NEURO

Question 1

Draw the brachial plexus

Answer 1

• C5 C6 roots form the superior trunk
• C5 forms the dorsal scapular nerve
• C5,6,7 form the long thoracic nerve
• C7 forms the medial trunk
• C8 and T1 form the inferior trunk
• Anterior divisions of the superior and medial trunks form the lateral cord. Lateral cord forms the musculocutaneous nerve.
• Posterior divisions (from the superior, medial and inferior trunk) form the posterior cord
• Posterior cord forms the axillary and radial nerves
• Anterior division of the inferior trunk forms the medial cord. Medial cord forms the ulnar nerve
• Medial cord combines with the lateral cord to form the median nerve

Question 2

Draw the anterior corticospinal tract

Answer 2

• Primary motor cortex
• Medullary pyramids (no decussation)
• Medullary pyramids travel in the anterior corticospinal tract
• Decussates in grey matter at the spinal level, also synapse here
• Exits spinal cord

Question 3

Draw the lateral corticospinal tract

Answer 3

• Primary motor cortex
• Down to medullary pyramids, decussates here
• Travels down the lateral corticospinal tract
• Synapses in the white matter at the spinal level the nerve exits

Question 4

Draw the pain pathway from the face

Answer 4

• Spinothalamic tract
• Enters pons (trigeminal nucleus)
• Descends to the medulla, enters the accessory sensory nucleus(?)
• Decussates in the medulla (synapse here)
• Ascends to the VPL of the thalamus (synapse here)
• Lateral area of the cortex

Question 5

Draw pain pathway from the leg/arm

Answer 5

• Enters cervical cord/ lumbar
• Decussates in the spinal cord grey matter, via dorsal column
• Synapses here
• Ascends in spinothalamic tract
• Synapses in the VPL of the thalamus
• Primary somatosensory cortex (arm/ leg area)

Question 6

Describe fine touch detection from the face

Answer 6

• Enters pons
• Decussates and synapses here
• Ascends to VPL of the thalamus (synapse)
• To face area of the primary somatosensory cortex
• Dorsal column medial lemniscus tract

Question 7

Describe fine touch detection from the lower and upper limb

Answer 7

• Lower limb enters level of lumbar vertebrae, gracile fasisculus to gracile nucleus in medulla (synapse followed by decussation)
• Upper limb sensation enters level of cervical vertebrae, cuneate fasciculus to cuneate nucleus in medulla (synapse followed by decussation)
• Enters medial lemniscus pathway between the medulla and pons
• Synapse in the VPL of the thalamus
• Third order neurone terminates in appropriate area of the primary somatosensory cortex