Neurology 3 - Brainstem Flashcards
Define the brainstem
The part of the CNS, exclusive of the cerebellum, that lies between the cerebrum and spinal cord
List the major divisions of the brainstem
- Medulla oblongata
- Pons
- Midbrain
What is the function of the general somatic afferent in the brainstem?
Sensation from skin and mucous membranes
What is the function of the general visceral afferent?
Sensation from GI tract, heart, vessels and lungs
What is the function of the general somatic efferent?
Innervates muscles for eye and tongue movements
What is the function of the general visceral efferent?
Preganglionic parasympathetic - innervate the gut.ect such as vagus nerve
What is the function of the special somatic afferent?
Sensory for vision, hearing and equilibrium
What is the function of the special visceral afferent?
Sensory for smell and taste
What is the function of the special visceral efferent?
Innervate the muscles involved in chewing, facial expression, swallowing, vocal sounds and turning the head
Where is the brainstem?
In the posterior cranial fossa
What is not bilateral in the brainstem? What is its function?
- The pineal gland at the roof
- Important for circadian rythms
What is the function of the superior colliculus?
- Located below the pineal gland. Contralateral
- Involved in coordinated neck and eye movement
What is the function of the inferior colliculus?
- Located below the superior colliculus. Contralateral
- Responsible for auditory reflex
What is below the optic chiasm?
The pituitary stalk/infundibulum
What is the significance of the pyramidal decussation?
It is the location of cross over of most motor nerves
Describe the development of the brainstem with its nerve nuclei
- Motor nerves tend to be medial, sensory tend to be lateral
- Medial to lateral: GSE, GVE, GVA, GSA
How can the midbrain be identified on MRI?
- Mickey mouse shape
- Cerebral aqueduct is only in the midbrain
- Cerebral peduncle (forms mickey mouse ears)
- Inferior colliculus
- Substantia nigra
How can the pons be identified in MRI?
- 4th ventricle
- Transverse fibres
- Middle cerebellar peduncle
How can the medulla be identified in MRI?
Upper - Pyramids inferiorly - Inferior olivary nucleus (wavy shape) - 4th ventricle Lower - Medulla has dorsal columns, central canal, and pyramidal decussation
Damage to which area causes each symptom of lateral medullary syndrome?
- Vestibular nuclei causes vertigo (loss of balance perception)
- Inferior cerebellar peduncle causes ataxia (change in gait)
- Spinal nucleus (trigeminal) loss of pain and temperature sensation
- Sympathetic tract (horners syndrome)
- Nucleus ambiguus (hoarse)
- Spinothalamic tract (pain and temperature perception from opposite side
List the cranial nerves and their class
1 - Olfactory (SVA) 2 - Optic (SSA) 3 - Oculomotor (GSE/GVE) 4- Trochlear (GSE) 5- Trigeminal (SVE/GSA) 6- Abductens (GSE) 7- Facial (GSE/SVE) 8- Vestibulocochlear (SSA) 9- Glossopharyngeal (GVE) 10- Vagus (GVE) 11- Accessory (GSE) 12- Hypoglossal (GSE)
Which nerves arise from the midbrain? What are their functions?
- Trochlear nerve comes from the posterior side of the midbrain
- Moves the eye
Which nerves arise from the cerebrum, and what are their functions?
- Olfactory nerve and optic nerve
- Olfactory nerve controls sense of smell
- Optic nerve controls sight
Which nerves arise from the ponto-midbrain junction? What is its function
- Oculomotor nerve
- Eye movement and pupillary constriction
Which nerves arise from the pons? What are their functions?
- Trigeminal nerve
- Sensory and motor to the face
Which nerves arise from the ponto-medullary junction? What are their functions?
- Abductens is medial, it controls eye movement
- Facial is more lateral, it controls expression and is also sensory (taste)
- Vestibulocochlear is the most lateral, it controls hearing and balance
Which nerves arise from the medulla oblongata, and what are their funcitons?
- Glossopharyngeal nerve is motor and sensory to the tongue and throat
- Vagus nerve is parasympathetic
- Accessory nerve is responsible for head, neck and shoulder movement as well as swallowing
- Hypoglossal nerve is anterior, it controls speech chewing and swallowing
What is the nucleus ambiguus?
- A SVE that helps muscles in the pharynx and laryngopharynx
- Has input and output from many of the cranial nerves
What is the edinger westphal nucleus?
- Parasympathetic input to the eye
- GVE
- Located in the midbrain
Where are the salivatory nuclei? What is its function?
- GVE from the glossopharyngeal and facial nerves
- Supplies the salivary glands
- In the pons and medulla
What is the nucleus solitarius? Where is it located?
- Located in the pons and medulla
- GVA
- Receives taste information
Where is the trigeminal nerve?
GSA all through the brainstem
What is horners syndrome?
- Loss of sympathetic control
- Small pupils
- Drooping eye
- Lack of sweating around the eye
What causes lateral medullary syndrome?
Thrombosis of the vertebral artery or PICA (posterior inferior cerebellar artery)
