Tri B - Central Nervous System Flashcards
Describe the Dura Mater
Tough and fibrous
2 layered;
Outer periosteal - thicker, close to cranial bones
Inner meningeal - forms infoldings
Name and describe the infoldings of the Dura Mater
Falx Cerebri - separates the 2 cerebral hemispheres
Falx Cerebelli - separates the 2 hemispheres of the cerebellum
Tentorium Cerebelli - separates cerebrum and cerebellum
Describe the Arachnoid Mater
Thin, web-like membrane - avascular
Can herniate through dura, forming arachnoid villi - filters CSF
Describe the Pia Mater
Very delicate, highly vascular
Closely follows convolution of brain
Supports network of blood vessels - includes choroid plexuses
Name the Spaces between cranial meninges
Extradural
Subdural
Subarachnoid
Describe the Spaces between cranial meninges
Extradural - between skull and dura
- potential space
Subdural - between dura and arachnoid
- potential space - serous fluid
Subarachnoid - between arachnoid and pia
- true space; trabeculae, CSF
- arachnoid cisterns, large pools of CSF near fissures
Describe the ventricular system
4 irregular shaped cavities
2 lateral, 3rd & 4th ventricles
CSF is produced by choroid plexuses - in walls of lateral and 4th, roof of 3rd
Describe CSF (cerebrospinal fluid)
Similar composition to blood- glucose, plasma proteins, minerals
What are the functions of CSF?
Support and protect the brain
Maintain pressure
Acts as a cushion/ shock absorber
Keep brain and spinal cord moist
Exchanges nutrients and waste
Describe the flow of CSF
Lateral Ventricles
–> interventricular foramina
–> third ventricle
–> cerebral aqueduct
–> fourth ventricle
to either
–> foramina of Luschka & foramen of magendie
–> subarachnoid space
or
–> central canal of spinal cord
Describe the cerebrum
Largest part of brain
Hemispheres joined by corpus callosum
Surrounds midbrain and diencephalon
Describe the cerebral cortex
2-4 mm thick outer layer
- contains functional cell bodies
Contains folds and grooves
Name and describe the different types of folds in the cerebral cortex
Gyri - exposed folds
Fissures - deepest grooves
Sulci - shallower grooves
Name and describe the different types of signals processed in the cerebral cortex
Sensory - receive and interpret sensory impulse
Motor - initiate movement
Association - complex integrative function (memory, emotions, reasoning)
Name and describe the different functional areas within the cerebral cortex
Frontal lobe - reasoning, planning, speech, movement
Parietal lobe - perception of stimuli; touch, temp, pain
Temporal lobe - auditory stimuli and memory
Occipital lobe - Aspects of vision
Describe the cerebral white matter
Nerve fibres - 3 directions
Association fibres - transmit between gyri of same hemisphere
Commissural fibres- transmit from gyri of one hemisphere to corresponding
Projection fibres - transmit from cerebrum to lower brain and spinal cord
Describe the Basal Ganglia
Groups of cell bodies - grey matter
-caudate nucleus
-lentiform nucleus
Relay stations
Imitation of fine motor control
What happens if there’s damage to the basal ganglia
Movement becomes jerky, clumsy, uncoordinated
Describe the diencephalon
Connects cerebrum to midbrain
Composed of hypothalamus and thalamus (structures that surround 3rd ventricle)
Describe the Thalamus
Paired oval masses of grey & white matter
Situated of each side of 3rd ventricle
Approx. 3cm length
Primarily relay station for sensory impulses
Describe the Hypothalamus
Composed of 12 pairs of nuclei
Links nervous to endocrine system via pituitary gland
Function: Homeostasis
Describe the Brainstem
Contains; Midbrain, Pons, Medulla Oblongata
Controls breathing, heart rate
Reticular formation extends through brainstem
Describe the Midbrain
Extends from pons to diencephalon - 2.5cm
Surrounds cerebral aqueduct
Contains both nucleus and tracts
Anterior - pair of fibre bundles - cerebral peduncles
Posterior - 4 rounded eminences - corporal quadrigemina
Describe the Pons
2.5cm long
Bridge connecting spinal cord with brain
Contains both nucleus and tracts
Helps control of respiration
Describe the Medulla Oblongata
3cm long
Contains all ascending/descending tracts
Anterior aspect - 2 “pyramids”
-Composed of largest motor tract
-Point where many nerves cross
Contains nuclei (controls breathing)
Describe the Cerebellum
Butterfly shaped
Each hemisphere consists of lobes - posterior, anterior, flocculondular
Folia - grey matter ridges
Arbor vitae - white matter tracts below folia
Cerebellar nuclei - grey matter masses, give rise to nerve fibres that transmit impulses
What is the function of the cerebellum and what does damage look like?
Controls posture, balance and coordination
Damage - ataxia - disruption of muscle coordination
Name the 2 endocrine glands in the brain
Pineal Gland
Pituitary Gland
Describe the Pineal Gland
Pea sized, protrudes from 3rd ventricle
Secretes melatonin
Starts to calcify in puberty
Describe the Pituitary Gland
Pea sized
Secretes hormone control of other glands
Describe the Limbic System
Ring of structures in inner border of cerebrum and floor of diencephalon
Primary role in emotions - pain, anger
- also involved in smell and memory
Contains:
Hippocampus - memory
Amygdala - rage
Mamillary bodies - olfaction
Describe arterial blood supply within the brian
15% cardiac output
2 internal carotid arteries
2 vertebral arteries
Describe the Circle of Willis
A ring of blood vessels
Located at base of brain
If on section is blocked, others can prevent tissue death
Describe the Dural Venous Sinuses
Endothelial lined spaces between periosteal and meningeal layers of dura
Large surface veins empty here
All brain blood drains through internal jugular vein
Name the Main Venous Sinuses
Superior Sagittal x1
Inferior Sagittal x1
Straight x1
Transverse x2
Sigmoid x2
