Neuro 3 - Brainstem and Cranial Nerves Flashcards
What is the brainstem?
- Part of CNS
- Exclusive of cerebellum
- Lies between cerebrum and spinal cord
What are the 3 major divisions of the brainstem?
- Medulla oblongata
- Pons
- Midbrain
Name the posterior features of the brainstem. (assuming we’ve cut through the cerebellum)
- Pineal gland (not bilateral)
- 2x superior colliculi
- 2x inferior colliculi
- CN 4 (Trochlear N)
What is the pineal gland for?
Vital for circadian rhythms - melatonin release
What forms the floor of the 4th ventricle?
The pons
What is cranial nerve number 1?
Olfactory N
Where does cranial nerve 1 synapse?
Olfactory bulb
What is cranial nerve number 2?
Optic Nerve
Where does CN 2 synapse?
Optic chiasm
From where does the trochlear N emerge?
Dorsal aspect of the brainstem
What lies behind the pituitary stalk?
Mammillary body (part of diencephalon)
They turn dark if alcohol abuse - due to neovascularisation
Which 2 nerves emerge at the midbrain level?
- Oculomotor n
2. Trochlear N
What do the cerebral peduncles do?
Functional and structural use.
Hold cerebral cortex onto brainstem
Which nerve emerges at the level of the pons?
Trigeminal N
Muscles of mastication are supplied by which nerve?
The trigeminal
At the ponto-medullary junction, what nerves are present?
CN 6, 7, 8 (medial to lateral)
What eye movement muscle does the abducens nerve supple?
The lateral rectus muscle
What is the facial nerve used for?
Muscles of facial expression
What is CN 6?
Abducens
What is CN 7?
Facial
What is CN 8?
Vestibulocochlear
Which nerves emerge from the lateral part of the medulla?
CN 9, 10, 11
What is CN 11, and what does it supply?
Accessory n, supplies shoulder muscles (e.g. trapezius and SCM)
CN 9?
Glossopharyngeal
CN 10?
Vagus
CN 12?
Hypoglossal, innervates tongue
What is the significance of the pyramidal decussation?
Where 90-95% of the motor fibres cross over. Anatomical basis for contralateral motor control
GSA?
General Somatic Afferent.
Sensory information from skin and mucous membranes
GVA?
General Visceral Afferent.
Sensory information from GIT, heart, vessels and lungs
GSE?
General somatic efferent.
In head = muscles for eye and Tongue movements
GVE?
General visceral efferent. Preganglionic parasympathetic (eg vagus n)
What are the Special somatic afferent nerves?
Optic and Vestibulocochlear
What are the special visceral afferent nerves?
Olfactory N, facial N, glossopharyngeal N
Smell and taste. (Glossopharyngeal posteriorly)
What are the special somatic efferent nerves?
Muscles involved in chewing, facial expression, swallowing, vocal sound and turning head
What is the dorsal root ganglion made up of?
Neural crest cells
In the brainstem, are motor neurones located medially or laterally?
Medially
What is the most medial cell column in the brainstem?
GSE
What GSE nerves are in the midbrain?
Oculomotor and Trochlear
Where does the abducens nerve arise from?
The ponto-medullary junction
Where is the abducens N nucleus located?
Within the pons
Which is the GSE N in the pons?
Abducens
Which 3 nuclei control eye movement?
Oculomotor, Trochlear and Abducens
Which GSE nucleus is in the medulla?
Hypoglossal
What are the GSE Nerves?
Oculomotor, abducens, trochlear, hypoglossal
Which cell column is just lateral to GSE?
SVE
Are there any SVE cells located in the midbrain?
NO
Which SVE nuclei are located in the pons?
Trigeminal, facial nerve
Which nerve supplies the muscles for mastication?
Trigeminal
What is the nucleus ambiguous used for?
Laryngeal movements
Name the SVE nucleus in the medulla
Nucleus ambiguous
Where does the accessory nerve have its nucleus?
In the crevice-spinal cord
Name the SVE nuclei.
Trigeminal, facial, nucleus ambiguous, accessory n
Which is the most lateral motor nerve cell column of the brainstem?
GVE (parasympathetic)
Name any GVE nuclei in the midbrain
Edinger-Westphal
What nerve provides PNS innervation to the eye?
Edinger westphal
What GVE nuclei are a the border between the pons and the medulla?
Salivatory nuclei
Edinger Westphal fibres follow which nerve fibres?
Oculomotor
Which GVE nuclei is present in the medulla?
Vagus
What are the GVE nuclei?
Edinger Westphal, salivary, vagus
What is the most medial sensory cell column?
GVA/SVA
Name the nuclei present in the GVA/SVA column
Solitarius
What is the nucleus solitarius used for?
Connects nerves responsible for taste
What part of the brainstem is the nucleus solitarius present?
Medulla
What is the medial sensory cell column?
GSA
What is found in the GSA column?
Trigeminal, present in midbrain, pons, medulla and CVS
What is the most lateral nuclei?
Vestibulocochlear.
What is the most lateral cell column?
SSA
What level of the brainstem is the vestibulocochlear nuclei present?
Pons & medulla
Midbrain has what distinct feature on MRI?
Mickey Mouse ears
Substantia nigra is present in the midbrain. It is almost absent in someone with?
Parkinsons
What are MRI features in the midbrain?
Inferior colliculus, cerebral aqueduct, substantia nigra, cerebral peduncle
What features on MRI are present on the level of the pons?
4th ventricle, middle cerebellar peduncle, transverse fibres
Where is the inferior olivary nucleus?
Medulla
Pyramids are in?
Medulla
Where is the pyramidal decussation?
Lower medulla
What are the 2 causes of lateral medullary syndrome?
Thrombosis of vertebral artery
Thrombosis of Posterior Inferior Cerebellar Artery (PICA)
What are the symptoms of lateral medullary syndrome?
- Vertigo
- Ipsilateral loss of thermal sense/pain in face
- Contralateral loss of thermal sense/pain in trunk and limbs
- Ipsilateral cerebellar ataxia
- Horners syndrome (lack of sweating)
- Hoarseness / difficulty of swallowing
What information does the inferior cerebellar peduncle carry?
Information about the bodies position in space
What problems occur in lateral medullary syndrome
- Vestibulocochlear nucleus
- Nucleus ambiguus
- Inferior cerebellar peduncle
- Spinal nucleus
- Spinothalamic tract
- Sympathetic tract
