surface anatomy of the brain

Surface anatomy of the brain

Dr Hytham Nafady

CT anatomy of the lobes of cerebral hemisphere

ANATOMYANATOMY Inferior sections

T

ANATOMYANATOMY

Ventricular sections

3rd BGFH

OH

Body

O

P

F

Superior sections

P

F

ANATOMYANATOMY

Lobar borders

Surface anatomy of

the lateral surface

Lateral surface of cerebral hemisphere

Sylvian fissure

Sylvian fissure

Frontal lobe

Frontal lobe

Superior frontal sulcus bifurcates to form superior precentral gyrus

Inferior frontal sulcus bifurcates to form inferior precentral gyrus

Superior frontal gyrus

• Rectangular (Bar shaped)

• Forms the upper most margin of the frontal lobe.

Inferior frontal gyrus

• Triangular gyrus (M shaped).

Divided by the anterior horizontal ramus and anterior ascending ramus into 3 portions.

1. Pars orbitalis.

2. Pars triangularis.

3. Pars opercularis.

Inferior frontal gyrus

Inferior frontal gyrus

Temporal lobe

Temporal lobe

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Temporal Sulci

32

Temporal Sulci

Superior temporal sulcus

Termination:

Angular sulcus (as it is straddled by the angular gyrus).

Inferior temporal sulcus

Termination:

become continuous with the inferior occipital sulcus.

Parietal lobe

Post-central gyrus:• Merges with the pre-central gyrus below the central

sulcus along the sub-central gyrus just above the sylvian fissure.

• Merges with the pre-central gyrus above the central sulcus along the para-central lobule on the medial surface of the hemisphere.

• The pre-central & post-central gyri form a continuous band of tissue around the central sulcus

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Central, Postcentral and Precentral Sulci

ascending bandof the cingulate

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Central, Postcentral and Precentral Sulci

ascending bandof the cingulate

Occipital lobe

Occipital sulci

Insular lobe

Insular lobe

Sulci:

Central sulcus.

Short insular sulcus.

Precentral sulcus.

Gyri:

Anterior insular lobule.

Posterior insular lobule.

Insular lobe

Surface anatomy of

the medial surface

Sulci of the medial surface

1. Callosal sulcus.2. Cingulate sulcus.3. Rostral sulci.4. Paracentral sulcus.5. Subparietal sulcus.6. Parieto-occipital sulcus.7. Calcarine sulcus.8. Anterior calcarine sulcus.

Gyri of the medial surface

Gyri of the medial surface

Cingulate SulcusDivides cingulate gyrus from precuneus and paracentral lobule

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Parieto-occipital Fissure and Calcarine Sulcus

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Parieto-occipital Fissure and Calcarine Sulcus

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Medial Frontal gyrus

-medial surface of superior frontal gyrus

Surface anatomy of

the inferior surface

Surface anatomy of the inferior surface

Temporo-occipital lobe

3 sulci:1. Lateral occipito-temporal sulcus.2. Medial occipito-temporal sulcus (collateral sulcus).3. Anterior calcarine sulcus.4 gyri:1. .2. Lateral occipito-temporal gyrus (fusiform gyrus).3. .4. (limbic lobe).

Localization of the central sulcus and related gyri

Axial plane Sagittal plane

Hand knob Hook sign

Gyral & cortical thickness.

Inferior frontal gyrus

Bracket sign Pars margianlis

L sign

Ω

M

L sign

• Superior frontal sulcus and precentral sulcus form an L.

Localization of the transverse temporal gyrus (Heschl’s gyrus)

Sagittal plane Supratemporal surface just lateral to the insula.

Omega shaped.

Coronal plane At the level of tent like convergence of the 2 fornices.

Axial plane At the level of massa intermedia.

Characteristic anterolateral course.

Broca’s area• Motor speech area.• Area 44.• Pars orpecularis & pars triangularis of the inferior frontal

gyrus in the dominant hemisphere.• Lesions of Broca’s area produce motor aphasia.• Auditory hallucinations are associated with increased

metabolism in Broca’s area & its analogue in the non dominant hemisphere.

Many women, but not men, have motor speech areas in the inferior frontal gyri bilaterally (Pugh et al. 1996; Shaywitz et al. 1995)

Broca’s infarction

• Acute infarct in the left inferior frontal gyrus in a patient with expressive aphasia.

Dronker’s area

• Precentral gyrus (posterior short gyrus) of the anterior lobule of the insula.

• Lesions of Dronker’s area produce speech apraxia.

Wernicke’s area

• Sensory speech area.

• Area 22.

• Posterior part of superior temporal sulcus.

Auditory association area

• Angular gyrus