(05) Spinal Cord Organization Flashcards
The spinal cord…
- communicates with the _____, by means of _______ and _____ pathways that form tracts in spinal ____ matter.
- Connects with ____ nerves, through _______ & _______ axons in _____ roots.
- gives rise to spinal reflexes, pre-determined by ______ circuits
- brain, ascending, descending, white
- spinal, afferent, efferent, spinal
- internueronal
(GROSS ANATOMY OF THE SPINAL CORD)
- The spinal cord is a cylinder of ___. The spinal cord exhibits subtle ____ and _____ enlargements produced by extra ___ withing segments that innervate ____. The region of spinal cord caudal to the lumbar enlargement is the _______.
A spinal cord ______ = a portion of spinal cord that gives rise to a pair (right and left) of spinal ____. Each spinal nerve is attached to the spinal cord by means of dorsal and ventral ____ composed of _____. Spinal segments, spinal roots, and spinal nerves are all identified numerically by region eg 6th cervical spinal segment.
- Sacral and caudal spinal roots (surrounding the _____ and _____ and streaming caudally to reach corresponding intervertebral _______) collectly constitute the ______.
Both the _____ (CNS) and _____ (PNS) are enveloped by meninges within the vertebral canal. Spinal nerves (which are formed in intervertebral foramina) are covered by connective tissue (____, ___, ____) rather than meninges.
- CNS, cervical, lumbosacral, neurons, limbs, conus medullaris.
- segment, nerves, roots, rootlets
- conus medullaris, terminal filament, foramina, cauda equina
- spinal cord, spinal roots, epinueriniun, perineurium, endoneurium
(SPINAL CORD HISTOLOGy)
- Central canal (derived from _______) is lined by _____ and filled with _____.
- Gray matter (derived from _______) is _______ shaped. It has a high density of _____ and _____, a high _____ density, and sparse ______. Gray matter regions include ____, ___, and ____. The intermediate substance featurs a _______ in thoracolumbar spinal segments.
White matter (derived from ____) is superficial to gray matter. It is composed of concentrated ________, ______, and low _______. White matter regions include, _____, _____, _____, and ______.
- embryonic neural cavity, ependymal cells, CSF
- embryonic mantle layer, butterfly, neuron cell bodies, gliocytes, capillary density, myelinated fibers, dorsal horn, ventral horn, intermediate substance, lateral horn
- embryonic marginal layer, myelatined fibers, glyocites, low capillary density, dorsal funiculus, ventral funiculus, lateral funiculus, white commisure
How many shcems have evolved for organizing neuron cell bodies within gray matter?
1] _________ - spinal gray matter is divided into ten laminae. The advantage is that ______, The disadvantage is that _________.
2] ______ - recognizeable clusters of cells are identified as nuclei (a nucleus is a profile of a cell column). Advantage? Disadvantage?
- 2, either can be used..
- Spinal Laminae, all neurons are included, laminae are difficult to distinguish
- Spinal nuclei, distinct nuclei are generally detectable, numerous neurons outside of distinct nuclei are not included
(Types of cell bodies)
All neurons found in spinal cord gray matter have _____ mutlipolar cell bodies. Based on _____ destination, spinal neurons can be divided into three major types, each of which has subtypes. What are those three types?
- multipolar, axon, efferent neurons, projection neurons, interneurons
(Efferent neurons; types of spinal neurons)
- Efferent neurons send axons into the _____ root. Cell bodies of efferent neurons are located in the _____ (_____ efferents) or in _______ (_____ efferents)
- Somatic efferent neurons (somatopically arranged in ventral horn):
______ - innervate ordinary skeletal muscle fibers (motor units); (neuron size is proportional to motor unit size)
_____ - innervate intrafusal muscle fibers (within muscle spindles)
- visceral efferent neurons: ______ and _____ neurons
- ventral, ventral horn, somatic, intermediate substance, visceral
- alpha motor neurons
- gamma motor neurons
- preganglionic sympathetic, parasympathetic
What are the three types of spinal neurons?
efferent, projection, interneuros
___________ send axons into spinal white matter to travel to the brain (or to a distal part of the _____ ). The axons form _____ associated with ______ spinal pathways that have different functions.
