the brain

Question 1

what are the functions of the brain?

Answer 1

• controls heart rate, respiration, blood pressure, and maintains homeostasis
• innervation of the head and neck
• high-level tasks: intelligence, conciousness, memory, emotion, behavior

Question 2

what are the four main parts of the brain?

Answer 2

• cerebrum
• diencephalon
• cerebellum
• brain stem (midbrain, pons, medulla oblongata)

Question 3

what is white and gray matter?

Answer 3

• gray matter is on the outermost part of the brain (cerebellar + cerebral cortex) and also the innermost regions (cerebral nuclei)
• gray matter is unmyelinated neurons and neuron cell bodies
• white matter is made of myelinated axons, lies deep to the cortex of the brain

Question 4

what is the diencephalon?

Answer 4

• surrounded by the cerebral hemispehere
• contains the 3rd ventricle
• lateral walls: thalamus
• floor: hypothalamus
• roof: epithalamus

Question 5

what is the thalamus?

Answer 5

• forms lateral walls of the 3rd ventricle
• filters somatosensory, visual, and auditory information (all except smell)
• ANY PART OF THE BRAIN (SENSORY OR NOT) THAT COMMUNICATES WITH CEREBRAL CORTEX MUST GO THROUGH THALAMUS

Question 6

what is the hypothalamus?

Answer 6

• main visceral control center of the body, regulates many activities
• controls autonomous nervous system
• regulates body temperature
• regulates hunger and thirst
• regulates sleep-wake cycle
• controls endocrine system
• controls emotional responses
• formation of memory

Question 7

what is the epithalamus?

Answer 7

• forms roof of the 3rd ventricle
• includes pineal gland
  + endocrine function, secretes melatonin for circadian rhythm

Question 8

what is the cerebrum?

Answer 8

• divides into 2 halves: left and right hemispehere
• each hemisphere is divided into 5 distinct lobes: frontal, parietal, occipital, temporal, insula (named for overlapping bones)

Question 9

what are gyri and sulci?

Answer 9

• gyri: ridges of brain tissue. ridges allow for more cerebral cortex to fit in the cranial vault (precentral and procentral)
• sulci: grooves between the gyri (central, parieto-occipital, and lateral

Question 10

what are the cerebral functions?

Answer 10

• intelligence, complex thinking
• 3 types of functional areas:
  + sensory: conscious awareness of sensation
  + association areas: intergrates information
• motor areas: voluntary motor functions

Question 11

what is the primary somatosensory cortex?

Answer 11

• receives information from somatic senses (touch, pressure, vibration, pain, proprioception)
• enables consciousness awareness of the senses. located in post-central gyrus

Question 12

what is the primary auditory + primary visual cortexes

Answer 12

• PVC: posterior/medial occipital lobe. receives visual information from the retina
• PAC: primary auditory cortex. receives and processes auditory information from the inner ear

Question 13

what is broca’s area?

Answer 13

• motor-speech area; controls motor movements for speech
• if damaged, can’t understand speech, but not speak fluently

Question 14

what is wernicke’s area?

Answer 14

• multimodal association area
• recognition and understanding of speech
• if damaged, can speak, but not comprehend language

Question 15

what is the white matter of the cerebrum?

Answer 15

• corpus callosum: largest visible band of comissural fibers (connects 2 halves)
• association fibers: short fibers that connect regions in the same hemisphere

Question 16

what is the cerebral neural (deep gray matter)?

Answer 16

• deep, paired masses of gray matter. AKA basal nuclei (ganglia)
• involved in motor control
• include caudate nucleus, putamen, amygdala, and globus pallidus. generally, cerebral nuclei start, stop, and regulate the intensity of voluntary movement

Question 17

what is the function of the brainstem?

Answer 17

• made up of the midbrain, pons, and medulla oblongata
• connects cerebrum and spinal cord
• start of the cranial nerves for innervations of the face and head
• autonomic and reflex centers needed for survival

Question 18

what is the midbrain?

