Developmental Neuroscience Notes - MEDS2001 PDF

DEVELOPMENTAL NEUROSICENCE NOTES- MEDS2001 ========================================== CONTENTS [DEVELOPMENTAL NEUROSICENCE NOTES- MEDS2001 1](#developmental-neurosicence-notes--meds2001) [ORIENTATION TO THE NERVOUS SYSTEM 1](#orientation-to-the-nervous-system) [KEY CNS STRUCTURES AND NEUROANATOM...

DEVELOPMENTAL NEUROSICENCE NOTES- MEDS2001 ========================================== CONTENTS [DEVELOPMENTAL NEUROSICENCE NOTES- MEDS2001 1](#developmental-neurosicence-notes--meds2001) [ORIENTATION TO THE NERVOUS SYSTEM 1](#orientation-to-the-nervous-system) [KEY CNS STRUCTURES AND NEUROANATOMY PART 1 4](#key-cns-structures-and-neuroanatomy-part-1) [CLINICAL PRESENTATIONS 10](#clinical-presentations) [brainstem 14](#_Toc179641455) [CRANIAL NERVES 20](#_Toc179641456) [MOTOR TRACTS 27](#_Toc179641457) [SENSORY SYSTEMS 33](#sensory-systems) [MOTOR CONTROL 40](#motor-control) [COGNITION I 48](#cognition-i) [Cognition II: Higher-order cognition, meta-processing; and the limbic system 55](#cognition-ii-higher-order-cognition-meta-processing-and-the-limbic-system) [PERCEPTION AND VISUAL RECEPTION 63](#perception-and-visual-reception) [Traumatic brain injuries 73](#traumatic-brain-injuries) [neurodegenerative conditions 77](#neurodegenerative-conditions) ORIENTATION TO THE NERVOUS SYSTEM --------------------------------- **Anatomical Language** - These are the main anatomical "pairs" indicating location: - MEDIAL and LATERAL - SUPERIOR and INFERIOR (DORSAL and VENTRAL) - ANTERIOR and POSTERIOR (ROSTRAL and CAUDAL) - LEFT and RIGHT **Sections through the brain** **White matter vs Grey matter** - White matter - Contains axons and myelin (fat) - this is what makes it white - Bundles of axons are called *tracts, lemnisci* or *peduncles* - Information from the CNS is **transmitted** via the white matter - Grey matter - Contains cell bodies - On the surface of the of the brain: *cortex* - In the CNS: *nuclei* - In the peripheral nervous system (PNS): *ganglia* - Information from the CNS is **integrated** in the grey matter  **Protective mechanisms** - Both the cerebral and spinal nervous structures have multiple levels of protection from injury - 1\. Skeletal structures - **Skull** - Supports, anchors and protects the brain. First line of defence from external trauma. - Cranium actually made up of 8 separate bones that fuse between 2-18 months - Enables passage through birth canal; then allows expansion to accommodate the growing brain - *Note:* some of these supportive structures can become dangerous - Fossae on the interior floor of the skull are sharp; can shear tissue after trauma e.g. MVA - **Spinal vertebrae** - Spinal cord sits within the spinal canal - Between the vertebral body (anterior part) and the posterior processes that the muscles of our back attach to it - Each vertebral body separated by intervertebral disc - Acts as shock absorption - Disc rupture/herniation can press on nerves - Nerves branch off from/back to the spinal cord in spaces between vertebrae - Can become 'pinched' **2. Meninges** -  Located between brain and skull; and surround the spinal cord - **Dura mater-** Tough, thick; attached to inner surface of the skull - **Arachnoid-** Looks like a spider web (hence the name) - **Pia mater-** Sits directly over the brain - Subarachnoid space: space for cerebrospinal fluid (see next) - *Some texts talk about a subdural space: some research suggest this is not a natural occurrence, but that a space can develop following damage* - **3. Ventricles/cerebrospinal fluid** - **CSF** - Fluid that circulates in the ventricles (cavities/spaces), subarachnoid space and through the spinal column - Purpose of CSF: - Regulation of extracellular fluid contents in the CNS - Electrolytes - Distribution/removal of metabolic products - Protection and support of the brain and spinal cord - Shock absorption - *Note:* If there is a blockage of the system that inhibits drainage/flow or excess CFS produced, intracranial pressure is increased hydrocephalus - In infants, the skull can expand; but once bones are fused, fluid has no where to go -- so it compresses brain tissues/structures. Life threatening. **Ventricles** **Mechanisms of injury/ damage/ dysfunction in the NS** **Primary and secondary injuries** - Contusions (bruising) - Lacerations (cuts) - Compressions (to spinal cord) - Diffuse axonal injury (tearing of axons) - Haemorrhage (bleeding) - Ischemia (occlusions/lack of blood) - Necrosis - Oedema (swelling) - Increased intracranial pressure (hydrocephalus) - Haematoma in the meninges (pooling of blood) - Risk of infection **Other considerations** - - Location - Left/right? - Lateral/medial? - Spinal level? - Focal or diffuse? - Specific or widespread? - Medical history (comorbidities) and/or other issues - Broken vertebrae -\> risk of spinal laceration - Previous disc herniation -\> risk of compression - Previous transient ischaemic attacks (TIA) **Impact** - As OTs in neuro, we are often working with clients either with uncertain diagnoses (or without one entirely). - We may know the mechanism and some of the associated primary