Neuro Flashcards
What are emergent properties, using the brain as an example?
The interaction of simple units to create properties which are not produced by a unit on its own.
In the brain there are 10^11 neurons which interact to produce human behaviour and consciousness.
Can axons regenerate in the CNS?
No
Can axons regenerate in the PNS?
Yes
Is the CNS sophisticated?
Yes
Is the PNS sophisticated?
No, with the exception of the enteric nervous system
Do tumours grow in the CNS?
Yes, they can be malignant or benign
Do tumours grow in the PNS?
Yes, they are usually benign
What are glymphatics?
Specialised lymphatic vessels in the brain which drain to the cervical lymph nodes.
What is the general function of the midbrain?
Eye movement, involuntary hearing, vision
What is the general function of the pons?
Feeding
Hearing and balance
What is the general function of the medulla?
Autonomic - via vagus nerve
Automatic - respiratory and cardiac centres
What is the general function of the cerebral hemispheres?
Language, cognition, and other higher functions
What is the general function of the spinal cord?
Contains central pattern generators which can be ‘switched on’ by the brain, allowing movement which we don’t have to think about e.g. walking, chewing, breathing
What are the layers of the cranial meninges?
Periosteal dura
Meningeal dura
Arachnoid
Pia mater
Describe the periosteal dura.
It is adhered to the skull.
Blood vessels lie between it and the skull
Describe the meningeal dura.
It is fused to the periosteal dura, but separates in some places.
Contains the dural venous sinuses and creates falx cerebri
Describe the arachnoid meningeal layer.
Loosely adhered to the meningeal dura.
CSF sits beneath it in the subarachnoid space
Describe the pia mater.
Sticks closely to the brain and spinal cord, into the folds.
Its role is to protect the brain by blocking chemicals and infectious agents.
What produces CSF in the brain?
Choroid plexus
What connects the third and fourth ventricles?
Cerebral aqueduct
Where does CSF enter the subarachnoid space from the ventricular system?
Small apertures near where the cerebellum attaches to the brainstem
What absorbs CSF from the subarachnoid space?
Arachnoid villi
Why is the central nervous system so susceptible to insult during development?
It begins early and is the last to finish
Describe spina bifida.
A failure of the posterior neuropore to close. It can occur anywhere along the length of the spine, although it is most common in the lumbosacral region. They may have neurological deficit.
Cognitive delay may be a result of subsequent hydrocephalus but isn’t a direct result of the spina bifida
What are the three types of spina bifida?
Spina bifida occulta - only the spinous processes are missing, often an incidental finding.
Spina bifida meningocoele - the meninges herniate through the unfused region of the lumbar spine
Spina bifida myelomeningocoele - the meninges and spinal cord herniate through the unfused region of the lumbar spine
What is anencephaly?
A failure of the anterior neuropore to close. It causes the absence of cranial structures as well as the brain, and is usually incompatible with death.
What is rachischisis?
A failure of neural fold elevation, so there is no closure at all. The nervous tissue is splayed and external so is incompatible with life.
How can you diagnose neural tube defects?
Raised maternal serum alpha-fetoprotein (due to the openness of the defect, non-specific)
Ultrasound scan
What can be taken to reduce the risk of neural tube defects?
Folic acid
How does development cause the creation of the cauda equina?
The vertebral column and spinal cord are the same length at the end of spinal cord development.
The vertebral column then continues to lengthen with the trunk, but the spinal roots still exit at the same point. The roots therefore have to stretch.