KAAP309 Lecture Notes - Lecture 12: Occipital Lobe, Medial Longitudinal Fissure, Central Sulcus
18 May 2018
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Chapter 12: Central Nervous System
I. Central Nervous system
II. CNS = brain + spinal cord
A. Surface anatomy includes cerebral hemispheres, cerebellum, and brain stem
III. Basic Pattern of the CNS
A. Spinal cord
1. Central cavity surrounded by a gray matter core
2. External to which is white matter composed of myelinated fiber tracts
B. Brain
1. Similar to spinal cord but with the additional areas of gray matter
2. Cerebellum has gray matter in nuclei and cortex
3. Cerebrum has nuclei and additional gray matter in the cortex
IV. Ventricles of the Brain
A. Arise from expasnion of the lumen of the neural tube
B. The ventricles are:
1. The paired C-shaped lateral ventrciles
2. 3rd ventricle found in the diencephalon
3. 4th ventricle, dorsal to the pons
V. Cerebral Hemispheres
A. Form the superior part of the brain and make up 83% of its mass
B. Gyri: ridges
C. Sulci: shallow grooves
D. Fissures: deep grooves
E. Are separated by the longitudinal fissure
F. Have three basic regions
1. Cortex
2. White matter
3. Basal nuclei
VI. Major Lobes, Gyri and Sulci of the Cerebral Hemisphere
A. Deep sulci divide the hemispheres into 5 lobes
1. Frontal
2. Parietal
3. Temporal
4. Occipital
5. Insula
B. Central suclus: separates the frontal and parietal lobes
C. Parieto-occipital sulcus: separates the parietal and occipital lobes
D. Lateral sulcus: separates the parietal and temporal lobes
E. The precentral and postcentral gyri border the central sulcus
VII. Cerebral Cortex
A. cortex: superficial gray matter; accounts for 40% of the mass of the brain
B. Enables sensation, communication, memory, understanding and voluntary
movements
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C. Each hemisphere acts contralaterally (controls the opposite side of the body)
D. Hemispheres are not equal in function
E. No functional area acts alone -- conscious behavior involves the entire cortex
VIII. Functional Areas of the Cerebral Cortex
A. The three types of functional areas are:
1. Motor areas: control voluntary movement
2. Sensory areas: conscious awareness of sensation
3. Association areas: integrate diverse information
B. Motor Areas
1. Primary (somatic) motor cortex
a) Location: precentral gyrus
b) Pryamidal cells whose axons make up the corticospinal tracts
c) Allow conscious control of precise,skilled, voluntary movements
d) Somatotopic map (homunculus)
2. Premotor cortex
a) Located anterior to the precentral gyrus
b) Controls learned, repetitious, or patterned motor skills
c) Coordinates simultaneous or sequential actions
d) Involved in the planning of movements
3. Broca’s area
a) Located anterior to the inferior region of the premotor area
b) Present in one hemisphere (usually to the left)
c) A motor speech area that directs muscles of the tongue
d) Is active as one prepares to speak
4. Frontal eye field
a) Located anterior to the premotor cortex and superior to Broca’s
area
b) Controls voluntary eye movement
C. Sensory areas
1. Primary somatosensory cortex
a) Location: postcentral gyrus
b) Receives information from skin and skeletal muscles
c) Exhibits spatial discrimination
d) Somatotopic map (homunculus)
2. Somatosensory association cortex
a) Located posterior to the primary somatosensory cortex
b) Integrates sensory information
c) Forms a comprehensive understanding of the stimulus
d) Determines size, texture, and relationship of parts
3. Visual and auditory areas
a) Primary visual (striate) cortex
(1) Seen on the extreme posterior tip of the occipital lobe
(2) Most of it is buried in the calcarine sulcus
(3) Receives visual information from the retinas.
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b) Visual association area
(1) Surrounds the primary visual cortex
(2) Interprets visual stimuli
c) Primary auditory cortex
(1) Located at the superior margin of the temporal lobe
(2) Receives information related to pitch, rhythm, and
loudness
d) Auditory association area
(1) Located posterior to the primary auditory cortex
(2) Stores memories of sounds and permits perception of
sounds
(3) Wernicke’s area
4. Olfactory, gustatory, and vestibular cortices
D. Association areas
1. Prefrontal cortex
a) Located in the anterior portion of the frontal lobe
b) Involved with intellect, cognition, recall, and personality
c) Necessary for judgment, reasoning, persistence, and conscience
d) Closely linked to the limbic system (emotional part of the brain)
2. Language areas
3. General (common) interpretation area
4. Visceral association area
Clickers
● Somatic motor cortex is located in this lobe
○ frontal
● Rare in cerebral cortex
○ Myelinated axons
Ch. 12B
I. Lateralization of Cortical Function
A. Lateralization
1. Division of labor between hemispheres
B. Cerebral dominance
1. designates the hemisphere dominant for language (left hemisphere in
90% of people)
C. Left hemisphere
1. Controls language, math, and logic
D. Right hemisphere
1. Insight, visual-spatial skills, intuition, and artistic skills
E. Left and right hemispheres communicate via fiber tracts in the cerebral white
matter
II. Cerebral white matter
A. Myelinated fibers and their tracts
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