Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Unit 11 > W1: The somatic nervous system > Flashcards

W1: The somatic nervous system Flashcards

1
Q

What are the different structural classifications of the nervous system?

A

The central nervous system - brain and spinal cord
The peripheral nervous system - cranial nerves and spinal nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the different functional classifications of the nervous system?

A

Sensory v motor
Somatic v autonomic

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What makes up the sensory components of the nervous system?

A

Sensory ganglia and nerves
Sensory receptors (at the surface and within the body)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What makes up the different motor components of the nervous system?

A

Visceral motor system - autonomic ganglia and nerves, consists of parasympathetic, sympathetic and enteric division

Somatic motor system - motor nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the different effectors in the nervous system?

A

The visceral system - smooth muscle, cardiac muscle and glands etc

The somatic system - skeletal/striated muscle

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the organisation of sensory nerves seen at the individual spinal cord level?

A

Dorsal and ventral rami converge on a spinal nerve, which then splits into dorsal and ventral root.
Dorsal rami carrier primary sensory afferents with cell bodies in the dorsal root ganglion, axon terminals are in the dorsal horn

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Describe the organisation of alpha motor neurons in the spinal cord?

A

Cell bodies in the ventral horn, project along the ventral root, into the spinal nerve then out along the dorsal or ventral rami

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Describe the location of sympathetic nerves at the spinal cord level.

A

Thoracolumbar output
Cell bodies in the lateral horn
Project out via the ventral root through the spinal nerve.
Travel past the grey rami then travel down the white (myelinated) rami, into the sympathetic chain ganglion where synapse occurs (may then travel up or down the vertebral level through the sympathetic chain ganglion), then travel out the grey rami

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Where are interneurons found in the spinal cord?

A

Found throughout.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are the different classifications of nerves to do with what they supply and where they are travelling?

A

Somatic afferent e.g carry localised pain
Somatic efferent - skeletal muscle activation
Visceral afferent - GI pain
Visceral efferent - GI muscle activation (vomiting)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is meant by a somatic afferent?

A

Somatosensory afferents within nerves - pain, touch, position, temperature and itch

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is meant by a somatic efferent?

A

Motor axons within nerves

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What is meant by a visceral afferent?

A

A viscerosensory afferent within nerves of the viscera and blood vessels

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is meant by a visceral efferent?

A

Smooth and cardiac motor axon within nerves
E.g gland and gut wall innervating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the red A broadmand area?

A

Area 6
Premotor area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the red B broadmann area?

A

Area 6
Supplementary motor area

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What is red C broadmann area?

A

Area 4
Primary motor cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What is green A broadmann area?

A

Area 1,2,3
Somatosensory cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is green B broadman area?

A

Visual cortex
17,18,19

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the green C broadmann area?

A

Auditory cortex
Area 41 and 42

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is the large purple area C?

A

Prefrontal cortex

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What is the purple A broadman area?

A

Posterior parietal cortex
Area 5,7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What is the role of the posterior parietal cortex?

A

Spatial representation of objects for planning and motor control.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What is the purple area B broadmann area?

A

The infarotemporal cortex
Area 20,21,37

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What is the Boradmann area shown in the smaller brain?

A

Gustatory cortex
Area 43.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What is important about the functional design of the primary motor cortex?

A

Has a topographic map of the body
Higher density of cortical neurons proportional to the degree of control in the body.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What is the layout of the topographic map in the primary motor cortex (M1)?

A
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

Describe how neurons supplying the face travel out of the motor cortex?

A

M1 neurons controlling the face travel along the corticobulbar tract
Project out through the genu part of the internal capsule

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

Describe how motor neurons travelling to supply the body leave the motor cortex?

A

Follow the corticospinal tract
Leave M1 (primary motor cortex) by projecting through the posterior limb of the internal capsule

30
Q

Describe the structure of the internal capsule.

A

Conists of an anterior limb, a genu and a posterior limb.
Shaped like a more than/less than sign, eating the lateral side

31
Q

What is the corticospinal tract?

A

Motor neurons from M1 that supply the axial and limbs, project through the posterior limb of the internal capsule
Then to cerebellar peduncles
To the medullary pyramids where most of the desecation occurs. (Description of the pyramids)
Desiccated: To the lateral funiculus which contains the lateral corticospinal tract in the white matter of the spinal cord
Not dedicated: to the anterior corticospinal tract in the white matter of the spinal cord, at the correct vertebral level will desiccate at the anterior white commissure.
Then re-enters the spinal cord and synapses in the ventral horn with a lower motor neuron which will travel to the skeletal muscle

32
Q

What is the proportion of fibres in the corticospinal tract that desicate at the destination of the pyramids?

