Chapter 13- Central Nervous System Flashcards
What does the neural tube develop into?
Brain ventricles and the aqueducts
Brain ventricles
Expansion of central cavity; gaps in the brain
4:
Lateral x2
Third- Within diencephalon
Fourth- Hindbrain
What is the cerebral aqueduct?
Tube between the 3rd and 4th Ventricle that runs through the midbrain
What is the interventricular foramen?
The connection between the lateral ventricles and the third ventricle
What are the median and lateral apertures?
Holes in the 4th ventricle that allows cerebrospinal fluid to escape and surround the brain
Path of Cerebrospinal Fluid
-Created in the choroid plexus of each ventricle
-Flows through the ventricles and central canal
-Escapes through the median and lateral apertures
-Flows through the subarachnoid space
-Enters arachnoid villi to dural venous sinus and reenters blood supply
Protections of the Brain
Skull
Meninges
Cerebrospinal fluid
Blood-brain barrier
Blood-brain barrier
Impermeable capillaries within the brain that prevent most toxins from entering the brain
-Tight junctions
-Not absolute
Meningeal Functions and Layers
Cover and protect CNS and enclose blood vessels
Dura mater- External
Arachnoid mater
Pia mater- Internal
Dura Mater
External and strongest meningeal layer
Sub-layers:
-Periosteal layer- Lines skull
-Meningeal layer- lines and subdivides brain
Dural sinus
Created when the sub-layers of the dura mater separate
Returns cerebrospinal fluid to blood supply
Subdural space
Between dura mater and arachnoid mater
Usually absent
Site of brain hematomas
Arachnoid mater
Middle meningeal layer
Contain arachnoid villi
Arachnoid villi
Projections through the dura mater into the dural sinus that allows CSF to pass into sinus
Subarachnoid space
Between arachnoid mater and pia mater
Site of CSF and blood vessels that supply brain
Pia mater
Most internal meningeal layer
Clings to brain and follows all convolutions
Regions of the brain and their contents
Cerebrum- Cortex and basal ganglia
Diencephalon- Thalamus, hypothalamus, and epithalamus
Brain stem- Midbrain, pons, medulla
Cerebellum
How much of the brain’s mass is the cerebrum?
83%
Structural features of the brain
Fissures- Deep grooves that divide the brain
Sulci- Grooves on the cerebrum that divide lobes
Gyri- Ridges of brain matter
Major fissures
Longitudinal fissure- Divide hemispheres
Transverse fissure- Separate cerebrum and cerebellum
Major sulci
Central sulcus- Divide frontal and parietal lobe
Parieto-occipital sulcus- Divide parietal and occipital lobes
Lateral sulcus- Separates temporal lobe from frontal and parietal
Primary Motor cortex
Located on pre-central gyrus
Contains pyramidal cells that control motor function
Pre-motor cortex
Anterior to pre-central gyrus
Controls complex movements and motor planning
Integrates with sensory feedback
Primary somatosensory cortex
Located on post-central gyrus
Responsible for touch perception
Association areas
Integrate sensory inputs with memories of past experiences
Somatosensory association area
Located posterior to post-central gyrus
Integrates touch information
Topographical organization of primary motor and somatosensory cortex
Corresponding body areas can be mapped onto brain tissue
Lower body areas are medial on brain
Large amount of neurons devoted to hands and face
Basal Ganglia
Nucleus located deep in the cerebrum that receives cortical input to coordinate movements
Starts, stops, and regulates movement intensity
Wernicke’s Area
Located in temporal lobe
Ties meaning with word
Broca’s Area
Located in premotor cortex
Plans motor speech production
Lateralization of function
Left brain- Written and spoken language, numbers, reasoning
Right brain- Emotions, artistic and spacial skills
Contralateral control of body
Types of Cerebral White Matter Tracts
Commissure
Association Fibers
Projection Fibers
Commissures
Connect Left and Right hemispheres
Ex- Corpus callosum
Association Fibers
Connect different parts of the same hemisphere
Projection Fibers
Run vertically to and from cortex
Corona Radiata and Internal Capsule
Corona Radiata
Projection fiber
Runs from the cortex to the thalamus
Internal Capsule
Projection Fiber
Runs between thalamus and basal nuclei
Diencephalon structures and location
Thalamus, Hypothalamus, and Epithalamus
Surround the third ventricle
Thalamus
80% of the diencephalon
Relay station for incoming sensory input
Organize, amplify, or tone down sensory signals
Hypothalamus
Lies between the optic chiasm and mammillary bodies
Visceral control center
Receives optic nerve input
Functions of the Hypothalamus
Control ANS
Emotional response via limbic system
Body temperature, hunger, thirst, behavior
Sleep-wake cycle
Endocrine system via pituitary gland
Memory formation
Epithalamus
Forms roof of third ventricle
Controlled by hypothalamus
Contains pineal gland
Pineal gland
Secretes melatonin
Controls sleep-wake cycle
How is the Sleep-Wake cycle regulated?
