Lecture 2: the Spinal and Autonomic Nerves (part 1 of 2) Flashcards Preview

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Flashcards in Lecture 2: the Spinal and Autonomic Nerves (part 1 of 2) Deck (45):

define encephalopathy

a disease in the brain


define myelopathy

a disease in the spinal cord


define peripheral neuropathy

a disease in the peripheral nerves


the presence of what 4 conditions differentiates peripheral neuropathy from CNS encephalopathy and myelopathy?

1. hyporeflexia, hypotonia (less muscle tone)
2. "denervation" atrophy
3. unilateral motor and/or sensory deficits
4. normal function cranial and caudal to nerve lesion site


are cenral lesions usually unilateral or bilateral?



what are the 4 main branches of spinal nerves?

1. dorsal branch
2. ventral branch
3. communicating branch
4. meningeal branch


what are the 4 anatomical parts to the typical spinal nerve?

1. roots
2. main trunk
3. the four primary branches
4. peripheral branches of these primary branches


where are roots of spinal nerves located?

within the vertebral canal


roots of spinal nerves are functionally associated with what?

functionally associated with the spinal cord even though they belong to the peripheral nervous system.


are dorsal roots and spinal (dorsal root) ganglia afferent or efferent in function?

afferent ie sensory


Are ventral roots afferent or efferent in function?

efferent ie motor


describe an identifying characteristic of the main trunk of typical spinal nerves and their location in most cases

it is typically very short and located in the intervertebral foramen


what is the spinal nerve formula for the horse?

C8 T18 L6 S5 Cd7


where does the first cervical nerve emerge from?

it emerges from the lateral vertebral foramen located in the atlas


where does the second cervical nerve emerge from?

it exits from the lateral vertebral foramen of the second cervical vertebrae (axis)


where does the eight cervical nerve run through?

the intervertebral foramen between the seventh cervical and first thoracic vertebrae


how many cervical nerves and cervical vertebrae are there in the horse?

8 cervical nerves but only 7 cervical vertebrae


what does the dorsal primary branch supply?

dorsal axial (epaxial) muscles and skin over the dorsal and dorsolateral body areas


what does the ventral primary branch supply?

supplies ventral axial (hypaxial) muscles, muscles of ventral and ventrolateral regions like the thoracic and pelvic limbs and skin over these regions


what do ventral branches of the lower cervical and thoraci region (C6 - T1 or T2) form?

the brachial plexus


what do ventral branches of L4 - S4 form? what does it supply?

the lumbosacral plexus which supplies the pelvic limb and the perineal region


what does the meningeal branch supply?

it supplies the coverings of the spinal cord (meninges), blood vessels in the vertebral canal, and the intervertebral discs. these are implicated in back pain


what is an identifiable physical characteristic of the meningeal branch?

its is very small - difficult to see grossly


where does the communicating branch (ramus communicans) run?

it runs from the main trunk of a spinal nerve to the sympathetic trunk and chain ganglia


what is the communicating branch associated with functionally?

visceral function


what is a somatic structure?

it is associated with the body wall (skin, subcuntaneous tissue, skeletal muscle, joints, tendons, etc)


what is a visceral structure?

associated with internal organs, smooth muscle, cardiac muscle and glands.


what is a cutaneous nerve?

peripheral nerves that go to the skin only


what are cutaneous nerves sometimes called? it can be misleading...

they are sometimes called sensory but this is a misleading name because they innervate the smooth muscle around blood vessels; thus contain visceral efferent nerve fibers


what are muscle nerves?

they are peripheral nerves that go to muscle only


what are muscle nerves also commonly called? why is it misleading?

muscle nerves are also commonly called motor nerves.

this is misleading because many nerve fibers in muscle are muscle afferents (sensory) from muscle proprioceptors


what are most large nerves? cutaneous or muscle nerves?

most are actually mixed nerves because they go to both skin and muscle.


is the femoral nerve a cutaneous nerve, muscle nerve or mixed nerve?

mixed because it branches peripherally into both cutaneous and muscle nerves


what are the functional components of cutaneous nerves (there are 3)

somatic afferents
visceral afferents
visceral efferents


where do the somatic afferents for cutaneous nerves come from?

from receptors in skin and subcutaneous tissue


where do the visceral afferents for cutaneous nerves come from?

from receptors in blood vessels


where do the visceral efferents for cutanoues nerves come from? what do these fibers supply?

postganglionic sympathetic fibers which have their cell bodies in chain ganglia. these fibers supply the smooth muscle of blood vessels to erector pilae muscles associated with hairs and sweat glands.

there are NO somatic Efferents because there is no striated muscle


define cutaneous area

the area of skin supplied by a given cutaneous nerve


what are the two zones within a cutaneous area?

overlap zones and autonomous zones


define overlap zone

an area supplied by more than one cutaneous nerve


define autonomous zone

an area supplied by only one cutaneous nerve


which region would experience anesthesia resulting from severe damage to one peripheral nerve and is thus the area of most diagnostic value in determining level of nerve damage in a patient?

the autonomous zone


what are the 4 functional components of muscle nerves?

1. somatic afferents (sensory)
2. visceral afferents (sensory)
3. visceral efferents (motor)
4. somatic efferents (motor)


the presence of which type of fiber distinguishes muscle nerves from cutaneous nerves?

somatic efferents


where can muscle nerves originate from?

1. dorsal or ventral primary branches
2. mixed nerves

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