Lab Spinal Nerves And Spinal Reflexes

Question 1

Where do spinal nerves originate?

Answer 1

• from the spinal cord
• pass through an intervertebral foramen, as they exit the vertebrae
• exception: Between skull and C1 and sacrum group (sacral foramina)

Question 2

31 pairs if spinal nerves, form 5 groups:

Answer 2

• cervical nerves 1-8
• thoracic nerves 1-12
• lumbar nerves 1-5
• sacral nerves 1-5
• coccygeal nerves 1 pair

Question 3

Divisions of spinal nerves as they branch towards the periphery of the body:

Answer 3

• roots
• rami
• plexuses

Question 4

Roots

Answer 4

• attached directly to the spinal chord

* join to form spinal nerves

Question 5

Two roots:

Answer 5

• dorsal root: carries sensory (afferent) info to dorsal horn of the spinal cord
• ventral root: carries motor (efferent) responses to the effector organ

Question 6

Rami (branching)

Answer 6

•after leaving the spinal cord spinal nerve forms 2 sometimes 3 branches called rami

Question 7

2 ramus

Answer 7

• dorsal ramus

* ventral ramus

Question 8

Dorsal ramus

Answer 8

• sensory and motor nerve fibers

* motor: innervate most if the deep muscles of the dorsal trunk, responsible for movement of the vertebral column

Question 9

Ventral ramus: distributed two ways-

Answer 9

1. Thoracic region- form intercostal nerves, extend along inferior margin of each rib
   - innervate the intercostals muscles and skin over the thorax
2. Plexus: remaining from the 5 major plexuses
3. Communicating rami: form thoracic and upper lumbar spinal cord regions, carry axons associated with the synaptic division if ANS
   - connect to synaptic chain ganglia

Question 10

Plexus

Answer 10

Intricate networks of spinal nerves in a braid like structure

Question 11

5 plexuses of the spinal nerves

Answer 11

•cervical 
•brachial
•lumbar
•sacral
•coccygeal 
*then branch off plexuses to reach all parts of trunks and limbs

Question 12

3 types of nerve calls that carry information between the spinal cord and peripheral nerves:

Answer 12

Somatic motor neurons
Autonomic motor neurons
Sensory neurons

Question 13

Somatic motor neurons

Answer 13

Control contraction of skeletal muscles in the neck, trunk and limbs

Question 14

Sensory neurons

Answer 14

Detect skin sensations and muscle position or stretch (proprioception)

Question 15

Autonomic motor neurons

Answer 15

These motor neurons form pathways leading to internal organs of the head, chest and abdomen

Question 16

Name the two upper plexuses of the spinal cord

Answer 16

Cervical plexus

Brachial plexus

Question 17

Name the three lower plexuses of the spinal cord

Answer 17

Lumbar plexus
Sacral plexus
Coccygeal plexus

Question 18

Cervical plexus

Answer 18

• composed of ventral rami of cervical nerves C1-4
• controls actions of head neck shoulders
• receives sensory info from the skin in these areas

Question 19

Brachial plexus

Answer 19

• arises from the ventral rami of cervical nerves 5-8 (C5-T1)
• controls arm, forearm and hand
• receives sensory info from skin in these areas
• most complex plexus
• 3 trunks, 2 divisions, 3 cords

Question 20

Lumbar plexus

Answer 20

• from ventral rami of lumbar nerves 1-4 (L1-4)
• ventral rami form anterior and posterior divisions
• then branch to form peripheral nerves

Question 21

Sacral plexus

Answer 21

• is lumbar 5 and sacral 1-3 spinal nerves
• ventral rami of these nerves form anterior and posterior divisions
• lead to peripheral nerves

Question 22

Coccygeal plexus

Answer 22

•composed of ventral rami from sacral nerves 4 and 5, and the coccygeal nerves

Question 23

What four plexuses arise from or originate from the ventral rami?

