Anatomy exam 3 - key brain areas

cerebrum

top of head, largest part of brain, right and light hemispheres, initiates and coordinates movement and regulates temperature.

cerebral cortex

where conscious mind if found. enables us to be aware of ourself and our sensations, to communicate, remember, understand, and initiate voluntary movements. motor (movement, speech), sensory (vision, auditory, sensation), multimodal association (memory, experience, action evaluation)

motor area: primary motor cortex

located in the precentral gyrus of the frontal lobe of each hemisphere, helps us to plan movements and coordinate information from everywhere. Direct link with perametal allows us to produce skilled voluntary movement, allows us to create a pathway that we call the corticospinal pathway

motor areas

control voluntary movement, lie in the posterior part of the frontal lobe

motor area: premotor cortex

anterior to the precentral gyrus in the frontal lobe, helps plan movements. Coordinates information from everywhere. Coordinates the movement of several muscle groups either simultaneously or sequentially, mainly by sending activating impulses to the primary motor cortex. The staging area for skilled motor activities.

motor area: broca’s area

Typically located in left hemisphere of brain, but could be in left, lies anterior to the inferior region of the premotor area. Important motor speech reason, enables speech production, planning speech, directs the muscles involved in speech production controls and coordinates muscles of tongue

sensory areas

areas concerned with conscious awareness of sensation

sensory areas: primary somatosensory cortex

in the postcentral gyrus of the parietal lobe, just posterior to the primary motor cortex. Receive sensory input from all sensor receptors of the body, allows for spatial discrimination/awareness

sensory area: somatosensory association area

• just posterior to the primary somatosensory cortex

  and has many connections with it. Integrates sensory inputs (temperature, pressure, and so forth) relayed to it via the primary somatosensory cortex to produce an understanding of an object being felt: its size, texture, and the relationship of its parts.

sensory area:primary visual cortex

• on the extreme posterior tip of the occipital lobe, but most of it is buried deep in the calcarine sulcus in the medial aspect of the occipital lobe. largest cortical sensory area. Receives visual information that originates on the retina of the eye. The visual space on the opposite side of the body is mapped to the primary visual cortex. Receives visual input from retina, most posterior aspect of occipital lobe.

sensory area: visual association area

• surrounds the primary visual cortex and covers much of the occipital lobe. Visual association area uses past visual experiences to interpret visual stimuli (color, form, and movement), enabling us to recognize a flower or a person’s face and to appreciate what we are seeing. We “see” with cortical neurons. Helps us to use past visual experience to interpret what we are seeing color form movement traffic patterns

sensory area: primary auditory cortex

• located in the superior margin of the temporal lobe next to the lateral sulcus. Sound energy exciting the hearing receptors of the inner ear causes impulses to be transmitted to the primary auditory cortex, where they are interpreted as pitch, loudness, and location. Sensory area that receives input from inner ear to be interpreted, stores memory and experience of sound.

sensory area: auditory association area

• permits the perception of the sound stimulus, which we “hear” as speech, a scream, music, thunder, and so on. Memories of sounds heard in the past appear to be stored here for reference.

sensory area: olfactory cortex

• lies on the medial aspect of the temporal lobe in a small region called the piriform lobe which is dominated by the uncus. Afferent fibers from smell receptors in the superior nasal cavity send impulses along the olfactory tracts that are ultimately relayed to the olfactory cortices. The outcome is conscious awareness of different odors. Deals with smell, closely tied with hippocampus.

sensory areas: gustatory cortex

a region involved in perceiving taste stimuli, is located in the insula just deep to the temporal lobe.

multimodal association areas

receive inputs from multiple senses and send outputs to multiple areas. Sensory receptors → primary sensory receptors → sensory association cortex → multimodal association cortex

multimodal association areas: prefrontal cortex

• in the frontal lobe, most complicated cortical region of all. learning and executive function, learning memory and focused attention, some personality

multimodal association areas: posterior association area

• a large region encompassing parts of the temporal, parietal, and occipital lobes. Facial and pattern recognition and spatial awareness

multimodal association areas: limbic association area

• emotional and memory. Includes the cingulate gyrus, parahippocampal gyrus, and hippocampus. Part of the limbic system, provides the emotional impact that makes a scene important to us. The hippocampus establishes memories that allow us to remember incidents.

Diencephalon

central core of forebrain, consists of thalamus, hypothalamus, and epithalamus. Gray matter areas.

