Unit 4: Brain Flashcards
How do the brain and spinal cord start out in an embryo?
The brain and spinal cord start out in early development as a hollow neural tube deriving from the ectoderm layer.
What does the neural tube look like at 3 weeks?
The anterior portion expands and constricts the develops the prosencephalon (forebrain), mesencephalon (midbrain) and rhombencephalon (hindbrain). The posterior portion becomes the spinal cord.
What does the neural tube look like at 7 weeks?
the secondary brain vesicles develop and the forebrain becomes the telencephalon (endbrain) and the diencephalon (interbrain). the hindbrain becomes the metencephalon (after brain) and the myelencephalon (spinal brain).
What does the neural tube look like at 11 weeks?
Each portion now becomes recognisable as regions of the adult brain which continue to develop throughout pregnancy and from sulci (grooves and gyri (ridges), tripling brain surface area.
What are the different regions of the developed brain?
Cerebrum- split into two hemispheres 83% of total brain mass
Cerebellum
Diencephalon- thalamus and hypothalamus
Brainstem- Midbrain, pons, medulla oblongata
What are the lobes of the cerebral cortex called?
Frontal lobe
Parietal lobe
Temporal lobe
Occipital lobe
They are named after the cranial bones they are adjacent to
What are the important landmarks of the brain and what do they show?
The median longitudinal fissure- separates the L and R hemispheres
The transverse cerebral fissure- separates the cerebral hemispheres from the cerebellum
The central sulcus- runs across both hemispheres and separates the frontal and parietal lobes
The lateral sulcus- runs across both hemispheres and separates the frontal and parietal lobes from the temporal lobe
What are some structural features when looking at a cross-section of the brain?
When looking across both hemispheres:
The cerebral cortex- made up of neuron cell bodies and unmyelinated axons meaning it is grey matter. There are also gyri and sulci. 40% of mass and made up of billions of neurons
The white matter- made up of neurons that have myelinated axons (myelinated with oligodendrocytes). It is a subcortical structure.
Basal ganglia and nuclei are regions of grey matter in white matter
What does the cerebral cortex do and what is it made up of?
It is the conscious decision making mind that allows us to make decisions process sensory information, initiate voluntary movement, communicate, remember and houses our awareness and personality.
It is made up of grey matter (unmyelinated axons, cell bodies and interneurons), glia and blood vesseles.
What is the structure of the diencephalon and what is its function?
It is the core of the forebrain and is surrounded by the cranial hemispheres.
Thalamus- has both L&R sides acts as a relay for sensory information going up to the cerebrum and motor information coming down. Almost all sensory information is passed through here. it is inferior to the corpus callosum which aids function. it is mostly made of grey matter. 80% of the diencephalon
Hypothalamus- maintains homeostasis via the ANS (more long term reflexes). it regulates temp, hunger, thirst, sleep cycles, gastrointestinal activity and the endocrine system via the pituitary gland (master endocrine gland) (controls anterior and stores hormones in posterior).
What is the structure and function of the brainstem?
Midbrain- in pain and fear suppression and controls the flight or fight response
Pons- regualtion of resperation
MO- RR, heart rate, BP, reflexes like vomiting, coughing sneezing and swallowing.
What is the structure and function of the cerebellum?
Mean ‘little brain’ Underneath cerebrum and adjacent to the brains stem. it consists of two hemispheres.
It coordinates smooth movement, balance and posture. It is also responsible for well-timed motor skills.
What are fluid-filled cavities in the brain called and what are their functions?
They are called ventricles and an area inside them called the carotid plexus makes CSF which provides cushioning and shock absorption as well as a metabolic function, nutrients and waste.
Lateral vent- project into hemispheres
Third vent- between R&L thalamus
Fourth vent- between pons and MO
What is the corpus callosum?
A bundle of tracts- that connect the L&R hemispheres of the cerebrum in order to pass information along. It makes up the largest collection of white matter in the brain. CC consists of commissures- tracts the run between L&R sides of hemis.
What is the structure and function of the meningies?
They are CT membranes that sit between the brain and skull and from additional protection.
Dura- outermost tough layer that forms several structures that separate the cranial cavities into compartments that protect the brain against displacement.
Arachnoid layer- blood vessels that are weblike in appearance that passes into the brain through the subarachnoid space.
Pia- a fine/delicate layer that is attache closely to the brain and connects with the lining of the ventricles- ependyma to form the choroid plexus- produce CSF