1) The optic nerve sends visual information to the hypothalamus
2) The hypothalamus sends signals to the epithalamus
3) The epithalamus exerts control on the pineal gland
4) The pineal gland secretes melatonin, which induces sleep
Midbrain
Surrounds cerebral aqueduct
Cerebral peduncles
Periaqueductal gray
Corpora quadrigemina
Substantia nigra
Red nucleus
Cerebral Peduncles
Located in midbrain
Connection from brain stem to thalamus
Corticospinal tracts (motor control) runs through
Periaqueductal Gray
Gray matter surrounding the cerebral aqueduct in midbrain
Responsible for fight-or-flight and visceral pain responses
Corpora quadrigemina
Superior and inferior colliculi
Control visual and auditory reflexes
Superior colliculi
Control visual reflexes
Inferior colliculi
Control auditory reflexes
Substantia Nigra
Site in the midbrain that produces dopamine
Linked with basal ganglia function
Red nucleus
Part of reticular formation function in the midbrain
Pons
Portion of brain stem that contains nuclei of cranial nerves V, VI, and VII
Trigeminal, abducens, and Facial nerves
Medulla Oblongata
Portion of brain stem that is continuous with the spinal cord
Site of pyramidal decussation- Motor tracks cross over
Contains nuclei of cranial nerves VIII-XII
Reticular formation functions
Medulla Oblongata Visceral Functions
Cardiac control center
Vasomotor center- Vasodilation and contriction
Medullary respiration center
Hiccupping, sneezing, swallowing, and coughing
Cerebellar Functions
Smooths and coordinates movements and maintains balance
Receives sensory input and adjusts movements
Ipsilateral control
Cerebellar Anatomy
2 hemispheres
Folia- Ridges and Fissures- Grooves
3 Lobes:
Anterior, posterior, and flocculonodular
Regions:
Cortical gray matter
Internal white matter
Deep cerebellar nuclei
Cerebral Peduncles
Connect cerebellum to the brain stem
Superior- Midbrain
Middle- Pons
Inferior- Medulla
Limbic System
Medial cerebral hemispheres and diencephalon
Cingulate gyrus, hippocampus, and amygdala
Emotional brain- Encodes, consolidates, and retrieves memories
Shift between thoughts and encodes pain as negative
Reticular formation
Medulla, pons, and midbrain
Brain arousal via Reticular Activating System
Reticular Activating System (RAS)
Maintains consciousness and alertness
Functions in sleep and arousal from sleep
Spinal cord
Extends from foramen magnum to L1/L2
Conus Medullaris
Inferior end of spinal cord
Filum Terminale
Connective tissue that connects spinal cord to coccyx
Cauda equina
Nerve roots at the base of the spinal cord
Denticulate ligaments
Anchor spinal cord to vertebrae
Spinal cord grooves
Posterior median sulcus (superficial)
Anterior median fissure (deep)
Spinal gray matter arrangement
H-Shaped
Gray commisure and horns
Anterior Horn- Motor Neurons
Lateral horn- Visceral motor
Posterior horn- Interneurons
Somatic- External
Visceral- Internal
Spinal white matter
Ascending Fibers- Sensory
Descending Fibers- Motor
Commissural Fibers- Connections
Ascending Pathways
Dorsal column- Discriminative touch
Spinothalamic- Pain and temperature
Posterior and Anterior Spinocerebellar- Subconscious proprioception
Pyramidal (Corticospinal) Pathway
Controls skeletal muscle control
-Pyramidal cells in pre-central gyrus
-Corona radiata
-Internal capsule
-Cerebral peduncles
-Pyramids of medulla
-Decussation
-Descending Corticospinal tract
Other Descending pathways
Tectospinal
Vestibulospinal
Rubrospinal
Reticulospinal
