SPINE Flashcards
pial folds that stretch from the surface of the cord to the dural sheath midway between the dorsal and ventral roots.
denticulate ligaments
denticulate ligaments NUMBER
20-21
has only a ventral root
C1
What arise from the conus medullaris
S4-5, Cox1
the tip of the vertebral spine corresponds to the level of the succeeding cord segment
cervical
the tip of the spine is two segments above the corresponding cord segment
upper thoracic spine
the tip of the spine is three segments above the corresponding cord segment
lower thoracic upper lumbar
The crowding of lumbosacral roots around the filum terminale
cauda equina.
carries blood vessels that supply and drain the spinal cord.
epipia
Rupture of bridging veins results in accumulation of blood and expansion of this space
SDH
contains adipose tissue and a venous plexus and is largest at the level of the second lumbar vertebra
Epidural space
the dura mater extends down to the level of
S1-S2
Asymmetry of the cord
more descending corticospinal tract fibers on the larger side.
found at L2 and above
dorsal spinocerebellar tract
cuneate tract (fasciculus) found at
T6 and above
intermedio-lateral cell column and the nucleus dorsalis of Clarke
between C8-L2
REXED I-IV
exteroceptive sensations
V and VI
Proprioceptive
relay between midbrain and cerebellum
VII
modulates motor activity, most probably via gamma neurons
VIII
Motor area
IX
dorsomedial cell group of Onuf
bulbocavernosus and ischiocavernosus
ventrolateral group of Onuf
external anal and urethral sphincters
two types of gamma motor neurons
static and dynamic
interposed between the recurrent axon collateral of an alpha motor neuron and the dendrite or cell body of the same alpha motor neuron.
Renshaw cell
mode of inhibition of Renshaw
recurrent inhibition
surrounds the central canal and contains neuroglia
Lamina X
2 types of neurons in SC GM
principal neurons and interneurons
2 types of principal
root and tract neurons
examples of tract
dorsal nucleus of Clarke, which gives rise to the dorsal spinocerebellar tract
Examples of root
alpha and gamma motor neurons in the ventral (anterior) horn and the autonomic (sympathetic and parasympathetic) neurons in the intermediolateral horn and S-2 to S-4 spinal cord segments, respectively.
WM organization
Posterior (dorsal) funiculus
Lateral funiculus
Anterior (ventral) funiculus
Conscious proprioception
gracile, cuneate
Unconscious proprioception
Dorsal and ventral spino-cerebellar
level of cuneate
above T6
Dorsal spina-cerebellar extent
above L2
Spinocervical thalamic (Morin’s)
Conscious proprioception
Pain and thermal sensations
Lateral spino-thalamic
Light touch
Anterior spinothalamic
Spinal Cord Ascending Tracts.
Gracile, Cuneate, Dorsal spina-cerebellar, Ventral spina-cerebellar, Spinocervical thalamic (Morin’s), Lateral spina-thalamic. Anterior spinothalamic
Spinal Cord Descending Tracts
Lateral corticospinal, Anterior cortico-spinal (bundle of Türck), Tract of Barnes, Rubrospinal, Lateral vestibule-spinal, Medial vestibule-spinal, Reticulospinal, Tectospinal, Descending autonomic,Monoaminergic
Control of skilled movement, modulation of sensory activity
Lateral corticospinal, Anterior cortico-spinal (bundle of Türck), Tract of Barnes
Rubrospinal origin
contra red nucleus
Control of muscles that maintain upright posture and balance
Lateral vestibule-spinal
Medial vestibulo-spinal
Head position in association with vestibular stimulation
from Medullary and pontine reticular formation, bilaterally
Reticulospinal
Head position in association with eye movement
Tectospinal
from Ipsilateral hypothalamus to Anterolateral funiculus
Descending autonomic
Raphe nucleus, locus ceruleus, periaqueductal gray to Lateral and anterior funiculi
Monoaminergic
Other tract for vibration
spinocervical thalamic tract
conveys to the cerebellum proprioceptive impulses from receptors located in muscles, tendons, and joints
Dorsal Spinocerebellar Tract
conveys to the cerebellum information pertaining to muscle contraction, including phase, rate, and strength of contraction.
Dorsal Spinocerebellar Tract
tract that terminates on the rostral and caudal portions of the vermis
Dorsal Spinocerebellar Tract
conveys impulses almost exclusively from Golgi tendon organs via Ib afferents.
Ventral Spinocerebellar Tract
transmits, to the cerebellum, information related to interneuronal activity and the effectiveness of the descending pathways.
