Lecture 2 Structure of the Nervous System Flashcards
Horizontal Section
- A slice through the brain parallel to the ground
Sagittal Section
- A slice through the brain parallel to the neuraxis and perpendicular to the ground
Midsagittal
- The plane through the neurosis perpendicular to the ground - Divides the brain into two symmetrical halves
Meninges
- The three layers of tissue that encase the central nervous system - The dura mater, arachnoid membrane, and the pia mater
Dura Mater
- The outermost of the meninges - Tough and flexible
Arachnoid Membrane
- From the greek Arachne, meaning “spider” - The middle layer of the meninges, located between the dura mater and the inner pia mater
Pia Mater
- The layer of the meninges adjacent to the surface of the brain; thin and delicate
Subarachnoid Space
- The fluid-filled space that cushions the brain - Located between the arachnoid membrane and the pia mater
Cerebrospinal Fluid
- A clear fluid, similar to blood plasma, that fills the ventricular system of the brain and the subarachnoid space surrounding the brain and spinal cord
Layers (surface to CNS)
- Dura mater - Arachnoid Membrane - Subarachnoid Space (blood vessels & Cerebrospinal fluid CSF)) - Pia Mater - CNS Tissue
Ventricular System and production of cerebrospinal fluid
- Ventricles (little bellies) - 4 hollow spaces located inside the brain - Each ventricle produces CSF - CSF supports the weight of the brain - Help reduce shock to the CNS caused by sudden head movements - Brain contains about 125 ml of CSF - Half life of CSF is about 3 hours - All CSF is replaced every six hours by the choroid plexus
Development of the CNS
- CNS development begins 18 days after conception - Neural tube develops by twenty-first day to give rise to the brain and spinal cord - Neural tube closes at day 28 & forms the ventricles, forebrain, midbrain, & hindbrain
Asymmetrical division
- Division of a founder cell that gives rise to another founder cell and a neuron, which migrates away from the ventricular zone towards its final resting place in the brain
Apoptosis (literally, a “falling away”)
- Death of a cell caused by a chemical signal that activates a genetic mechanism inside the cell
Forebrain
- The most rostral of the three major divisions of the brain; includes the telencephalon and diencephalon
Cerebral hemisphere
- One of the two major portions of the forebrain, covered by the cerebral cortex
Subcortical region
- The region located within the brain, beneath the critical surface - Contains the limbic system and the basal ganglia
Sulcus
- A groove in the surface of the cerebral hemisphere, smaller than a fissure
Fissure
- A major groove in the surface of the brain, larger than a sulcus
Gyrus
- A convolution of the cortex of the cerebral hemispheres, separated by sulk or fissures
Primary visual cortex
- The region of the posterior occipital lobe whose primary input is from the visual system
Calcarine fissure
- A fissure located in the occipital lobe on the medial surface of the brain; most of the primary visual cortex is located along its upper and lower banks
Primary auditory cortex
- The region of the superior temporal lobe whose primary input is from the auditory system
Lateral fissure
- The fissure that separates the temporal lobe from the overlying frontal and parietal lobes
Primary somatosensory cortex
- The region of the anterior parietal lobe whose primary input is from the somatosensory system
Central sulcus
- The sulcus that separates the frontal lobe from the parietal lobe
Primary motor cortex
- The region of the posterior frontal lobe that contains neurons that control movements of skeletal muscle - The connections of this region are contralateral - The left primary motor cortex controls the right side of the body and vice versa
Frontal Lobe
- The anterior portion of the cerebral cortex, rostral to the parietal lobe and dorsal to the temporal lobe. This includes everything in front of the central sulcus
Parietal lobe
- The region of the cerebral cortex caudal to the frontal lobe and dorsal to the temporal lobe
Temporal Lobe
- The region of the cerebral cortex rostral to the occipital lobe and ventral to the parietal and frontal lobes
Occipital lobe
- The region of the cerebral cortex caudal to the parietal and temporal lobes. This is located posterior to the central sulcus
Sensory Association Cortex
- Those regions of the cerebral cortex that receive information from regions of the primary sensory cortex. Perception takes place here and memories are stored here
