BRAIN Flashcards
Brain Protection:
Cranial Meninges
(a) Dura mater: Outer most layer
(b) Arachnoid mater: Middle layer
(c) Pia mater: Inner layer
Only____of the body’s weight, but requires ____ of the body’s oxygen supply.
2%
20%
Circulatory anastomosis that supplies blood to brain and surrounding structures; stems from the two internal carotid arteries.
“Circle of Willis”
Blood brain barrier allows passage of
lipid soluble materials such as O2, CO2, alcohol, anesthesia
Cerebrospinal Fluid
a. Circulates through the subarachnoid space around the brain and spinal cord, central canal,
and through cavities in the brain called ventricles.
Brain Stem contains the
medulla oblongata, pons, and midbrain
Diencephalon contains the
thalamus, hypothalamus, and pineal gland
Cerebellum
“little brain;”
Functions for balance and equilibrium and coordination
Cerebrum
Largest, most superior part
Three major regions : Brain Stem
Medulla Oblongata
Pons
Midbrain
Medulla Oblongata Characteristics
Regulates the rate and force of the heart and the diameter of the vessels
Medullary rhythmicity area regulates breathing
Nuclei associated with touch, pressure, vibration and proprioception lie in the posterior part of the medulla.
Associated with cranial nerves VIII-XII
Pons Characteristics
“Bridge” medulla to the midbrain and above
Ascending (sensory) and descending (motor) tracts
Contains nuclei
a) Motor relay from cerebrum to cerebellum
b) Helps control breathing
c) associated with cranial nerves V-VIII
Midbrain Characteristics
Connects the pons to the diencephalon
Associated with cranial nerves CN III and IV
Midbrain Characteristics:
Cerebral peduncles
Large tracts that contain axons of motor neurons from cerebrum to rest of brainstem and spinal cord
Midbrain Characteristics:
Red nuclei
Coordinate muscular movement
Midbrain Characteristics:
Superior colliculi
involved in scanning eye movement and responses to visual
stimuli
Midbrain Characteristics:
Inferior colliculi
response to auditory input and startle reflex
Diencephalon:
Thalamus
1) Major sensory relay center
2) Contributes to motor functions
3) Plays role in consciousness
Diencephalon:
Hypothalamus
1) Lies inferior to thalamus and superior to the pituitary gland; important for homeostasis
2) Control of pituitary and hormone production
3) Control and integration of the ANS
4) Regulation of emotional and behavior patterns
5) Regulation of eating and drinking
6) Control of body temperature
7) Regulation of circadian rhythms, sleep and awakening patterns
Diencephalon:
Pineal Gland (part of the endocrine system)
Secretes melatonin which promotes sleepiness and contributes to setting the body’s
biological clock
Cerebellum
Tree-like appearance (seen in sagittal section) of white matter and gray nuclei
Cerebellum Functions
(a) Receives wide range of sensory input from muscles, joints, tendons, eyes, equilibrium
receptors in inner ears and visual receptors
(b) Compares actual movements with intended ones
(c) Helps to smooth and coordinate skeletal muscle contractions
(d) Helps execute skilled motor activities
(e) Regulates posture and balance essential for skilled motor activities
Cerebrum Structure:
Longitudinal Fissure
Divides the cerebrum into right and left cerebral hemispheres
Cerebrum Structure:
Corpus Callosum
Broad band of white matter containing axons that connects the right and left
spheres internally
Cerebrum layers: Cortex
superficial grey matter
Cerebrum layers: White Matter
myelinated and unmyelinated axons to communicate between
hemispheres (Corpus Callosum), within the same hemisphere, and to the brain
stem (and body)
Cerebrum layers: Basal Ganglia
Assist in motor control, emotions, behavior, executive function (cognitive
processes)
The folds of cerebrum are called
gyri (gyrus)
The shallow grooves are called
sulci (sulcus)
Precentral gyrus anterior to the central sulcus:
Primary motor area
Postcentral gyrus posterior to the central sulcus:
Primary somatosensory area
Central sulcus is what
separates frontal and parietal of the hemisphere
Functional Areas of the Cerebral Cortex: Sensory Areas
Primary somatosensory area:
Postcentral gyrus
Functional Areas of the Cerebral Cortex: Sensory Areas
Primary visual area:
Occipital lobe
Functional Areas of the Cerebral Cortex: Sensory Areas
Primary auditory area:
Temporal lobe
Functional Areas of the Cerebral Cortex: Sensory Areas
Primary gustatory (taste) area:
Base of postcentral gyrus
Functional Areas of the Cerebral Cortex: Sensory Areas
Primary olfactory (smell) area:
Medial aspect of temporal lobe
Motor areas initiate movements
(a) Located anterior to the central sulcus
(b) Primary motor area: Precentral gyrus of the frontal lobe in each hemisphere
1) Each region controls voluntary contractions of specific muscles on the opposite
side of the body
Somatosensory association area
Integrates and interprets somatic sensations: storage of memories of past
sensory experiences
Posterior
Premotor area
Generates nerve impulses causing a specific group of muscles to contract
in a specific sequence
Wernike’s area
Interprets meaning of speech by recognizing spoken words and
translation of words to thoughts.
Broca’s Speech area
(1 Interact with the premotor area and primary motor area to regulate
breathing and speech muscles.
(2 Located in the left hemisphere in 97% if persons.
Limbic System Characteristics
Called “emotional brain”: plays primary role in pain, pleasure, anger, affection and in
behavior
Controls the nervous system’s involuntary behavior related to survival
Lateralization
Brain controls opposite side of the body: All sensory and motor pathways cross in CNS
Left hemisphere
important for spoken and written language, numerical and
scientific skills, and reasoning
Right side Hemisphere
more involved with spatial and pattern recognition, emotional content
of language, generating images of sight, sound, taste, and smell
CN I:
Olfactory: Special sensory-smell
CN II:
Optic: Special sensory-vision
CN III:
Oculomotor: Motor-control of eye movements
CN IV:
Trochlear: Motor-control of eye movements
CN V:
Trigeminal: Mixed
(1) General sensory: Touch, pain, pressure, hot, cold on face
(2) Motor: To muscles used for chewing
CN VI:
Abducens: Motor-control of eye movements
CN VII:
Facial: Mixed
(1) Special sensory (taste) from anterior 2/3 of tongue
(2) Motor to muscles of facial expression, tear glands, and some salivary glands
CN VIII:
Vestibulocochlear: Special sensory – ear
(1) Vestibular branch: Sensory for equilibrium
(2) Cochlear branch: Sensory for hearing
CN IX:
Glossopharyngeal: Mixed
(1) Sensory for posterior 1/3 of tongue, pharynx, and palate
(2) Sensory for blood pressure: Located in the carotid bodies
(3) Motor to pharyngeal muscles (swallowing), salivary gland (parotid)
CN X:
Vagus: Mixed (the major parasympathetic nerve)
(1) Sensory from pharynx, ear, diaphragm, visceral organs in thoracic and abdominal cavities
(2) Motor to palatal and pharyngeal muscles (swallowing and voice); to viscera in the
thoracic and abdominal cavities
CN XI:
Accessory: Motor to voluntary muscles including sternocleidomastoid and trapezius
(move head, shoulders)
CN XII:
Hypoglossal: Motor to tongue (swallowing and speech)
