Cranial nerves Flashcards
What is the diencephalon?
thalamus and hyperthalamus
What are cerebellar peduncles?
White fibre tracts. 3 of these connect the cerebellum to the brainstem
What do all the ascending and descending pathways in the brain pass through?
Brainstem
How many of the cranial nerve nuclei pass through the brainstem?
9 - 3 to 12 (excluding 11)
What canal is in the closed medulla and what does it eventually form?
An extension of the central canla of the spinal cord that eventually widens to form the 4th ventricle in the open medulla ?
What is the organisation of the brain stem from the posterior to the anterior part? (Horizonal cross section)
Tectum (roof)
Ventricular system
tegmentum
base
What is the difference between the fibres in the optic nerve and optic tract?
In the optic nerve the axons have come from one eye but in the optic tract the axons have come from both eye. Therefore if you have an optic nerve legion it will effect one eye whereas if you have an optic tract legion it will effect both eyes
When viewing the midbrain as a horizontal cross section 4 bumps occur at the posterior, What are these called and what are they associated with?
Superior colliculi (on top)- visual Inferior colliculi (below superior)- auditory
What descending tracts go through the cerebral peduncles?
Cortcospinal- go to muscles below the head e.g. limb and trunk muscles Corticobulbar- go to muscles of the face and mastication
what cranial nerves emerge at the midbrain level?
III and IV
What are some key parts of the pons?
4th ventricle - ventricular system much larger in the pons than in the midbrain as in midbrain its only a small hole (aquaduct)
3 pairs of peduncles- Superior cerebellar peduncle, middle cerebellar peduncle and inferior cerebellar peduncle (these connect the cerebellum to the pons)
Which Cranial Nerves go through the pons?
V, VI, VII, VIII
What is just below the Pons?
Open upper medulla
Why is the open upper medulla named as such?
Because the forth ventricle doesn’t really have a roof the cerebellum forms this
What nucleus is in the open upper medulla?
Inferior olivary nucleus
What cranial nerves emerge from the medulla?
IX, X, XII
What is the main difference between the open and closed medulla?
In the closed -The forth ventricle has moved anteriorally and has closed up so it is more like a tube now due to being enclosed by neural tissue
Where is the open and closed medulla in respect to the cerebellum?
open is next to the top of the cerebellum closed is next to the bottom of the cerebellum
What are the main parts of the closed medulla?
- All 4 dorsal columns
- central canal
- Decussation of pyramids
What is the scientific name for the horizontal cross section through the open and closed medulla?
open- Rostral (continuation of the spinal cord)
closed- Caudal
What does the anterior surface of the medulla have?
Pyramids- contain descending voluntary movement tracts
Why do the dorsal columns disappear during their journey from the caudal to the rostral part of the medulla ?
Dorsal columns- these disappear by the time they reach the rostral part of the medulla because they are the fibre tracts of the primary sensory neurons and as they go up they synapse onto the nuclei of the dorsla columns in the rostral area
What is on the surface of the posterior medulla?
dorsal columns
What motor pathway has fibres which cross in the medulla?
corticospinal
Where does the CNS blood supply come from?
2 arterial systems:
Anterior- internal carotid system( 1 pair of arteries) Feeds most of the cerebral hemispheres and forebrain
Posterior- vertebral basilar (1 pair of arteries) Feeds the brainstem
What are the names of all the cranial nerves?
I -Olfactory
II- Optic
III- Oculomotor
IV- Trochlear
V- trigeminal
VI- Abduchens
VII- Facial
VIII- Vestibulocochlear
IX-Glossopharyngeal
X- Vagus
XI- Accessory
XII- Hypoglossal
What is the nucleus modality and function of the oculomotor CN?
Nucleus- Oculomotor - Edinger-Westphal Modalitiy- General Sensory efferent (GSE) -General Visceral efferent (GVE) Funtion- Move eye - accomodation reflux - pupillary reflex
