Central Nervous System (CNS) Flashcards
CNS
Consists of Brain and Spinal Cord
Integration, decision making, and processing of signals
Peripheral Nervous System (PNS)
Consists of nerves and ganglia
Signals traveling to/from targets in the periphery
Afferent and Efferent signals
CNS and PNS are connected via a constant feedback loop
Sensory info → AFFerent
incoming info, INTO CNS
Motor info → EFFerent
outgoing info, FROM CNS to PNS
CNS
Major Divisions:
Cerebral cortex
Diencephalon
Cerebellum
Brainstem
continues inferiorly as the spinal cord
Cerebral Cortex
Outermost layer of brain
Associated w/ higher lever processing and functioning
Divided into right and left hemispheres
Folded to increase SA for info processing
gyri - bumps/folds of cortex
sulci - grooves/indentations
fissure - deep sulcus
longitudinal fissure divides hemispheres
Cerebral Cortex: Matter
Each hemisphere is made up of white and gray matter
“Matter” = made up of different parts of CNS cells called NEURONS
Grey Matter vs. White Matter
Cerebral Cortex: Corpus Callosum
Major white matter tract found beneath the cerebral cortex
Largest collection of white matter w/in brain
Connects left and right hemispheres and carries info received in one hemisphere over to the other
Clinical Correlation: Split Brain Syndrome and Hemisphere Dominance
Corpus callostomy: when corpus callosum = surgically severed as a last-resort tx of pt suffering from epilepsy → can stop seizures from spreading from one hemisphere to the other
Pts known as “split brain” pts due to lack of connection between left and right hemispheres (most deficits = language related)
Speech → generated in left hemisphere (dominant hemisphere for language)
Cerebral Cortex: Each Hemisphere has 4 Lobes
Frontal = cognition, control of voluntary movement
Parietal = processes info about pain, temp, taste, touch, and vibration
Temporal = processes memories and auditory info
Occipital = primarily responsible for processing visual sensation
Key Cortical Areas and their Specific Functions
Cerebral Cortex: Central Sulcus
Separates parietal lobe from frontal lobe
Precentral gyrus → represents primary motor cortex in frontal lobe
Post-central gyrus → represents the primary somatosensory cortex in parietal lobe
Cortical Homunculus: Motor and Sensory Mapping of Cortex
Frontal - Broca’s Area
Function:
motor production of speech and articulation
damage to this area results in “non-fluent aphasia”
^poor or absent grammar // omitting common words // difficulty forming complete sentences // difficulty w/ articulating sounds and words
Parietal/Temporal/Occipital = Wernicke’s Area
Function
language interpretation and understanding
damage to this area results in “fluent aphasia”
^results in articulating sentences that have the appropriate cadence but lack the right words // jumbling words together in a seemingly arbitrary sequence // inserting made-up, nonsense-like words into sentences // being unaware that you may be articulating something incomprehensible to others
INDIVIDUALS W/ WERNICKE’S APHASIA ≠ ABLE TO COMPREHEND WHAT IS BEING SAID TO THEM
Diencephalon
Large mass of grey matter found between the cerebrum and brainstem
Thalamus → major relay center for all incoming sensory info (EXCEPT olfaction/smell)
Hypothalamus → coordinates autonomic nervous system & pituitary gland to regulate body temp, maintain homeostasis, control appetite, manage sexual behavior, regulate emotional responses
Brainstem
Connects cerebrum w/ spinal cord
Coordinates motor control signals sent from brain to body
Controls autonomic functions
HR, RR, BP
- *Composed of 3 Parts:**
- *midbrain**
- *pons**
- *medulla oblongata**
Cerebellum
Located posteriorly
Sits inferior to occipital and temporal lobes
“Little brain” in Latin
Coordinates and regulates movement, posture, and balance
Functions in proprioception → the perception or awareness of the position and movement of body
^signals from soft tissues of muscles, tendons, ligaments, skin sent to CNS
CNS Imaging
CNS Imaging
Cortical Injuries
The Spinal Cord
Inferior continuation of the brainstem
Coordinates motor and sensory signals between brain and body
Sensory signals = AFFerent and ASCEND up the cord to the brain
Motor signals = EFFerent and DESCEND down the cord from the brain to the peripheral system
Connected to the PNS via spinal nerves (31 pairs of nerves)
Spinal Cord Contd.
Runs from foramen magnum to L1/2 intervertebral disc
in newborn ends at 4th lumbar vertebrae
growth of cord stops at age 5
Conus Medullaris: termination of the spinal cord
Cauda Equina: remaining spinal nerves traveling w/in the canal
Internal Anatomy of Spinal Cord
Similar to the cortex (comprised both grey and white matter)
- *2 grooves** on the cord which are helpful for orientation
- *anterior median fissure (deep opening)**
- *posterior median sulcus (shallow line)**
Signals ascend/descend the cord via white matter “columns” (posterior → sensory only // anterolateral → motor&sensory)
Signals of the Nervous System
Protection of the CNS
Bone:
skull // vertebral column
Connective tissues:
meningeal layers
**Fluid:** cerebrospinal fluid (CSF)
Meninges of Brain Contd.
Periostal dura (outer layer)
Meningeal dura (inner layer)
forms folds of tissue that separate cranial cavity into sections
separated by “venous sinuses”
Meninges of Spinal Cord
Vertebral Column
Epidural space:
filled w/ fat for additional protection
Dura mater:
1 layer only: meningeal layer
thicker than other meninges:
Subdural Space:
NO! ONLY PATHOLOGICAL
Arachnoid mater:
named for its “web-like” appearance
Subarachnoid space:
where you find CSF
Pia mater:
tightly adhered to neural tissue itself
Meninges of Spinal Cord
Injecting into Meningeal Spaces
Ventricular System of CNS
Ventricles of CNS
Flow of CSF w/in Ventricles
Flow of the CSF
Meninges of Brain
