14. Nervous System II Flashcards
What does the central nervous system consist of?
The brain and the spinal cord
What are the connective tissue layers that cover the brain and spinal cord?
(Overall name, and the 3 specific layers)
The Meninges
1) Dura Mater - tough fibrous outer later
2) Arachnoid mater - middle layer of collagen and elastic fibres
3) Pia mater - thin inner most layer containing blood vessels
What are the two gaps between the meninges called and where are they located?
1) Subdural space between the dura mater and the arachnoid mater.
2) Subarachnoid space between the arachnoid mater and pia mater
What 2 haemorrhages can occur in the spaces between the meninges and how do they differ?
Subdural haematoma - as this is venous blood is develops slowly
Subarachnoid haemorrhage - arterial bleed so rapid (feels like being hit in the back of the head - an explosive headache).
What is cerebrospinal fluid (CSF)?
A clear liquid that protects the brain and spinal cord from mechanical and immunological trauma.
Where can you find cerebrospinal fluid (CSF)?
Subarachnoid space
Ventricles (cavities) of the brain
Central canal of the spinal cord
What cells make cerebrospinal fluid and how much of it?
Ependymal cells make 500ml / day
List 4 functions of the cerebrospinal fluid.
1) Supports and protects the brain and spinal cord acting as a shock absorber.
2) Maintains uniform pressure around the brain
3) Keeps brain and spinal cord moist
4) Circulates nutrients and waste
5) Provides optimal chemical environment for nerve signalling
What arteries supply blood to the brain?
Vertebral & carotid arteries
What is the purpose of the blood brain barrier?
To protect the brain from toxins, harmful substances and bacteria that enter the bloodstream.
Describe how the blood brain barrier works.
Astrocytes maintains tightness of the capillaries and the junctions between the cells.
What can pass through the blood brain barrier? (4)
- Lipid soluble substances
- Glucose
- Gases (eg oxygen and carbon dioxide)
- Ions
Name the 4 main parts of the brain
1) Brain steam
2) Diencephalon
3) Cerebrum
4) Cerebellum
Of the 3 sections of the brainstem, provide:
- their name
- key functions
- the nerves they contain
Medulla oblongata
- contains respiratory & cardiac centres
- controls reflexes such as vomiting
- contains 4 cranial nerves (9-12)
- contains motor tracts
Pons
- helps control breathing
- contains 6 cranial nerves (5-8)
- relays motor tracts
Midbrain
- controls subconscious muscle activities
- eye reflexes and tracking
- 2 cranial nerves (3-4)
Of the 3 sections of the diencephalon, provide:
- their name
- key functions
Thalamus:
- Major relay centre of sensory information
Epithalamus:
- Connects limbic system to other parts of the brain
- Contains the pineal gland
Hypothalamus:
- Hormone regulation and homeostasis
- Controls ANS
- Controls body temperature
- Regulates emotions and behavioural patterns
Describe the main functions of the cerebellum
- Maintenance of posture and balance
- Coordinating complex movements
- Correction of errors during ongoing movement
What can damage the cerebellum?
- Chronic alcohol abuse
- Coeliac’s disease
- Thiamine (Vit B1) deficiency
What are the 2 main functions of the cerebrum?
- Sensory perception
- Motor control of skeletal muscles
What are the 4 areas of the cerebrum and name 1 function for each?
- Frontal lobe - motor skills
- Temporal lobe - hearing
- Parietal lobe - sensory interpretation
- Occipital lobe - vision
What is the limbic system?
It’s the area of the brain that is active with different emotions.
Name 3 key structures found in the limbic system.
1) Hypothalamus
2) Hippocampus
3) Amygdala
How much of the cardiac output does the brain receive?
20% / 750ml per minute
What is the meeting point of the carotid and vertebral arteries called?
Circle of Willis
What’s the 1st cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Olfactory nerve
Located in cerebrum
Sense of smell
Sensory
What’s the 2nd cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Optic nerve
Cerebrum
Vision
Sensory
What’s the 3rd cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Oculomotor
Midbrain
Eye movement, eyelids, pupil size
Motor
What’s the 4th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Trochlear
Midbrain
Eye movement
Motor
What’s the 5th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Trigeminal
Pons
Facial Sensations, chewing
Sensory and motor
What’s the 6th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Abducens
Pons
Abducts eyes
Motor
What’s the 7th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Facial nerve
Pons
Facial expressions, Taste, salivary glands
Sensory & motor
What’s the 8th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Vestibulocochlear
Pons
Hearing, balance
Sensory
What’s the 9th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Glossopharyngeal
Medulla
Taste, swallowing, tongue sensations
Sensory & motor
What’s the 10th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Vagus
Medulla
Sensory/motor functions in chest/abdomen
Sensory & motor
What’s the 11th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Accessory nerve
Medulla
Neck and shoulders
Motor
What’s the 12th cranial nerve?
Where is it located?
What is its function?
Is it sensory or motor?
Hypoglossal
Medulla
Tongue movement
Motor
What spinal nerves continue beyond the conus (end of the spinal cord)?
Cauda equina
Where does the spinal cord end?
L2 at the conus
Briefly describe what the spinal cord consists of.
White matter around the outside consisting of bundles/tracts of myelinated axons. These tracts make up the motor tracts (descending) and sensory tracts (ascending)
Butterfly shape of grey matter in the middle consisting of cell bodies and dendrites receiving incoming and outgoing information.
What are the 3 spinal cord tracts?
