15/16. Brain Flashcards
Basic parts of the brain
Cerebrum (2 hemispheres)
Cerebellum
Brain stem
Diencephalon
Hollow cavities called ventricles
Brain stem consists of
Midbrain, pons, medulla oblongata
Diencephalon consists of
Thalamus
Epithalamus
Hypothalamus
Development of the brain
Develops from the rostrum end of the neural tube
Constrictions form 3 primary vesicles:
Prosencephalon (forebrain)
Mesencephalon (midbrain)
Rhombencephalon (hindbrain)
Caudal end of neural tube becomes spinal cord
Prosencephalon (forebrain) consists of
Telencephalon (cerebrum)
Diencephalon (thalamus-y-things)
Mesencephalon (midbrain) consists of
Only the mesencephalon
Rhombencephalon (hindbrain) consists of
Metencephalon (pons, cerebellum)
Myelencephalon ( medulla oblongata)
What are ventricles of brain (not types)
Cavities in brain, continuous with central canal of spinal cord
Filled with cerebrospinal fluid (CSF) and lined by ependymal cells that produce CSF
Cerebrospinal fluid (CSF)
Produced from blood and nourishes and protects brain and spinal cord
Ventricles of the brain include
Lateral ventricles (1&2)
Third ventricle
Fourth ventricle
Location of lateral ventricles (1&2)
Within cerebrum
Location and connections of third ventricle
Within diencephalon
Connected to lateral ventricles via interventricular foramina
Location, connections, and openings of fourth ventricle
Within brainstem
Connected to 3rd ventricle via cerebral aqueduct (midbrain)
3 openings (apertures) to subarachnoid space
External protection of brain
Skull, meninges, and CSF
Internal protection of brain
Blood-brain barrier made by astrocytes
Characteristics of meninges
3 connective tissue layers external to brain and spinal cord
Layers create potential spaces between them
Layers of meninges
Dura mater (“tough mother”) - has 2 layers
Arachnoid mater (“webbed mother”)
Pia mater (“delicate mother”)
Only pia mater follows contours of the brain
Types of dural folds in brain
Falx cerebri, falx cerebelli, and tentorium cerebelli
What does the falx cerebri separate
Separate left and right cerebral hemispheres
What does the falx cerebelli do
Separates left and right sides of cerebellum
Function of tentorium cerebelli
Separates cerebrum and cerebellum (like a tent over cerebellum)
Types of dural venous sinuses
Superior saggital sinus, inferior saggital sinus, straight sinus, confluence of sinuses, transverse sinus, and sigmoid sinus
Locations of superior and inferior saggital sinus
In falx cerebri
Function of straight sinus
Drains inferior saggital sinus and great cerebral vein from vein
Function of confluence of sinuses
Junction of superior saggital sinus and straight sinus
Location of transverse sinus
In tentorium cerebelli
Function of sigmoid sinus
Carries blood from transverse sinus to jugular foramen
Overall circulation of CSF
CSF in ventricles
CSF returned to blood by arachnoid granulations (of villi) projecting into dural sinuses from subarachnoid space
Specific circulation of CSF
Lateral ventricles - interventricular foramina - third ventricle - cerebral aqueduct - fourth ventricle - apertures - subarachnoid space - arachnoid granulations - dural venous sinuses
General features of cerebrum
Surface is wrinkled with ridges (gyro) and valleys (sulci) to increase surface area
Deep valleys are fissures
Consists of gray matter (cell bodies and non-myelinated axons) and white matter (mostly myelinated axons)
Types of fissures in the cerebrum
Longitudinal fissure (separates right and left hemispheres)
Lateral fissure (separates temporal lobe from frontal & parietal lobes)
Transverse cerebral fissure (separates cerebrum from cerebellum)
Gray matter in cerebrum consists of
Cerebral cortex (outer layer of gray matter)
Brain nuclei (concentrations of cell bodies)
Perform complex neural functions
Location and function of white matter in cerebrum
Deep to cortex, surround nuclei
Allow for rapid processing between areas
5 lobes of cerebrum
Named for associated skull bones
Frontal, parietal, temporal, occipital, and insula (deep to lateral fissure)
Further lines and regions of the lobes of cerebrum
Central sulcus - separates frontal and parietal lobes
Parieto-occipital sulcus - separates parietal and occipital lobes
Lateral fissure - separates temporal lobe
Pre central gyrus- motor
Post central gyrus - sensory
General function of cerebral cortex
Sensory areas receive input and are aware of stimuli
Association areas process info from multiple sources
Motor areas control motor response
Pathway of cerebral cortex function
- Primary sensory cortex
- Sensory association areas
- Multimodal association areas
- Motor areas
Types of sensory areas of cerebral cortex
Primary somatosensory cortex, primary visual cortex, primary auditory cortex, primary olfactory cortex, and gustatory cortex & visceral sensory cortex
Location and function of primary somatosensory cortex
Found in post central gyrus (parietal)
Receive sensation from skin on opposite side of body (touch, pressure, pain, proprioception)
Location and function of primary visual cortex
Occipital lobe
Receives visual info from retina
Location and function of primary auditory cortex
Superior edge of temporal lobe
Conscious awareness of sound
Location and function of primary olfactory cortex
Medial side of temporal lobe
Conscious awareness of smell
Location and function of gustatory cortex & visceral sensory cortex
Located in insula
Awareness of taste, pain, pressure, hunger, etc.
