Clinically Applied Neuroanatomy

Question 1

What are the fuctions of the different lobes of the brain?

Answer 1

• Frontal lobe is for decision making and image processing
• Parietal lobe is invovled in the processing of sensation
• Temporal lobe is mostly to do with memory and hearing
• Occipital lobe is concerned with vision

Question 2

Describe the visual pathway

Answer 2

Question 3

Which visual disturbances are associated with which lesions in the optic pathway?

Answer 3

Question 4

What is the anatomy of the spinal cord?

Answer 4

Question 5

Describe the anatomy of the sensory tract (light touch, vibration and proprioception)

Answer 5

• Axons enter the spinal cord
• Caudal fibres enter fasciculus gracilis (below T6) and rostral fibres enter fasciculus cutaneous (above T6)
• Ascend to nucleus gracilis and cutaneous
• Secondary neurons cross midline and form medial lemniscus
• Ascends through rostral pons and midbrain and terminates in the VPL of the thalamus

Question 6

Describe the anatomy of the sensory tract (pain and temperature)

Answer 6

• Axons enter spinal cord
• Travel up 1-2 segments then synapse in posterior horn
• Secondary neurons cross midline and ascend as anterolateral tract
• Terminates in VPL of thalamus

Question 7

Describe the anatomy of the motor tract (corticospinal tracts)

Answer 7

• Originates from primary motor cortex
• Passes through corona radiata, posterior limb of internal capsule and then descends through crus cerebri
• Broken into bundles in pons and then descends as pyramids in anterior part of medulla
• 85-90% cross over at junction of medulla and spinal cord
• Crossed go to lateral corticospinal tract and uncrossed to anterior corticospinal tract
• Terminates at LMN

Question 8

What does the posterior root do?

Answer 8

• Carries sensory information

Question 9

What does the anterior root do?

Answer 9

• Carries motor information

Question 10

What are the different patterns of sensory loss?

Answer 10

Question 11

How do reflexes work?

Answer 11

Question 12

Describe the embryological development of the brain

Answer 12

Question 13

Upper motor neurone

Answer 13

• Starts in the motor cortex and terminates in brainstem motor nuclei or anterior horn cell within spinal cord
• Comprises brain, brainstem and spinal cord

Question 14

Lower motor neurone

Answer 14

• Starts at motor nucleus with brainstem (or anterior horn cell within cord) and terminates in the muscle
• Comprises nerve root, plexus, peripheral nerve, neuromuscular junction and muscle

Question 15

UMN pattern weakness

Answer 15

• Tone increased
• Little atrophy (disuse)
• Tendon reflexes brisk
• Ankle clonus may be present
• Plantar response - extensor
• May take 1-2 weeks to develop

Question 16

LMN pattern weakness

Answer 16

• Wasting/fasciculations
• Tone - reduced
• Decreased/absent reflexes
• No clonus seen
• Plantar response - flexor

Question 17

Brain lesions

Answer 17

• Most commonly cause contralateral facial weakness and spastic hemiparesis
• Cerebral cotex
  
  • Contralateral sensory disturbance and weakness
  • May be other cortical signs (i.e. dysphagia, hemianopia, sensory inattention)
• Internal capsule
  
  • Dense hemiplegia (face/arm/leg)
• Thalamus
  
  • Hemi-sensory disturbance

Question 18

Brainstem lesions

Answer 18

• Caused crossed signs with ipsilateral cranial nerve palsies and contralateral spastic hemiparesis and sensory loss
• Midbrain
  
  • Oculomotor disorder
• Pons
  
  • Facial weakness, sensory disturbance, vertigo, deafness
• Medulla
  
  • Dysphagia, dysarthria, dysphonia, weakness/wasting of tongue