somatic nervous system

Question 1

Nervous system made up of

Answer 1

CNS (brain and spinal cord) and PNS (spinal nerves and cranial nerves)

Question 2

axons in the CNS are called

Answer 2

tracts

Question 3

cell bodies in the CNS are called

Answer 3

nuclei

Question 4

axons in the PNS are called

Answer 4

nerves

Question 5

cell bodies in the PNS are called

Answer 5

ganglia

Question 6

Afferent

Answer 6

sensory axons that conduct towards CNS in dorsal root

Question 7

efferent

Answer 7

motor axons that conduct away from CNS in ventral root

Question 8

roots vs rami

Answer 8

roots are separated by afferent and efferent while rami are mixed (afferent, efferent) but separated by dorsal and ventral

Question 9

dorsal rami supply…

Answer 9

the intrinsic muscles of the back (motor) and the skin of the back (sensory)

Question 10

the ventral rami supply…

Answer 10

extrinsic muscles of the back, ventral muscles and the overlying parts of the dermatome.

Question 11

the ventral primary and dorsal primary rami also carry…

Answer 11

postganglionic sympathetic axons for blood vessels, smooth muscle cells and glands

Question 12

upper cervical dorsal rami

Answer 12

C1-suboccipital nerve; only motor. no cutaneous branches thus, there is no C1 dermatome
C2: motor and gives rise to greater occipital nerve which is a cutaneous nerve
C3: cutaneous branch is the lesser occipital nerve

Question 13

plexus are made of up from the ventral primary rami. Name the plexus

Answer 13

cervical, brachial , thoracic intercostal, lumbar and sacral

Question 14

cervical plexus

Answer 14

Consists of the ventral rami of C1-C4 spinal nerves. Peripheral nerves emerging from the cervical plexus provide cutaneous innervation to the back of the head, neck, shoulder, and upper thoracic region. They also provide motor innervation to muscles of the anterior neck and the diaphragm.

Question 15

brachial plexus

Answer 15

Consists of the ventral rami of C5-T1 spinal nerves. Peripheral nerves emerging from the brachial plexus provide cutaneous and motor innervation to the skin and muscles of the upper limb

Question 16

intercostal plexus

Answer 16

Consist of the ventral rami of T1-T11 spinal nerves that course within the intercostal spaces along the costal groove of their associated rib to innervate the skin and muscles of the intercostal spaces

Question 17

lumbar plexus

Answer 17

Consists of the ventral rami of T12-L4 spinal nerves. Peripheral nerves emerging from the lumbar plexus provide cutaneous innervation to the skin of the lower abdominal wall, perineum, anterior thigh, and medial thigh. They also provide motor innervation to muscles of the perineum, anterior thigh, and medial thigh.

Question 18

sacral plexus

Answer 18

Consists of the ventral rami of L4-S3 spinal nerves. Peripheral nerves emerging from the sacral plexus provide cutaneous and motor innervation to the skin and muscles of the lower gluteal region, posterior thigh, posterior leg, and foot.

Question 19

sensory transduction: the different modalities

Answer 19

touch, pain, temperature, proprioception, vibration

Question 20

afferent sensory information travels into the DRG and into the CNS (spinal cord) via a

Answer 20

1st order neuron.

Question 21

how many neurons are there in sensory transduction

Answer 21

3- first order (goes into CNS–into cord). second order goes from cord to thalamus (dessucation occurs in second order in the cord). then third order originates in the thalamus and travels into the cerebral cortex (the humunculus)

Question 22

neurons of output from motor cortex

Answer 22

upper motor neuron in primary motor cortex (in cerebral cortex) travels down to brainstem where it splits into a cranial nerve and a cortico-spinal tract and ends in the spinal cord. it meets there the lower motor neuron that exits through the ventral root into the spinal nerve.

Question 23

neurons of output from motor cortex

Answer 23

upper motor neuron in primary motor cortex (in cerebral cortex) travels down to brainstem where it splits into a cranial nerve and a cortico-spinal tract and ends in the spinal cord. it meets there the lower motor neuron that exits through the ventral root into the spinal nerve.

Question 24

how spinal nerves exit the IVF

Answer 24

CERVICAL : of the 8 cervical spinal nerves, the first 7 emerge superior to their corresponding vertebrae
C 8 spinal nerve emerges between vertebrae C7 & T1
THORACIC : all thoracic spinal nerves exit below their respective vertebrae, but still above their corresponding IVDs
LUMBAR : same as thoracic spinal nerves

Question 25

the sacral level of the cord is at the

Answer 25

conus medullaris L1-L2

Question 26

the cauda equina is located in the

Answer 26

lumbar cistern

Question 27

in the middle of the cauda equina is the

Answer 27

filum terminale (pia mater)

Question 28

in a newborn the cord (conus medullaris) ends at L3

Answer 28

important to know for anesthesia

Question 29

layers of the meninges

Answer 29

Dura mater (removable), arachnoid mater(also removable to reveal subarachnoid space that contains CSF), pia mater (unremovable and makes up denticulate ligaments that separate ventral and dorsal roots of the spinal nerves)

Question 30

best placement for lumbar puncture

Answer 30

below L2, L3-L4 is best (look for iliac crests which should be at the level of L4)