Topography of the Brain Flashcards
How is the structure of the brainstem similar to the structure of the spinal cord?
Like the spinal cord, the brainstem has central grey matter surrounded by peripheral white matter
What cranial nerve do not come off the brainstem?
Cranial Nerves 1 and 2
- Olfactory nerve
- Optic nerve
What (very basically) does the brainstem do/ give off?
Cranial nerves III-XII
-Brainstem uncle are involved with 10 of the 12 cranial nerves, so innervation of head and neck.
Tracts from Spinal Cord
-Pathway for fibre tracts running between higher and lower centres
Vital centres e.g. cardiorespiratory centre:
-BRAINSTEM CENTRES PRODUCE THE RIGIDLY PROGRAMMED AUTOMATIC BEHAVIOUS ESSENTIAL FOR SURVIVAL
What makes up the brainstem?
Medulla (inferiorly)
Pons (middle)
Midbrain (superiorly)
Where does the Medulla (oblongata) come from and what is its position?
Develops from hindbrain vesicle.
Cavity is the 4th ventricle
Continues as spinal cord at foramen magnum of cranium.
Lower part of medulla resembles spinal cord in structure
What are the surface features of the Medulla?
Pyramids (elevation of motor tract fibres)
Motor fibres start to cross lower down pyramid = decussation (crossing over)
Olives laterally
Connected to cerebellum by inferior cerebellar peduncle.
Cranial nerves IX, X, XI and XII from its surface
What are the 2 cross sectional parts of the medulla?
Caudal part = closed part
-Closed around IV ventricle
Cranial part = open part
-Open with IV ventricle posteriorly
What is contained in the white matter of the medulla?
-Pyramidal tract:
(tract with fibres going down)
-Medial lemniscus:
(tract with fibres going up)
Inferior cerebellar penduncle
Other tracts
What is contained within the grey matter of the medulla?
Cranial nerve nucleii
Inferior olivary nucleus
Nucleii of the reticular foramen
Sensory nucleii
(gracile and cuneate)
What are the Nucleii of the reticular foramen?
Contain vital centres
Set of interconnected nuclei that are located throughout the brainstem.
The neurons of the reticular formation all play a crucial role in maintaining behavioral arousal and consciousness
What is the inferior olivary nucleus?
Major source of input for the cerebellum
Where does the pons develop from?
Develops from the metencephalon part of hindbrain vesicle
What relation is the pons to the IV ventricle?
Pons is anterior to the IV ventricle
What are the surface features of the pons?
Middle cerebellar peduncle
Cranial nerves V, VI, VII and VIII originate from its surface
How does the middle tract differ in the pons compared to the medulla?
Tracts aren’t one complete structure
Motor fibre bindles separated by pontine nucleii
What are the contents of the pons white matter?
Middle cerebellar peduncle
Medial lemniscus (sensory)
Pyramidal tract (motor)
What are the contents of the grey matter of the pons?
Cranial nerve nucleii
Pontine nucleii
(involved in learning motor skills)
Nucleii of reticular formation
What does the midbrain develop from and what is in its central cavity?
Develops from the mesencephalon
Central cavity has the cerebral aqueduct
What are the surface features of the midbrain?
Cerebral peduncle
Superior cerebellar peduncle
Corpora quadrigemina
(superior and inferior colliculus)
Origin of Oculomotor (CN III) and Trochlear (CN IV)
How does the trochlear nerve (CN IV) differ from all the other nerve routes?
Only nerve to originate posteriorly
What is the corpora quadrigemina?
Made up of:
- Superior colliculi
- –Visual reflex
- Inferior colliculi
- –Auditory reflex
4 nodules at the posterior of the midbrain (bellow diencephalon and above superior cerebellar peduncle
What are the features of the midbrain section?
Central cavity contains the cerebral aqueduct (connects III and IV ventricles)
Periaqueductal grey matter with nucleus for III and IV cranial nerves
White matter embedded Nucleii surrounds the periaqueductal grey matter
Red nucleus (containing lots of iron)
Black bands of the substantial nigra can be seen in specimen
Give an introduction to the structure of the cerebellum
Right and left hemispheres separated by Vermis
Each hemisphere has an anterior, posterior and tiny flocculonodular lobe
Surface has sulci and folia
Three cerebellar peduncles connect it to brainstem
Cerebellar tonsils also present
What forms the grey and white matter of the cerebellum?
Grey matter:
- Cortex on surface
- Deep nucleii
White matter:
- Arbor vitae
- Cerebellar peduncles