A

85% desiccate at the desiccation of the pyramids
Remaining 15% travel in the anterior corticospinal tract and will desciate in the anterior white comissure

33
Q

What is the pattern of the corticobulbar tract?

A

Originates from M1 for supply of the face
Projects through the genu of the internal capsule
Synapses with the cranial motor nuclei found within the midbrain, pons and medulla

34
Q

What is the pattern of synapsis for the Upper Motor Neurons in the corticobulbar tract with the cranial motor nuclei?

A

CN3,4,5,6 - bilateral
CN7 splits into upper and lower - upper is bilateral and lower is contralateral
Nucleus ambiguous - CN9,10,11 (cranial accessory) - bilateral
CN11 (spinal accessory) - bilateral
CN12 - contralateral only.

35
Q

How does the corticobulbar tract underpin the difference between how a stroke and bells palsy present?

A

Stoke - upper motor neuron lesion
Bells - lower motor neuron lesion

Upper face - bilateral synpasis from the corticobulbar tract
Lower face - contralateral synapsis

Therefore in an upper motor neuron lesion, the upper face would recover (as can still be supplied by opposite side of brain) but the lower side of the face would remain damage.
However in a lower motor neuron lesion neither part of the face would recover

36
Q

Define what is meant by a lower motor nueron

A

A neuron that directly innervates muscle

37
Q

What nuclei in the brainstem give rise to lower sensory neurons?

A

The trigeminal sensory nucleus
The vestibular and cochlear nuclei
Nucleus solitarus

38
Q

What nuclei in the brain stem gives rise to lower motor neurons?

A

Edinger-Westphal nucleus
Oculomotor nucleus
Trochlear nucleus
Trigeminal motor nucleus
Abducens nucleus
Facial motor nucleus
Superior and inferior salivatory nuclei
Nucleus ambiguous
Dorsal motor nucleus of the vagus
Hypoglossal nucleus

39
Q

Define what is meant by an upper motor neuron

A

Control lower motor neurons

40
Q

What is an example of an upper motor neuron?

A

Layer 5 Betz neurons - whose axon form the corticospinal and corticobulbar tract.

41
Q

What do proprioceptive afferents do?

A

Sense muscle tension

42
Q

What are the different type of muscle fibres?

A

Extrafusal muscle fibres - cause muscle tension/contraction
Intrafusal muscle fibres - sense tension in the muscle

43
Q

What afferents innervates the intrafusal muscle fibres?

A

Type 1a and type 2 afferents

44
Q

What structures play a role in proprioception of skeletal muscle?

A

Intrafusal muscle fibres - innervates by type 1a and type 2 afferents
Golgi tendon organs - innervated by type 1b proprioceptors

45
Q

What is a Golgi tendon organ?

A

Role is proprioception
Loacted within the collagen fibres of tendons and within joint capsules
Recieves information from a muscle tendon about tension

46
Q

What is the response in a skeletal muscle during passive muscle stretching?
In relation to proprioception

A

GTOs are under tension due to stretch
Intrafusal muscle fibres are under tension
Therefore, type 1a and type 2 (IMF) and type 1b (gto) afferents will show activity

47
Q

What is the response in the skeletal muscle during active muscle contraction in relation to active muscle contraction?

A

GTO is under tension (think as pulled by muscle)
Intrafusal fibres relax in length as the muscle shortens around them
Therefore - activity in the T1a and Type 2 afferents is none existent
and activity from Type 1b afferents is high

48
Q

What is an intrafusal muscle fibre?

A

Located deep within the muscle
Sense muscle tension to contribute to proprioception
Have a swelling in the middle called a nuclear bag fibre
Are innervated by type 1a and 2 afferents (proprioception)
and gamma motor nuerons to contract them

49
Q

What are the different types of motor neurons found in skeletal muscle?

A

𝞪 motor neurons - innervate extrafusal fibres - generate contractile force
𝞬 motor neurons - innervate intrafusal muscle fibres - stimulate to contract to maintain sensitivity of proprioception

50
Q

How does proprioception adapt to different levels of muscle contraction?

A

Gamma motor neurons - innervate intrafusal fibres - cause to contract - this shortens the fibre hence increases tension again - leads to higher sensitivity of proprioception.
THis is all relative to the level of alpha motor neuron activity

51
Q

What is meant by a gain of proprioception?

