum.
Termination of Cerebellar System
At the AHCs of the different levels of the spinal cord.
Control by Cerebellar System
It controls the same side of the body.
Functions of Cerebellar System
- Co-ordination the voluntary motor activity initiated by pyramidal system.
- Maintenance of equilibrium
Origin of LMN
- In the AHCS of the different levels of the spinal cord.
Termination of LMN
At the voluntary muscles.
Functions of LMN
Transmission of the motor impulse from the AHCS to the voluntary muscles.
Components of LMN
AHCS, PN, NMJ & Voluntary muscles.
Read Voluntary Motor pathway & Reflex arc from Notes
…
Def of Deep Reflex (Tendon Jerk)
This is an INDUCED (Dynamic) local axon stretch reflex.
What is Deep Reflex (Tendon Jerk) Induced by?
It is induced by:
- Sudden stretch of the muscle by tapping the tendon with a hammer.
- This induced sudden stretch will suddenly & temporarily activate the local axon reflex → this will result in sudden transient contraction of the muscle (jerk).
Components of Deep Reflex
Types of Deep Reflex
- Normal deep reflex (Tendon Jerk).
- Pathological deep reflex.
Def of Pathological Reflexes
- reflexes which are normally absent → its presence indicates U.M.N.L. (Don’t elicit them in patient with normal or hyporeflexia)
Examples of Pathological Reflexes
adductor, patellar and finger flexion reflexes
Effect of Pyramidal System on Deep Reflexes
The deep reflex receives inhibition from the Pyramidal system
UMNL & Deep Reflexes
UMNL results in loss of inhibition on the deep reflex, leading to:
- Increased deep reflex (hyperreflexia) below the level of the lesion.
- Appearance of pathological reflexes.
LMNL & Deep Reflexes
LMNL results in interruption of the reflex arc, leading to:
- Decreased deep reflex (hyporeflexia) at the level of the lesion.
Def of Muscle Tone
This is a SPONTANEOUS (Static) local axon stretch reflex:
Why is Muscle Tone spontaneous?
It is spontaneous because:
- The length of any skeletal muscle is shorter than the distance between the origin & the insertion (bone growth is faster than soft tissue growth) → so any muscle is always in a state of persistent spontaneous slight stretch.
- This spontaneous persistent stretch will persistently activate the local axon reflex → this will result in persistent (maintained) contraction of the muscle (tone).
Pyramidal & Extrapyramidal system & Muscle Tone
The Muscle tone receives inhibition from the Pyramidal & Extrapyramidal systems
UMNL & Muscle Tone
LMNL & Muscle Tone
LMNL results in interruption of the reflex arc, leading to:
- Decreased muscle tone (flaccidity) at the level of the lesion.
Def of Clonus
- Sudden sustained stretch of the muscle tendon
- Results in: Rapid, Rhythmic, Regular contractions.
What does Clonus Indicate?
Severe pyramidal lesion due to loss of inhibition on the stretch reflex.
Sites of Clonus
Ankle, patella, wrist.
When does Clonus stop?
The stretch is stopped.
Def of Superficial Reflex
- Reflex whose afferent is a superficial sensory. → (E.g. Planter reflex & abdominal reflex).
- Take facilitator fibers from both U.M.N. & L.M.N. so, they are absent in both U.M.N. L. (below the level) & L.M.N.L (at the level)
examples of Superficial Reflex
- Plantar Reflex
- Abdominal Reflex
Stimulus in Plantar Reflex
Scratching of the skin at the lateral side of the sole.
Center of Plantar Reflex
S1
Types of Responses in Plantar Reflex
- Normal (flexor response): Flexion of toes.
- Babinski sign (extensor respone)
- Absent (equivocal) response:
Normal reflex for Plantar Reflex
Flexion of toes.
Babniski sign in Plantar Reflex
Absent Reflex in Plantar Reflex
Stimulus in Abdominal Reflex
Scratch from lateral to medial.
Response in Abdominal Reflex
Abdominal muscle contraction.
Control of Abdominal Reflex
Stimulated by pyramidal tract
When is Abdominal Reflex Lost?
Pyramidal tract lesion
Def of Fasiculations
oscillatory movements of the muscles caused by an irritating lesion of the AHCs
Compare between UMNL & LMNL
what are somatic Sensations?
What are visceral sensations?
All sensations from internal viscera reaching the CNS via the Cautonomic nerves”
what are special sensations?
Including vision, hearing, smell & taste reaching the CNS via the Cranial nerves”
Sesnory Pathways
Areas of frontal Lobe
- Motor Area
- Premotor area
- Area of VCEM
- Broca’s Area
- Exner’s Area
- Prefrontal Area
- Paracentral Area
Function of Motor Area (Area 4)
Effect of Lesion in Motor Area (Area 4)
Function of Premotor Area (Area 6)
Lesion of Premotor Area (Area 6)
Function of Area of Voluntary Conjugate Eye Movement (Area 8)
Effect of Lesion in Area of Voluntary Conjugate Eye Movement (Area 8)
Site of Broca’s Area (Area 44)
Function of Broca’s Area (Area 44)
Lesion in Broca’s Area (Area 44)
Site of Exner’s Area (Area 45)
Function of Exner’s Area (Area 45)
Lesion in Exner’s Area (Area 45)
Function of Prefrontal Area
Lesion in Prefrontal Area
Function of Paracentral Lobe
Lesion in Paracentral Lobe
What are Parietal Lobe Areas?
Function of Cortical Sensory Area (Area 3,1,2)
Lesion in Cortical Sensory Area (Area 3,1,2)
Function of
- ANGULAR GYRUS (AREA 39) → IN THE DOMIÑANT HEMISPHERE)
- SUPRA-MARGINAL GYRUS AREA 40) → IN THE DOMINANT HEMISPHERE)
Lesion in
- ANGULAR GYRUS (AREA 39) → IN THE DOMIÑANT HEMISPHERE)
- SUPRA-MARGINAL GYRUS AREA 40) → IN THE DOMINANT HEMISPHERE)
Areas of Temporal Lobe
Lesion in Auditory Sensory Area (Area 41,42)
Function of Auditory Association Area (Area 22)
(Wernicke Area)
Site of Auditory Association Area (Area 22)
(Wernicke Area)
Lesion in Auditory Association Area (Area 22)
(Wernicke Area)
Auditory agnosia
the patient hears but does not understand (recognize) what he hears
Word deafness
Inability to understand spoken words but Speech production, reading and writing are normal
Sensory or receptive aphasia
- Inability to understand spoken or written words.
- The patient’s speech is fluent, but words are used inappropriately leading to neologism
Jargon / central / syntactical aphasia
Form of severe receptive aphasia with failure to produce correct words leading to neologisms and paragrammatism
Function of Limbic System
Lesion in Limbic System
Areas of Occipital Lobe
Function of Visual Sesory area (area 17)
Lesion in Visual Sesory area (area 17)
Function of Visual Associative Area (Area 18,19)
Lesion in Visual Associative Area (Area 18,19)