and secondary injuries; and need to determine the associated impact we are likely to see - [OR] we may know the signs/symptoms the person is presenting with; and need to work backward to determine possible mechanism - While we do not diagnose, we are often integral to this process -- thanks to our knowledge of neuro structures and associated functions; and conducting associated observations and screens to document the person's functional presentation - **This is what this unit is equipping you to be able to do** KEY CNS STRUCTURES AND NEUROANATOMY PART 1 ------------------------------------------ **Cerebral cortex** - Cortex- meaning outer - Responsible for social behaviours/cognition (anterior part) and motor function (posterior part) +-----------------------------------+-----------------------------------+ | | - Function/role | +===================================+===================================+ | | - | +-----------------------------------+-----------------------------------+ | | - | +-----------------------------------+-----------------------------------+ | | - Voluntary motor movement | +-----------------------------------+-----------------------------------+ | | - Motor planning/praxis | +-----------------------------------+-----------------------------------+ | | - Supports postural control | +-----------------------------------+-----------------------------------+ | | - Language | | | production/expression (verbal | | | or written) | +-----------------------------------+-----------------------------------+ | | - Executive function | | | (reasoning, judgment, | | | planning, organisation); | | | Working memory | | | | | | - Aspects of social | | | interactions (dis/inhibition, | | | patience, etc) | +-----------------------------------+-----------------------------------+ | | - Cognitive planning of | | | movement | +-----------------------------------+-----------------------------------+ **Parietal Lobes** - Responsible primarily for sensory detection, perception and interpretation -- supports awareness and understanding of both the body and the environment - Also has a role in attention and arithmetic (mathematics) +-----------------------------------+-----------------------------------+ | Key areas/landmarks | - Function/role | +===================================+===================================+ | **Postcentral gyrus** | | +-----------------------------------+-----------------------------------+ | **Primary somatosensory cortex** | - Receipt of tactile and | | | proprioceptive information | +-----------------------------------+-----------------------------------+ | **Somatosensory association | - Interpretation of sensory | | cortex** | information (includes | | | tactile, visuospatial and | | | auditory) | +-----------------------------------+-----------------------------------+ | **Wernicke's area** | - *(covered in temporal)* | | | | | ***(parieto-temporal area)*** | | +-----------------------------------+-----------------------------------+ **Temporal lobes** - Responsible for hearing and language, much of it buried in the lateral fissure - The medial aspect of the temporal lobe contains the limbic system (including the hippocampus, hypothalamus and amygdala) which is responsible for memory, emotion regulation and behavior +-----------------------------------+-----------------------------------+ | Key areas/landmarks | - Function/role | +===================================+===================================+ | Lateral fissure | | +-----------------------------------+-----------------------------------+ | Superior temporal gyrus | | +-----------------------------------+-----------------------------------+ | Inferior temporal gyrus | | +-----------------------------------+-----------------------------------+ | Primary auditory cortex | - Receipt of auditory | | | information | +-----------------------------------+-----------------------------------+ | Associative auditory cortex | - Interpretation of auditory | | | information | +-----------------------------------+-----------------------------------+ | Wernicke's area | - Speech and language | | | comprehension (written and | | *(parieto-temporal area)* | verbal) | +-----------------------------------+-----------------------------------+ **Occipital lobes** - Responsible for visual processing - Note that more of the occipital lobe is located on the medial surface of the hemisphere +-----------------------------------+-----------------------------------+ | Key areas/landmarks | - Function/role | +===================================+===================================+ | **Parieto-occipital sulcus** | | +-----------------------------------+-----------------------------------+ | **Primary visual cortex** | - Receipt of visual | | | information; distinguishing | | | intensity of light/object | | | shape/size/location | +-----------------------------------+-----------------------------------+ | **Visual association cortex** | - Interpretation of visual | | | information | +-----------------------------------+-----------------------------------+ **\ ** **Insula** - Sometimes considered the fifth lobe but