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Spinal Nerves and ANS - Coggle Diagram

Spinal Nerves and ANS

Spinal cord & Nerve Roots

Describe the organization of the paired spinal nerves arising from the spinal cord.  How many spinal nerves arise at each spinal cord level (cervical, thoracic, lumbar, sacral, coccygeal)?

Naming Convensions

How are spinal nerves named/designated?

Between what vertebrae does the C2 spinal nerve arise on each side? C3?  C4?  C5?  C6?  C7?  C8?

Between what vertebrae does the T1 spinal nerve arise on each side? T5?  L1?  L5?

Disc Herniation

Herniation of a cervical intervertebral disc at C5/6 results in pain over the skin on the lateral forearm and palmar surface of the thumb; the brachioradialis reflex is also affected.  What nerve is most likely compressed

Structural Details about the vertebral canal & spinal cord

Nerve Roots

What is conus medullaris?  At what vertebral level does it terminate?

Cauda Equina & Lumbar Puncture

What is cauda equina?  Is it dorsal and ventral rami, spinal nerves, or dorsal and ventral roots?

What is the lumbar cistern? What does it contain?  In what space it is located? Why is it clinically relevant?

Diagram how the spinal nerve is constructed, including dorsal and ventral roots, true spinal nerves, as well as dorsal and ventral rami.

Dorsal & Ventral Rami

What does the dorsal ramus of each spinal nerve supply?  The ventral ramus?

Ventral Rami

What does it mean that ventral rami remain segmental in the thorax and anterior abdominal wall?

What does it mean that ventral rami merge to form a plexus in the neck, upper and lower limbs?

Dermatomes

What is a dermatome?  What anatomical landmark is located at the T4 dermatome?  At the T10 dermatome? At the L1 dermatome?

What part of the hand is innervated by the C6 dermatome

What is the difference between a dermatome and cutaneous innervation? (how would a C6 dermatome lesion present?  How would a median nerve lesion present in terms of sensory symptoms?)

Answers

Cutaneous innervation refers to area of skin innervated by a peripheral nerve. A dermatome is a strip of skin supplied by sensory branches of dorsal & ventral rami from one spinal cord level. C6 lesion would affect every nerve that stems from C6 ventral & dorsal Rami or the clinical nerve root/ true spinal N. Median nerve lesion only affects things innervated by the median N & median N branches.

What nerve fiber types run through dorsal and ventral rami of spinal nerves?

What nerve fiber types run through the dorsal and ventral roots of spinal nerves?

Where are the cell bodies of neurons that supply skeletal muscles?  Where are the cell bodies of neurons supplying the skin?

What is a myotome?  How can motor function be used to diagnose what spinal nerve levels are malfunctioning?

Through what opening do spinal nerves exit the vertebral canal?

Spinal cord length

Is the spinal cord the same length as or shorter than the vertebral column?  Why is this important?

What occupies the vertebral canal below L1 vertebral level?

Meningeal Layers: Pia Matter

What pia mater specializations support the spinal cord?  How are these oriented?

Visceral Nervous System

Visceral Motor

Parasympathetic Division

Where are parasympathetic nerves observed?  Are they in spinal nerves?  Do they use the sympathetic chain?

Sympathetic Division

What type of nerve fiber activates sweat glands in the skin of the back?  Sympathetic or parasympathetic? (Think about what system would be dominant when you are nervous, making you sweaty!)  Trace the pathway of sympathetics from the spinal cord to the skin of the back.

What is the difference in white vs gray rami in the sympathetic system? Which are more numerous and why?

answer

White rami connect sympathetic preganglionic neurons to paravertebral ganglion (aka sympathetic chain, adjacent to vertebral bodies) where they can synapse w/ postganglionic neurons. White rami has this name b/c its myelinated. White rami are only found at T1 – L2. White Rami also contain general visceral afferent fibers whose cell bodies are located in the lateral horn of the spinal cord & the dorsal root Ganglia. Grey rami carry postganglionic fibers from postganglionic neurons back to the peripheral nerves and are found at every vertebral level that exists a sympathetic ganglion.

Compare and contrast the pathways that transport sympathetics to the limbs and body wall vs to internal organs.  Which use gray rami?  Which use splanchnic nerves?

Visceral Sensory

What do visceral sensory neurons supply?  Why can irritation of visceral sensory neurons result in referred pain in the arm (as in heart attack)?  How does the circuitry of somatic and visceral sensory neurons allow for referred pain?