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neurons
cells specialized for nervous system function
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nerves
collections of their processes
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what are the two subdivisions of the nervous system
- peripheral nervous system (PNS)
- -INcludes all parts of the system that are outside of the bony casings of the skull and spinal column
- central nervous system (CNS)
- -INcludes all parts of the system that are within the skull and spinal column
- -spinal column encases and protects the brain
- *spinal cord and brain are continuous at the foramen magnum (hole at the base of the brain)
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anatomical postion
the reference position
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cephalic
nose end (also synonymous with rostral
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caudal
buttocks end (tail end in lower animals)
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dorsal
back (also posterior)
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ventral
front (also anterior)
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what does dorsal and ventral mean in the most cephalic region in the brain
superior (d) and inferior (v)
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medial
towards the midline
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lateral
away from the midline
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sagittal section
anterior-posterior cut which shows either the right or left side of the brain or spinal cord, usually sliced in the midline
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parasagittal section
sliced lateral to the midline
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coronal section
left-right cut which shows the dorsal or ventral side, made in the cerebral hemispheres or cerebellum-a top view of the hemispheres
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what is the spinal cord made of?
- part of the CNS
- long column of:
- -afferent nerve fibers ascending carrying info to brain
- -efferent nerve fibers descending, carrying commands from brain
- -interneurons and the cell bodies of these neurons
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much infor processing takes place where in regards to the spinal cord
takes place locally in the spinal cord itself via local circuit neurons
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how is info transmitted to the brain
Info from outside world enter the spinal cord and commands from the CNS exit the spinal cord via spinal nerves
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cauda equina
since the spinal cord doesn't grow the same length as the spinal column, the bundle of spinal nerves that descends in the spinal column before exiting is called the cauda equina
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what are the subdivisions of the spinal cord, in descending order
- cervical vertebrae-first 7
- thoracic vertebrae-12
- lumbar-5
- sacral-5
- coccygeal-1-3
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what do spinal nerves do?
- carry motor and sensory info to and from the body
- correspond to vertebral level at which they exit (on the left and right)
- ed c1 is 1st cervical nerve
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what happens if the spinal cord is severed?
- function to all muscles below the level of the damage is lost
- -if an individual has a spinal cord injury at the level of
- -c2, motor innervation to all muscles of respiration will be lost
- -t6, motor innervation to the lower intercostals and all the accessory muscles of expiration will be lost
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how are spinal nerves numbered?
- sections of the spinal cord corresponding to the spinal nerves and overlying vertebrae are numbered in the same manner:
- -the area of skin innervated by nerves related to a particular segment of the spinal cord is a dermatome
- -the spinal cord has enlargements in lower cervical and lumbosacral areas known as the:
- -brachial plexus and lumbosacral plexus
- -formed by large numbers of nerve cell bodies and processes that collect in those areas
- -ex-afferent and efferent nerves in the lumbosacral plexus innervate the lower extremeties
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glia
other cells of the nervous system that support neurons
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gray matter
areas of the cns composed primarily of cell bodies, as collections of neuron cell bodies appear grayish in color
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white matter
areas composes primarily of neuron processes as a result of some specialized glia wrapping themselves around the processes of many neurons (forming insulating fatty layers, appearing whitish in color)
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dorsal roots
afferent nerves that pierce the spinal cord, bundled together
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dorsal root ganglia
cell bodies outside of the spinal cord
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ventral roots
efferent nerves that leave the spinal cord, bundled together (named for the side of the spinal cord they enter or exit)
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what are the divisions of the brain
- brainstem
- -medulla oblongata
- -pons
- -midbrain
- diencephalon
- thalamus
- epithalamus
- hypothalamus
- cerebellum
- cerebrum (collectively the cerebral hemispheres)
- neuraxis-brainstem and spinal cord
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what are the 3 parts of the cerebellum and cerebrum
- 1. cortex-most superficial part of each structure, primarily gray matter/neuron cell bodies
- 2. beep cerebellar nuclei-groups of cell bodies deep within the cerebellum
- 3. basal ganglia-groups of cell bodies deep within the cerebrum
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the cerebral cortex is divided into what lobes
- frontal, parietal, temporal and occipital
- wrinkled hillocks and grooves on the cortex: gyri and sulci
- deep sulci known as fissures
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divides precentral gyrus of the frontal lobe from the postcentral gyrus of the parietal lobe
central sulcus or fissure of rolando
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separates the parietal and occipital lobes
parietooccipital sulcus
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hides within the lateral sulcus or ______ ______ and is part of the cortex
sylvian fissure, insula
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divides left and right hemis
longitudinal fissure
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corpus callosum
massive white structure included in the fiber bundles connecting the two hemispheres
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what do the "wrinkles" of the brain allow for?
allow a lot of surface area to be contained and packed into the small area of the skull
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brodmann's numbers
how some areas of the brain are still identified, based on what some neuroanatomists referred to patches of the cortex with a uniformly similar cell pattern
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hippocampus
portion of the cerebral cortex, hidden w/in the sylvian fissure, and is named for its seahorse shape in cross-section
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substantia nigra
in the midbrain, and is named for its black appearance (lesions have been implicated in parkinsons's disease)
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caudate nubleus and ventricles
large internal spaces
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superior and inferior colliculi
located at the rostral end of the brainstem
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striatum
basal ganglia, caudate nucleus, globus pallidus, and putamen (as well as the substantia nigra and the subthalamic nucleus)
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the brainstem
- phylogenetically the oldest part of the brain, and is the extension of the spinal cord inside the skull
- area of transition between the cerebrum and the spinal cord where many important functions are controlled
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what happens in the most caudal region of the brainstem
there is some descending pathways decussate (cross) in the pyramids (roughly triangular in shape)
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cranial nerves
- efferent and afferent fibers related to parts of the brainstem
- 12 pairs with 2 roles: bring info from the special senses and somatic senses of the face and head into the brain, and they send commands out to the muscles and glands of the head and neck to control behavior
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meninges
tough membranes that protect the soft, gelatinous nervous system from contusion and infection
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cerebrospinal fluid
cushions the nervous system (important part of the circulatory system of the cns)
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