pons Flashcards
Where is the pons located?
The pons is located in front of the cerebellum.
What does the pons connect?
The pons connects the medulla oblongata to the midbrain.
What is the length of the pons?
The pons is about 1 inch (2.5 cm) long.
What does the pons look like?
The pons is a bridge-like structure that connects the right and left cerebellar hemispheres.
What is the shape of the anterior surface of the pons?
The anterior surface of the pons is convex (curved outward).
What do the transverse fibers of the pons form?
The transverse fibers form the middle cerebellar peduncle. (MCP)
What structure does the basilar groove contain?
The basilar groove contains the basilar artery.
Which cranial nerve exits from the anterior surface of the pons?
The trigeminal nerve (CN V) exits from the anterior surface of the pons.
What are the two parts of the trigeminal nerve?
The trigeminal nerve has:
- A motor root (small, medial part).
- A sensory root (large, lateral part).
Which cranial nerves exit between the pons and medulla?
From medial to lateral:
1. Abducens nerve (CN VI)
2. Facial nerve (CN VII)
3. Vestibulocochlear nerve (CN VIII)
Why is the posterior surface of the pons not visible?
The posterior surface is hidden by the cerebellum.
What part of the 4th ventricle does the pons form?
The pons forms the upper half of the floor of the 4th ventricle.
What are the boundaries of the posterior surface of the pons?
The boundaries are:
- Lateral boundary: Superior cerebellar peduncles.
- Middle boundary: Median sulcus (divides into left and right halves).
What is the medial eminence?
The medial eminence is a slightly raised area next to the median sulcus.
What groove lies next to the medial eminence?
The sulcus limitans lies next to the medial eminence.
What structure causes the facial colliculus?
The facial colliculus is caused by facial nerve fibers looping around the abducens nucleus.
What is the substantia ferruginea and why is it bluish-gray?
The substantia ferruginea is a bluish-gray area due to deep pigmented nerve cells.
Which structure overlies the vestibular nuclei?
The area vestibuli overlies the vestibular nuclei.
What are the two main divisions of the pons?
The two main divisions are:
1. Tegmentum (Posterior Part)
2. Basal Part (Anterior Part)
What structure separates the tegmentum and basal part?
The trapezoid body separates the tegmentum and basal part.
What are the two levels of pons sections?
The two levels are:
1. Caudal (Lower) Part → Passes through facial colliculus.
2. Cranial (Upper) Part → Passes through trigeminal nuclei.
What happens to the medial lemniscus as it enters the pons?
The medial lemniscus rotates as it enters the pons.
Where is the medial lemniscus located inside the pons?
It is located at the front of the tegmentum.
What other structures accompany the medial lemniscus?
The spinal lemniscus and lateral lemniscus.
Which nerve loops around the abducens nucleus?
The facial nerve (CN VII).
What structure does this looping form?
It forms the facial colliculus.
Where is the medial longitudinal fasciculus located?
The MLF is located beneath the 4th ventricle floor.
What structures does the MLF connect?
The MLF connects:
- Vestibular & cochlear nuclei → Balance & hearing.
- Oculomotor, trochlear, abducens nuclei → Eye movement control.
Where is the medial vestibular nucleus (MVN) located?
It is located close to the abducens nucleus.
Which vestibular nuclei are present in the pons?
The medial, lateral, and superior vestibular nuclei.
Which nuclei are responsible for hearing?
The anterior and posterior cochlear nuclei.
Where is the superior cerebellar peduncle (SCP) located?
It is located behind the trigeminal motor nucleus.
Which fibers contribute to the trapezoid body?
Transverse fibers from cochlear nuclei & trapezoid nuclei.
What are pontine nuclei?
Small clusters of nerve cells in the basilar part of the pons.
Where do corticopontine fibers come from?
They come from the midbrain crus cerebri.
What do axons from pontine nuclei form?
They form the transverse fibers of the pons.
Where do these axons cross and enter?
They cross the midline and enter the middle cerebellar peduncle. (MCP)
What is the main pathway between the cerebral cortex and cerebellum?
The middle cerebellar peduncle. (MCP)
