ANS Lecture

Question 1

ANS

Answer 1

Part of the nervous system that controls the involuntary activity in the body (smooth muscle, cardiac muscle, glandular tissue).

Question 2

Central control centers of ANS

Answer 2

Brain and brainstem

Question 3

Peripheral system:motor system

Answer 3

In peripheral system, the motor system directly supplies target tissues.

Involves sympathetic nervous system and parasympathetic nervous system. They often have reciprocal innervation (counter effects)

Question 4

Visceral afferents

Answer 4

Sensory neurons that supply target tissues of ANS (smooth muscle. cardiac muscle, glandular tissue) but are NOT considered to be a part of ANS by most individuals.

Sensory axons often travel along same route as the sympathetic and parasympathetic nerve axons.

Question 5

Examples of ANS effects

Answer 5

Sympathetic stimulations and parasympathetic stimulation often have counteractve effects.
Ex=Pupil dilation (sympathetic)
       Pupil constriction (parasympathetic)

Question 6

Special ANS effect with blood vessels

Answer 6

Sympathetic stimulation can cause constriction (alpha receptors) AND dilation (beta receptors) in BLOOD VESSELS.

Question 7

Sympathetic nervous system origin

Answer 7

Thoracolumbar spinal cord (T1-L4)

Question 8

Parasympathetic nervous system origin

Answer 8

Sacral spinal cord and brainstem

Question 9

Somatic efferents vs Visceral efferents (ANS)

Answer 9

Somatic efferents- CNS is directly connected to target muscle through 1 motor neuron (skeletal muscle is good example)

Visceral efferent- like a “relay race”. Long preganglionic axon extends from CNS to a ganglia which communicates with postganglionic axon that will communicate with target tissue.

Question 10

Cell bodies of preganglionic neurons of sympathetic and parasympathetic nervous system found where

Answer 10

CNS
Sympathetic: thoracolumbar spinal cord (T1-L4)
Parasympathetic: sacral spinal cord and brain stem (CNN 3, 7, 9, 10)

Question 11

Explain preganglionic/postganglionic relay

Answer 11

Axon of pregang neuron travels in a peripheral nerve (spinal or cranial nerve) to synape on a specific postgang nerve. The axon of postgang neuron travels in a peripheral nerve to synape to specific target tissue to inhibit or stimulate target tissue.

Question 12

Ganglia

Answer 12

Collection of neuronal cell bodies found outside CNS.

Question 13

ANS ganglia

Answer 13

Postgang neurons are found in ganglia

Note, not all ganglia are associated with ANS

Question 14

Sympathetic nervous system ganglia

Answer 14

Most are visible in gross dissection (head, thorax, abdomen, pelvis)

• ->paravertebral (beside vertebral column)
• ->prevertebral (further away from vertebral column)

Question 15

Sympathetic ganglia need to ID in lab

Answer 15

Middle cervical ganglion
Cervicothoracic ganglion
Sympathetic trunk ganglion

Question 16

Part of the sympathetic trunk

Answer 16

Cervical, thoracic, lumbar, sacral

Question 17

ANS bilateral or unilateral

Answer 17

Bilateral. On left and right side of the body

Question 18

Parasympathetic length of axons and ganglia

Answer 18

Pregangs are long
Postgangs are short and right next to tissue its going to innervate

Ganglia are at or in wall of target organ

Question 19

Crainial nerve X functions

Answer 19

Vagus nerve
ANS-parasympathetic
Sensory from viscera to brain (accounts for 80% of axons in the vagus nerve)
Motor to skeletal muscles of the larynx via recurrent laryngeal nerve

Question 20

Vagus nerve orientation

Answer 20

Vagus nerve starts out (from tympano occipital fissure) following the vagosympathetic trunk on L and R side
Vagus nerve leaves trunk around middle cervical ganglia
Vagus nerve splits into dorsal and ventral branches on L and R side
Dorsal and ventral vagal branches from each side unite to give a singular dorsal trunk and a singular ventral trunk

The single ventral and single dorsal trunk will pass through diaphragm with the esophagus to supply abdominal organs.

Question 21

Sympathetic trunk

Answer 21

Runs lateral to vertebral column on each side. It carres axons mainly from pregang neurons destined to specific ganglion.

Question 22

Ansa subclavia

Answer 22

Sympathetic trunk divides to form this loop which wraps around subclavian artery (between cervicothoracic and middle cervical ganglia)

Question 23

Ramus communicans

Answer 23

Communicating branch between a spinal nerve and the sympathetic trunk.

Question 24

Cranial cervical ganglia

Answer 24

Most cranial ganglia. At head

Question 25

Middle cervical ganglia

Answer 25

Supplies heart, lungs, other thoracic viscera

Question 26

Cervicothoracic ganglia

Answer 26

thoracic viscera, supplies thoracic limb (via brachial plexus), neck (via vertebral nerve)

Question 27

Sympathetic trunk ganglia

Answer 27

Spinal nerves of the trunk, pelvic limbs and tail. Found along the symp trunk in the thoracic, lumbar, and sacral regions.

Question 28

Celiacomesenteric ganglia

Answer 28

Supploes abdominal viscera

Question 29

Caudal mesenteric ganglia

Answer 29

Supplies caudal abdominal viscera, pelvic viscera (via hypogastric nerve)

Question 30

Splanchnic

Answer 30

Sympathetic pregang axons supplying Caudal mesenteric ganglia,`

Question 31

Plexus

Answer 31

Mixed collection of axons traveling in close proximity to one another.

Question 32

Horner’s Syndrome

Answer 32

Loss of sympathetic innervation to the head

• ->miosis: small pupil
• ->Enophthalmos:sunken eye ball
• ->ptosis: droopy eyelid
• ->Protrusion of 3rd eyelid