Diencephalon: thalamus

• consists of bilateral egg-shaped nuclei, which form the superolateral walls of the third ventricle. Plays a key role in mediating sensation, motor activities, cortical arousal, learning, and memory. Sensory switchboard for information, determines where along somatosensory cortex it needs to go, directs input towards cortical areas of the brain, nuclei based on locations (ex. Dorsal nuclei), nuclei projects fibers from them, acts as a relay station for info coming into the cortex, can sort modify input information, something involved in memory arousal (attentive state of the brain) and learning

Diencephalon: hypothalamus

• caps the brain stem and forms the inferolateral walls of the third ventricle. Extends from the optic chiasma to the posterior margin of the mammillary bodies. Autonomic control center, anterior aspects are parasympathomimetic anterior areas similar to parasympathetic activities, heavily involved in regulating endocrine system, main control unit for regulating things involved in homeostasis of body (control of temp, nutrition and hydration), biological rhythms (sleep-wake cycling), controls blood pressure and heart contraction, pupil dilation, emotion learning and memory.

Diencephalon: epithalamus

• forms the roof of the third ventricle. Extending from its posterior border and visible externally is the pineal gland or body. Contains pineal gland, melatonin sleep-wake cycler.

Midbrain

located between the diencephalon and pons. On its ventral aspect two bulging cerebral peduncles form vertical pillars that seem to hold up the cerebrum. Cerebral peduncles contain pyramidal motor tracts, periaqueductal gray = nucleus that plays a role in pain reduction and fight or flight and helps to suppress information, corpora quadrigemina (superior and inferior colliculi)

Midbrain: cerebral peduncles

fiber tracts, connect the midbrain to the cerebellum dorsally

midbrain: cerebral aqueduct

• connects the third and fourth ventricles. Delineates the cerebral peduncles ventrally from the tectum, the midbrain’s roof. Surrounded by periaqueductal gray matter which included the oculomotor and trochlear nuclei

midbrain: corpora quadrigemina

• largest midbrain nuclei, raise four domelike protrusions on the dorsal midbrain surface

medulla

Most inferior part of the brain stem. It blends imperceptibly into the spinal cord at the level of the foramen magnum of the skull. Medulla and the pons form the ventral wall of the fourth ventricle. Pyramids where parameter tracts pass through and decussation of the pyramids, heavily involved in autonomic reflexes, cardiac motor center, heavily involved in vomiting hiccups sneezing and coughing.

pons

location of cranial nerves 5 6 and 7, they're pontine groups for regulation.

cerebellum

primarily for regulating and smoothing out highly complex coordinating activities, involved in learning and memory (coordinated patterns). Located dorsal to the pons and medulla, protrudes under the occipital lobes of the cerebral hemispheres, from which it is separated by the transverse cerebral fissure.

hippocampus

does not store memories, creates them

amygdala

part of the emotional brain (sensory gateway to emotions) interpret sensory stimuli emotionally

reticular formation/ reticular activating system

sends signals to maintain alertness, filters out 99% of all stimulus. Extends through the central core of the medulla oblongata, pons, and midbrain. Composed of loosely clustered neurons in what is otherwise white matter. Sends a continuous stream of impulses to the cerebral cortex, keeping the cortex alert and conscious and enhancing its excitability.

wernicke’s area

comprehension of language

multiple sclerosis

gradually destroys the myelin sheath in the CNS (autoimmune disease)

Alzheimers Disease

degeneration of the brain, results in dementia, exhibit memory loss, shortened attention span, disorientation, and eventually language loss

Parkinson’s Disease

degeneration of the dopamine-releasing neurons of the substantial nigra. As the neurons deteriorate, the dopamine-deprived basal nuclei they target become overactive. symptoms persistent tumor at rest, forward-bent walking posture and shuffling, and stiff facial expression. Slow initiating and executing movement

Concussion

alteration in brain function, usually temporary, following a blow to the head. May be dizzy or lose consciousness. typically mild and short lived, mild concussion can be damaging, and multiple concussions over time can be damaging.

• mild traumatic brain injury

• testing: reaction time

• sound sensitivity, delayed processing, vestibular difficulties, parasympathetic withdrawal, heart rate variability, emotional swings, massive very rapid pull dilation

• over time can cause emotional status to decline and cognitive processing to delay

• does NOT always result in loss of consciousness

• headaches, dizziness sensitive to light and sound, migraine, headaches, impulsivity, rapid emotional changes

• recovery between 7-14 days most within 30, some do not recover

Sulci

shallow grooves that separate gyri

gyri

elevated ridges of tissue

fissures

longitudinal fissure - separates cerebral hemispheres

transverse cerebral fissures - separates the cerebral hemispheres from the cerebellum