Central Nervous System Flashcards
Cerebrum
largest and most superior portion of the brain, Right and left hemispheres separated by the longitudinal fissure
Cerebral cortex
Outer layer of gray matter, deep under the gray matter is white matter and some deep areas of gray matter called basal nuclei
Gyrus
Elevated ridges on the surface separated by sulci (shallow grooves) and fissures (deep grooves)
Frontal lobe
- Primary motor cortex lies in the precentral gyrus
- controls somatic motor neurons that excite skeletal muscles on contralateral side
- Premotor cortex-motor planning
- Prefrontal cortex-intellect, reasoning, judgement, concern for others, personality traits, and management of emotions.
Precentral gyrus
Contains the primary motor cortex
Parietal lobe
- Primary somatosensory cortex-postcentral gyrus
- Receives impulses involved in touch, pain, pressure and stretch
- Somatosensory association cortex-Integrates sensory input into understanding based on past experiences
Postcentral gyrus
contains primary somatosensory cortex
Temporal lobe
- Primary auditory cortex-receives sensory information for sense of hearing
- Auditory association cortex- interprets sound into context
- Olfactory cortex-sensory input for sense of smell
- Hippocampus- functions important for memory formation
- Part of limbic system-functions important for emotions and memories
Occipital lobe
- Primary visual cortex- receives sensory input for vision
* Visual association cortex- Surrounds the primary, more complex visual processing
Insular lobe
- Found hidden deep within the lateral sulcus*
- Primary gustatory cortex- receives sensory input for taste
- Functions as part of the limbic sytem processing emotions
Tracts
white matter in the CNS consisting of bundles of axons
Corpus Callosum
Largest tract in the brain, connects the left and right hemispheres of the cerebrum
Broca’s Area
- In frontal lobe, left hemisphere only
* controls muscles involved in speech production
Wernick’s Area
- In temporal lobe, left hemisphere only
* Important for language comprehension
Basal nuclei/ basal ganglia
Gray matter deep in the cerebrum
- Striatum (includes caudate nucleus and putamen)-Adjust stopping, starting and intensity of movements after receiving input from cerebral cortex
- Globus pallidus-works with striatum to regulate motivation
- Amygdala- almond shaped, deep in temporal lobe, important for negative emotions
Diencephalon
Superior to brain stem, surrounded by cerebral hemispheres, encloses the third ventricle, consists of hypothalamus/ thalamus, etc
Lateral ventricle
- Form the walls of the third ventricle
* Relay station for all incoming sensory impulses except olfaction
Intermediate mass
Connects left and right halves of the thalamus
Thalamus
Relays sensory and motor signals to the cerebral cortex
Hypothalamus
- Four Fs- Feeding, fornication, and fight or flight
- Autonomic control center-controls ANS centers in the brain stem and spinal cord
- emotional responses-fear, anger, pleasure
- Hunger-Responds to changes in levels of nutrients and hormones
- Water balance and thirst- osmoreceptors detect concentrations of body fluids
- Controls body temperature-Initiates cooling or heating mechanisms
- Connects to pituitary and regulates endocrine system
Infundibulum
connects pituitary gland to hypothalamus
Mammillary bodies
Important for memory- damage due to thiamine deficiency syndrome causes impaired memory
*connect to the medial temporal lobe through the fornix
Pineal gland
Secretes melatonin which regulates your day-night cycles
Brainstem
consists of midbrain, pons and medulla oblongata
Midbrain
- Superior portion of the brain stem directly inferior to diencephalon.
- Consists of
- corpora quadrigemina (4 protrusions on dorsal surface, superior colliculli-visual reflexes and inferior colliculli- auditory reflexes)
- cerebral peduncles
- cerebral aqueduct (Connects 3rd and 4th ventricles)
Pons
- Bulging region of brain stem between midbrain and medulla
* Contains respiratory control centers
Medulla oblongata
- Base of the brain stem
- Contains vital reflex centers that regulate the cardiovascular, digestive, and respiratory centers
- Consist of meduallry pyramids and medullary olives
Medullary pyramids
Longitudinal ridges on the ventral surface of medulla
*contain motor tracts that cross over before they continue down the spinal cord
Medullary olives
Relay information to the cerebrum and cerebellum
Cerebellum
- Posterior to the pons and medulla
- densely packed with small neurons
- Fine tunes motor commands based on sensory feedback and learning from previous experiences
Folia (leaves)
Horizontal folds in the outer gray matter of cerebellar cortex
Arbor vita (Tree of life)
Inner white matter, branches of the cerebellum
What are the three meninges of the brain?
Pia mater, arachnoid mater and dura mater
Dura mater
Superficial layer, consists of two layers of fibrous CT that are fused except for areas where they are separated to enclose dural sinuses
Arachnoid mater
Loose middle layer, subarachnoid space contains CSF and blood vessels, arachnoid villi extend through dura mater into superior sagittal sinus
Pia mater
deepest layer, clings tightly to the brain following every sulcus
Ventricle
Cavity within the brain that is filled with cerebrospinal fluid
Right and left lateral ventricles
C shaped cavities within the cerebrum
Septum pellucidum
Thin membrane at midline separating right and left lateral ventricles
Third ventricle
Formed by the medial walls of the thalamus
Fourth ventricle
Inferior to the third ventricle and is continuous with the central canal of spinal cord
Cerebral aqueduct
Connects third and fourth ventricle, runs through midbrain
Cerebrospinal Fluid / CSF
fluid found in and around the brain and spinal cord, cushions brain and spinal cord, transports nutrients and waste
Choroid plexus
Cluster of capillaries found on the roof of ventricles, *Responsible for the formation of CSF
*ependymal calls selectively transport material between blood and CSF
What is the function of the spinal cord?
- Contains ascending (sensory info) and descending tracts (motor info) of the CNS
- Integrates and processes information (functional independence)
Structure of the spinal cord
Runs from the foramen magnum to L1/L2 through the vertebral foramen
Cervical enlargement
Expanded superior end of spinal cord is larger because there are numerous nerves going to/from the upper limbs
Lumbar enlargement
expanded inferior end is larger because there are numerous nerves supplying the lower extremities
Conus medullaris
Cone shaped tapered end of the spinal cord located st the level of the L1/L2 vertebrae
Filum terminale
Meninges extending inferior from conus to anchor spinal cord to coccyx
Cauda equina “horse tail”
lower lumbar and sacral spinal nerves travel inferior past the conus through vertebral foramen before exiting the spinal column
Anterior median fissure
Deep crease along the ventral surface
Posterior median sulcus
Shallow groove along dorsal surface
White matter
contains myelinated axons located superficial to gray matter, tracts traveling up and down the spinal cord
Tract
Axons in the CNS
Nerve
bundles of axons in the PNS
Gray matter
non-myelinated (cell bodies, dendrites, axon terminals)
Dorsal horns
contain sensory axon terminals and interneurons
Ventral horns
Contain somatic motor neuron cell bodies
Lateral horns
contain preganglionic autonomic motor neuron soma
Dorsal root
Contain axons of sensory neurons entering the spinal cord
Ventral root
contain axons of motor neurons leaving the spinal cord
Ascending tracts
Axons carrying sensory info to the brain
Descending tracts
Axons carrying motor commands from the brain to the periphery
Posterior white colums
contains major ascending tracts carrying the somatosensory information
*medial to posterior gray horns
Anterior and lateral white columns
contain major descending tracts that regulate the motor neurons of the ventral gray horn