Ventral Spinocerebellar Tract
two other indirect pathways from the spinal cord to the cerebellum:
spino-olivo-cerebellakr pathway
spino-reticulo-cerebellar pathway
Which impulses arrive sooner, direct or indirect pathways?
direct
accounts for the presence of kinesthesia and discriminative touch after total interruption of the posterior funiculus
spinocervical thalamic tract
concerned with transmission of pain and temperature sensations
Lateral Spinothalamic Tract
fibers conveying pain sensations are located _______ and those conveying thermal sense are located most _________
anterior, posterior
Other modalities for pain sensation
reticular system and a spinotectal pathway
gate-control theory of pain
tonic-slowly adapting-continuous flow of activity-open gates
phasic-rapidly-fire in response to a stimulus
Two types of pain receptors
unimodal nociceptors responding to nociceptive stimuli and polymodal nociceptors responding to nociceptive, chemical, and mechanical stimuli.
Three types of spinothalamic neurons
low-threshold mechanoreceptors in laminae VI to VII,
high-threshold, nociceptive-specific nociceptors in lamina I,
and wide-dynamic-range neurons in laminae IV and V responding to both mechanoreceptor and nociceptor stimulation.
Substance P, excitatory or inhibitory?
excitatory
enkephalins are inhibitory pr excitatory
inh
This tract carries light touch stimuli
Anterior Spinothalamic Tract
80 percent of the CS tract from
primary motor cortex (Brodmann’s area 4) and the premotor cortex (area 6)
somatotopic organization of the CST
cervical fibers are most medial, followed laterally by the thoracic, lumbar, and sacral fibers
uncrossed fibers remain in the anterior funiculus
anterior corticospinal tract (bundle of Türck)
______ percent of the corticospinal fibers remain uncrossed (Figure 3-18) in the lateral funiculus (tract of Barnes) and influence ipsilateral motor neurons
2 to 3 percent
_____ percent of the fiber population consists of large-caliber fibers (
3%
They terminate in the same laminae as the corticospinal tract and similarly facilitate flexor motor
Rubrospinal tract
The two tracts constitute the dorsolateral pathway for movement, in which the _____ tract initiates movement and the ______corrects errors in movement
CST, RST
The impulses conducted in this system facilitate extensor motor neurons that maintain upright posture.
Lateral Vestibulospinal Tract
They exert a facilitatory effect on flexor motor neurons. The tract plays a role in control of head position.
Medial VST
The pontine reticulospinal tract is located in the ______ funiculus of the spinal cord, whereas the medullary reticulospinal tract is located in the ______funiculus.
anterior, lateral
Descending Autonomic Pathway originate from _______ and terminate from ________
hypothalamus, anterolateral SC
Neuropeptides released at dorsal horn
Glutamate (main), others: substance P, somatostatin, and vasoactive intestinal peptides
The _______ region has more neuropeptides compared with other regions of the spinal cord
Lumbosacral
primary nociceptive and non-nociceptive afferents in the dorsal horn
Sub-stance P
The marked reduction of substance P immunoreactivity in lamina II in patients with
profound analgesia
Riley-Day syndrome
Stretching a muscle (by tapping its tendon) will activate the muscle spindle of the intrafusal muscle fiber (primary annulospiral endings).
MYOTATIC (STRETCH) REFLEX
INVERSE MYOTATIC REFLEX
Ib fibers
3 mechanisms for reflexes
- length-controlling mechanism subserved by the annulospiral endings of the intrafusal fiber
- tension-controlling mechanism subserved by the Golgi tendon organ
- follow-up control system in which extrafusal muscle fiber length follows intrafusal muscle fiber length
group III nerve fibers which facilitate ipsilateral flexor motor neurons and (2) inhibition of ipsilateral extensor motor neurons
FLEXOR REFLEX
(1) facilitation of extensor motor neurons and (2) inhibition of flexor motor neurons
CROSSED EXTENSION REFLEX
The urinary bladder receives efferent innervation from three sources:
(1) sympathetic supply via the hypogastric nerve, (2) parasympathetic supply via the pelvic nerve, and (3) somatic supply via the pudendal nerve
Sympathetic afferents
may extend rostrally up to the fourth thoracic segment (T-4), but most are in the upper lumbar and low thoracic level
Parasympathetic afferent
enter the cord between S-2 and S-4
Somatic afferents
S2-4
associated with tonic activity in the sympathetic neurons and Onuf’s nucleus
BLADDER filling
nhibition of sympathetic outflow, activation of parasympathetic outflow (contraction of detrusor muscle), and inhibition of Onuf’s nucleus (relaxation of external sphincter).
Bladder emptying (micturition)
Descending pathways for micturition
travel in the lateral funiculus just ventral to the denticulate ligament and lateral corticospinal tract
the coordination of urine storage and voiding takes place in the ____
pons
reat difficulty emptying the bladder, because when the bladder contracts, the urethral sphincter also contracts
detrusor–sphincter dyssynergia
pontine micturition center
Barrington nucleus, M-region
mportant during the filling phase of the bladder and is called the pontine continence center.
L-region), ventral and lateral to the Barrington area,