Brainstem and Cranial Nerves Flashcards
What is the brainstem?
the part of the CNS, exclusive of the cerebellum , that lies between the cerebrum and spinal cord
major divisions:
- medulla oblongata
- pons
- midbrain
What is the roof of the midbrain known as?
tectum
What is in volved in melatonin production and circadium rhythm?
pineal gland
What is the colliculus involved in?
Superior - coordination of eye and neck movement
Inferior - auditory responses
What does the trochlear nerve supply?
superior oblique muscle of the eye
What nerve emerges between the cerebral peduncle?
occulomotor
What nerve emerges at the level of the pons?
trigeminal nerve
What nerves emerge at the junction between the pons and the medulla?
anducens
facial
vestibulocochlear
Which nerves emerge from the lateral side of the medulla?
glossopharyngeal
vagus
accessory (trapezius and sternocleidomastoid muscles)
What are the pyramids?
continuation of the corticospinal tract
What percentage of fibres cross over at the pyramidal decussation?
90-95%
What is the general functional classification of the cranial nerves?
General somatic afferent (to CNS) (GSA):
- Skin and mucous membrane sensation.
General visceral afferent (GVA):
- GI tract, heart, vessels and lungs.
General somatic efferent (away from CNS) (GSE):
- Muscles for eye and tongue.
General visceral efferent (GVE): Preganglionic PNS
What is the special functional classification of cranial nerves?
Special somatic afferent (SSA) - vision, hearing, equilibrium (optic and vestibulocochlear)
Special visceral afferent (SVA) - smell and taste (olfactory, facial [anterior] and glossopharyngeal [ posterior])
Special visceral efferent (SVE) - chewing, facial expression, swallowing, vocal sounds and turning head
Describe the organisation of the embryonic spinal cord?
dorsal Alar plate
the ventral Basal plate
the nerves are also clumped according to their purpose so the GSA fibres for example are all clumped.
During development the Alar plate splits and you get a lateral movement so in the brainstem the sensory nuclei are lateral while the motor nuclei remain medial.
cranial nerve nuclei are arranged in the brainstem with sensory nuclei lateral and the motor nuclei in the midline.
Where do the cranial nerve nuclei lie?
Midbrain:
Sensory - Trigeminal (middle)
Motor - Edinger Westphal (medial), oculomotor (medial), trochlear (medial)
Pons:
Sensory - Trigeminal
(middle), vestibulocochlear (lateral)
Motor - Trigeminal (middle) , abducens (medial), facial(middle) , salivary
Medulla:
Sensory - Trigeminal (middle), solitarius (medial)
Motor - Salivary (lateral), vagus (lateral), ambiguus (middle) , hypoglossal (medial)
Cervical Spinal Cord: Sensory - Trigeminal (middle)
Motor –Accessory (middle)
