PNS

Question 1

Peripheral nerve (LMN) - motor (efferent) originate from

Answer 1

motor nuclei (CN) or anterior horn cells (spinal nerves)

Question 2

Peripheral nerve (LMN) - sensory (afferent) originate

Answer 2

in cells outside of brainstem or spinal cord with sensory ganglia (CNs) or DRG (spinal nerves)

Question 3

Peripheral nerve (LMN) - autonomic nervous system fibers

Answer 3

Sympathetic fibers at thoracolumbar spinal segments

Parasympathetic fibers at craniosacral segments

Question 4

CNs - all nerves are distributed ___ except ___

Answer 4

All to head and neck except X which is distributed to thorax and abdomen

Question 5

CNs - pure sensory =

Answer 5

I (olfactory)
II (optic)
VIII (vestibulocochlear)

Question 6

CNs - pure motor =

Answer 6

III (oculomotor)
IV (trochlear) 
VI (abducens) 
Those three control eye mvmnts and pupillary constriction
XI (accessory)
XII (hypoglossal) 
These are SCM, trap, tongue

Question 7

CNs - mixed =

Answer 7

V (chewing, sensations from head)
VII (facial expression, sensations from head, taste)
IX (swallowing, sensation from head, alimentary tract, heart, vessels, lungs, taste)
X (swallowing, voice sounds, alimentary tract, heart, vessels, lungs, taste)

Question 8

Spinal nerves - each has a ventral and dorsal root - Ventral (anterior) root =

Answer 8

Efferent (motor) fibers to voluntary muscles (alpha and gamma motor neurons) and to viscera, glands, and smooth muscles

Question 9

Spinal nerves - each has a ventral and dorsal root - Dorsal (posterior) root =

Answer 9

Afferent (sensory) fibers from sensory receptors from skin, joints, muscles
Each dorsal root has a DRG except for C1

Question 10

Dermatome =

Answer 10

specific segmental skin area innervated by sensory spinal axons

Question 11

Myotome =

Answer 11

refers to skeletal muscles innervated by motor axons in a given spinal root

Question 12

Motor unit consists of

Answer 12

alpha motor neuron and the muscle fibers it innervates

Question 13

In the cervical spine, numbered roots exit

Answer 13

horizontally above the corresponding vertebral body with C8 exiting below C7 and above T1

Question 14

In the thoracic, lumbar and sacral spine - the roots exit

Answer 14

below the corresponsing vertebral body

Question 15

Spinal cord ends at

Answer 15

level L1

Question 16

After emerging from intervertebral foramen, each spinal nerve divides into

Answer 16

large anterior ramus (supplying muscles and skin of anterolateral body wall and limbs) and a small posterior ramus (supplying muscles and skin of the back)
Each ramus has motor and sensory fibers

Question 17

Cervical plexus arises from

Answer 17

C1-C4 nerve roots

Question 18

Brachial plexus arises from

Answer 18

C5 - T1 nerve roots

Question 19

Lumbar plexus arises from

Answer 19

T12 - L4

Question 20

Sacral plexus arises from

Answer 20

L4 - S3