Brain

Brain - 4 main parts: 

  • Brain stem 

  • cerebellum 

  • diencephalon 

  • cerebrum 

Brain Stem 

  • medulla oblongata 

  • Location? Superior to spinal chord  

  • Contains medullary rhythmicity area to control breathing  and CV center to control heart rate  

  • Reflex centers: hiccups, vomiting, coughing, sneezing, swallowing 

 

 

  • Pons 

  • Location? Superior to the med. Ob.  

  • Contains two areas associated with breathing pneumotaxic and apneustic areas 

  • Other functions? Head movements due to visual and auditory stimuli 

 

 

  • Midbrain 

  • Located between pons and diencephalon  

  • Function? Relay station between brain and spinal cord; Especially for visual, auditory, and tactile responses 

  • Identify significance of the following: 

  • Cerebral peduncle  

  • “foot of the brain” 

  • Conducts info between pons and cerebrum 

  • Corpora quadrigemina 

  • Superior Colliculi (x2) – reflex center for eyes, head and neck due to visual stimuli 

  • Inferior Colliculi (x2)- reflex center for head, neck, trunk movements due to auditory stimuli 

  • Substantia nigra 

  • High content of melanin which is a precursor for dopamine (a type of neurotransmitter ) 

  • Connection to Parkinson’s Disease? 

 

 

Cerebellum 

  • Location? posterior and inferior portion  

  • What are sulci and gyri? sulcus- grove gyrus- folds  

  • Function? 

  • Coordinates muscle activity 

  • Balance and posture  

Diencephalon 

  • Consists of 

  • Thalamus 

  • Makes up most of diencephalon 

  • Function? 

  • Relay station for sensory info 

  • Passes info onto cerebral cortex  

 

 

  • Hypothalamus 

  • Location? Below the thalamus  

  • Attaches to the pituitary gland by a stalk called the infundibulum  

 

 

  • Functions: 

  • Controls endocrine system function via initiating release or inhibiting release of hormones from the anterior pituitary gland. It also produces the hormones oxytocin and ADH(anti diarrhetic hormone) which are then release by the posterior pituitary 

  • Controls autonomic (ANS) nervous system 

  • Regulates emotion and behavior in conjunction with the limbic system 

  • Regulate body temperature  

  • Regulate food intake (hunger) 

  • Regulate water balance via thirst  

  • Sleep/wake patterns 

 

 

  • Epithalamus 

  • Dorsal portion of the diencephalon 

  • Pineal gland lies at posterior border and secretes the hormone  

Melatonin which controls sleep/wake cycle 

  • Increase levels at night associated with sleep  

  • Decrease levels at daytime associated with awake  

Cerebrum 

  • Has gyri and sulci; also fissures and lobes 

  • What fissure divides into left and right hemispheres? Longitudinal  

  • What sulcus separates frontal and parietal lobes? Central  

  • Cerebral cortex (Gray Matter) conscious mind 

  • 4 lobes: Frontal, Parietal, Occipital, Temporal 

Frontal Lobe 

  • Broca’s area – speech  

  • Frontal eye field – voluntary eye movements  

  • Somatic motor control – voluntary muscle control (fine motor control) manipulating small movements  

  • Premotor cortex – propitious and pattern movements  

  • Other functions? Memory  

 

 

Temporal 

  • Primary auditory cortex –hearing  

  • Wernicke’s area –interprets speech – hearing the words and know what the are understanding  

Parietal 

  • Primary sensory cortex- identifying a particular body region  

  • Sensory association areas- integrate sensory input and compares to past expierences  

 

 

 

Occipital 

  • Primary visual cortex- image formation  

  • Other functions? - visual association area attaches meaning  - comparing things and putting meaning to it  

 

 

Cranial Nerves 

  • 12 total (10 emerge from brainstem and 2  from cerebrum) 

  • See associated table in handout for additional information 

 

 

Cerebral white Matter (not within cortex) 

  • Contains tracts: 

  • Association fibers – connect different parts of the same  hemisphere 

  • Commissural fibers – transmit between hemispheres; largest is the corpus callosum 

  • Projection fibers – makes ascending (from the spinal cord) and descending tracts (to the spinal cord)- cross over  
     
     
     

  • Basal ganglion (aka basal nuclei) 

  • Lies deep within white matter 

  • Clusters of cell bodies 

  • Receive input from and provides output to the cerebral cortex and diencephalon 

  • Other motor functions? 

  • Automatic skeletal muscle movements  

 

 

Differences between the two hemispheres (distinguish between specialties): 

  • Left Hemisphere: 

  • Controls the right side 

  • Receives sensory info from right side 

  • Speech and written language 

  • Numbers and scientific skill 

  • Reasoning 
     
     
     

  • Right Hemisphere: 

  • Controls the left side 

  • Receives sensory info from left  side 

  • Music and art 

  • Space and pattern  perception 

  • Emotion  of speech and facial expressions 

  • Comparing mental images of sight, sound , touch, taste, smell  
     
     
     

Electroencephalogram (EEG ) 

  • Records electrical  activity of brain neurons 

  • Patterns are called brain waves 

  • Height of peak is called amplitude 

  • Frequency is the number of peaks in 1second  and measured by the unit hertz  (#2) 

  • Four classes of EEG brain waves: 

  • alpha waves – low amplitude; regular and rhythmic; awake and calm 

  • beta waves – high frequency; rhythmic but irregular; awake and alert 

  • Theta waves – low frequency; very irregular; common in children 

  • Delta waves – high amplitude; low frequency; deep sleep