Lower Medulla

Question 1

Name this, state its function and pathway[5 marks].

Answer 1

Pyramid.

• Decussation forms the lateral corticospinal tract(90%), anterior corticospinal tract(8%) and uncrossed lateral corticospinal tract.(2%)
• Descending pathways:
  • Motor pathway from somatosensory area–>internal capsule–>crus cerebri–>pons and medulla.
  • Motor signals for face and neck musculature.

Question 2

Name this and state its function.

Answer 2

Nucleus Gracilis.

• Sensory information from lower limbs and body, carrying ascending tracts to postcentral gyrus.

Question 3

Name this , state its function, pathway and tract its involved to.

Answer 3

Nucleus cuneatus.

• Sensory information from upper limbs of the body.
  
  • Terminates somatosensory cortex.

Cuneatus receptors–>Dorsal roots–>nucleus cuneatus–>Thalamus–>somatosensory cortex.

• Dorsal medial lemniscus pathway.

Question 4

Name this and state its function.

Answer 4

Inferior olivary nucleus:

• Fine motor and co-ordination. project to the ICP( to Cerebellar cortex and deep cerebellar nuclei).

Question 5

Name this and state its function.

Answer 5

Medial lemniscus.

Question 6

Name this, state its functions within their tracts, different tracts and regulators of the their tracts.

Answer 6

Reticular formation.

Ascending tracts:

• _Ascending reticular activating system_:
  
  • consciousness and sleep cycles.
    
    • regulated by hypothalamus.

Descending tracts:

• Reticulospinal tract:
  
  • Co-ordinate movement , function and posture..
  • Projects to spinal cord motor neurons.

Question 7

Name this.

Answer 7

Spinal Trigeminal nucleus.

• Sensory tract the ipsilateral portion of the face.

Question 8

Name this.

Answer 8

Spinal trigeminal tract.

Question 9

Questions:

• Difference in ascending and descending pathways of Reticular formation.
  
  • Descending: reticulospinal tract.
  • Ascending: reticular activating system.
  • What is the ascending pathway regulated by?
  • Difference in function.

Answer 9

Descending pathway:

• Reticulospinal tract:
  
  • co-ordinate fine motor control.

Ascending pathways:

• Reticular activating system:
  
  • Establishes sleep cycles, consciousness and arousal.
    
    • Regulated by Hypothalamus.