Motor Association Cortex (Premotor Cortex)
- The region of the frontal lobe rostral to the primary cortex; also known as the premotor cortex. Controls overall motor behavior
Prefrontal Cortex
- The region of the frontal lobe rostral to the motor association cortex. This region is involved in formulating plans and strategies
Corpus Callosum
- A large bundle of axons that interconnects corresponding regions of the association cortex on each side of the brain
Neocortex
- The phylogenetically newest cortex, including the primary sensory cortex, primary motor cortex, and association cortex
Limbic Cortex
- Phylogenetically old cortex, located at the medial edge of the cerebral hemispheres; part of the limbic system
Cingulate gyrus
- A strip of limbic cortex lying along the lateral walls of the groove separating the cerebral hemispheres, just above the corpus callosum
Limbic system
- A group of brain regions including the anterior thalamic nuclei, amygdala, hippocampus, limbic cortex, and parts of the hypothalamus, as well as their interconnecting fiber bundles
Hippocampus
- A forebrain structure of the temporal lobe, constituting an important part of the limbic system; includes the hippocampus proper, dentate gyrus, and subiculum
Amygdala
- A structure in the interior of the rostral temporal lobe, containing a set of nuclei
Fornix
- A fiber bundle that connects the hippocampus with other parts of the brain, including the mammillary bodies of the hypothalamus
Mammillary bodies
- A protrusion of the bottom of the brain at the posterior end of the hypothalamus, containing some hypothalamic nuclei - Serve as relay stations in reflexes related to the sense of smell
Basal ganglia
- Part of the telencephalon, including the caudate nucleus, the globes plaids, and the putamen - Parkinson’s disease is caused by degeneration of the caudate nucleus and putamen - Parkinson’s disease includes weakness, tremors, rigidity of the limbs, poor balance and difficulty initiating movements
Thalamus ( Greek thalamus, “inner chamber”)
- The largest portion of the diencephalon, located above the hypothalamus; contains nuclei that project information to specific regions of the cerebral cortex and receive information from it.
Projection fiber
- An axon of a neuron in one region of the brain whose terminals form synapses with neurons in another region
Hypothalamus
- A group of nuclei in the diencephalon situated beneath the thalamus - Controls the autonomic nervous system - Controls the anterior and posterior pituitary glands - Organizes behavior such as fighting, feeding, fleeing, and mating
Hypothalamus- Optic chiasm
- A connection between the optic nerves where half of the fibers of the optic nerve cross to the contralateral side
Hypothalamus- Anterior pituitary gland
- The “master gland” - The anterior part of the pituitary gland; an endocrine gland whose secretions are controlled by the hypothalamic hormones
Hypothalamus- Neurosecretory cell
- A neuron that secretes a hormone or hormone-like substance
Hypothalamus - Posterior pituitary gland
- The posterior part of the pituitary gland; an endocrine gland that contains hormone-secreting terminal buttons of axons whose cell bodies lie within the hypothalamus
Hindbrain-metencephalon Hindbrain
- The most caudal part of the brain; includes the mesencephalon and myelencephalon
Hindbrain-metencephalon Cerebellum (little brain)
- A major part of the brain located dorsal to the pons, containing the two cerebellar hemispheres, covered with the cerebellar cortex; important component of the motor system
Hindbrain-metencephalon Cerebellar peduncle
- One of three bundles of axons that attach each cerebellar hemisphere to the dorsal pons
Hindbrain-metencephalon Pons (‘bridge’)
- The region of the metencephalon rostral to the medulla, caudal to the midbrain, and ventral to the cerebellum; appears to be important in sleep and arousal
Hindbrain-metencephalon Medulla oblongata
- The most caudal portion of the brain, located in the mylencephalon, immediately rostral to the spinal cord - Includes nuclei that control vital functions such as the cardiovascular system, respiration, and skeletal muscle tone.
Spinal Cord
- The cord of nervous tissue that extends caudally from the medulla
Spinal root
- A bundle of axons surrounded by connective tissue that occur in pairs, which fuse and form a spinal nerve
Spinal Cord Dorsal Root
- The spinal root that contains incoming (afferent) sensory fibers