Answer 18

• located between the diencephalon and pons
• internal cavity is cerebral aqueduct (part of brain ventricles)
• tectal plate: site for reflexes
• superior colliculi for visual reflexes
• inferior colliculi response to sound

Question 19

what is the pons?

Answer 19

• located between midbrain and medulla
• separated from cerebellum by 4th ventricle

Question 20

what is the medulla oblongata?

Answer 20

• most caudal part of the brain stem, continuous with spinal cord
• pyramid carry voluntary motor output from cerebrum to spinal cord
• fibers “decussate” or cross-over, so left controls right, and right controls left

Question 21

what is the cerebellum?

Answer 21

• functions:
  + fine-tunes/tweaks body movements
  + coordinates body movement
  + maintain posture and equilibrium
• 2 hemispheres connected by vermis
• folia are leaf-like folds that increase surface area
• outer cortex is gray matter, white matter is arbor vitae
• processing:
  + receives information from cerebrum on movements planned
  + compares planned movement with current body position
  + sends instructures back to cerebral cortex to readjust/refine motor commands

Question 22

what is the limbic system?

Answer 22

• involved with emotion and motivation, creatining, storing, and retreiving memories
• includes:
  + cingulate gyrus: emotional response
  + hippocampus: stores memory
  + amygdala: processes fear
• all are linked together byt the fornix

Question 23

what are the meninges?

Answer 23

• membranes that surround and protect the brain
• cerebrospinal fluid: cushions the brain
• blood brain barrier: protects the brain from exposure to toxins

Question 24

what are the functions of the meninges?

Answer 24

• cover and protect CNS
• enclose and protect blood vessels to CNS
• contain and circulate cerebrospinal fluid

Question 25

what is the pia mater?

Answer 25

innermost layer, follows the curves of the brain, very delicate, lots of blood vessels

Question 26

what is the arachnoid mater?

Answer 26

• superficial to pia mater, looks like spiderwebs.
• subarachnoid space: web-like threads attach arachnoid mater to pia mater. filled with CSF

Question 27

what is the dura mater?

Answer 27

• “hard mother” - outermost layer
• two laters of dense fibrous connective tissue (meningeal and periosteal). in some sports, separate to form dural sinuses (drainage for brain) inside

Question 28

what are the dural venous sinuses?

Answer 28

• drain blood from the brain and into the internal jugular veins
• major sinuses:
  + superior saggital
  + straight
  + transverse
  + sigmoid

Question 29

what are the ventricles?

Answer 29

• fourth interconnected cavities or expansions within brain for circulating CSF
• laternal ventricles (2) communicate with third ventricle via interventricular foramen
• 3rd ventricle drains into 4th ventricle via cerebral aqueduct

Question 30

what is cerebrospinal fluid?

Answer 30

• brain and spinal cord “float” in CSF: prevents damaging
• resists compressive forces, cushions against trauma
• feeds brain, removes waste, carries chemical signals
• made in choroid plexuses
• flows through ventricles and into subarachnoid spaces
• absorbed into dural venous spaces
• processes and circulates 500 mL/day

Question 31

what are the arteries of the neck and head?

Answer 31

• the right and left common carotid carotid arteries both ascend into the neck and head and divides into internal and external carotid arteries
• internal and external carotid arteries feed the head, brain, and orbital regions

Question 32

describe the blood supply to the brain

Answer 32

• internal carotid divides into anterior and middle cerebral arteries
• anterior cerebral artery joins anterior communicating artery
• middle cerebral artery supplies parts of termporal and parietal lobes (~80% of cerebrum)
• right and left vertebral arteries merge to become basilar artery, which divides into posterior cerebral artieries
• these are connected by posterior communicating arteries

Question 33

what is the circle of willis?

Answer 33

• anastomosis to protect brain’s bloody supply (allows re-routing of blood)
• formed by posterior cerebral (L,R), posterior communicating (L,R), internal carotid arteries (L,R), anterior cerebral arteries (L,R), anterior communicating arteries (L,R)