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Anatomy > Introduction to the Nervous System > Flashcards

Introduction to the Nervous System Flashcards

1
Q

What Do Nerves Do?

A

Sensory Functions: Enable us to perceive internal and external environments.

Special Senses: Vision, hearing, taste, smell, and balance

Motor Functions: Facilitate appropriate responses to stimuli.

  • Voluntary: Skeletal muscle movement (locomotion)
  • Involuntary: Smooth muscle, gland, and cardiac muscle actions
    Reflex Functions: Automatic, rapid responses to stimuli.
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2
Q

Anatomical Subdivisions

A

Central Nervous System
Peripheral Nervous System

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3
Q

Describe the CNS

A

Brain
Spinal Cord
Central controller

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4
Q

Describe the PNS

A

All other nerve tissue not within the CNS
Spinal nerves
-connect with spinal cord
Cranial nerves
-connect with brain
Autonomic nerves
-organs, smooth muscle, glands
-visceral afferents
-sympathetic nerves
-parasympathetic nerves
Wiring

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5
Q

Describe The Neuron

A

Basic unit of nervous system
Collection of nerve cell bodies:
in CNS = Nucleus
in PNS = Ganglion

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6
Q

Describe Nerves

A

Bundles of Axons (nerve fibres): Wrapped in connective tissue, traveling to/from same regions or structures.
Can branch off as smaller bundles
Named Nerves: Larger nerves serving the body wall, cavities, and organs

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7
Q

What is in a Nerve?

A

A single nerve fiber (axon) only conducts action potentials for ONE of six modalities:
1. Somatic sensory function
2. Somatic motor function
3. Special sensory function
4. Visceral afferent function
5. Sympathetic function
6. Parasympathetic function

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8
Q

Motor Vs Sensory

A

Motor (efferent):
Action potential towards body wall, body cavity or organ
Sensory (afferent):
Action potential towards brain

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9
Q

Describe The Brain

A

outermost layer of the cerebral hemispheres cortex
consists of gyri and sulci

4 lobes of each cerebral hemisphere
named according to cranial bone they lie deep to

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10
Q

What is the Cranial Nerves

A

12 pairs - need to know name, number (Roman numerals), modality and function(s), where they connect to CNS, route through and exit from cranium

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11
Q

CN I

A

-olfactory nerve
-sensory (special)

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12
Q

CN II

A

optic nerve
sensory (special)

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13
Q

CN III

A

oculomotor nerve
motor (somatic & parasym.)

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14
Q

CN IV

A

trochlear nerve
motor

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15
Q

CN V

A

trigeminal nerve
both

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16
Q

CN VI

A

abducent nerve
motor

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17
Q

CN VII

A

facial nerve
both (spec.sensory, somatic motor & parasym.)

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18
Q

CN VIII

A

vestibulocochlear nerve
sensory (special)

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19
Q

CN IX

A

glossopharyngeal nerve
both (spec.sensory, somatic motor & parasym.)

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20
Q

CN X

A

vagus nerve
both (somatic sensory, somatic motor & parasym.)

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21
Q

CN XI

A

spinal accessory nerve
motor

22
Q

CN XII

A

hypoglossal nerve
motor

23
Q

Where Cranial Fossae Foraminae for CNs to enter/exit cranial cavity:

A
24
Q

Course of a Cranial Nerve

A
25
Q

The Spinal Cord

A

Passes through foramen magnum

Protected by vertebral canal

Has 4 segments:
cervical
thoracic
lumbar
sacral/coccygeal

Has 2 enlargements
cervical
lumbosacral

Connects bilaterally with spinal nerves
8 cervical - C1-C8
12 thoracic - T1-T12
5 lumbar - L1-L5
5 sacral - S1-S5
1 coccygeal - Co
spinal cord ends at L1/L2 IV disc level
conus medullaris
Adult vertebral column is longer than the adult spinal cord
lumbar and sacral spinal nerve roots have to descend in the vertebral canal to their respective intervertebral foraminae
cauda equina (horse’s tail)

26
Q

How are Spinal nerves named?

A
  • according to the vertebrae above it
  • except in the cervical region, where
    they are named according to the
    vertebrae below it
  • C8 spinal nerve exits between C7 and T1
    vertebrae
27
Q

Vertebral Column

A

33 vertebrae in total
7 cervical
12 thoracic
5 lumbar
5 sacral
fused to form 1 sacrum
4 coccygeal
fused to form 1 coccyx

28
Q

Rules of spinal nerve anatomy:

A
  • spinal nerves supply the soma (body wall)
  • located only within the intervertebral foramina
  • from the intervertebral foramina they connect with
  • structures of the soma via rami
  • the spinal cord via roots and rootlets
29
Q

Anatomy of Spinal Nerves

A
30
Q

Spinal Nerves and Body Segments

A

each pair of spinal nerves supplies one ‘strip’ of the soma

posterior rami
-supply small posterior strip

anterior rami
-supply the remainder of the posterior part, the lateral and the anterior parts of the strips

-supply all of the limbs

31
Q

What is a Dermatomes

A

area (strip) of skin supplied by both the anterior and posterior rami of a spinal nerve

T4 dermatome – nipple

T10 dermatome – umbilicus

32
Q

List Nerve Plexuses

A

Cervical plexus
C1-C4 anterior rami
Posterior scalp, neck wall and diaphragm

Brachial plexus
C5-T1 anterior rami
Upper limb

Lumbar plexus
L1-L4 anterior rami
Lower limb

Sacral plexus
L5-S4 anterior rami
Lower limb, gluteal region and perineum

33
Q

Functional Subdivisions - Somatic nervous system

A

Soma includes:
-head and neck walls
-chest walls
-back
-the diaphragm
-abdominal wall
-pelvic wall
-limbs

Structures:
-skin
-fascia
-skeletal muscle
-skeleton
-internal lining of body cavities

34
Q

Somatic Sensation- Sensations felt by body wall

A

sensed by mechanoreceptors:
-coarse touch
-fine touch
-vibration
-proprioception
sensed by thermoreceptors:
-temperature
sensed by nociceptors:
-pain

35
Q

Describe Somatic Sensation

A
  • Somatic sensory mechanoreceptors in the L2 dermatome are stimulated
  • Action potentials (APs) travel via axons in the L2 anterior ramus
  • These axons pass through the lumbar plexus to the L2 spinal nerve
  • APs continue through the dorsal (posterior) root ganglion, dorsal roots, and rootlets
  • APs reach the posterior horn of the L2 spinal cord segment
  • APs cross the midline and ascend towards the brain
36
Q

Describe Motor Innervation

A

Somatic motor axons cross in the brainstem and descend to the anterior horn.
APs travel through anterior rootlets, roots, and spinal nerves.
APs continue via lumbar plexus nerves to synapse on lower limb skeletal muscles.
Skeletal muscles contract, moving the lower limb.

37
Q

Spinal Reflexes

A

-reflex is extremely rapid

-misses out pathway to brain

-involuntary response

38
Q

Functional Subdivisions - Autonomic nervous system

A

Includes
Viscera e.g. heart, lungs, intestines, kidneys
glands (mucous, sweat, salivary etc.)
smooth & cardiac muscle
external lining of organs

Locations
internal organs in body cavities
chest cavity, pelvic cavity, abdominal cavity

body wall organs
sweat glands, arrector smooth muscles, arterioles

39
Q

Describe the Autonomic Nervous System

A

Auto = self , nomos = law
Internal environment:
-Sensory neurones
-Sensations from organs to CNS
-Motor Neurones

40
Q

Role of Sensory neurones in ANS

A

sense the internal environment (organs)
organs sensory nerves are called ‘visceral afferent’

41
Q

Role of Sensations from organs to CNS in ANS

A

-Touch
-Temperature
-Pain
-Ischaemic
-Colicky

Described as:
– dull, achy, nauseating
- poorly localised

42
Q

Role of Motor Neurones
in ANS

A

-respond to changes in internal environment
dual motor control
-Many internal organs have both a sympathetic & parasympathetic nerve supply
-Both motor controls
-‘Accelerator’ or ‘brake’

43
Q

3 Things Sympathetic Division of ANS supplies

A
  • all internal organs
  • body wall organs
  • arterioles
44
Q

How do the following structures respond during ‘Flight or fight’

pupils, heart, lungs. GI tract, Liver, Adrenal Glands, Arterioles, Skin

A

Pupils - dilate
Heart - rate increases
Lungs - bronchioles dilate
GI tract - motility is reduced
Liver - glucose released into the blood
Adrenal glands - adrenaline/noradrenaline released
Arterioles - dilate or constrict- skin feels cold & looks pale
Skin - hair stands on end & sweat produced

45
Q

Describe Sympathetic Outflow

A

Descends the spinal cord and exits with T1-L2 spinal nerves.
Travels to sympathetic chains along the vertebral column.
Distributes via spinal nerves, anterior/posterior rami, to body wall structures.
Follows arteries to supply head, neck, and skin.
Travels via splanchnic nerves to reach organs.

46
Q

Which segments of the spinal cord have lateral horns and why?

A

T1- L2
for cell bodies of the next sympathetic neurones in the chain

47
Q

Parasympathetic Division of ANS

A

Often supplies same internal organs as sympathetic division
Does not supply body wall organs or arterioles
Rest & Digest
-Returns to homeostasis
-Compliments / Opposes the sympathetic system

48
Q

How do the following structures respond during ‘Rest and Digest’

pupils, heart, lungs, GI tract, liver, bladder

A

Pupils - constrict
Heart - rate decreases
Lungs - bronchioles constrict
GI tract - motility is increased
Liver - glucose synthesis
Bladder – sphincter relaxes

49
Q

Describe Parasympathetic Outflow

A
  • Parasympathetic axons exit via cranial nerves III, VII, IX, X, and sacral spinal nerves.
  • Target internal organs, not the body wall.
  • Cranial ganglia supply the lacrimal and salivary glands.
  • Vagus nerve innervates neck, chest, and mid-gut organs.
  • Sacral nerves carry axons to the hindgut, pelvis, and perineum
50
Q

Modalities – Neuron Types

A

Anatomy (8 decks)

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