Projection neurons may be categorized according to the types of _______ that ultimately excite them
- projection neurons, spinal cord, tracts, ascending
- stimulation
- _____________ have axons that remain within spinal gray matter. Interneurons are interposed between _________ (from peripheral nerves or brain) and ______ (efferent neurons). By establishing local circuits, interneurons _________ input to output and thus determine the ________ of the spinal cord (spinal reflexes)
- interneurons, spinal input, spinal output, hardwire, inherent reflex responses
_______ = the first neuron in a spinal reflex or ascending spinal pathway
- primary afferent neurons have their unipolar cell bodies in _____. Receptors are found at the ______ of their axons. Their axons traverse _____, penetrate the spinal cord (at the ______) and bifurcate into ____ and _____ brances which extend over several segments within white matter of the ______.
_______ branches from the cranial and caudal branches enter the gray matter to synapse on ______ and _____.
In some cases (discriminative touch), the cranial branches of the incoming axons ascend directly to the _____ where they synapse on ____ of the pathway.
- primary afferent neuron
- spinal ganglia, peripheral terminations, dorsal roots, dorsolateral sulcus, cranial, caudal, dorsal funiculus
- collateral, interneurons, projection neurons
- brainstem, projection neurons
______ = chains of neurons carrying info from peripheral receptors to brain
Neuronal sequence: ________ synapse on ____ typically located in spinal grey matter. The axons of projection neurons join _____ and synapse on neurons in the _____. In the case of concious sensation, the pathway leads to _____ that project to the _____.
Note: The function of a particular pathway is determined by:
1] the _____ neurons that are excited by the _____ (stimulus);
2] the particular ______ that are synaptically excited by the _____ neurons; and
3] where the _____ neurons synapse in the brain. Thus projection neurons not only form the anatomical_____, they are critical in determining the _____.
- ascending spinal pathways
- primary afferent neurons, projection neurons, ascending tracts, brain, thalamic neurons, cerebral cortex
- primary afferent, envrionmental energy
- projection neurons, primary afferent
- projection, tracts, physiological response
(SPINAL PATHWAY - PRIMARY AFFERENT NEURON)
just look at this
look at it
(in general pathways may be categorized into three broad functional types)
1] _____ (e.g., pricking pain, warmth, cold, discriminative touch, kinesthesia) requires a specific _____ pathway to the _____ which, in turn, sends an axonal projection to the _____. Generally there are three neurons in the _____ pathway and the axon of the projection neuron decussates and joins a _____
2] _____ (emotional & alerting behavior) information involves _____ pathways to the brainstem. Projection neurons are _____. They receive synaptic input of different ______ and signal an ongoing magnitude of _____, but they cannot signal where or what activity.
3] _____ control involves ascending spinal pathways principally to the _____ or _____ that project to the cerebellum. Generally there are only _____ neurons in a subconscious pathway and the axon of the projection
neuron joins an _____
______ = sequence (chain) of neurons synaptically linked to convey excitability changes from one site to another
- Conscious discrimination/localization, ascending spinal, contralateral thalamus, cerebral cortex, conscious, contralateral tract
- Affective related, ascending spinal, non-specific, modalities, sensory activity
- Subconscious sensory feedback for posture/movement, cerebellum, brainstem nuclei, two, ipsilateral tract
- pathway
STUDY FIGURE ON P46
DO IT
(Descending Spinal Pathways)
Axons of brain projection neurons travel in _____ tracts in spinal _____. They arise from various locations in the _____ and synapse primarily on _____.
By synapsing on interneurons, descending tracts regulate:
1] _____ (which utilize the same interneurons);
2] _____ (for posture and movement); and
3] _____, i.e., the brain is able to regulate sensory
- descending, white matter, brain, spinal interneurons
- spinal reflexes
- excitability of efferent neurons
- excitability of spinal projection neurons
