Nervous System Flashcards - ANS, CNS/PNS, Plexuses, Dermatomes, Reflexes

A set of practice flashcards covering CNS/PNS divisions, autonomic nervous system, nerve plexuses, dermatomes/myotomes, reflex arcs, and related topics from the notes.

What are the two functional divisions of the Peripheral Nervous System (PNS)?

Sensory (afferent) division and Motor (efferent) division.

Which division of the nervous system is responsible for 'rest and digest' and reduces heart rate and pupil dilation?

Parasympathetic division.

Which division of the nervous system is responsible for 'fight or flight' and increases heart rate and dilates airways?

Sympathetic division.

What are the two main functional subdivisions of the nervous system in addition to CNS/PNS?

Somatic nervous system (voluntary, skeletal muscles) and Autonomic nervous system (involuntary, visceral, smooth/cardiac muscle and glands).

What is the dorsal (posterior) root ganglion?

A cluster of sensory neuron cell bodies in the dorsal root of a spinal nerve.

Define a dermatome.

An area of skin innervated by the cutaneous sensory branches of a single spinal nerve.

Define a myotome.

A group of muscles supplied by a single spinal nerve.

Which roots form the cervical plexus and what is a key nerve it gives rise to?

Ventral rami of C1-C5; includes the phrenic nerve.

Which roots form the brachial plexus and what are its major terminal nerves?

Ventral rami C5-T1; Musculocutaneous, Axillary, Median, Ulnar, and Radial nerves.

Which roots form the lumbar plexus and what are its major nerves?

Ventral rami L1-L4; major nerves include Femoral and Obturator nerves.

Which roots form the sacral plexus and what are its major nerves?

Ventral rami L4-S4; major nerves include Sciatic, Pudendal, Superior and Inferior Gluteal nerves.

What is shingles and where does the Varicella Zoster virus reside?

Shingles is caused by Varicella Zoster virus; it remains dormant in the dorsal root ganglion.

What is a spinal nerve composed of?

A nerve formed by the joining of ventral (motor) and dorsal (sensory) roots; contains mixed fibers.

What is the difference between white ramus communicans and gray ramus communicans?

White ramus carries preganglionic sympathetic fibers into the sympathetic chain (myelinated); gray ramus carries postganglionic sympathetic fibers back to the spinal nerve (unmyelinated).

Where are sympathetic chain ganglia located?

Along the sympathetic trunk near the vertebral column (paravertebral ganglia).

What neurotransmitters are released by preganglionic and postganglionic neurons in the ANS?

Preganglionic neurons release acetylcholine (ACh); postganglionic neurons typically release norepinephrine (NE) in the sympathetic system and ACh in the parasympathetic system (sweat glands are an exception for sympathetic with ACh).

What receptors do nicotinic and muscarinic acetylcholine receptors correspond to in the ANS?

Nicotinic receptors are on postganglionic neurons; muscarinic receptors are on target organs (effector cells) in the parasympathetic system.

What receptors respond to norepinephrine on target cells?

Adrenergic receptors (alpha and beta).

Which cranial nerves carry parasympathetic fibers?

Oculomotor (III), Facial (VII), Glossopharyngeal (IX), and Vagus (X).

From what regions does the parasympathetic (craniosacral) outflow originate, and what is the typical length of preganglionic vs postganglionic neurons?

Originates from brainstem and sacral spinal cord (craniosacral); long preganglionic and short postganglionic neurons; ganglia near the target organ.

Where are the sympathetic preganglionic and postganglionic neuron cell bodies located?

Preganglionic cell bodies in the thoracic and lumbar spinal cord (T1-L2); postganglionic cell bodies in the sympathetic chain ganglia near the spinal cord.

Which reflex arc components define a basic reflex, in order?

Stimulus → Sensory receptor → Sensory neuron → Integration center → Motor neuron → Effector.

Is the patellar (knee-jerk) reflex monosynaptic or polysynaptic, and which nerve is involved?

Monosynaptic; involves the femoral nerve and quadriceps muscle.

What is reciprocal inhibition in the context of the stretch reflex?

The antagonist muscle is inhibited while the agonist muscle contracts, ensuring smooth movement.

What is Erb's palsy and which neural structure is typically affected?

Injury to the brachial plexus during childbirth, leading to weakness/paralysis of upper limb muscles.