Answer 23

Cervical plexus
Brachial plexus
Lumbar plexus
Coccygeal plexus

Question 24

3 divisions of the autonomic nervous system ANS

Answer 24

•sympathetic
•parasympathetic
•enteric
( all control actions of the internal organs)

Question 25

Arrangement of cells

Answer 25

•nerve cells originate in brain or spinal cord •pass to internal organs via cranial or spinal nerves •pathway to organs is a two cell circuit -w/ a junction between cells forming a ganglion

Question 26

Parasympathetic pathways

Answer 26

* originate in cranial nerves (III, VII, IX, X) of the brain | * or in sacral region S2-4 (pelvic splanchnic nerves)

Question 27

Parasympathetic pathways: cell bodies of preganglionic neurons located in the brain stem and sacral regions of the spinal cord (craniosacral):

Answer 27

Usually involve activating vegetative functions Ex digestion Dedication Urination

Question 28

Vagus nerve

Answer 28

Cranial nerve •extends from brain into chest and abdomen to control internal organ functions •joins with sympathetic nerves to form plexuses around stomach and heart

Question 29

Pelvic nerves

Answer 29

Originated from spinal nerves S2-4 •pass through ventral rami •then form nerves leading to pelvic organs

Question 30

Sympathetic pathway (fight or flight)

Answer 30

Originate from spinal nerves T1-L2 •motor nerves pass through spinal nerves to form special nerves •or end in ganglion, in one of two chains of ganglia that parallel spinal cord

Question 31

Cell bodies of sympathetic pthwy preganglionic neurons located in the thoracic and upper lumbar regions (thoracolumbar):

Answer 31

Usually involve with preparing body for physical activity

Question 32

Main nerves of sympathetic pathways

Answer 32

Sympathetic | Splanchnic

Question 33

Spinal reflexes

Answer 33

* involuntary automatic predictable response to stimuli * purpose: self preservation * somatic: removal from painful stimuli * autonomic: blood pressure

Question 34

Reflex pathways (arcs)

Answer 34

* a functional unit composed of a series of nerve cells | * follow a specific pathway to and from the spinal cord

Question 35

General pathway

Answer 35

* info travels into and out of spinal cord in one direction only * impulse pathway may either pass upwards towards the brain or downward to activate other muscle groups

Question 36

Reflex pathway components

Answer 36

``` 1 sensory receptor 2 sensory neuron 3 interneuron 4 motor neuron 5 effector organ ```

Question 37

Somatic motor and sensory nerve pathways: cervical 1-4

Answer 37

Plexus: cervical Peripheral nerves: phrenic - muscles and skin of the head neck and shoulder - diaphragm

Question 38

Somatic motor and sensory nerve pathways: cervical 5-8 | Thoracic 1

Answer 38

Plexus: brachial Peripheral nerves:axillary, musculocutaneous, median, radial, ulnar •muscles and skin of the shoulder arm,forearm, arm forearm and hand

Question 39

Somatic motor and sensory nerve pathways: thoracic 2-12

Answer 39

* no plexus * peripheral nerves: intercostals * muscles between the ribs; skin of the chest and abdomen

Question 40

Somatic motor and sensory nerve pathways: lumbar 1-4

Answer 40

•Plexus: lumbar •peripheral nerves: lliohypogastric- muscles and skin of the abdomen and buttocks llioinguinal- skin and muscles of external genitals and abdomen wall genitofemoral- external genitals femoral- skin and muscles if the anterior hip and thigh obturator-muscles and skin of the median thigh •

Question 41

Somatic motor and sensory nerve pathways: lumbar 5, sacral 1-3

Answer 41

•plexus: sacral •peripheral nerves: **sciatic- tibial: posterior thigh and leg, muscles and skin median and lateral planter: posterior and planter foot, skin and muscles Common peroneal fibular: superficial and deep peroneal: anterior leg and foot, skin and muscles **pudendal: perineum and external genitals skin and muscles

Question 42

Somatic motor and sensory nerve pathways: sacral 4-5, coccygeal

Answer 42

Plexus: coccygeal •nerves: coccygeal •perineum and coccyx skin and muscles

Question 43

Patellar reflex test

Answer 43

Femoral nerve

Question 44

Triceps brachii reflex test

Answer 44

Radial nerve

Question 45

Autonomic motor nerves: Sympathetic division

Answer 45

* communicating rami * superior and inferior cervical ganglia * chain ganglia * organ plexuses (esophagus, heart, stomach)

Question 46

Autonomic motor neurons, parasympathetic division

Answer 46

Vagus nerve | Organ plexuses