Pons

Question 1

Where is the pons located in relation to the midbrain and medulla?

Answer 1

Located below the midbrain and above the medulla
acts as a connection between the cerebrum and cerebellum

Question 2

What does the pons develop from?

Answer 2

The embryonic metencephalon

Question 3

What demarcates the midline of the ventral surface of the pons and where the basilar artery is located?

Answer 3

The basilar groove

Question 4

What is the pontomedullary junction?

Answer 4

Important anatomical landmark defined by the angle between the lower border of the pons and the superior border of the medulla

Question 5

Which cranial nerves originate from the ventral surface of the pons?

Answer 5

1. CN V (trigeminal) - originates from the lateral aspect of the mid pons
2. CN VI (abducens) - originates from the pontomedullary junction, close to the midline
3. CN VII (facial) - originates from the cerebellopontine angle, the more lateral aspect of the pontomedullary junction
4. CN VIII (vestibulocochlear) - originates laterally to the facial nerve

Question 6

What is the floor of the IVth ventricle composed of?

Answer 6

dorsal surface of the pons and the medulla

Question 7

How is the pons connected to the cerebellum?

Answer 7

via the middle cerebellar peduncles

Question 8

What are the two major components of the pons?

Answer 8

ventral pons and the tegmentum

Question 9

What is the ventral pons responsible for?

Answer 9

Contains the pontine nuclei, which are responsible for coordinating movement. Fibres from the pontine nuclei cross the midline and form the middle cerebellar peduncles on their way to the cerebellum

Question 10

The tegmentum is the evolutionary older part of the pons which forms part of the reticular formation, what is this?

Answer 10

Set of nuclei found throughout the brainstem that are responsible for arousal and attractiveness

Question 11

Clinical link - what would happen if the tegmentum part of the pons was damaged?

Answer 11

Could cause anosognosia for hemiplegia - where patients are unaware of their paralysis

Question 12

The rest of the pons is made up of tracts passing through the pons, including?

Answer 12

1. descending corticospinal tracts - responsible for voluntary motor control of the body
2. descending corticobulbar tracts - responsible for voluntary motor control of face, head and neck
3. ascending medial lemniscus tracts - responsible for fine touch, vibration and proprioception
4. ascending spinothalamic tracts - responsible for pain and temperature sensation

Question 13

What provides blood supply to the pons?

Answer 13

Blood supply is formed by branches of the vertebrobasilar system:
- most of the pons is supplied by the pontine arteries (branches of the basilar artery)
- a smaller part of the blood supply comes from the anterior inferior cerebellar artery and the superior cerebellar artery