Nervous System

120-Functional Anatomy

What is the CNS? What does it derive of?

Central Nervous System;

Brain & spinal cord

What is the PNS? What does it derive of?

Peripheral Nervous System;

All the nerves outside of the spinal cord (cranial nerves, brachial plexus, spinal nerves, lumbosacral plexus)

What is the ANS? What does it derive of?

Autonomic Nervous System;

Sympathetic & parasympathetic (controls mostly visceral structures)

What is a neuron? What are the 3 types of neurons?

Nerve cell;

1. Afferent

2. Efferent

3. Interneuron

What is an afferent neuron? Which way does it travel?

Sensory nerve (arrives) ; Body → brain

What is an efferent neuron? Which way does it travel?

Motor (exit) ; Brain → body

What is an interneuron? Which way does it travel?

Connecting neuron ; Connects afferent and efferent neurons together so they can all communicate

What is an upper motor neuron?

Cell bodies in the cerebral cortex, brainstem, and cerebellum

What is an lower motor neuron?

Cell bodies in the anterior horn of the spinal cord

What are dendrites? What do they do?

Branch-like extensions that receive impulses from the previous neuron to pass it to its’ neuron’s cell body

What is a neuron cell body? What does it do?

The central structure of a neuron that contains the nucleus & plasma

What is an axon? What does it do?

A long slender projection that carries the impulses from that neuron’s cell body out towards the next neuron

What is a myelin sheath? What does it do?

White, fatty substance surrounding the axons and dendrites of neurons within the CNS & PNS

• Does NOT surround the cell bodies

What are the nodes of ranvier? What do they do?

Separations within the myelin sheath that help speed up the impulse conduction within the myelin fibers as they travel through the neuron

• Think like a speed up boost in mario kart

  • Every ½ mm

What are synapses?

Small gaps that junction between axon, dendrite & interneuron

• Neurotransmitter released → reaches opposite side of synapse → creates an electrical impulse

What are electrical impulses?

Generated in the cell body (soma), they travel through neurons to others to communicate

What is gray matter? Where is it located?

The unmyelinated cell bodies & nerve fiber in the CNS

• Within the cerebral cortex & central portion of SC

What is white matter? Where is it located?

The myelinated nerve fiber in the CNS

• Within the deep parts of the brain & superficial parts of the SC

What vertebrae make up the cervical portion of the spine? What nerve roots?

Vertebrae: C1-C7

Nerve Roots: C1-C8

What vertebrae make up the thoracic portion of the spine? What nerve roots?

Vertebrae: T1-T12

Nerve Roots: T1-T12

What vertebrae make up the lumbar portion of the spine? What nerve roots?

Vertebrae: L1-L5

Nerve Roots: L1-L5

What vertebrae make up the sacral portion of the spine? What nerve roots?

Vertebrae: S1-S5

Nerve Roots: S1-S5

What nerve root(s) connect to the diaphragm & trapezius?

C3

What nerve root(s) connect to the deltoid & biceps, wrist extensors, and triceps?

C4-C7

What nerve root(s) connect to the hand?

C8-T1

What nerve root(s) connect to the intercoastals?

T3-T6

What nerve root(s) connect to the abdominals?

T7-T12

What nerve root(s) connect to the hip & legs?

L3-S2

What nerve root(s) connect to the foot?

L5-S2

What nerve root(s) connect to the bowel & bladder?

S4-S5

What is a tract?

Ascending & descending myelinated nerve fibers organized within SC → columns

What are posterior columns? Where do their synapses connect? What do they help control?

ASCENDING ;

Synapse w/ nuclei in posterior root ganglion;

Sensations of proprioception, pressure & vibration

What are anterior columns? Where do their synapses connect? What do they help control?

DESCENDING;

Synapse w/ nuclei in anterior horn;

Motor

What is the frontal lobe in charge of? Where is it located?

Movement, speech & personality ; Anteriorly

What is the parietal lobe in charge of? Where is it located?

Touch & pressure; texture, weight, size & shape; (some) reading ;

Superiorly & laterally

What is the occipital lobe in charge of? Where is it located?

vision ; posteriorly

What is the temporal lobe in charge of? Where is it located?

Behavior, hearing & language ; Inferiorly & laterally

What is the cerebellum in charge of?

Muscle tone, coordination & posture

What is the first level of protection for the CNS?

Skull & vertebrae

Where is the body of a vertebrae located? What is its job?

The actual main base of spine (anteriorly); The weight-bearing portion

Where is the intervertebral foramen of a vertebrae located? What is its job?

Formed by the inferior vertebral notch of the upper vertebrae + superior vertebral notch of the lower vertebrae ;

Spinal nerves exit through here

What is the second level of protection for the CNS?

Meninges

What is the ‘hole’ that is located between the base of the skull & the vertebral canal called?

Foramen magnum

Which layer of the meninges makes up the dura mater? What is another name for it?

Thick, fibrous, tough outer layer; Hard mother

Which layer of the meninges makes up the arachnoid mater? What is another name for it?

Thinner middle layer ; Spider

Which layer of the meninges makes up the pia mater? What is another name for it? What does it contain?

Innermost layer ; Tender mother ;

Contains blood vessels of the brain & SC

What is the third level of protection for the CNS?

cerebrospinal fluid (CSF)

What does cerebrospinal fluid do? Where is it located?

Shock absorption ; Surrounds the brain & SC

What is the midbrain in charge of?

visual reflexes

What is the medulla oblongata in charge of?

ventilation, respiration, heart rate, & blood pressure

From superior to inferior, what are the 3 portions of the brainstem?

