Brain Structures, planes and mechanisms

CNS and what it consists of

Central Nervous System: primary processing center of the body that controls all conscious and unconscious actions, thoughts, and bodily functions.

• Cerebral Hemisphere

• Brainstem

• Cerebellum

• Spinal Cord

PNS and what it consists of

Nerves:

• Cranial

• Spinal

• Ganglia (nerve clusters)

What is encased in bone, CNS or PNS

CNS

Anatomical Planes: Anterior

Front

Anatomical Planes: Posterior

Back

Anatomical Planes: Superior

Above (up)

Anatomical Planes: Inferior

Below (down)

Anatomical Planes: Medial

Toward midline (middle)

Anatomical Planes: Lateral

Away from midline (away from middle)

Anatomical Planes: Dorsal

The back of the body and top of the head

Anatomical Planes: Ventral

Bottom surface (Belly) of the brain

Anatomical Planes: Rostral

Upper front of brain (where beak/nose would be)

Anatomical Planes: Caudal

Tail-end of brain (brainstem/spinal cord)

Sagittal (or median) plane

Divides left/right hemispheres

Transverse or horizontal plane

Divides top/bottom of the brain

Coronal or frontal plane

Divides front and back of brain

Ipsilateral

(same side of body)

Contralateral

opposite side - contradictory of body

Frontal Lobe

speech and decision-making (planning, emotion, cognitive function)

Parietal Lobe

Speech and sensory integration →

Temporal Lobe

Hearing

Occipital Lobe

Vision

Insula

Considered the 5th lobe! (also called insular cortex)

• Located beneath the Sylvian fissure

• Processes visceral emotions

• Involved in consciousness (including some speech)

• Some homeostasis

• Some motor control (some swallowing)

• Body awareness & ownership (sense of self) - somatoparaphrenia

Gyri and Sulci

Hills (gyri) and valleys (sulci)

More wrinkles → more surface area → more grey matter

Sylvian Fissure (Lateral sulcus)

separates temporal from frontal and anterior parietal lobes

Central Sulcus

separates frontal + parietal lobe (one continuous sulcus)

Longitudinal Fissure

deep groove separating the brain’s left and right cerebral hemispheres.

Transverse Fissure

Separates the cerebrum from the cerebellum

White Matter

myelinted neuronal axons (a neuron’s wire that carries electrical signal away from the cell body)

Grey matter

cell bodies (main part of neuron containing the nucleus)

Tract

Many axons traveling together in the CNS

One major tract is the ____ (+ describe it)

corpus callosum - a huge bundle of myelinated axons (white matter) connecting the left and right cerebral hemispheres. (info from one hemisphere goes to other)

Corpus - body

Callosum - tough, like callous

Functional Mapping

Grey matter cells organized in relation to function of region (different locations are arranged according to what the process or control

Example of Somatotopic functional mapping

body parts organized spatially in the brain:

Precentral Gyrus or “Motor Strip” within Frontal Lobe

• Motor strip

Example of Tonotopic functional mapping

Auditory cortex (organ of corti)

Retinotopic

Visual cortex

Nerves

long neuronal axons that travel together

• Like a tract, BUT it’s in the PNS

• i.e., cranial and spinal nerves

Ganglion

a cluster of nerve cells (which would be in PNS)

Afferent Nerves

Info coming from outside to the brain

Efferent Nerves

Information coming from the brain to the effectors

Dorsal root ganglia

afferent sensory nerves

Spiral ganglion in auditory nerve

• first neurons to fire an action potential 

Lateralization/Specialization

• Specialization = different brain areas have specialized functions.

• Lateralization = a function is primarily associated with one cerebral hemisphere.

• Speech/language → usually left hemisphere.

• Motor control is contralateral → left brain controls right side of body and vice versa.

Frontal Lobe Subdivisions (5)

• Broca’s area: speech/language PRODUCTION (coordination of tongue and other parts of the vocal apparatus)

• Prefrontal Cortex: executive functioning

• Premotor cortex: could be direct control/motor planning

• Primary motor: main area to generate motor impulses

• Supplementary motor area: sequencing and planning, connected to basal ganglia

Primary Motor Cortex

• @ precentral gyrus

• Filled with motor neurons that extend to brain stem & spinal cord for muscle contractions

• Timing, strength, speed on contractions

• Somatotopic organization

• Ventral portion important for speech control

Parietal Lobe

• Somatosensory cortex = touch, temperature, vibration, proprioception;

• posterior parietal = sensory association/integration

• Angular gyrus – high-level language (metaphor), math, memory, spatial cognition, written language

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• Supramarginal gyrus – Relating speech to words, actions, somatosensation, motor planning (possibly integrating feedback)

Temporal Lobe

Primary auditory cortex/Heschl's gyrus = basic auditory processing; superior temporal gyrus = higher-level auditory/speech perception; Wernicke's area = language comprehension Planum temporale – Lateralized, speech perception (L), music perception (R), central Wernicke’s, less asymmetric in dyslexics Middle temporal gyrus – Name of objects & actions

Broca’s area

speech and gesture production (In/between/below prefrontal and premotor (though often considered premotor)

• Inferior , posterior portion of frontal lobe

• Lateral surface of left hemisphere (usually)

• Speech expression

• Speech comprehension (esp. complex sentences)

• Production and processing of speech-like gestures

Damage of Broca’s area leads to:

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• Stuttering – subactive Broca’s

• Broca’s/expressive aphasia

Arcurate Fasciculus

(Curved bundle) TRACT (bundle of axons) b/w Broca’s and Wernicke’s, damage leaves typical B. and W. function, but impairs mimicry

Wernicke’s Aphasia and Where it is

Posterior superior portion if temporal lobe (back towards top)

• Lateral surface (usually left) of cerebellum

• Speech recognition

Damage of Wernicke’s

words sound fluent and has syntax, but makes no sense: Fluent/Wernicke’s aphasia

• Hard time understanding speech/language