QS Study

The cerebrum is convex and is related to the cranial vault. It is about 2-5 mm thick and accounts for about 80% of the brain’s totaling mass. Functions include thinking and reasoning, memory, consciousness, attention, perceptual awareness and language.

Functional areas of cerebrum –

(A) In frontal tube:

(i) Motor area or primary motor area (Brodmann’s area 4):

Location – Precentral gyms and paracentral lobule.

Function –

  • It controls voluntary movements of the opposite side of the body.
  • It also controls micturition and defecation.

(ii) Premotor area or secondary motor area (Brodmann’s area & part of area 8, 44 & 45):

Location – Anterior part of precentral gyms and posterior parts of superior, middle and inferior frontal gyri.

Function – It coordinates skilled voluntary movements.

(iii) Supplementary motor area:

Location – In the medial frontal gyres on the medial surface of the hemisphere and anterior to a paracentral lobule.

Function – Movements of contralateral limbs.

(iv) Frontal eye field or motor eye field (parts of area 6, 8 & 9):

Location – Posterior part of middle frontal gyms just in front of area 6.

Function – Controls conjugate deviation of eyes to the opposite side.

(v) Motor speech area of Broca (Brahman’s area 44 & 45):

Location – Pars triangularis and pars opercularis.

Function – Centre for speech.

(vi) Prefrontal cortex (area 9.10, 11 & 12):

Location – Greater parts of superior, middle & inferior frontal gyri, orbital gyri, most of the medial frontal gyms, anterior half of cingulate gyros.

Function – Concerned with the makeup of individuals personality.

Functional Areas of Cerebrum 1

Fig: Functional areas of Cerebrum

(B) In parietal lobe:

(i) Primary somesthetic area (Brodmann’s area 3, 1 & 2):

Location – Postcentral gyms and posterior part of paracentral lobule.

Function – Responsible for conscious, perception of general senses (pain, temperature, and touch), tactile discrimination and proprioception.

(ii) Secondary somesthetic area:

Locution – In the superior lip of the posterior limb of lateral fissure.

Function – Unknown.

(iii) Somesthetic association area (area 5 & 7):

Location – Superior parietal lobule, between sensory & visual area.

Function – To receive & integrate different sensory modalities.

(C) In occipital lobe –

(i) Primary visual area (Brodmann’s area 17):

Location – In the walls of the posterior part of calcarine sulcus.

Function – Receives & perceives visual information.

(ii) Secondary visual area (Brodmann’s area 18 & 19):

Location – It surrounds the primary visual area on the medial & lateral surfaces of the hemisphere.

Function – It relates the visual information received by the primary visual area to past visual experiences.

(D) In temporal lobe:

(i) Primary auditory area (Brodmann’s area 41 & 42)

Location – In the inferior wall of the lateral sulcus.

Function – It receives & perceives auditory information.

(ii) Auditory association area (Brodmann’s area 22):

Location – Posterior to the primary auditory area in the lateral sulcus & in the superior temporal gyms.

Function – Interpretation of sounds.

(iii) Sensory speech of Wernick: Permits understanding of the written and spoken language and enables a person to read a sentence, understand it & say it loudly.

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