Gross Anatomy Day 2 Flashcards
What regions are in the supratentorial compartment?
Telencephalon and diencephalon
What cranial nerves are in the supratentorial compartment
I and II
What actions/functions/behaviors are associated with the supratentorial compartment?
- awake and oriented
- olfactory and visual systems
- cognition and language
- emotion and behavioral regulation
- hypothalamic and pituitary functions
What are the regions in the infratemporal compartment?
Brainstem and cerebellum
What part of the brainstem is in the infratentorial compartment
CN 3-12
What major part of the brain is in the infratentorial compartment and what does it do?
Cerebellum, motor coordination
What is contained in the vertebral compartment
Spinal cord, dorsal and ventral roots
When motor and somatosensory exams re conducted, what compartment is being tested?
Vertebral compartment
What compartment is responsible for reflexes
Vertebral compartment
What causes herniation syndrome?
Various intracranial masses
What are 4 types of cranial herniations
- subfalcine herniation
- central herniation
- uncal transtentorial herniation
- tonsillar herniation
Herniations: effects on brain tissue vs dural partitions
- initially, it is the brain tissue that is displaced and injured
- with progression of mass effect, dural partitions can be displaced as well
- in radiology, shifts in dural partitions and brain can be detected
What could cause a midline shift
Supratentorial mass, causing subfalcine herniation
What is the average normal value for intracranial pressure?
<20cm (200mm) H20
<15cm (150mm) Hg
How is intracranial pressure measured?
- lumbar puncture (subarachnoid space around cauda equina)
- neurosurgical insertion of intracranial monitors/ catheters
Contra indications for lumbar punctures
- suspected increased supratentorial pressure (can cause herniations!)
- infection or mass in the path of manometer needle insertion
What are some causes of intracranial pressure
- hydrocephalus (too much CSF)
- brain edema (accumulation of water content)
- hemorrhage
- tumor or other mass
Symptoms of increases intracranial pressure
- headache
- nausea and vomiting (vomiting can occur in the absence of nausea)
- impaired consciousness
- skull (bulging fontanelles)
- increases systemic blood pressure
- papilledema
Increases intracranial pressure causes rippled effect along perimeter (elevation) and loss of sharp contours, due to congestion and swelling of axons
Papilledema
Sensory (pain) innervation of dura, falx, tentorium
Mostly trigeminal nerve (CN5), some vagus (CN10), cervical nerves
Meningeal irritation syndrome
- Headache/pain
- Neck stiffness (nuchal rigidity)
- Impairment or loss of consciousness
Mechanism of neck stiffness in meningeal irritation syndrome
Might be cervical spinal reflex circuit: sensory input activates motonerons and increases muscle tone in neck
Various potential causes or sources of meningeal irritation syndrome
- inflammation
- infection (meningitis)
- pressure (bleeding, growing intracranial mass)
Does intracranial pressure have to be present to have meningeal irritation syndrome?
No
Kernigs test and sign
- Passive flexion of hip
- Passive extension of knee
- Kernigs sign is pain with knee extension
What is kernigs sign
Pain with knee extension
What are the physical exam tests and signs of meningeal irritation syndrome
- kernigs
- brudzinskis
Brudzinskis test and sign
- With passive flexion of neck
- Patient feels pain in neck
- The sign is the spontaneous, on voluntary hip and knee flexion
What is brudzinskis sign
Spontaneous involuntary hip and knee flexion
What is the reflexive response to neck flexion and pain in brudzinskis test mean?
Possibly an unconscious compensatory response to reduce dural tension and pain induced by the neck flexion
Clinical presentation of CNS infections
- diffuse neurological signs (meningeal irritation or increase intracranial pressure)
- focal neurological signs (abscesses and parasitic cysts can lead to focal or multifocal lesions and signs
What can lead to focal or multifocal lesions and signs of the CNS?
Abscesses and parasitic cysts
Diagnostic approach for CNS infections
- history
- physical exam
- knowledge of micro
- lab tests
- neuroimaging
Immune system in CNS
- few immune cells within CNS
- specific types of brain cells act as immune cells
Barriers to CNS infection
Specific anatomical or physiological barriers
- infection gets in when the barriers are disrupted (trauma, immunodeficiency)
- some direct and open routes do exits
Viral entry into CNS via PNS neurons
- some viruses can directly enter PNS through axon terminals
- once inside, viruses can be transported backwards to the cell body in a ganglion, spinal cord, or brain.
- some can go further back across synapses and thus spread further (trans synaptic spread, rabies)
What are the 3 potential channels for entry into the CNS that do not include traumatic breach of skull, or disruption of blood brain barrier or blood CSF barrier
- Emissary veins (from scalp Gino superior sagittal sinus)
- Veins from face to cavernous sinus
- Cribiform plate possibly
Infection of dura or arachnoid and pia?
Meningitis
Infection of parenchyma of brain or spinal cord
Encephalitis
Why is the meningeal artery point of potential traumatic injury and epidural hemorrhage?
It’s branches cross multiple suture lines
Cerebral veins drain via ________ into superior sagittal sinus
Bridging veins
Typically caused by a tear in the bridging veins at the dura-arachnoid interface
Subdural hemorrhage
Most common origin of subarachnoid hemorrhage
Aneurysms
Symptoms of subarachnoid hemorrhage
- diffuse neurological signs
- meningeal irritation signs
- increase intracranial pressure
- detectable by lumbar puncture and neuroimaging