also seen as an extension of the temporal lobe and limbic system - Located deep in the lateral fissure - Main function is related to survival including: - Gustation (taste) - Sensation of viscera (i.e. organs) - Autonomic functions - Homeostatic functions - Also linked to having a role in emotional processing (linked to the limbic system) **Corpus Callosum** - Bundle of nerve fibres -- largest commissure in the brain - Connects left and right hemispheres -- enables communication between the hemispheres Primary= receipt of information Association= interpretation of information **Left vs right hemisphere dysfunctions** +-----------------------------------+-----------------------------------+ | **Left hemisphere** | **Right hemisphere** | +===================================+===================================+ | - Right-side | - Left-side | | | | | - Movement control | - Movement control | | | | | - Sensory information | - Sensory information | | | | | - More 'concrete' cognitive | - Interpreting perceptual and | | processes | spatial information | | | | | - Language (expression and | - Reading maps; creating | | interpretation of words)- | music/art | | aphasias | | | | - Abstract interpretation | | *Corpus callosum enables the two | | | hemispheres to have some | - Other aspects of language | | differentiated functions* | (e.g. tone, underlying | | | emotion) | +-----------------------------------+-----------------------------------+ **Diencephalon** - Consists of the: - **Thalamus** - Largest part of the diencephalon - Made up of 2 thalamic nuclei - **Hypothalamus** - Located inferior to the thalamus, in the medial part of middle cranial fosse close to optic chiasm and mammillary bodies - *(note: some texts now refer to these separately)* - Epithalamus - Subthalamus (we won't focus on these structures) **Functions of the Thalamus** - Information relayed from different parts of the CNS to the cerebral cortex - Processing of emotions and some memory - Integration of visual information and touch - Regulation of consciousness, arousal and attention **Basal Ganglia Cerebellum Brain Stem**  CLINICAL PRESENTATIONS ---------------------- +-------------+-------------+-------------+-------------+-------------+ | **Name of | **Structure | **Definitio | **What does | **Impact on | | clinical | /s | n** | it look | occupation? | | presentatio | damaged** | | like?** | ** | | n/ | | | | | | issue** | | | **(i.e. | | | | | | what would | | | | | | I need to | | | | | | observe to | | | | | | indicate | | | | | | possible | | | | | | issue?)** | | +=============+=============+=============+=============+=============+ | **Broca's | The left | Expressive | Reduced | If no | | Aphasia** | side of | (non-fluent | speech | Wernicke's | | | Frontal | ) | (limited to | impact can | | | lobe | aphasia | several | still read | | | (Broca's | | words at a | and | | | areas) | Difficulty | time) | understand | | | | producing | | speech | | | | language | Limited | | | | | (written or | vocabulary | Know what | | | | verbal) in | | they want | | | | a clear way | 'Clumsy' | to say | | | | | formation | (usually | | | | | of sounds | have | | | | | | insight re: | | | | | Difficulty | difficultie | | | | | 'finding' | s | | | | | words | | | | | | | It\'s | | | | | Difficulty | frustrating | | | | | writing | when they | | | | | (jumbled, | can't say | | | | | incorrect | what they | | | | | words) | want (tip | | | | | | of the | | | | | | | | | | | [- | | | | | | ]{.underlin | | | | | | e} | | | | | | | | | | | | | | | | | | | | | | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Wernicke' | Left | Receptive/f | Speak well | They may | | s | posterior | luent | and often | not know | | aphasia** | temporal | aphasia | in long | that what | | | region | | sentences, | they're | | | (Wernicke's | Difficultie | but | saying does | | | area) | s | sentences | not make | | | | with | don't | sense- it | | | | comprehensi | connect | is | | | | on | /make sense | frustrating | | | | of spoken | and may | when people | | | | (and | include | don't | | | | written) | irrelevant/ | understand | | | | words | nonsense | them | | | | | words | | | | | | | - Occupat | | | | | [Remember]{ | ion | | | | |.underline} | | | | | | if we have | - Rapport | | | | | difficulty | buildin | | | | | comprehendi | g | | | | | ng, | | | | | | this will | - Informa | | | | | have a | tion | | | | | flow-on | gatheri | | | | | impact on | ng | | | | | the | about | | | | | expression | other | | | | | | areas- | | | | | Difficultie | cogniti | | | | | s | on | | | | | with both | | | | | | reading and | - Interve | | | | | writing | ntion | | | | | | deliver | | | | | | | | | | | [ | | | | | | ]{.underlin | | | | | | e} | | | | | | | | | | | | | | +-------------+-------------+-------------+-------------+-------------+ | **Hemiplegi | Right | Hemi= half | - Paresis | [Living | | a** | primary | | /paralysis | with right | | | motor | Plegia = | | hemiplegia | | | cortex | loss of | - Tot | and the | | | | muscle | al | things I do | | | | function | los | to become | | | | | s | more | | | | **Hemiplegi | of | independent | | | | a** | mov | - | | | | = **loss of | ement: | YouTube](ht | | | | muscle | par | tps://www.y | | | | function/we | alysis | outube.com/ | | | | akness | | watch?v=rBf | | | | in one side | - Par | G1Q-3GdE)  | | | | of the | tial | | | | | body** | los | | | | | | s | | | | | As part of | of | | | | | an UMN | mov | | | | | lesion, | ement: | | | | | usually | par | | | | | also see | esis | | | | | hypertonia/ | | | | | | spasticity | - Oft | | | | | | en | | | | | Hypertonia: | see | | | | | Increased | ter | | | | | tone/resist | med | | | | | ance | 'he | | | | | to passive | miparalysis | | | | | movement | /hemiparesi | | | | | | s/**hemiple | | | | | Spasticity: | gia**' | | | | | type of | of | | | | | hypertonia, | con | | | | | whereby | tralateral | | | | | muscles | sid | | | | | continuousl | e | | | | | y | | | | | | contract | - Hyperto | | | | | | nia/spastic | | | | | Due to | ity | | | | | damage | | | | | | [anywhere | - Inc | | | | | along the | reased | | | | | pathway for | ton | | | | | voluntary | e/resistanc | | | | | motor | e | | | | | control | to | | | | | ]{.underlin | pas | | | | | e} | sive | | | | | | mov | | | | | | ement | | | | | | | | | | | | - Spa | | | | | | sticity: | | | | | | typ | | | | | | e | | | | | | of | | | | | | hyp | | | | | | ertonia, | | | | | | whe | | | | | | reby | | | | | | mus | | | | | | cles | | | | | | con | | | | | | tinuously | | | | | | con | | | | | | tract | | | | | | | | | | | | - Clonus | | | | | | | | | | | | - Return | | | | | | of | | | | | | primiti | | | | | | ve | | | | | | reflexe | | | | | | s | | | | | | (due to | | | | | | loss of | | | | | | volunta | | | | | | ry | | | | | | control | | | | | | ) | | | | | | E.g. | | | | | | Babinsk | | | | | | i | | | | | | common | | | | | | | | | | | | - Abnorma | | | | | | l | | | | | | muscle | | | | | | synergi | | | | | | es, | | | | | | as | | | | | | agonist | | | | | | /antagonist | | | | | | pairs | | | | | | of | | | | | | contrac | | | | | | tion/relaxa | | | | | | tion | | | | | | aren't | | | | | | in sync | | +-------------+-------------+-------------+-------------+-------------+ | **Apraxia: | | Difficultie | - Can | Client with | | Ideomotor** | | s | usually | ideomotor: | | | | with [motor | still | | | | | Difficulty | ts | | | | | with | (thanks | Be prepared | | | | initiation | to | to discuss | | | | and | basal | your | | | | execution | ganglia | obs/interpr | | | | of planned | ), | etations | | | | movement | but | | | | | sequences | can't | Useful | | | | | do | video | | | | | things | resource | | | | | on | | | | | | request | https://www | | | | | or copy |.youtube.co | | | | | -- as | m/watch?v=7 | | | | | they | 4BeyDnH-EE | | | | | can't | | | | | | make | | | | | | the | | | | | | plan | | | | | | for how | | | | | | to do | | | | | | it. | | | | | | | | | | | | - Impreci | | | | | | se, | | | | | | awkward | | | | | | , | | | | | | clumsy | | | | | | movemen | | | | | | ts | | | | | | | | | | | | - Difficu | | | | | | lty | | | | | | manipul | | | | | | ating | | | | | | objects | | | | | | | | | | | | - How to | | | | | | adjust | | | | | | grasp; | | | | | | in-hand | | | | | | manipul | | | | | | ation | | | | | | | | | | | | - Usually | | | | | | due to | | | | | | [pre-mo | | | | | | tor | | | | | | cortex | | | | | | damage] | | | | | | {.underline | | | | | | } | | | | | | | | | | | | - often | | | | | | on left | | | | | | side | | +-------------+-------------+-------------+-------------+-------------+ | **Apraxia: | | Difficultie | - Issues | Client to | | ideational* | | s | with | watch: | | * | | [understand | percept | | | | | motor tasks | of | | | | | that were | objects | | | | | conceptual | | | | | | aspects of | - E.g | | | | | motor tasks |. | | | | | - | Cor | | | | | sequencing, | rect | | | | | organising | use | | | | | task, | /purpose | | | | | planning | of | | | | | for it | obj | | | | | | ects | | | | | | -- | | | | | | wha | | | | | | t | | | | | | is | | | | | | it | | | | | | for | | | | | | | | | | | | - | | | | | | *Think | | | | | | | | | | | | the | | | | | | | | | | | | Little | | | | | | | | | | | | Mermaid | | | | | | | | | | | | brushing | | | | | | | | | | | | her | | | | | | | | | | | | hair | | | | | | | | | | | | with | | | | | | | | | | | | a | | | | | | | | | | | | fork!* | | | | | | | | | | | | - Wha | | | | | | t | | | | | | is | | | | | | the | | | | | | req | | | | | | uired | | | | | | seq | | | | | | uence | | | | | | of | | | | | | act | | | | | | ions | | | | | | e.g | | | | | |. | | | | | | the | | | | | | ord | | | | | | er | | | | | | in | | | | | | whi | | | | | | ch | | | | | | you | | | | | | nee | | | | | | d | | | | | | to | | | | | | put | | | | | | clo | | | | | | thes | | | | | | on | | | | | | for | | | | | | dre | | | | | | ssing | | | | | | | | | | | | - Usually | | | | | | due to | | | | | | [prefro | | | | | | ntal | | | | | | cortex | | | | | | and/or | | | | | | parieta | | | | | | l | | | | | | lobe | | | | | | damage | | | | | | (common | | | | | | ly | | | | | | on left | | | | | | side)]{ | | | | | |.underline} | | +-------------+-------------+-------------+-------------+-------------+ | | | | - | | +-------------+-------------+-------------+-------------+-------------+  **Two key things to remember with hemiplegia:** 1. Remember the brain controls the muscles of the opposite side of the body (because of the medullar decussation) - So right sided brain damage (e.g. to the primary motor cortex) impacts the left side of the body: so we call this left hemiplegia 2. The specific parts of the body that are affected are impacted by which specific parts of the primary motor and its associated tracts are damaged - This is represented via something called the **homunculus** (see picture) - Hemiplegia can impact lower limbs, upper limbs, trunk and/or face so when we're observing for hemiplegia (or it's on a referral), we want to be thinking about which parts of body are affected +-----------------+-----------------+-----------------+-----------------+ | - **Name of | - **What it | - **Caused by | - **Draw a | | deficit** | means/issue | damage | diagram/ins | | | it | to:** | ert | | | creates** | | a picture | | | | | representin | | | | | g | | | | | the deficit | | | | | OR describe | | | | | the | | | | | deficit** | +=================+=================+=================+=================+ | - **Ptosis** | - | - | - | +-----------------+-----------------+-----------------+-----------------+ | - **Left | - | - | - | | homonymous | | | | | hemianopia* | | | | | * | | | | +-----------------+-----------------+-----------------+-----------------+ | - **Right | - | | - | | homonymous | | | | | hemianopia* | | | | | * | | | | +-----------------+-----------------+-----------------+-----------------+ | - **Bitempora | - | - | - | | l | | | | | hemianopia* | | | | | * | | | | +-----------------+-----------------+-----------------+-----------------+ | - **Unilatera | - | - | - | | l | | | | | blindness** | | | | +-----------------+-----------------+-----------------+-----------------+ | - **Nystagmus | - | - | - | | ** | | | | +-----------------+-----------------+-----------------+-----------------+ | - **Strabismu | - | - | - | | s** | | | | +-----------------+-----------------+-----------------+-----------------+ []{#_Toc179641455.anchor}brainstem **Brainstem** +-----------------------+-----------------------+-----------------------+ | - **Primary | | | | function is | | | | survival** | | | | | | | | - Overall controls: | | | | | | | | - Respiration | | | | | | | | - Cough and gag | | | | reflexes | | | | | | | | - Pupillary | | | | response | | | | | | | | - Swallowing | | | | reflex | | | | | | | | - Consists of three | | | | main structures: | | | | | | | | - Midbrain | | | | | | | | - Pons | | | | | | | | - Medulla | | | | | | | | - Have some | | | | unique | | | | functions | | | | but also | | | | many | | | | shared | | | | ones | | | | | | | | Contains the | | | | Reticular Formation | | | | (RF) | | | +=======================+=======================+=======================+ | **Midbrain** | - Function in | | | | automatic | | | | reflexive | | | | behaviours: | | | | | | | | - Vision | | | | | | | | - Audition | | | | | | | | - Motor control | | | | | | | | - Alertness | | | | | | | | - Temperature | | | | regulation | | | | | | | | - Sleep/wake | | | | cycles | | | | | | | | - *Some via | | | | the RF | | | | (see | | | | later)* | | | | | | | | - Origin of 2 | | | | cranial nerves: | | | | | | | | - III | | | | oculomotor | | | | (midbrain-pon | | | | s | | | | junction) | | | | | | | | - IV trochlear | | +-----------------------+-----------------------+-----------------------+ | **Pons** | - Relay system |  | | | spinal cord, | | | | cerebellum and | | | | cerebrum | | | | | | | | - Cerebellar | | | | peduncles: | | | | information about | | | | the body's | | | | position in space | | | | | | | | - Cerebellar | | | | Peduncles | | | | (brainstem) | | | | Cerebellum | | | | Thalamus | | | | Cerebellar | | | | Peduncles | | | | (brainstem) | | | | Spinal Cord | | | | | | | | - Makes unconscious | | | | motor adjustments | | | | based on sensory | | | | information e.g. | | | | shifting weight | | | | | | | | - Origin of cranial | | | | nerves: | | | | | | | | - V trigeminal | | | | | | | | - VI abducens, VII | | | | facial, VIII | | | | vestibulocochlear | | | | | | | | - (VI-VIII all | | | | pons-medulla | | | | junction) | | +-----------------------+-----------------------+-----------------------+ | **Pons -- cerebellar | |  | +-----------------------+-----------------------+-----------------------+ | **Medulla** | - Where the brain |  | | | cord; considered | | | | an extension of | | | | the spinal cord | | | | | | | | - The motor and | | | | sensory tracts | | | | pass through the | | | | medulla | | | | | | | | - Descending | | | | motor tracts | | | | -- carry | | | | motor | | | | information | | | | from the | | | | brain to the | | | | spinal cord | | | | | | | | - Ascending | | | | sensory | | | | tracts -- | | | | carry sensory | | | | information | | | | from the | | | | spinal cord | | | | to the brain | | | | | | | | - Contains the | | | | pyramids -- | | | | decussation | | | | (crossover) of | | | | the descending | | | | motor tracts | | | | | | | | | | | | | | | | - Origin of cranial | | | | nerves: | | | | | | | | - IX | | | | glossopharyng | | | | eal | | | | | | | | - X vagus | | | | | | | | - XI accessory | | | | | | | | - XII | | | | hypoglossal | | | | | | | | - Via the RF, | | | | contains centres | | | | for: | | | | | | | | - Blood | | | | pressure | | | | | | | | - Heart rate | | | | | | | | - Respiration | | | | | | | | - Vasoconstrict | | | | ion | | | | and dilation | | | | | | | | - Reflexive | | | | functions of | | | | vomiting, | | | | coughing, | | | | sneezing & | | | | swallowing | | +-----------------------+-----------------------+-----------------------+ | **Reticular | - The reticular |  is | ) | | | a group of | | | | interconnected | | | | neurons located | | | | in the brainstem | | | | and spinal cord | | | | | | | | - Is connected to | | | | the cerebral | | | | cortex, | | | | hypothalamus, | | | | thalamus, and | | | | cerebellum | | | | | | | | - Roles: | | | | | | | | - Postural | | | | control (via | | | | reticulospina | | | | l | | | | tract) | | | | | | | | - Visceral | | | | motor | | | | function e.g. | | | | cardiac/respi | | | | ratory | | | | muscles | | | | | | | | - Controls gag, | | | | cough, | | | | sneeze, | | | | swallow, | | | | vomit | | | | reflexes | | | | | | | | - Pain | | | | regulation | | | | | | | | - Arousal/alert | | | | ness/wakefulness | | | | via the | | | | Reticular | | | | Activating | | | | and | | | | Inhibitory | | | | Systems | | | | | | | | - Sleep/wak | | | | e | | | | cycles | | | | (balances | | | | arousal/w | | | | akefulness | | | | with calm | | | | state/sle | | | | ep) | | | | | | | | - Conscious | | | | ness | | | | | | | | - Filtering | | | | of | | | | sensory | | | | informati | | | | on, | | | | alerts | | | | the | | | | cortex | | | | about | | | | what to | | | | attend to | | | | (focusing | | | | attention | | | | on | | | | important | | | | informati | | | | on) | | +-----------------------+-----------------------+-----------------------+ **Damage to the Brainstem/RF** - [Often life-threatening] due to ANS functions and role in consciousness - Impact on: - ANS/unconscious functions (respiration, heart rate, etc) - Consciousness coma - Sensory and motor pathways (due to transiting through the brainstem) - Cranial nerves - **E.g. Locked-in syndrome** - Usually caused by damage to anterior part of the pons - Causes complete paralysis of voluntary muscles except those of the eyes, due to interruption to nerves/motor tracts from brain to most muscles *(except the oculomotor nerve -- see cranial nerves)* - Also impacts facial control, breathing, swallowing, speaking BUT consciousness and cortical functions are preserved (i.e. cognition and awareness largely intact) []{#_Toc179641456.anchor}CRANIAL NERVES **Cranial nerves** - 12 paired nerves that originate in the cerebrum or brainstem - Compared to spinal nerves originate in the spinal cord - Are considered to be part of the peripheral nervous system - Nerves that have a motor function are [lower motor neurons] connected to the brain via the corticobrainstem tract (upper motor neuron) - *This will make more sense when we cover motor tracts* - May have motor or sensory functions [or] both - Relate mostly to functions of the face/head/neck, but also extend to other areas **Cranial Nerve Functions** - - - - - **Harry Potter and the Cranial Nerves** 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. +-----------------------------------+-----------------------------------+ | **Olfactory** | - Function: Smell | | | (olfaction=sense of smell) | | | | | | - Sensory | | | | | | - Sends information from | | | [chemoreceptors] | | | in the nose to the frontal | | | lobe (olfactory bulb) | | | | | | - Then the | | | | | | - Hippocampus | | | (long-term memory of | | | smells) | | | | | | - Smell and memory | | | very strongly | | | linked | | | | | | - ANS areas | | | (hypothalamus) | | | | | | - Areas response for | | | emotional response | | | (amygdala) | | | | | | - Areas that link it to | | | taste information | +===================================+===================================+ | **Optic** | - Function: Vision (visual | | | acuity) | | | | | | - Sensory | | | | | | - About transmitting visual | | | information NOT eye | | | movement | | | | | | - Send information from | | | receptors of the retina to: | | | | | | - Brainstem (unconscious | | | responses e.g. pupillary | | | reflexes) | | | | | | - Occipital lobes for | | | interpretation of visual | | | information | +-----------------------------------+-----------------------------------+ | **Oculomotor, trochlear, | - As group, called the | | abducens** | extraocular motor nerves | | | | | | - All innervate muscles that | | | control movements of the eye: | | | | | | - Oculomotor: up; down; | | | medial; lateral | | | | | | - Trochlear: down+medial | | | (intorsion-primary); some | | | lateral via rotation | | | | | | - Abducens: lateral | | | | | | - Oculomotor also | | | | | | - Lift the eyelid | | | | | | - Controls certain reflexes | | | | | | - Pupillary