Organisation Of Brainstem Flashcards
Label the posterior view of the Brainstem
- Pineal gland
- Superior colliculus
- Inferior colliculus
- Trochlear Nerve
- 4th ventricle - pons
- Dorsal column
Describe the role of Pineal gland, superior colliculus, inferior colliculus, trochlear Nerve and Dorsal column
Pineal gland - on midline, important for circadian rhythm - releases melatonin
Superior colliculus - coordinated neck and eye movement
Inferior colliculus - protective auditory reflex
Trochlear nerve - CNIV (the only CN at posterior and coordinated eye movement - extrinsic muscles of eye)
Dorsal - touch and pain - upper and lower limb
Label the anteroinferior view of Brainstem
Diagram consisting of midbrain, pons and medulla oblongata
What structures are found in the midbrain
At the top - optic chiasm (CNII - optic nerves converge)
Midline - Pituitary stalk - infundibulum (base of hypothalamus)
Midline - occulomoter nerve (CNIII) - movement of eye
Cerebral peduncle - motor tract and allows for voluntary muscle control
What structures found in the pons and ponto-medullary junction?
At the pons - only trigeminal nerve (CNV) - touch and sensation through head and neck
At the ponto-medullary junction - Abducens (CNVI - muscles of eye LR) and Facial (CNVII - innervates facial muscle) and Vestibulocochlear (CNVIII - balance and hearing)
What structures found at the medulla
3 nerves that emerge together - Glossopharyngeal (CNIX - sensory and motor innervation of tongue and pharynx) and Vagus (CNX - main PNS nerve projects down to viscera) and Accessory (CNXI - sternocleidomastoid so turning of the head).
The hypoglossal emerges differently - CNXII - musculature of the tongue.
Structures superior to the Brainstem
Olfactory (CNI) - smell
What is the cerebral peduncle
Contains the motor fibres and turns into pyramids and pyramidal decussation
What are the 4 functional subtypes of the Cranial nerves and their functions
GSA - towards the spinal cord and brain - sensation of skin and mucous
GVA - toward the spinal cord and brain - sensations of GI tract, heart, lungs and vessels
GSE - away from spinal cord and brain - muscles from eye and tongue movement
GVE - away - preganglionic parasympathetic
What are the special subtypes and their actions
SSE - only cranial nerves - vision, hearing and equilibrium
SVA - comes from 3 CN in nucleus solitaries (CNI smell and the three tastes)
SVE - chewing, facial expression, swallowing, vocal sound and turning head.
Describe the development of the Brainstem.
Embryonic spinal cord (alar plate) - dorsal root (GVA GSA) separated from ventral root (GVE GSE) via sulcus limitans.
In the Brainstem (embryonic rhombocephalon) the alar plate opens up and you have ventricles with the motor medial and sensory lateral separated via sulcus limitans.
Arrangement of cranial nuclei in subtypes
GSE - CNIII, CN VI, CNXII SVE - CNV, CNVII, CNXI GVE - CNX SSA - CNVIII GSA - CNV look at diagram
Distinguishing parts of the brain stem
Midbrain - Mickey Mouse, inferior colliculus, cerebral aqueduct, substantia nigra (dopamine release) and cerebral peduncle
Pons - 4th ventricle, transverse fibres, middle cerebellar peduncle
Medulla - still have 4th ventricle, pyramids, inferior olivary nucleus (wavey).
Lower medulla - junction with spinal cord is round, dorsal column, central canal, gracilis (smaller column) and cunateous ( sesonry info) and pyramidal decussation.
Lateral medullary syndrome
Thrombosis of the veterbral artery or PICA causes symptoms of: vertigo, ipsilateral cerebellar ataxia (unsteady feet), ipsilateral loss of pain of face, horners syndrome (loss of sympathetic syndrome of eye eg drooping), hoarseness and difficulty swallowing, controlateral loss of pain and sense in trunk and limbs
LOOK AT DIAGRAM ON SLIDE
