Neuroanatomy

Question 1

General sensory pathway anatomy

Answer 1

1st order neuron: From periphery to central grey matter where it synapses with 2nd order neuron, pseudounipolar body in dorsal root ganglion

2nd order neuron: from central grey matter crosses to other side and then synapses in thalamus

3rd order neuron: from thalamus to somatosensory cortex in postcentral gyrus on parietal lobe

Question 2

Anatomy and function of spinothalamic tract

Answer 2

Function: Coarse touch, pain, temperature

Cross right after synapsing to 2nd order neuron

Question 3

Anatomy and function of dorsal columns

Answer 3

Function: Proprioception and fine touch
Fasciculus gracilis for legs (T7 and below), fasciculus cuneatus for arms (T6 and above)
1st order neuron ascends ipsilaterally until medulla where they synpase in nucleus gracilis/cuneatus, from here they cross and ascend to thalamus as medial lemniscus

Question 4

Anatomy and function of trigeminal tracts

Answer 4

Same as spinothalamic and dorsal column tracts but enter at level of brainstem instead of at level of spinal cord from where they then go to synpas with 3rd order neurons in thalamus in the trigeminothalamic tract

Question 5

Anatomy and function of corticospinal tract

Answer 5

Function: Motor control of non-cranial muscles
From prefrontal gyru upper order neurons descending through capsula interna and decussate in decussatio pyramidum at level of medulla, descend down to lower order neurons, synapse in spinl grey matter and then leave through anterior horn

Question 6

Anatomy and function of corticobulbar tract

Answer 6

Same as corticospinal but innervate cranial nerve nuclei in brainstem

Question 7

Extrapyramidal pathways

Answer 7

Vestibulospinal and reticulospinal starting from reticular and vestibular nuclei in brainstem are important for muscle tonus and posture

Question 8

How many segments does the spinal cord have?

Answer 8

31
8 cervical
12 thoracic
5 lumbar
5 sacral
1 coccygeal

Question 9

At which level does the spinal cord terminate in adult

Answer 9

L1-L2

Question 10

Dorsal root and ventral root function

Answer 10

Dorsal root contains afferent/sensory fibres, ventral root contains motor/efferent fibres

Question 11

Location of sensory and motor neuronal cell bodies in spinal cord

Answer 11

Sensory: Dorsal ganglia
Motor: Central grey matter of spinal cord

Question 12

Where to the spinal nerves exit relative to their vertebrae?

Answer 12

C1-C7 nerves leave above C1-C7 vertebrae, C8 nerve leaves below C7 vertebrae and remainder leaves below their corresponding vertebrae

Question 13

Whats Chipaults Rule

Answer 13

Describes shift of corresponding spinal cord segments and vertebrae
Spinous process of upper C = Cord segments
Spinous process of lower C = Segment+1
(e.g. C7 vertebra = C8 segment)
Spinous process of upper T = Segment+2
Spinous process of lower T = Segment+3
Vertebrae T10-T12=Lumbar segments L1-L4
Vertebrae T12-L1(Epiconus)=Segments L5-S2
Vertebrae L1-L2(Conus)=Segments S3-S5 and Co

Question 14

Whats the lateral horn and where do you find it?

Answer 14

In thoracic and upper lumbar segments of the spinal cord, it contains preganglionic sympathetic neurons.

Question 15

Which types of motor neurons exist in the ventral horn and whats the difference?

Answer 15

Alpha motor neurons: Innervate extrafusal muscle fibres

Gamma motor neurons: Innervate intrafusal fibres (within muscle spindles)

Question 16

Which cort segments correspond to the 
Biceps reflex
Triceps reflex
Quadriceps reflex
Achilles tendon reflex

Answer 16

Biceps - C5
Triceps - C7
Quadriceps - L3
Achilles - S1