Spinal Cord Part 2 (Exam 1) Flashcards
The gray matter of the spinal cord is a well organized population of neurons with a centrally located, _________________ configuration. When viewed in transverse section, these dorsal and ventral gray columns are termed dorsal and ventral horns (2 dorsal and 2 ventral horns). In addition to dorsal and ventral horns, spinal segments ____________ have a lateral horn formed by a cluster of visceral efferent (autonomic/ANS) neurons that occupies a position lateral and dorsolateral to the central canal on either side
H shaped, T1-L1/L2
Because the limbs have more skeletal muscle than the thoracic wall, spinal segments that supply the limbs have a much larger ventral horn than do those segments that supply only trunk musculature. This causes grossly visible enlargements. What are the 2 enlargements and where are they located?
cervical enlargement is from C4-T1
lumbosacral enlargement is from L2-S3
Spinal cord grey matter can be functionally classified into 3 different ways. What are they?
1) 4 main columns
2) 6 different named nuclei
3) 10 rexed laminae
What are the 4 main columns in spinal cord grey matter?
-dorsal horn
-intermediate column
-lateral horn
-ventral horn
The ________________ horn contains neurons that receive somatosensory info from the body, which is then transmitted via the ascending pathways, to the brain
dorsal/posterior
The _______________ horn largely contains motor neurons that exit the spinal cord to innervate skeletal muscle
ventral/anterior
The ______________ column and ___________ horn contains neurons that innervate visceral and pelvic organs
intermediate, lateral
What are the 6 prominent nuclei (groups of neuronal cell bodies) in the spinal cord called?
1) marginal zone (also called MZ or posterior marginalis)
2) substantia gelatinosa (SG)
3) nucleus proprius (NP)
4) dorsal nucleus of clarke (DNC)
5) interomediolateral nucleus (IMN)
6) lateral motor neurons and medial motor neurons (MNs)
Which nucleus is located at the tip of the dorsal horn, and is important for relaying pain and temp sensation to the brain?
marginal zone (also called MZ or posterior marginalis)
Which nucleus is located at the top of the dorsal horn, and is important for relaying pain, temp., and light touch sensation to the brain?
substantia gelatinosa (SG)
Which nucleus is located in the “neck” of the dorsal horn and relays mechanical and temperature sensation to the brain?
nucelus proprius (NP)
Which nucleus is the most dorso-medial nuclei and relays unconscious proprioceptive info to the brain, and is only found in spinal cord segments C8-L3?
dorsal nucleus of clarke (DNC)
note: it sends most of its info to the cerebellum and some info to the cerebral cortex
Which nucleus is located in the intermediate column and lateral horn and relays sensory info from viscera to the brain, and autonomic signals (sympathetic innervations) from the brain to the visceral organs?
interomediolateral nucleus (IMN)
Which nucleus is located in the ventral horn and is composed of motor neurons that innervate visceral and skeletal muscles?
lateral motor neurons and medial motor neurons (MNs)
Bror Rexed identified layers, or laminae, within the spinal cord where cells were grouped according to their structure and function, rather than solely on location. Using the method of Rexed, gray matter of the human spinal cord is partitioned into _______ layers of spinal laminae designated by roman numerals
10
Laminae 1-6 are in the __________ horn
dorsal
Laminae 7-10 are in the _________ horn
ventral
The _______________ at the apex of the dorsal horn is spinal lamina I, the head of the dorsal horn, corresponding to the substantia gelatinosa, is spinal lamina II, and the neck of the dorsal horn is designated spinal lamina III, IV, and V
marginal nucleus
Laminae I-VI comprise the entirety of the dorsal horn, where alternatively the spinal cord nuclei, ____________________________________________________ are located
marginal zone, substantia gelatinosa, and nucleus proprius
Which lamina makes up the tip of the dorsal horn and is responsible for receiving noxious (pain or damage) stimuli and these stimuli can be mechanical, chemical, or thermal?
lamina I
Which lamina is involved in the reception of all sensory related stimuli (both noxious and non-noxious), and specifically moderates the sensation of pain, and has direct communication with lamina 3 and 4 and corresponds with the spinal cord nucleus known as the substantia gelatinosa?
lamina II
Which lamina controls the sensations of proprioception (awareness of positioning of body parts) and light touch? Cells in this layer connects with cells in layer 4, 5, and 6 and partially corresponds with nucleus proprius
lamina 3
Which lamina is involved in the reception and distribution of non-noxious sensory information and processing and cells connect with lamina II and partially corresponds with nucleus proprius?
lamina 4
Which lamina relays sensory info- particularly nociceptive sensory signals- to the brain via the lateral spinothalamic tracts? This lamina also receives descending info from the brain via the corticospinal and rubrospinal tracts
lamina 5
Which lamina is only present in the cervical and lumbosacral enlargements and contains many relatively small interneurons that are involved in the modulation of spinal reflexes and reception of sensory info from muscle spindles, specifically those that are involved with proprioception and sends info to the brain via ipsilateral spinocerebellar pathways?
lamina 6
Which lamina along with lamina 9 form the middle region between the dorsal and ventral roots?
lamina 7
Which lamina is this?
-Large, heterogenous zone that varies through the length of the spinal cord
-receives info from lamina 2-6 (sensory input) and from viscera
-relays motor info back to the viscera
-gives rise to cells involved in the function and regulation of the ANS
-partially responds to the dorsal nucleus of clarke
lamina 7
Somatic motor neurons originate in the ventral gray horn and give rise to the ability to voluntarily control body parts. What are the lamina involved here?
lamina 8 and 9
Which lamina is the most prominent in the cervical and lumbar vertebral levels and is involved in the modulation of motor output to skeletal muscles and partially corresponds to the lateral and medial motor neurons (its a lower motor neuron)?
lamina 8
Which lamina is composed of clusters of large alpha motor neurons that innervate striated muscles? The sizes and shapes vary between spinal cord levels and partially correspond with the lateral and medial motor neurons
lamina 9
Which lamina surrounds the central canal of the spinal cord and is known as the grey commissure? The axons decussate from one side of the spinal cord to the other
lamina 10
Surrounding the gray matter of the spinal cord, with its distinct neuronal __________, are numerous longitudinally oriented myelinated fibers that form the white matter of the spinal cord
columns
The white matter of the spinal cord is divisible into 3 large bundles of fibers called funiculi. What are the 3?
dorsal, ventral, and lateral funiculus
note: these 3 funiculi have smaller bundles called fasciculi or tracts which can be ascending or descending
Among the many _____________ tracts in the spinal cord are those carrying impulses for pain, temp., touch, pressure, proprioception, and vibration. Also these tracts carry impulses to the cerebellum
ascending
________________ in the spinal cord are motor tracts that influence skeletal muscles plus tracts carrying impulses for autonomic reflexes and the regulation of autonomic activity
Descending
Are ascending pathways sensory or motor?
sensory
Are descending tracts sensory or motor?
motor
What is the myotatic reflex?
-its a monosynaptic (1 synapse so no interneurons are involved here) and ipsilateral muscle stretch reflex (MSR)
-it has both an afferent and efferent limb
-the afferent limb includes a muscle spindle (receptor) and a spinal ganglion neuron and its la fiber
-the efferent limb includes an anterior horn motor neuron that innervates the striated muscle (effector)
What are some commonly tested myotatic reflexes?
-ankle jerk
-knee jerk
-biceps jerk
-forearm jerk
-triceps jerk
if theres a slow reflex or its absent then this is a problem
