Telencephalon Flashcards
Anatomically, R and L cerebral hemispheres are
Equivalent
Pallium
Outer convoluted gray cerebral cortex
Centrum semiovale
Underlying mass of white fibers
Basal ganglia
Deep within white matter; collections of neuron cell bodies
Lobes are named for
Overlying bones
Largest lobe
Frontal lobe
Smallest lobe
Occipital lobe
Functions of telencephalon
- Final integration of neural mechanisms
- Initiation center for voluntary actions
- Memory and associative memory
- Abstract thinking - basis of emotional response
Thickest part of cortex
Precentral gyrus
Thinnest part of cortex
Calcarine sulcus
Subdivisions of cortex
Neocortex
Allocortex
Neocortex
Phylogenetically new
Occupies 90% of cortex
6 Laminae of neocortex
- Molecular lamina I
- External granular lamina II
- External pyramidal lamina III
- Internal granular lamina IV
- Internal pyramidal lamina V
- Multiform lamina VI
Molecular layer
Lamina I
Outermost lamina (nearest pia mater) Filled with synaptic activity
External granular layer
Lamina II
Small, closely packed granular neurons
Axons extend into deeper lamina of same cortex (does not reach white matter)
Aka Intracortical Association Layer
External pyramidal layer
Lamina III
Small pyramidal neuron cell bodies
Axons extend out of cortex to white matter, then return to gray
Aka Intercortical Association Layer
External granular layer + external pyramidal layer
Thinking part of cortex
Associative Cortex
Internal granular layer
Lamina IV
Thalamic inputs arrive here
Well developed in sensory areas
Internal pyramidal layer
Lamina V
Large pyramidal shaped neuron cell bodies (includes Betz cells)
Axons project to other brain and cord centers from here (corticospinal and corticobulbar fibers)
Multiform layer
Lamina VI
Mix of incoming and outgoing fibers
Lamina V + lamina VI
Projection laminae
Brodmann Area #4 confined to
Precentral gyrus of frontal lobe
Brodmann Area #4
Function
Voluntary motor initiation, especially in distal extremities, facial and oral musculature
Only area to contain Betz cells
Brodmann area #4
Brodmann area #4 has well developed ___ laminae
Projection
V and VI
No other single area contributes more fibers to pyramidal system than the
Precentral gyrus
Brodmann areas 1, 2, 3
Location
Post central gyrus of parietal lobe
Brodmann areas 1, 2, 3
Function
Somesthetic cortex (body sensing) Pain, thermal, deep and light touch, vibratory, kinesthetic input received and integrated into conscious sensation
Specific thalamic efferent from __ and ___ are abundant in areas 1, 2, 3
VPL
VPM
Lamina __ is well developed in areas 1,2,3
IV
Also projection cortex; V, VI
Areas 6 and 8
Location
Just in front of area #4
Areas 6 and 8 also referred to as
Premotor regions
Areas 6 and 8 are good ___ and contribute fibers directly and indirectly to pyramidal system
Motor initiation centers
Area #6
Function
Influence on proximal portions of extremities (hips and shoulders)
Area #8
Function
Initiates voluntary movements of eyes
Fibers from #8 stimulate LMN that move 6 extraocular eye muscles
Location of LMN that move extraocular eye muscles
Nuclei of CN III, IV, VI
Areas 9, 10, 11, 12 known as
Prefrontal region
Newest of neopallial structures
Areas 9, 10, 11, 12
Areas 9, 10, 11, 12 have highly developed ___ and associative input arrives from all cortical regions
Associative cortex (lamina II, III)
Areas 9, 10, 11, 12
Function
Elaboration of thought
Abstract reasoning
Imagination
Emotions
Area #44 also referred to as
Broca’s Speech Area
Area #44 location
Frontal operculum along lateral inferior surface of frontal lobe
Broca’s Speech Area
Function
Motor speech center
Area #44 directs area #4 neurons that initiate
Tongue, laryngeal, and pharyngeal musculature in process of speaking
Frequently affected in strokes due to middle cerebral artery
Area #44
Aphasia
Loss of power to communicate through writing, speaking, or signs
Damage to Broca’s area results in
Motor aphasia
Dysphasia
Partial or unusual loss of communicative ability
Speech is dominant on __ side of brain
Left
If area 44 is damaged on non-dominant side, patient will have difficulty with…
Prosodic language
Areas 17, 18,19 occupy
Bulk of cortex in occipital lobe
Areas 17,18,19 collectively make up
Visual cortex
Area 17 located along
Calcarine sulcus
Area 17 receives fiber input from
Lateral geniculate body