Description
Ch. 15 11/1/15 4:03 PM
Major Brain Structures: Embryonic through Adult
• In human embryo Brain forms from cranial part of Neural Tube, undergoes growth in different regions and forms 3 primary brain vesicles (Forebrain, Midbrain, Hindbrain)
• Forebrain (Separates into two brain vesicles as a newborn) o Telencephalon - which forms the Cerebrum
???? Cerebrum (cerebral cortex)- 13 weeks, by 26 it
overgrows all other parts of the brain, responsible for
our ability to function at a higher level than other
animals, allows us to think creatively, most developed,
Don't forget about the age old question of What is gender schema theory?
fastest growing
✂ Right Hemisphere
✂ Left Hemisphere
✂ Longitudinal Fissure – divides right and left
hemisphere, deep sulci
✂ Each Hemisphere is Divided into Regions (Frontal
lobe, Occipital lobe, Parietal lobe, Temporal lobe,
Insula)
• Insula – small lobe deep to the lateral
sulcus, under the temporal lobe
• Frontal Lobe – responsible for motor
function, responsible for higher thinking,
planning, abstract thinking
• Parietal Lobe – main area of sensory,
general sensation (pain, touch, temp.,
pressure), responsible for sensation of
taste, participate in recognition of speech
• Occipital Lobe – visual cues, colors, shapes, We also discuss several other topics like What contains each level of maslow’s hierarchy of needs?
depth perception
• Temporal Lobe – interpretation of audio
signals, meaning of speech
✂ As the brain grows it becomes folded and forms
the Gyri and the Sulci in the cerebrum
• Gyrus - Protruding part, folds of cortical
tissue
o Pre-central Gyrus - in front of the
central sulcus, movement, motor
cortex, responsible for precision of
muscle contractions, more precise
movement = more neurons more
signals to more muscles
o Post-central Gyrus – behind central
sulcus, interpretation of senses
o Alzheimers Disease – neurons are
disappearing and gyri become narrow
and the sulci widen
• Sulcus - gap between the gyri
o Lateral Sulcus – deep groove that
separates frontal and parietal lobe
from temporal lobe
o Central Sulcus – marks the boundary
with the parietal lobe
✂ When cut the Cerebrum coronally
• Cerebral cortex Gray matter – cell bodies of If you want to learn more check out What do you call a single statistic that is calculated from the sample data and that is used to test the hypothesis?
the neurons, so numerous they want to be
on the outside because surface area larger
on the outside, all axons extend in forming Don't forget about the age old question of It lives on the outside of organisms and feeds on
bodily fluids by puncturing the skin, what is it?
subcortical white matter Don't forget about the age old question of What are the four lobes of the brain?
• Subcortical White Matter – axons of neurons
o Diencephalon - forms the Thalamus, Hypothalamus, and Epithalamus (only need to know the thalamus and Hypothalamus)
???? Thalamus – relay station for info travelling to cerebral cortex, the place that knows where the information has to process, responsible for awareness of emotional states
???? Hypothalamus – responsible for homeostasis (balance) of temperature, letting you know when you have to eat (1. Autonomic functions, 2. Produce hormones, 3. Emotional and behavioral drives, 4. Body Temperature)
✂ Contains the pituitary gland – epithelial tissue, We also discuss several other topics like What type of dyslexia that can read nonwords and regularly spelled words better than irregularly spelled words?
master endocrine gland: stimulate adrenal gland
and thyroid gland to produce hormones
Other Features of the Cerebrum
Cerebral Nuclei (also called basal nuclei and mistakenly called the Basal Ganglia – clusters, paired, irregular masses of gray matter buried deep within the central white matter in the basal region of the cerebral hemispheres.
• Cerebral Nuclei have the following components:
o Caudate Nucleus - person begins to walk, the neurons in this nucleus stimulate the appropriate muscles to produce the pattern and rhythm of arm and leg movements for walking o Amygdaloid body – expanded region at tail of Caudate
Nucleus, participates in expression of emotion, control of
behavior, and development of moods
o Putamen & Globus Pallidus – both are two masses of gray matter between external surface of insula & lateral wall of diencephalon, together they form the Lentiform Nucleus
???? Putamen – controls muscle movement at subconscious level
???? Globus Pallidus – excites and inhibits activities of the
thalamus to control & adjust muscle tone
o Corpus Striatum – the striped or striated appearance of the internal capsule as it passes by the Caudate Nucleus and
Lentiform Nucleus
• Basal Ganglia Disorders
o Parkinson’s Disease - Stiff frozen limbs and rigid muscles o Hypokinesia = slowness of movement, Comes from dopamine depletion
o Hyperkinesia - excessive movement, Arises from
degeneration of caudate nucleus
o Huntington’s Disease (Chorea) - Excessive motion & flailing limbs
• Midbrain
o Doesn’t change very much
o Posterior Region of Midbrain (aka Tectum) – most posterior and superior part
???? Contains Two pairs of sensory nuclei (Superior and
Inferior Colliculi) collectively called the Corpora
Quadrigemina or Tectal Plate or Quadrigeminal plate
✂ Corpora Quadrigemina – quick movements of the
head and neck
• Superior Colliculus – visually track moving
objects and control reflexes such as turning
the eyes and head in response to visual
stimulus
• Inferior Colliculus – control reflexive turning
of the head & eyes in direction of sound
o Anterior Region of the Midbrain (aka Tegmentum) – most anterior, takes information from cerebrum and cerebellum and issues commands to erector spinae muscles to maintain posture while standing, bending at waist, & walking
???? Red Nucleus
???? Substantia Nigra (“Black substance”) – make a lot of
dopamine (which affects brain processes that control
movement, emotional response, and ability to
experience pain and pleasure)
???? Cerebral Peduncles – most anterior
• Hindbrain – divides in two vesicles
o Pons – brainstem nuclei and respiratory centers responsible for proper rhythm of respiration, houses sensory and motor cranial nerve nuclei for the trigeminal (CN V), abducens (CN VI), and facial (CN VII) cranial nerves.