reflex | | | *(constriction with | | | light)* | | | | | | - Accommodation | | | *(adjustments for | | | light)* | | | | | | - Convergence *(think | | | cross-eyed)* | +-----------------------------------+-----------------------------------+ | **Trigeminal** | - Sensati | | | on | | | of the face -\> branches into | | | three zones | | | | | | - Pain; temperature; touch | | | | | | - Cornea sensation (relays info | | | that triggers facial corneal | | | reflex i.e. blink) | | | | | | - Controls the muscles that | | | move | | | | | | - the jaw for chewing | +-----------------------------------+-----------------------------------+ | **Facial** | - Transmit information from the | | | taste receptors on the tongue | | | (anterior part) | | | | | | - Controls muscles that create: | | | | | | - Facial expressions | | | | | | - Eyelid closure | | | | | | - Some functions of the | | | middle ear | | | | | | - Corneal reflex (closes eyelid | | | when | | | | | | - cornea touched); also create | | | tears. | | | | | | - ***Note:*** almost all | | | cranial nerves stay | | | ipsilateral (same side) | | | except for part of the facial | | | nerve | | | | | | - Nerves that control | | | muscles of the lower | | | face: cross over (i.e. R | | | controls L) | | | | | | - Nerves that control | | | muscles of the upper | | | face: | | | [bilateral:] | | | one ipsilateral, one | | | contralateral (i.e. have | | | dual input on both sides | | | of the face -- so there's | | | a back up) | | | | | | - *This becomes | | | important in | | | distinguishing facial | | | nerve damage versus | | | damage at the higher | | | cortical/brain level* | +-----------------------------------+-----------------------------------+ | **Vestibulococchlear** | - Two branches: | | | | | | - **A | | | uditory | | | nerve** -- transmits | | | information from the | | | cochlear hearing | | | (audition) | | | | | | - **Vestibular nerve** -- | | | transmit information from | | | the inner ear balance, | | | equilibrium, position of | | | the head in space, | | | sensations of | | | vertigo/dizziness | +-----------------------------------+-----------------------------------+ | **Glossopharyngeal; Vagus; | - All play in big role in | | Accessory; Hypoglossal** | swallowing and/or speaking | | | | | | - **Glossopharyngeal:** | | | | | | - Taste (with facial -- | | | posterior tongue) | | | | | | - Gag and swallowing | | | reflexes | | | | | | - Salivation | | | | | | - **Vagus** | | | | | | - Taste (from palate, | | | epiglottis) | | | | | | - Controls muscles of | | | larynx, pharynx, | | | upper oesophagus | | | | | | - Also gag and | | | swallowing | | | reflexes | | | | | | - **Accessory** | | | | | | - Larynx elevation for | | | swallowing | | | | | | - Also head | | | flexion/extension, | | | contralateral | | | rotation; shoulder | | | elevation, | | | flexion \>90 (via | | | sternocleidomastoid; | | | upper trap) | | | | | | - **Hypoglossal** | | | | | | - Tongue movement | +-----------------------------------+-----------------------------------+ | **Vagus** | - Vagus nerve additionally has | | | a big role in parasympathetic | | | nervous system response | | | | | | - Heart | | | | | | - Pulmonary system | | | | | | - Oeosophagus | | | | | | - Gastrointestinal tract | +-----------------------------------+-----------------------------------+  []{#_Toc179641457.anchor}MOTOR TRACTS Motor Tracts **Motor divisions of the nervous system** - Execution of motor commands/movement, through carrying motor information from the central nervous system to: - Somatic NS - skeletal muscles - Autonomic NS - smooth & cardiac muscle - glands, adipose tissues - Somatic nervous system is our focus for this lecture - Made up of descending motor tracts (also called descending motor pathways) - Role: Execution of motor movements (voluntary and involuntary/automatic) via skeletal muscle contractions **Motor pathways divided into:** - Upper Motor Neurons (UMN): - Originate in the cerebrum (primary motor cortex) - Travel through the internal capsule, to the brainstem/spinal cord - Essentially within the CNS - Lower Motor Neurons (LMN): - Essentially begin where the nerve exits the brainstem/spinal cord (then called cranial/spinal nerves), to the end point at the muscles - Our peripheral NS **Two key groups of motor tracts** - **Pyramidal** - Originate in the cerebral cortex - Carry motor fibres to the spinal cord and brainstem (and then beyond) - Responsible for voluntary control of muscles of the face and body - ***Corticospinal, corticobulbar*** - **Extrapyramidal** - Originate in the brainstem - Carry motor fibres to the spinal cord (and then beyond) - Responsible for involuntary/automatic control of muscles (tone, balance, posture) - ***Vestibulospinal, reticulospinal, rubrospinal*** - ***(also tectospinal but not covering this)*** **Key descending motor tracts** **Corticospinal tracts** - The corticospinal tracts originate in the primary motor cortex (precentral gyrus) - The lateral corticospinal tracts (majority of fibres) - Decussate (crossover) at the pyramids - Innervates LMNs that control skeletal muscles of the upper and lower