Midbrain → pons → medulla oblongata

At what point within the spine does the spinal cord stop but nerve roots continue?

Conus medullaris ; At L2

What are the nerve roots from L2 - Co1 called?

Cauda equina

What is the filum terminale?

Thread-like non-neural filament that extends from conus medullaris to attach to coccyx

What is the 1st cranial nerve? Sensory or motor, and function?

Olfactory

Sensory : smell

What is the 2nd cranial nerve? Sensory or motor, and function?

Optic

Sensory : sight

What is the 3rd cranial nerve? Sensory or motor, and function?

Oculomotor

Motor: eye muscles

What is the 4th cranial nerve? Sensory or motor, and function?

Trochlear

Motor : eye muscles

What is the 5th cranial nerve? Sensory or motor, and function?

Trigminal

Sensory : Face

Motor : Chewing muscles

What is the 6th cranial nerve? Sensory or motor, and function?

Abducens

Motor : Eye muscles

What is the 7th cranial nerve? Sensory or motor, and function?

Facial

Sensory : Tongue

Motor : Facial expressions

What is the 8th cranial nerve? Sensory or motor, and function?

Vestibulocochlear

Sensory : Hearing & equilibrium

What is the 9th cranial nerve? Sensory or motor, and function?

Glossopharyngeal

Sensory : Taste, pharynx, & middle ear

Motor : Pharynx muscles

What is the 10th cranial nerve? Sensory or motor, and function?

Vagus

Sensory : Heart, lungs, & GI

Motor : Heart, lungs, & GI

What is the 11th cranial nerve? Sensory or motor, and function?

Accessory

Motor : Sternocleidomastoid & trapezius muscles

What is the 12th cranial nerve? Sensory or motor, and function?

Hypoglossal

Motor : Tongue muscles

What is the acronym for sensory & motor correlations to cranial nerves?

Some Say Marry Money But My Brother Says Big Brains Matter More

What are dermatomes?

Areas of skin supplied with sensory fiber of specific spinal cord levels

• Complete anesthesia can only occur if 2 or more spinal nerves are not intact

What are myotomes?

All the muscles that receive motor innervation from specific SC levels

• Loss of full motor function within a muscle requires all spinal segments to be affected

What are plexus composed of?

Anterior rami (other than throacic)

What spinal nerves is the cervical plexus comprised of?

C1-C4

What spinal nerves is the brachial plexus comprised of?

C5-T1

What spinal nerves is the lumbosacral plexus comprised of?

L1-S3

Medially to laterally, what are the 5 sections seperated as for the brachial plexus?

Roots → trunks → divisions → cords → peripheral nerves

What part of the brachial plexus does the suprascapular nerve break off from? What nerve roots create it?

Superior trunk ; C5-C6

What part of the brachial plexus does the lateral pectoral nerve break off from? What nerve roots create it?

Lateral cord ; C5-C7

What part of the brachial plexus does the musculocutaneous nerve break off from? What nerve roots create it?

Lateral cord ; C5-C7

What part of the brachial plexus does the axillary nerve break off from? What nerve roots create it?

Posterior cord ; C5-C6

What part of the brachial plexus does the median nerve break off from? What nerve roots create it?

Combination of lateral & medial cords ; C6-T1

What part of the brachial plexus does the radial nerve break off from? What nerve roots create it?

Continuation of posterior cord ; C5-T1

What part of the brachial plexus does the ulnar nerve break off from? What nerve roots create it?

Continuation of medial cord ; C8-T1

What part of the brachial plexus does the lower subscapular nerve break off from?

Posterior cord

What part of the brachial plexus does the upper subscapular nerve break off from?

Posterior cord

What part of the brachial plexus does the thoracodorsal nerve break off from?

Posterior cord

What part of the brachial plexus does the medial pectoral nerve break off from?

Medial cord

What part of the brachial plexus does the dorsal scapular nerve break off from?

Anterior ramus of C5

What creates the femoral nerve within the lumbosacral plexis?

L2-L4

What creates the superior gluteal nerve within the lumbosacral plexis?

L5-S2

What creates the obturator nerve within the lumbosacral plexis?

L2-L4

What creates the sciatic nerve within the lumbosacral plexis? How does it split?

L4-S3;

Common fibular : L4-S2

Tibial : L4-S3

What vertebrae create the lumbar plexus?

L1-L4

What vertebrae create the sacral plexus?

L5-S3

What vertebrae create the lumbosacral trunk?

L4-L5

Describe how motor impulses travel through the body.

1. Brain

2. Lateral & anterior tracts of SC

3. Cell bodies in the anterior horns

4. Exit to anterior roots

5. Into peripheral nerves

6. Muscles

Describe how sensory impulses travel through the body.

1. Body

2. Peripheral nerves

3. Cell bodies of SC housed in dorsal root ganglion

4. Into posterior horns of SC

5. Brain

What is the 1st degree of nerve injury classification?

Neuroplexia (localized myelin damage)

What is the 2nd degree of nerve injury classification?

Axonotmesis (Axon severed; Endoneurium intact)

What is the 3rd degree of nerve injury classification?

Axonotmesis (Axon & endoneurism severed)

What is the 4th degree of nerve injury classification?

Axonotmesis (Loss of continuity of all layers of peripheral nerve EXCEPT endoneurism)

What is the 5th degree of nerve injury classification?

Neurotmesis (Complete disruption of entire nerve)