1) Dorsal columns - ascending tract for light touch, vibration, proprioception.
2) Spinothalamic tract - ascending tract for pain and temperature
3) Corticospinal tract - descending for voluntary movement.
What is Raised Intracranial Pressure?
An increase in the pressure within the cranial cavity. This compression of blood vessels leads to reduced oxygen to the brain
List 3 causes of raised intracranial pressure.
- Tumours
- Haemorrhage
- Hydrocephalus
- Meningitis
List 4 signs/symptoms of Raised Intracranial Pressure.
- Headaches (worse on awakening)
- Vomiting often without nausea
- Visual disturbance
- Pupil fixed / dilated in one eye
- Impaired mental state
What is Hydrocephalus?
An abnormal accumulation of cerebrospinal fluid occupying the cerebral ventricles and subarachnoid space.
Usually due to impaired absorption but can be due to excessive secretion.
Provide 1 cause each for hydrocephalus in small children and adults.
Small children:
Infection
Congenital malformation
Older children & adults:
Tumour
Trauma
Meningitis
List 3 signs/symptoms of hydrocephalus
- Headaches (worse in the morning)
- Increase in head circumference in infants
- Vomiting
- Blurred vision
- Impaired motor skills
What allopathic treatment is there for hydrocephalus?
Shunt
Diuretics
Ventricular drain
What is meningitis?
Inflammation or infection of the meninges.
What can cause meningitis?
Viral (most common 90%) - herpes simplex
Bacterial (most severe)
Fungal or parasitic microorganisms.
List 4 signs/symptoms of meningitis
- Fever
- Sudden onset of severe headache
- Neck stiffness
- Vomiting
- Petechiae (skin rach - tiny hemorrhages)
How might meningitis be treated allopathically?
Antibiotics (if bacteria)
Antivirals (if viral)
Corticosteroids
Intravenous fluids
List 3 potential complications of meningitis
- Swelling (and raised intracranial pressure)
- Septicaelmia (if bacteria)
- Seizures
What is concussion?
Temporary loss of neuronal function due to a head injury.
List 3 common signs/symptoms of concussion
- Loss of consciousness
- Memory loss
- Heachache
- Disorientation
What is a cerebral contusion?
A type of traumatic brain injury that causes bruising of the brain with ruptured blood vessels and oedema.
Usually caused by a blunt blow to the head.
What is the difference between a coup and a contrecoup injury?
Coup = damage on the same side as the trauma
Contrecoup = damage to the brain also appears on the opposite side as the trauma
List 5 causes of headaches
- Dehydration
- Tension headache
- Congested sinuses
- Hypoglycaemia
- Migraines and cluster headaches
- Medication induced
- Tumour
- Haemorrhage
What is a migraine?
A neurological condition that results in recurrent severe heachaches
List 4 causes migraines?
- Cerebral depolarisation causing initial vasoconstriction (aura) and subsequent vasodilation.
- Low serotonin
- Food additives
- Stress
- Hormonal changes
- Poor sleep
List 4 signs/symptoms of migraines
- Aura
- Unilateral, pulsating headache
- Photophobia
- Phonophobia
- Nausea and vomiting
Provide 2 headache red flags
- First onset over 50yrs
- Thunderclap headache (subarachnoid haemorrhage)
- Signs of meningitis - accompanied by neck stiffness, non-blanching rash
- Signs of raised intracranial pressure - worsening in the morning, uneven pupils, vomiting and no nausea.
What is epilepsy?
Sudden, hyper-excitable, and uncontrolled neuronal activity in the brain.
(Symptom, not a disease)
List 3 causes of epilepsy
(Idiopathic)
Brain tumour
Cerebral haemorrhage
Head trauma
CNS infection
List 4 common triggers for epilepsy
Hypoglycaemia
Fever
Sleep deprivation
Dehydration
Stress
Flickering lights
Drugs and alcohol
Pesticides
Briefly describe 2 types of seizures
Petit mal seizures: aka an absence seizure
Non-convulsive
Lasts 10-30 seconds
Seen mainly in children
Grand mal seizure:
Convulsive
Lasts around a minute
What natural treatment is there for epilepsy?
Magnesium
Sleep hygiene
Stress management
Ketogenic diet - increases GABA production which suppresses excess electrical activity
What is sciatica?
Pain due to the compression or irritation of the sciatic nerve (which is the longest and widest nerve in the body)
List 3 signs/symptoms of sciatica
- Pain in the lower back and buttock
- Pain radiating down the posterior leg
- Pins and needles and numbness
- Weak calf
- Absent ankle jerk reflex
What are 2 common causes of sciatica?
Disc herniation (L4/5 or L5/S1)
Compression against piriformis muscle
What test can be done to help diagnose a disc herniation?
Straight leg raise test (SLRT)
Patient lies on their back and you raise one of their legs whilst keeping it straight to about 45 degrees.
A positive result is pain in this initial 45 degrees.
What are the dangers of aspartame?
It’s a neurotoxin with neuro-excitatory properties.
Linked to widespread neurological damage and a variety of symptoms and conditions, including MS, Parkinson’s, and balance problems.
How might you test someone’s proprioception?
Romberg’s test:
The patient stands with feet together, then close their eyes. Positive Romberg’s if sways after closing eyes.
Name 2 reflex neurological examinations
1) Deep Tendon Reflexes - (knee or ankle)
2) Cutanous Reflexes (plantar or abdominal)
