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The ciliospinal reflex (pupillary-skin reflex) consists of dilation of the ipsilateral pupil in response to pain applied to the neck, face, and upper trunk. If the right side of the neck is subjected to a painful stimulus, the right pupil dilates (increases in size 1-2mm from baseline).
It is important to distinguish the ptosis caused by Horner's syndrome from the ptosis caused by a lesion to the oculomotor nerve. In the former, the ptosis occurs with a constricted pupil (due to a loss of sympathetics to the eye), whereas in the latter, the ptosis occurs with a dilated pupil (due to a loss of innervation to the sphincter ...
The ciliospinal center (also known as Budge's center [1]) is a cluster of [citation needed] pre-ganglionic sympathetic neuron cell bodies located in the intermediolateral cell column (of the cornu laterale) at spinal cord segment (C8: Anatomic variation) T1-T2 [2]
One reason why this effect is so strong may be that Attwell et al., (2001) trained animals for only 4 days at an ISI that is outside of a range known to be optimal for learning [150–300 ms is an optimal CS-US interval and the magnitude of learning decreases as the ISI is increased (Schneiderman and Gormezano, 1964; Smith, Coleman, and ...
The SCG receives pre-ganglionic sympathetic afferents from the ciliospinal center which synapse in the ganglion. Post-ganglionic efferents then leave the SCG and join the internal carotid nerve plexus of the internal carotid artery, accompanying first this artery and subsequently its branches to reach the orbit and ultimately innervate the dilator pupillae muscle to mediate pupillary dilatation.
The responses can have a variety of causes, from an involuntary reflex reaction to exposure or inexposure to light—in low light conditions a dilated pupil lets more light into the eye—or it may indicate interest in the subject of attention or arousal, sexual stimulation, [4] uncertainty, [5] decision conflict, [6] errors, [7] physical ...
The hypothalamospinal tract includes fibres by which the hypothalamus projects to the ciliospinal center in the spinal cord, a part of a brain circuit regulating pupillary dilatation as part of the pupillary reflex. [3] Some axons of the tract contain oxytocin. [1]
The simplest reflex is initiated by a stimulus, which activates an afferent nerve. The signal is then passed to a response neuron, which generates a response. Reflexes are found with varying levels of complexity in organisms with a nervous system. A reflex occurs via neural pathways in the nervous system called reflex arcs.