o Medulla Oblongata – brainstem nuclei, respiratory & cardiac control centers (stimulates things like heart rate speeding up and monitoring of normal functions of the heart)
o SEPARATE YET CONNECTED Cerebellum – responsible for coordination of movement, balance, equilibrium, skilled
movement, diseases produce “ataxia”
Brain and Cranial Nerves
• 2 sets of 12 Cranial nerves, they are paired 12 on left and 12 on right
o Cranial Nerve I: Olfactory – bipolar neurons in nasal cavity, carries smell
???? Olfactory Bulb forms cable like structure that travels into the brain that carries the smell to the temporal
lobe for interpretation
o Cranial Nerve II: Optic – receptors are cones and rods that are sensitive to colors and intensities/shades, info travels through optic nerve and cross the optic chiasm so part of what left eye sees the right eye see and vice versa. Allows us to form 3D image, interpreted in the Visual Cortex
(occipital lobe)
o Cranial Nerve III: Oculomotor – responsible for eye movement, movement originates in Frontocerebral lobe specifically in the prefrontal gyrus
???? Stimulates the
✂ Superior Rectus
✂ Medial Rectus
✂ Inferior Rectus
✂ Inferior Oblique
o Cranial Nerve IV: Trochlear – Superior Oblique, eye o Cranial Nerve V: Trigeminal – all general sensation from the head, sensory: skin of face, forehead, teeth, lips, gum, (touch, pain), Motor: muscles of mastication
o Cranial Nerve VI: Abducens – lateral rectus is the muscle activated by these nerves, eye
o Pneumonic = [LR6(SO4)]AO3 for what the optic nerves innervate, cranial nerve 6 moves the Lateral Rectus muscle (abduction of the eye, eyes going outwards), Superior Oblique is innervated by cranial nerve 4, All Other- the ocular motor nerve moves all others (inferior oblique, medial, inferior, & superior rectus)
o Cranial Nerve VII: Facial – Sensory: taste to anterior 2/3 of tongue, motor: muscles of facial expression, parietal lobe is where taste is recognized
???? Bell’s Palsy – inflammation of facial nerve, paralysis of CN VII (facial nerve), loss of motor to muscles of facial expression, stapedius muscles, taste anterior 2/3
tongue
o Cranial Nerve VIII: Vestibulocochlear – nerve responsible for hearing and balance, sensory: vestibular portion = sense of balance, sensory: cochlear portion = sense of hearing
o Cranial Nerve IX: Glossopharyngeal – provides pathway for taste to travel, sensory: taste to posterioe 1/3 of tongue, motor: pharyngeal muscles (swallowing)
o Cranial Nerve X: Vagus – wanders away from the cranium, provides mixed stimulation for and from the thorax and entire abdominal cavity, Sensory: to pharynx, ear canal, visceral organs in thorax & abdominopelvic cavity, Motor: pharyngeal muscles and visceral organs in thorax & abdominopelvic cavity
o Cranial Nerve XI: Accessory Nerve – motor innervation, provides stimulation to sternocleidomastoid and trapezius o Cranial Nerve XII: Hypoglossal – Motor: to tongue muscle, originates in pre-central gyrus
• Cranial Meninges – connective tissue covering the brain o Dura Mater – superficial outermost, tough protective layer “tough mother”
???? Dural Folds
✂ Falx Cerebri- Double layer of the dura mater
inside of the longitudinal fissure
✂ Falx Cerebelli – double layer of dura that
separates right and left hemisphere of cerebellum
✂ Tentorium Cerebelli - Double layer of dura mater
between cerebellum and cerebrum
✂ Superior Sagittal Sinus – formed by dual layer of
dura
o Arachnoid Mater – beneath the dura mater, spiderweb looking layer
o Pia Mater – “Delicate mother”
o The space between the pia and arachnoid is filled with cerebrospinal fluid, the cells producing this are the glial cells, fluid provides suspension for the brain and a sort of
protection
• Ventricles of the Brain – fluid filled cavities within the brain, don’t contain any neurons don’t respond to sensation, lined by glial cells (ependymal cells) that are cuboidal epithelial cells
o Lateral Ventricles – fluid produced in both right and left ventricle
o Third Ventricle – narrow space, from here the fluid flows posteriorly under brain and brain stem into fourth ventricle o Fourth Ventricle – in the posterior under the cerebellum, pathway from third to fourth is called cerebral aqueduct
o Flow of Cerebrospinal Fluid (CSF)
???? Made by choroid plexus (exists in lateral ventricles)
???? Exits ventricles via arachnoid granulations
HOMEWORK TABLE 15.7
Responsible for the roman numerals of the cranial nerves, names, functions (not the parasympathetic association)
National Geographic Link for testing ourselves not for studying Exam NOT next Thursday but following Tuesday (November 10)