limbs, and fine motor control of the hands - The anterior corticospinal tracts - remain ipsilateral as they pass through the medulla - but decussate at the spinal cord level - Innervates LMNs that control skeletal muscles of the neck, shoulders, and trunk (i.e. postural control) - Meaning both ultimately innervate contralaterally **Corticobrainstem tracts** - The corticobrainstem tracts originate in the primary motor cortex (precentral gyrus) - Innervate [cranial nerve] LMNs that control muscles of the face, tongue, pharynx, larynx, sternocleidomastoid and trapezius - *Note: We aren't going to go into detail regarding specific decussation of corticobrainstem and subsequent cranial nerves, ipsi versus bilateral -- there is enough to learn here without focusing in on this!* - What is important to remember, is that most cranial nerves have bilateral supply (i.e. a back up). The exceptions are: - Parts of the facial nerve creates contralateral lower facial droop - Hypoglossal nerve tongue deviation - Even this can impact overall tongue function, impacting swallowing, speech **Pyramidal tracts** **Extrapyramidal system** - Actually a series of structures - Connected to the motor cortex, but with many of the ultimate functions (via the tracts) influenced by the basal ganglia - More on the BG next week - All originate in areas of the brainstem, including the reticular formation - This is why the RF has a role in postural control **Extrapyramidal tracts** **Damage to motor pathways** Consequences/presentation is dependent on the location of damage. Some key areas; - - - - - - - +-----------------------+-----------------------+-----------------------+ | Internal capsule | - Bundle of axons | | | | which transmit | | | | information | | | | between the | | | | cortex and the | | | | thalamus (both | | | | motor and sensory | | | | information), | | | | basal ganglia, | | | | brainstem and | | | | spinal cord | | | | | | | | - All the fibres | | | | fanning out at | | | | the cortex are | | | | called the corona | | | | radiata. As these | | | | converge lower | | | | down, this forms | | | | the internal | | | | capsule. | | | | | | | | - Damage to a small | | | | area here can | | | | obviously **cause | | | | quite widespread | | | | impact** | | | | functionally | | | | (e.g. weakness or | | | | sensation issues | | | | to lots of the | | | | contralateral | | | | side of the | | | | body.) | | +=======================+=======================+=======================+ | Thalamus, Basal | - The thalamus, |  | | | brainstem provide | | | | connection and | | | | relay between | | | | multiple areas in | | | | the CNS for motor | | | | information | | | | | | | | - Damage to these | | | | structures is | | | | therefore going | | | | to impair the | | | | pathways they | | | | mediate | | | | | | | | - Basal ganglia and | | | | brainstem: | | | | particularly | | | | extrapyramidal | | | | tracts (linked to | | | | and originate in | | | | these structures) | | | | | | | | - Medullary pyramid | | | | of the brainstem: | | | | damage here | | | | impacts ability | | | | for motor | | | | messages to | | | | descend out to | | | | muscles | | +-----------------------+-----------------------+-----------------------+ | Upper Motor Neuron | - Damage to UMN's | | | (UMN) lesions | -- often as a | | | | result of brain | | | | injury (cortex, | | | | brainstem) | | | | | | | | - **Common signs:** | | | | | | | | - Paresis/paralysis | | | | | | | | - Total loss of | | | | movement: | | | | paralysis | | | | | | | | - Partial loss | | | | of movement: | | | | paresis | | | | | | | | - Often see | | | | termed | | | | 'hemiparalysi | | | | s/hemiparesis/**hemip | | | | legia**' | | | | of | | | | contralateral | | | | side | | | | | | | | - Hypertonia/spasti | | | | city | | | | | | | | - Increased | | | | tone/resistan | | | | ce | | | | to passive | | | | movement | | | | | | | | - Spasticity: | | | | type of | | | | hypertonia, | | | | whereby | | | | muscles | | | | continuously | | | | contract | | | | | | | | - Clonus | | | | | | | | - Type of | | | | involuntary | | | | muscle | | | | contraction | | | | | | | | - Creates | | | | uncontrollabl | | | | e, | | | | rhythmic, | | | | shaking | | | | movements | | | | (large | | | | motions) | | | | | | | | - Return of | | | | primitive | | | | reflexes (due to | | | | loss of voluntary | | | | control) | | | | | | | | - E.g. Babinski | | | | common | | | | | | | | - Abnormal muscle | | | | synergies | | | | | | | | - As | | | | agonist/antag | | | | onist | | | | pairs of | | | | contraction/r | | | | elaxation | | | | aren't in | | | | sync | | | | | | | | - Co-contra | | | | ction | | | | of both | | | | | | | | - Spasticit | | | | y/hyperreflexia | | +-----------------------+-----------------------+-----------------------+ | Lower Motor Neuron | - Damage to LMN's | | | (LMN) lesions | -- peripheral | | | | nerve injuries; | | | | conditions like | | | | spinal muscular | | | | atrophy, polio | | | | (proper term | | | | poliomyelitis) | | | | | | | | - **Common signs:** | | | | | | | | - Paralysis | | | | | | | | - A complete | | | |