Brainstem and cranial nerves Flashcards
What is the brain composed of?
Brain is comprised forebrain, midbrain and hindbrain
What forms the brainstem?
Midbrain
Pons
Medulla
What passes through the brainstem?
All ascending and descending pathways pass through the brainstem
Many synapse here in relay nuclei or arise directly from or synapse in other brainstem nuclei
How is the cerebellum connected to the brainstem?
Cerebellum connected to brainstem by 3 cerebellar peduncles (white fibre tracts)
What nuclei are in the brainstem?
Contains nuclei of 9 of the 12 pairs of cranial nerves – III to XII (except XI)
What is the internal structure of the brainstem?
Base
Tegmentum
Tectum roof
Ventricular system
What are the more detailed components of the brainstem (posterior)?
Pineal gland
Superior colliculus
Inferior colliculus
Dorsal columns
Trochlear nerve
What are the more detailed components of the brainstem (anterior)?
Optic chiasm
Pituitary stalk
Mammillary body
Cerebral peduncle
Medullary pyramids
Pyramidal decussation
Cerebral peduncles – descending tracts what are these?
Corticospinal and corticobulbar
Label this diagram of the midbrain.
*cranial nerves III and IV emerge at this level
What are components of the pons?
Pontine nuclei, transverse fibres and descending pathways
Cranial nerves V, VI, VII & VIII emerge at this level
Label this diagram of the pons.
Middle cerebellar peduncle
4th ventricle
What cranial nerves emerge at from medulla?
Cranial nerves IX, X & XII emerge from medulla
Label this diagram of the open (upper) medulla.
Label this diagram of the closed (lower) medulla?
What type of continuation is the medulla?
Rostral continuation of spinal cord
Which motor pathway has fibres which cross at the medulla?
Corticospinal
Describe the surfaces of the medulla.
Anterior surface has pyramids (descending tracts)
Posterior surface has dorsal columns
Posterior surface divided into open and closed
What does the closed (lower) medulla have?
Closed has extension of central canal of spinal cord
Canal widens to form 4th ventricle in open medulla
What does CNS blood supply come from?
anterior and posterior arterial systems
Anterior arterial system is derived from which vessels?
Internal carotid system
(Most of the cerebral hemispheres)
Posterior arterial system is derived from which vessels?
Vertebrobasilar
(brainstem)
What is the brainstem blood supply split into?
Circle of Willis
Vertebrobasilar system
What are these cranial nerves on the brainstem?
What are the 2 types of nuclei in the brainstem?
Efferent (motor) nuclei
Afferent (sensory) nuclei
Do you understand/ remember some of this diagram?
Y/N
How can cranial nerves be grouped?
according to their functional components
What are the groups of the cranial nerves according to their functional components? (7)
General somatic afferent (GSA)
General somatic efferent (GSE)
General visceral afferent (GVA)
General visceral efferent (GVE)
Special somatic afferent (SSA)
Special visceral afferent (SVA)
Special visceral efferent (SVE)
What are General visceral efferent (GVE)?
Fibres are the preganglionic parasympathetic neurons to cranial, thoracic and abdominal viscera
What are General visceral afferent (GVA)?
Fibres carry sensation from viscera of head, neck, thorax and abdomen
What are General somatic efferent (GSE)?
Fibres innervate skeletal muscles
What are General somatic afferent (GSA)?
Fibres carry general sensation from skin, muscles, joints of head and neck
What are Special visceral efferent (SVE)?
Innervate skeletal muscles of the jaw, face, larynx and pharynx
What are Special visceral afferent (SVA)?
Fibres carry taste sensation
What are Special somatic afferent (SSA)?
Fibres carry special senses of hearing and balance
What nerves emerge from the pons?
Cranial nerves V-VIII
What cranial nerves emerge from the midbrain?
Cranial nerves II & IV
What does the anterior aspect of midbrain have?
mammillary bodies, cerebral peduncles, medullary pyramids
What does the posterior aspect of midbrain have?
pineal gland, colliculi, dorsal columns
