Lab C

Serve as the main pathways for autonomic signals

brainstem and spinal cord

Which regions of the spinal cord does the sympathetic division originate in?

thoracic and lumbar region

The different nuclei of the hypothalamus are responsible for what autonomic functions (name a few)?

temperature regulation, osmoregulation, sleep, circadian rhythms, arousal, stress, energy expenditure, memory

The hypothalamus is organized into many functionally specialized ______ that together help coordinate _________ function.

nuclei, autonomic

What does the ventromedial hypothalamus (VMH) do?

energy balance, autonomic control

hypothalamo-spinal tract

pathway through which the hypothalamus sends commands to autonomic neurons

Where is the hypothalamo-spinal tract located?

brainstem and spinal cord

What’s the dorsal motor nucleus of vagus (DMNX) responsible for?

parasympathetic output

The hypothalamus sends coordinated signals to both the __________ and _________ autonomic targets

sympathetic, parasympathetic

Where does the hypothalamo-spinal tract terminate?

in the intermediolateral cell column/lateral horn

Where do preganglionic sympathetic neurons originate?

in the lateral horn

sympathetic trunk/chain

chain of sympathetic ganglia running alongside the vertebral column

Where is the pre and post ganglionic synapse in the sympathetic nervous system

• in the sympathetic chain/paravertebral ganglia OR

• in a prevertebral ganglion OR

• on the adrenal medulla

Where is the pre and post ganglionic synapse for all innervations above the diaphragm?

in the sympathetic trunk

Where do the sympathetic preganglionic neurons that innervate the heart and lungs originate?

lateral horn in thoracic spinal cord

Where do the sympathetic pre and post ganglionic neurons that innervate the heart and lungs synapse?

in the sympathetic chain

What structure do the postganglionic neurons that innervate the heart travel through?

the cardiac plexus

What structure do the postganglionic neurons that innervate the lungs travel through?

the pulmonary plexus

Where do the sympathetic preganglionic neurons that innervate the small intestine originate?

lower thoracic spinal cord

Where do the sympathetic pre and post ganglionic neurons that innervate the small intestine synapse?

superior mesenteric ganglion

What other ganglion besides the celiac ganglion is important for small intestine functions?

superior mesenteric ganglion

Some of the preganglionic neurons that innervate the small intestine also form what nerve?

greater splanchnic nerve

What do neurons in the GI tract operate?

peristalsis, enzyme secretion

splanchnic nerve

innervates visceral organs (liver, SI, colon, kidneys)

What’s unique about the sympathetic innervation of the adrenal medulla?

preganglionic fiber synapses directly onto the target organ

What does having the preganglionic neuron synapsing directly on the adrenal medulla allow for?

rapid release of epi/adrenaline

What is a plexus?

a network of intersecting nerves

What’s the point of a plexus

• resilience; if a pathway is damaged, there’s redundancy to ensure continued function

• efficiency; integrate autonomic and sensory inputs

Which spinal segments are the only ones to contain sympathetic preganglionic neurons?

T1-L3

What’s inside the lateral horn/intermediolateral cell column?

sympathetic preganglionic neuron cell bodies

Pathway for a sympathetic neuron

• lateral horn

• ventral root (w/ visceral efferent fibers)

• white ramus

  • synapse and then through gray ramus

  • up/down the chain

  • to prevertebral ganglia or beyond

Sympathetic post-ganglionic nerves exiting through the gray ramus are going to innervate the…

blood vessels and skin

Origin of thoracic sympathetic nerves

T1-T5

Origin of abdominal sympathetic nerves

T5-L2

Origin of adrenal medulla sympathetic nerves

T5-T11

Origin of pelvic sympathetic AND parasympathetic nerves

S1-S5

Neurons innervating the adrenal medulla exit the sympathetic trunk via the…

grater splanchnic nerve

Neurons innervating the adrenal medulla pass through what structure after exiting the sympathetic trunk but before reaching their target

celiac ganglion

The parasympathetic nervous system originates in which two locations

the brainstem and the sacral spinal cord

Which cranial nerves have parasympathetic functions?

3, 7, 9, 10 (oculomotor, facial, glossopharyngeal, vagus)

What does the facial nerve innervate?

lacrimal glands, salivary glands

Where does the facial nerve synapse when innervating the lacrimal glands?

pterygopalatine ganglion

Where does the facial nerve synapse when innervating the salivatory glands?

submandibular ganglion

What does the oculomotor nerve innervate?

eye

Where does the oculomotor nerve synapse?

ciliary ganglion

What does the glossopharyngeal nerve innervate?

salivary glands

Where does the glossopharyngeal nerve synapse?

otic ganglion

What does the vagus nerve innervate?

heart, lungs, GI tract, kidneys

What are the pelvic organs innervated by?

the greater pelvic splanchnic nerve

Where does the oculomotor nerve originate?

edinger-westphal nucleus (midbrain)

Where do the facial and glossopharyngeal nerves originate?

salivatory nuclei (medulla)

Where does the vagus nerve originate?

DMNX, nucleus ambiguus (medulla)

Origin of sacral preganglionic parasympathetic somas in the spinal cord

intermediate gray zone (sacral spinal cord)

Cardioacceleratory center function

activates sympathetic pathways to increase heart activity, NE on heart, adrenal gland activation

Cardioinhibitory center function

activate parasympathetic pathways to decrease heart activity, vagus releases Ach on heart

Location of cardioacceleratory center

C1 region of vasomotor area

The cardioacceleratory center is typically ACTIVE unless inhibited by the…

nucleus of the solitary tract (NTS)

Cardioinhibitory center components

vagal nucleus, nucleus ambiguus (stimulate vagus to release Ach on heart)

both the cardioacceleratory and cardioinhibitory centers receive input from what brain structure

the NTS

Plexuses of the enteric nervous system

• myenteric plexus

• submucosal plexus

Myenteric plexus function

peristalsis

Submucosal plexus function

GI secretions

What CN regulates enteric NS activity?

vagus nerve

What parasympathetic nerve regulates enteric NS activity?

greater pelvic nerve

Do both sympathetic and parasympathetic pathways play a role in regulating the enteric nervous system?

yes

What do the post-ganglionic neurons in the oculomotor pathway control?

pupillary constriction, lens accomodation

Do the short or long ciliary nerves arise from the oculomotor nerve?

short

What do long ciliary nerves do?

convey sensory and sympathetic fibers to the eye

What is the carotid plexus?

network of sympathetic fibers wrapped around the internal carotid artery

When the radial muscles of the iris contract, the pupil _______

dilates

When the circular muscles of the iris contract, the pupil __________

constricts

What brain structure provides the somatic motor component of CN 3?

oculomotor nerve nucleus

edinger-westphal nucleus

parasympathetic nucleus of the oculomotor nerve

Pupillary light reflex pathway - parasympathetic

• light enters eye

• retina —> sensory info through optic nerve

• optic chiasm, optic tracts

• pretectal nuclei (midbrain), relay point

• edinger-westphal nucleus (midbrain)

• preganglionic fibers w/ CN 3

• ciliary ganglion

• postganglionic fibers w/ short ciliary nerves

• Ach on CIRCULAR muscles of iris (constriction)

Pupillary light reflex pathway - sympathetic

• no light

• hypothalamus, processing info that there’s no light

• neurons travel through hypothalamospinal tract to T1

• synapse in lateral horn

• preganglionic neuron goes to sympathetic chain and ascends

• synapse in superior cervical ganglion

• postganglionic neurons form carotid plexus

• postganglionic fibers join nasociliary nerve

• fibers travel through long ciliary nerves

• NE on RADIAL muscles of iris (dilation)