ANS Flashcards
where do presynaptic LMN originate of the sympathetic division
lateral/inermediate horn of the thoracolumbar spinal cord and leave the cord through the rami communicans
spine
sympathetic division
- ganglia are located in the paravertebral sympathetic trunks, or the median, prevertebral ganglia in the thoracic and abdominal cavities
- postsynaptic neurons travel in spinal nerves to their target
head
sympathetic division
synapse occurs in the cranial cervical ganglia
where do presynaptic LMN originate of the parasympathetic division
craniosacral CNS
where do postsynaptic nerves originate of the parasympathetic division
in ganglia close to the innervated organ
what parasympathetic cranial nerves innervate the head
CN - III, VII, IX, X
what does cranial nerve X innervate
viscera of the thorax and abdomen (travels in vagosympathetic trunk)
what does the sacral parasympathetic nerves innervate
pelvic viscera
parasympathetic innervation of head: eye - iris and lens and PLR and accomodation (origin, ganglion, and pathway)
origin
- PS nucleus of CN III
ganglion
- ciliary ganglion
pathway
- travels with CN III
sympathetic innervation of the eye
- fibers travel from the midbrain in the tectotegmentospinal tract to synapse on presynaptic LMNs in the cranial thoracic cord (C8-T5)
- LMNs travel through the vagosympathetic trunk to synapse in the cranial cervical ganglion
- they then travel with the ophthalmic branch of CNV to the eye
- sympathetic innervation suuplies smooth muscle of the orbit, the upper eyelid and the iridal dilator muscle
what is horner syndrome
damage to sympathetic innervation of the eye results in:
- miosis
- ptosis
- enophthalmosis
other signs of horner syndrome damage may include:
- peripheral vasodilation
- sweating in horses
parasympathetic innervation of the eye
- presynaptic neuron originates in parasympathetic nucleus of III and travels in CN III
- fibers synapse in the ciliary ganglion
- postganglionic ciliary nerves innervate the smooth muscle constrictor of the pupil
abnormalities of the PLR may be due to either:
afferent (CNII) or efferent (CNIII) dysfunction
visceral afferents of urination
- receptors in the bladder wall and neck are sensitive to stretch or pressure
- afferents from the urinary bladder and sphincter travel in the pelvic nerve
somatic innervation of urination
somatic innervation from the pudendal nerve causes contraction of the external urethral sphincter and urinary retention
sympathetic innervation of urination
- sympathetic innervation causes relaxation of the detrusor muscle and contraction of smooth muscle in the bladder neck
- fibers arise from L1-L5 synapse in the caudal mesenteric ganglion and travel in the hypogastric nerve
parasympathetic innervation of urination
- causes contraction of the detrusor muscle of the bladder and passive opening of the internal urethral sphincter
- fibers arise from S1-S3 and travel in the pelvic nerve
damage to UMN in spinal cord, cerebrum and cerebellum
urination
- urinary and fecal incontinence
- bladder that is full and difficult to express
damage to LMN in sacral cord, pelvic or pudendal nerves
- urinary and fecal incontinence
- bladder is distended, flaccid and easy to express
