Anatomy Lecture 1 PNS Flashcards by Imogen Smedley

What is the basic unit of the nervous system?

Neurones

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Define a nucleus

Collection of nerve cell bodies in the CNS

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Define a ganglion

Collection of nerve cell bodies in the PNS

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What is the function of the dendrite?

Increases the surface area to receive and conduct information towards the nerve cell body

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What is the function of the nerve axon?

Conducts information away from the cell body towards other neurones or effectors

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Name the myelin sheath in the PNS

Schwann cell

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Name the myelin sheath in the CNS

Oligodendrocyte

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What is the commonest type of neurone?

Multipolar

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Where are multipolar neurons

ANS and skeletal muscle motor neurones

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What is a mutlipolar neurone?

Has 2 + dendrites

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What is a unipolar neurone?

Has a double process

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What is a unipolar neurone also called?

Pseudounipolar or sensory

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Is a cell body in the CNS a multipolar or unipolar neurone?

Multipolar

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Is a cell body in the PNS a multipolar or unipolar neurone?

Unipolar

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In the ANS, where is the nerve cell body of the 1st presynaptic (preganglionic) neurone located?

In the grey matter of the CNS

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In the ANS, where is the nerve cell body of the postsynaptic (postganglionic) neurone located?

In autonomic ganglia in the PNS

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Define a nerve

Collections of axons surrounded by connective tissue and blood vessels in the PNS

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What is a nerve referred to in the CNS?

Tract

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Are tracts in the CNS more often single or mixed modality?

Single modality

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How many pairs of spinal nerves are there?

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How many spinal nerves are there in each vertebral segment?

8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

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Which structure of a vertebrae conveys spinal nerves?

Intervertebral foramen

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Where do spinal nerves become called the anterior and posterior ramus?

Beyond the intervertebral foramen

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Are the anterior or posterior rami larger?

Anterior rami

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What is innervated by the posterior ramus?

Back of body wall

Are spinal nerves sensory or motor?

Trick question, spinal nerves are all mixed modality

What modality is contained within anterior rootlets?

Somatic and / or autonomic motor fibres

What modality is contained within posterior rootlets?

Sensory information

What modality is contained within the rami of spinal nerves?

Always mixed modality

What path do sensory axons follow to reach the spinal cord?

Spinal nerve to Posterior root to Posterior rootlets to Posterior horn of spinal cord

What path do motor axons follow to reach spinal nerves?

Anterior horn of spinal cord to Anterior rootlets to Anterior roots to Spinal nerve

What is the dorsal root ganglion?

Location of cell bodies of primary afferent neurones

What axon modality is never contained within spinal nerves?

Parasympathetic fibres

What axon modalities does every spinal nerve pair supply a body segment with?

General sensory Somatic motor Sympathetic (to skin and arteriole smooth muscle)

Define a dermatome

Area of skin supplied with sensory innervation from a single spinal nerve

Define a myotome

The skeletal muscles supplied with motor innervation from a single spinal nerve

What dermatome map is used in Dundee?

Foerster map

What dermatome is the male nipple?

T4 segment

What dermatome is the umbilicus?

T10 segment

What dermatome is the upper limb?

C5 -T1

What dermatome is the lower limb, gluteal region and perineum?

L2 - Co1

What dermatome is the posterior scalp, neck and shoulder?

C2 - C4

What is the clinical importance of dermatomes?

For testing function of spinal nerves

"Intermingled anterior rami from a number of adjacent spinal nerves" is the definition of what?

Nerve plexus

What level are the spinal nerves of the cervical plexus (for the posterior scalp, neck and diaphragm)?

C1 - C4

What level are the spinal nerves of the brachial plexus (for the upper limb)?

C5 - T1

What level are the spinal nerves of the lumbar plexus (for lower limb)?

L1 - L4

What level are the spinal nerves of the sacral plexus (for the lower limb, gluteal region and perineum)?

L5 - S4

Where does sympathetic outflow exit the spinal cord?

With T1 - L2 spinal nerves

After leaving the spinal cord, where do sympathetic nerve fibres go?

Into the anterior and posterior rami of all spinal nerves

What structures do sympathetic nerve fibres supply to maintain sympathetic tone?

Sweat glands, skin arrector muscles, arterioles

What is significant about the T1 - L2 vertebral of the spinal cord in relation to sympathetic outflow?

Have lateral horns | for the cell bodies of the next sympathetic neurone in the chain

Where do presynaptic sympathetic axons synapse before supplying the heart?

T1 or cervical paravertebral ganglia

Where do presynaptic sympathetic axons synapse before supplying the lungs?

Upper thoracic paravertebral ganglia

Where do postsynaptic sympathetic axons pass into, to supply the heart and lungs?

Cardiopulmonary splanchnic nerves

Where do presynaptic sympathetic axons synapse before supplying abdominopelvic organs?

Prevertebral ganglia

Name the prevertebral ganglion that supplies the foregut

Celiac ganglion

Name the prevertebral ganglion that supplies the kidney

Aorticorenal ganglion

Name the prevertebral ganglion that supplies the midgut

Superior mesenteric ganglion

Name the prevertebral ganglion that supplies the hindgut and pelvic / perineal organs

Inferior mesenteric ganglion

Where do sympathetic axons synapse to supply the adrenaline and noradrenaline secreting cells of the adrenal medulla

Directly onto the cells (but pass through the aorticorenal ganglion)

How do parasympathetic presynaptic axons leave the CNS

Via sacral spinal nerves and CNIII, CNVII, CNIX, CNX

What structures in the head are supplied by parasympathetics?

Eye, lacrimal glands, salivary glands

How far in the GI tract does CNX supply?

Midgut

Where do parasympathetic fibres synapse when supplying the eye?

Ciliary ganglion

Where do parasympathetic fibres synapse when supplying the parotid gland?

Otic ganglion

Where do parasympathetic fibres synapse when supplying the lacrimal gland?

Pterygopalatine ganglion

Where do parasympathetic fibres synapse when supplying the sublingual and submandibular salivary glands?

Submandibular ganglion

Where do parasympathetic fibres synapse when supplying organs of the chest and abdomen as far as the midgut?

Directly on the organ they're supplying

REMEMBER CRANIAL NERVE BRAINSCAPE (also part of PNS)

PLZ

What vertebral level does the carotid birfurcate?