The Spinal Cord Flashcards

1
Q

What is a plexus

A

A branching network of intersecting nerves including afferents and efferents

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2
Q

What is the dorsal horn

A

Part of the spinal cord
Includes sensory nuclei that receive and process incoming somatic sensory information

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3
Q

What is the ventral horn

A

Part of the spinal cord Includes
Includes cell bodies of motor neurones that send axons of spinal nerves to striated muscles

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4
Q

What is the spinal cord divided into starting from the top (cervical)

A

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal nerve

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5
Q

What is are the branches of nerves called after the spinal cord ends

A

Cauda equina

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6
Q

Describe the structure of a nerve

A

Endometrium wraps each axon
Axon bundles- fascicles- surrounded by perineurium
Entire nerve surrounded by epineurium

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7
Q

True or false: plexuses have both sensory and motor neurones

A

True

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8
Q

What are rami

A

Divisions of spinal nerves

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9
Q

How is the lumbar plexus formed

A

Formed by anterior rami of nerves from T12-L5
Nerves pass in front of the hip joint and serve the anterior part of the thigh

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10
Q

How is the sacral plexus

A

Formed by anterior rami of nerves from L4-S5
Provides motor and sensory nerves to posterior thigh, foot and pelvis

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11
Q

How are spinal cords formed

A

By joining dorsal and ventral roots of the spinal cord

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12
Q

How is a peripheral nerve formed

A

Anterior and posterior rami of several spinal nerves join together
In arm and leg they form a plexus first
Arm- brachial plexus
Leg- lumbrosacral plexus

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13
Q

What are the nerve roots for the femoral nerve

A

L2-L4

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14
Q

What are the three different types of peripheral nerves

A

Sensory, motor and mixed

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15
Q

What is the function of sensory nerves

A

Send afferent sensory information from the body to the brain via the spinal cord

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16
Q

What is the function of motor nerves

A

Send efferent motor information from the brain to the body via the spinal cord

17
Q

What is a mixed nerve and what is its function

A

Carry both sensory and motor info
Include spinal nerves and 4 of the cranial nerves

18
Q

Where is the synapse for motor nerves

A

On muscles at neuromuscular junctions- the motor endplate

19
Q

What does the synapse release at a neuromuscular junction

A

Neurotransmitter acetylcholine

20
Q

What does acetylcholine activate

A

Nicotine acetylcholine receptors

21
Q

What occurs after ACh activates nAChRs

A

A small local depolarisation- end plate potential

22
Q

What does an end plate potential trigger

A

An action potential leading to a muscle contraction

23
Q

Describe the steps of generating an action potential at a neuromuscular junction

A

Synapse releases acetylcholine
Activates nicitonic acetylcholine receptors
Causes small local depolarisation known as end plate potential
End plate potential triggers action potential
Leads to muscle contraction

24
Q

How is a neurotransmitter released in a synapse

A

Ca2+ enters through ca2+ channels
Vesicle with neurotransmitter inside brought close to membrane
Vesicle fuses with membrane
Transmitter released by exocytosis

25
What type of channel is nicotinic acetylcholine receptor
Cation permeable ligand-gated ion channel
26
What occurs in the post synaptic knob after ACh has binded to generate an action potential
3 Na+ enters 2 K+ exits Leads to knob becoming more positive Exceeds threshold End plate potential formed Leads to AP
27
What is myasthenia gravies
Autoimmune disease where AB produced against nAChRs Inability to activate muscles at neuromuscular junctions Causes muscle weakness and fatigue
28
What are the clinical signs of myasthenia gravis
ptosis- drooping of eyelid eye rotation
29
What is the function of neuromuscular blocking agents and what does this cause
Block transmission at neuromuscular junctions Cause paralysis of skeletal muscles
30
What kind of molecule is a neuromuscular blocking agent
Competitive antagonist
31
How can neuromuscular block be overcome
By increasing the concentration of ACh
32
What are some clinical uses of neuromuscular blocking agents
Paralyse vocal cords during endotracheal intubation Relax skeletal muscles during surgery Permit mechanical ventilation in patients with poor lung function
33
What is patellar reflex
Known as knee jerk reflex Tested to see the integrity of L2-L4 spinal nerves
34
What is Westphals sign
Absence of patellar reflex
35
What can westphals sign be used to diagnose
Peripheral nerve disease- dorsal sensory columns of the spinal cord Lesions in the primary motor cortex Interruption of sensory or motor neurones in the femoral nerve
36