Page 365 - Clinical Anatomy

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350 The central nervous system

Central sulcus
Sensory area Motor area

Broca's
speech area
Visual area
Auditory area

(a)

Motor area Sensory area

Cingulate sulcus
Visual area

Fig. 247◊Localization of
function in the cerebral
cortex. (a) Lateral aspect.
(b) (b) Medial aspect.

4◊◊Broca’s speech area. Lesions of the area around the posterior part of the
inferior frontal gyrus of the dominant (usually the left) hemisphere were
shown by Broca to affect the motor element in speech.
5◊◊Frontal association cortex (clinically called the prefrontal cortex). This com-
prises a considerable part of the frontal lobe and is one of the remarkable
developments of the human brain. Its afferents are derived from the thala-
mus, limbic area and also from other cortical areas; it probably sends effer-
ents to the thalamus and hypothalamus. From a functional point of view
the lateral aspect of the frontal lobe appears to be related to ‘intellectual
activity’ (i.e. cognitive functions—analysis, judgement and planning), the
medial and orbital surfaces to affective (or emotional) behaviour and the
control of autonomic activity.

Parietal lobe
The parietal lobe is bounded anteriorly by the central sulcus and behind by
a line drawn from the parieto-occipital sulcus to the posterior end of the
lateral (Sylvian) sulcus. The important cortical areas of the parietal lobe are
as follows.
1◊◊The primary somato-sensory cortex. The postcentral gyrus receives affer-
ent fibres from the thalamus and is concerned with all forms of somatic sen-
sation. Details of localization along the sensory cortex are considered on
pages 355–6.
2◊◊The parietal association cortex, comprising the remainder of the parietal
lobe, is concerned largely with the recognition of somatic sensory stimula-