Types of motor areas of cerebral cortex
Primary motor area and motor speech area (Broca’s area)
Location and function of primary motor cortex
Precentral gyrus (frontal)
Control skeletal muscle activity on opposite side of body
Axons descend pyramidal tracts (see brain stem)
Types of association areas of cerebral cortex
Posterior association area, anterior association area, and Limbic system
Location and function of posterior association area
Integrates all types of sensory information for a unified perception of sensory input
Werneke’s area- left hemispheres, involved with understanding written and spoken language
Location and function of anterior association area
Prefrontal cortex
Receives highly processes sensory info, coordinates motor responses
Thinking, remembering, reasoning, planning, memory, problem solving
Location and function of limbic system
Medial side of cerebral hemispheres
Cingulate gyrus, hippocampus, parahippocampal gyrus, amygdala
Involved in memory, emotion, fear
Sensory and motor homunculi
Body regions map onto pre central and post central gyri
Amount if cortex devoted to a region is related to sensitivity or control of that region
E.g., face and hand are very sensitive and under fine motor control
Function of white matter of the cerebrum
How areas of cerebral cortex communicate with each other and with brainstem and spinal cord
Bundled into large tracts
Fibers of white matter cerebrum
Commissural fibers, association fibers, and projection fibers
Characteristics of commissural fibers
Cross from one side of CNS to other
Allow brain to function as a whole
Includes corpus collosum- above lateral ventricles
Characteristics of association fibers
Connect different parts of same hemisphere
Characteristics of projection fibers
Descend or ascend from cerebral cortex to other parts of CNS
Characteristics of diencephalon
3 paired structures: thalamus, hypothalamus, and epithalamus
Mostly gray matter
Form walls of third ventricle
Characteristics of thalamus
Gateway to the cerebral cortex
Contains many thalamic nuclei
Receives, filters, and relays somatic sensory information to cerebral cortex
Characteristics of hypothalamus
Many brain nuclei controlling many body functions/activities:
main control of autonomic nervous system (cardiac/smooth muscle and glands)
main control of endocrine system through pituitary gland
regulates body temp
regulates hunger and thirst
connections with limbic system to control emotions
regulate sleep-wake cycle, directs pineal gland when to secrete melatonin
Characteristics of epithalamus
Small group of brain nuclei and pineal gland
Pineal gland secretes melatonin for circadian rhythm and is influence by hypothalamus
Characteristics of brainstem
Midbrain (superior), pons (middle), and medulla oblongata (inferior)
Outer white matter with brain nuclei (gray matter)
Multiple functions
Functions of the brainstem
Passageway for fiber tracts between spinal cord and cerebrum
Gives rise to 10 cranial nerves
Responsible for many critical automatic behaviors
Integrates auditory and visual reflexes
Characteristics of midbrain
Superior part of brainstem
Cerebral aqueduct runs through it
Cerebral peduncles are anterior pillars (descending motor fibers (pyramidal motor tracts))
Contains colliculi and substantia nigra
Location and function of Colliculi of midbrain
4 bumps on the posterior side
2 superior colliculi responsible for visual tracking of moving objects
2 inferior colliculi responsible for reflexive response to sound
Characteristics of substantia nigra
Assists with control of voluntary movement
Contains neurons with melanin granules
Parkinson’s disease
Degeneration of neurons of midbrain leading to tremors, loss of coordination in movements, etc.
Characteristics of pons
Middle part of brainstem, anterior to cerebellum
Pontine (relay) nuclei send copies of motor commands to cerebellum from cerebrum to coordinate voluntary movement
Contains pontine respiratory center
Characteristics of medulla oblongata
Inferior part of brainstem
Relay nuclei for sensory & proprioceptive info to cerebrum and cerebellum
Contain pyramidal motor tracts where decussation (crossing over) of pyramids occurs
Includes reticular formation
Characteristics of reticular formation
3 nuclei found in medulla oblongata that act as:
Cardia center (controls heart rate and force of contraction)
Respiratory center (controls basic breathing rhythm)
Vasomotor center (regulates blood pressure)
Characteristics of cerebellum
Attached to back of brainstem
Right and left hemispheres like cerebrum
Folia- folds
Functions of cerebellum
Refines skeletal muscle movement so movement is smooth and coordinated (rough draft from cerebrum is relayed through pons)
Stores “muscle memory”
Receives proprioceptive input from skeletal muscles for body part positioning (relayed through medulla oblongata)
Pathway of action for cerebellum
Motor commands are sent from premotor cortex to spinal cord
Pons relays a copy of the motor commands to cerebellum
Cerebellum compares desired movements with real-time position of body parts
Cerebellum makes adjustments to plan and sends those adjustments to cerebrum