A

Increase in the sensitivity of proprioception
Done by increasing y motor nueroon contraction relative to alpha motor neuron contraction - allows the intrafusal muscle fibre to shorten and increase tension alongside a shortening muscle

This is controlled by lower subconscious circuits and upper conscious circuits.

52
Q

What is the role of inhibitory interneurons in the spinal cord?

A

Are GABAergic neurons - inhibit motor neurons - hence prevent contraction
Are considered upper motor neurons

53
Q

What is the consequence of a damaged inhibitory interneuron?

A

Type of upper motor neuron
Results in spasticity or clonus of the joint

54
Q

What is the function of the reticulospinal tract?**

A

Responsible for subconscious motor control e.g posture and breathing
Role in preparatory and movement-related activities.
Co-ordination of motor signals.
Role in spinal reflex arcs
Unconscious proprioception

55
Q

What makes up the reticulospinal tract?

A

Pontine reticular formation orignates in the pontine tegmentum, travel through the medullar and into the spinal cord through the reticulospinal tract to synapse.
The medullary reticular formation originates in the gigantocellularis, will also travel in the reticulospinal tract to spinal in the spinal cord.
Fibres can be found scattered in throughout the ventral and lateral columns of the spinal cord.

56
Q

What does additional reading suggest is the function of the reticulospinal tract?

A

Pontine reticulospinal fibres - extensor muscles
Medullary reticulospinal tract flexor muscles

Normally act in a balanced coordinated fashion to control muscle tone.
Act on both alpha and gamma motor nuerons.

57
Q

What is meant by a vestibular sensation?

A

A sense of balance/head position

Helps maintain equilibrium , posture, head position and clear vision with movement.

58
Q

What are the different vestibular reflexes?

A

Vestibulospinal reflex
Vestibulocollic reflex
Vestibulo-ocular reflex

59
Q

What is the role of the vestibulospinal reflex?

A

Sense head movement
Stops falling over by innervating the spinal cord LMNs, often cause extension of upper limbs and flexion of lower limbs to protect from impact of fall.
Controls body balance

60
Q

What is the role of the vestibulocollic reflex?

A

Keeps your head up by innervating cervical lower motor neurons
Stabilises the position of the head.

61
Q

What is the role of the vestibular-ocular reflex?

A

Keeps your gaze fixed by innervating cranial nuclei of 3,4,6 - the extra-ocular nerves.

62
Q

What is the link between all the different vestibular reflexes?

A

The vestibular nuclei
A bilateral structure found in the floor of the fourth ventricle in the medulla.
Upper motor nuerons will synpase in the ventral horn with lower motor neurons

63
Q

What is meant by tectum in neuroanatomy?

A

The roof - e.g the cerebral aqueduct between the 3rd and 4th ventricles
Tectum = the superior colliculus and the inferior colliculus (found in midbrain)

64
Q

What is the role of the superior and inferior colliculus?

A

Superior colliculus - responsible for visual reflexes
Inferior colliculus - auditory refelxes

65
Q

What is the tectospinal tract?

A

Originates in the superior colliculus/inferior colliculus of the midbrain
Desicates in the dorsal tegmental decussation, ventral to the periaqueductal grey matter.
Descends in the medial part of the ventral funiculus of the spinal cord
Synapse in the ventral horn, typically with upper cervical cord motor neurons

66
Q

What is the role of the tectospinal/tectobulbar tract?

A

Reflex orientation of the head and neck motor movements in response to visual and auditory stimuli

Tectospinal responsible fir head and back movements terminates in spinal cord
Tectobulbar responsible for movement of eyes and head - terminates in brain stem

67
Q

What is the function of the corticospinal tract?

A

Control primary motor activity to the somatic system aka voluntary control of skeletal muscle
From the neck downwards - innervates lower motor neurons that are spinal nerves.

68
Q

What is the function of the corticobulbar tract?

A

Provides motor innervation input to cranial nerve nuclei

69
Q

What is the function of the spinothalamic tract?

A

Responsible for pain
Responsible for temperature
Responsible for crude touch
Responsible for conscious proprioception

70
Q

What is the function of the dorsal column medial lemniscus pathway?

A

responsible for light touch and vibration

71
Q

What are the different tracts responsible for proprioception?

A

Conscious - DCML - from the periphery to Primary sensory cortex.
Unconscious proprioception - the reticulospinal tract.

Unit 11 (21 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions