Anatomy Bones and Muscles · MU Pleven

138. Telencephalon. Localisation of the functions. Cerebral asymmetry.

Covers the functional areas of each cerebral lobe: frontal motor and prefrontal regions, the Broca and Wernicke speech areas, parietal somatosensory areas, temporal auditory and olfactory areas, and occipital visual areas. It explains the somatotopic body representations (motor and sensory homunculi) and notes that speech centres lie in the dominant hemisphere. It closes with a short section on Brodmann's histological classification of cortical areas.

Inside: 4 sections · 8 labelled pictures · 10 flashcards · 6 min

Topic 137 of 236 in the MU Pleven syllabus for Anatomy Bones and Muscles (Medicine, Year 2). The free AceMed note covers it in 4 sections, about 846 words (6 min of reading), with 10 flashcards.

In this note

  1. CORTICAL AREAS
  2. Functional cortical areas
  3. 3) Temporal lobe:
  4. 4) Occipital lobe:

Functional cortical areas

1) Frontal lobe:

- Its posterior part (precentral area) is responsible for motor functions, while its anterior part (prefrontal area) is responsible for higher mental functions.

Premotor area:

- It plans the movements, inhibits muscle tone, and adjusts the posture to start the movement.

Primary motor area:

- It initiates skilled voluntary movements for contralateral ½ of body which are planned in premotor area.

Frontal eye field:

- It is responsible for voluntary conjugate eye movements (to contralateral side), and NOT reflex eye movements.

prefrontal area:

- It is responsible for intelligence and normal expression of emotions. Also has a role in ability to predict consequences of actions.

Broca's area (motor speech area):

- It receives data from sensory speech area (Wernicke's area) to create sequence of muscle contractions to be sent to motor area to produce intelligible words.

N.B:

  • Supplementary motor area: it is an area on the medial surface of cerebral hemisphere (medial frontal gyrus).
  • The body is represented bilaterally in this area (its stimulation evokes movements in limbs on both sides).
  • It stores programmed sequences for stereotyped movements and contains superior speech center.
  • Motor homunculus: it is the body representation within the cortical areas.
  • The primary motor cortex corresponds point by point with specific regions of the contralateral side of the body.
  • This means that activity of certain portion in the primary motor cortex results in contraction of specific peripheral muscles.
  • The contralateral side of the body is represented upside down (face is down, while foot area is in paracentral lobule).
  • The body representation depends on skill, not the size of the organ (parts with fine skilled movements occupy larger areas (hands)).

2) Parietal lobe:

- It contains general sensory areas (1st and 2nd somatosensory areas, sensory association area, and sensory speech center of Wernicke's).

1st somatosensory area:

- It receives sensory information about the contralateral ½ of the body from anterior thalamic nuclei. Its anterior part receives cutaneous stimuli, while its posterior part receives proprioceptive impulses.

2nd somatosensory area:

- It is located on the upper lip of lateral sulcus just behind the central sulcus. It receives transient sensory stimuli from both sides of the body (brush strokes).

Gustatory (taste) area:

- It is located in parietal operculum of insula (upper lip of lateral sulcus). It receives ipsilateral solitario-thalamo-cortical fibers.

Sensory speech (Wernicke's) area:

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