Brain
Anatomy & Functions
The cerebrum consists of two hemispheres that are separated by a large
groove: fissure longitudinalis. Both hemispheres are connected via the
corpus callosum, anterior and posterior commissures.
Frontal Lobe Planning future actions,
executive functions, memory, language,
motivation, problem solving, making decisions,
personality.
Parietal Lobe somatic sensation/senses
(smell, taste, touch). Process sensory and spatial
awareness, eye-hand coordination.
Temporal Lobe emotions and memory.
Smelling, tasting, perception, aggression, sexual
behavior, language center, speech.
Occipital Lobe Sight and recognition.
Insula controls homeostatic functions, regulation immune system, adds emotional context to
sensory input.
Grooves are called sulci and the twists are called gyri.
Brain consists of two shades of color:
- Gray matter neuronal cell bodies and dendrites, only few myelin. Receive and processing.
- White matter axonal fibers, myelinated. Transmits information to other locations.
Three regions of the brain:
,Forebrain (prosencephalon)
Telencephalon
Cortex sheet of neural tissue that is outermost to the cerebrum of the mammalian brain. (4 lobes)
Basal ganglia important in motor control.
- Caudate nucleus plays a role in other nonmotor functions as procedural learning,
associative learning and inhibitory control of action.
- Globus pallidus controls conscious and proprioceptive movements.
- Putamen prepares and aids in movement of the limbs.
- Thalamus relaying sensory and motor signals, as well as regulation of consciousness and
alertness.
- Amygdala prepares the body for action in the face of danger.
- Subthalamic nucleus (red nucleus ruber) communicates with motor neurons in the spinal
cord.
- Substantia nigra release dopamine, innervates the basal ganglia.
- Dorsal striatum caudate nucleus and putamen together.
Limbic system controls emotions, learning and memory.
- Hippocampus major role in learning and memory. Projects information to cortical regions
that give memories meaning and connect them with other connected memories.
- Fornix cognition and episodic memory recall.
- Mammillary body recollective memory.
- Hypothalamus controls your hormone
system, releases hormones to the
pituitary gland, which sends hormones
out to different organs.
- Amygdala emotional regulation and
smell perception and encodes emotions.
- Anterior nucleus of thalamus display
functions pertaining to memory.
- Cingulate cortex important interface
between emotional regulation, sensing
and action. Highly influential in linking
motivational outcomes to behavior.
,Other structures:
Tractus opticus relaying visual
information to the LGN.
Chiasma opticum transmit visual
information from the optic nerves to the
occipital lobes of the brain.
Nervus opticus transmits electrical
impulses from the eyes to the brain.
Bulbus olfactorius the sense of smell.
Broca’s area region in frontal lobe of dominant hemisphere, functions linked to speech production
and language processing.
Wernicke’s area region of the brain that contains
motor neurons involved in the comprehension of written
and spoken language. Located in the posterior third of
the upper temporal convolution of the dominant
hemisphere.
Tectum dorsal side of midbrain.
Tegmentum region in front of the ventricular system
Superior colliculus optic tectum/optic lobe, seeing.
Inferior colliculus auditory
Diencephalon
Thalamus relay station to the cerebral cortex. Directing almost all incoming sensory information to
the appropriate regions of the cortex, to be processed further.
Hypothalamus control of autonomic nervous system, emotional behavior, body temperature, food
intake, water balance & thirst, sleep-wake cycle, endocrine system, sexual behavior.
Midbrain (mesencephalon)
Colliculi superior receive visual information and are involved in visual processing.
Colliculi inferior receive auditory information.
Hindbrain (rhombencephalon)
Metencephalon
Cerebellum coordination of movement, balance, memory, proprioceptive information (sense of
body position and self-movement).
Pons vital, unconscious reflexes; cardiovascular, respiratory, coughing, swallowing and sneezing.
Myelencephalon (medulla oblongata)
Pineal gland a secretory gland in the brain midline, which secretes melatonin.
Cerebellum consists of two cerebellar hemispheres separated by the vermis.
Brainstem
Contains of the midbrain, pons, and medulla oblongata combined.
Ventricular system
Telencephalon 1st & 2nd lateral ventricles.
Mesencephalon cerebral aqueduct.
Rhombencephalon 4th ventricle.
, Foramina connection between two ventricles.
Filled with cerebrospinal fluid (CSF), produced by the choroid plexus, which functions as shock
absorber and provides a medium of exchange of materials, including nutrients, between blood
vessels and brain tissue. CSF flows in the ventricles (30ml) and in the subarachnoid space (120ml).
The ventricles are lined with the membrane called choroid
plexus, a highly vascular membrane that produces CSF by
filtering blood. Ependymal cells are on the inside of the
ventricles.
The connections between two ventricles are called foramen.
CNS-microenvironment everything that surrounds neurons.
Has to be protected because it has a continuous supply of
energy, a constant level of ion concentrations, and a constant level of amino acids, signal molecules.
Cerebrospinal fluid (CSF)
Function absorption of shocks, reduce weight, waste management, keep pressure equal.
Composition K+, amino acids and proteins in a lower concentration compared to plasma.
Production ultrafiltration, iso-osmotic secretion. (independent on intracranial pressure). NaCl will
result in a net diffusion of water into the CSF.
Carbo anhydrase splits CO2 into bicarbonate in order to produce acid molecule, which are necessary
to get the Na into the epithelial cells.
Absorption transcytosis, fluid containing vacuoles. (dependent on intracranial pressure)
Brain extracellular fluid (BECF)
Space between brain cells, exchange between CSF and BECF via ependymal cells and pial-glial
membrane (between BECF and subarachnoid CSF).
Route for metabolites and paracrine communication.
Composition ~ CSF
Blood brain barrier (BBB)
No BBB in the plexus choroideus and in circumventricular organs. Has specific membrane
transporters for glucose.
Consists of:
- Endothelial cells, connected through tight junctions.
- Basal membrane
- Astrocyte endfeet
Neural tube and neural crest
Neural tube spinal cord + brain
Neural crest schwann cells + meninges + ganglia of the
sympathetic and parasympathetic systems + adrenal medulla +
cells of the spinal ganglia.
Spinal cord
Pass information between CNS and PNS.
- 8 cervical