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Superior temporal gyrus

The superior temporal gyrus (STG) is a prominent convolution forming the uppermost part of the temporal lobe, extending from the temporal pole anteriorly to the angular gyrus posteriorly. It lies below the lateral (Sylvian) fissure and above the middle temporal gyrus.

Functionally, it contains critical auditory and language-processing regions, including the primary auditory cortex (Heschl’s gyrus) and Wernicke’s area in the dominant hemisphere. The STG plays an essential role in sound perception, speech comprehension, memory encoding, and social cognition. Lesions here often result in receptive aphasia, auditory hallucinations, or impaired speech perception.

Synonyms

  • STG

  • Gyrus temporalis superior

  • Superior temporal convolution

Arterial Supply

  • Primarily supplied by branches of the middle cerebral artery (MCA), especially the superior temporal branches.

  • Minor contribution from the posterior cerebral artery (PCA) in the posterior segment.

Venous Drainage

  • Drained mainly by the superficial middle cerebral vein (Sylvian vein).

  • Additional drainage via small temporal cortical veins, which empty into the transverse and cavernous sinuses.

Function

  • Auditory Processing: Primary auditory cortex (Heschl’s gyrus, part of STG) receives auditory input from the thalamus.

  • Language Perception: Wernicke’s area (posterior STG, dominant hemisphere) is essential for comprehension of spoken language.

  • Social Cognition & Integration: Involved in processing social cues and integrating auditory with visual and other sensory inputs.

MRI Appearance

T1-weighted images:

  • Cortex: Intermediate gray signal (gray matter)

  • White matter: Bright compared to cortex

  • CSF in Sylvian fissure: Dark (low signal)

  • Lesions:

    • Infarcts: Hypointense with cortical thinning

    • Tumors: Low-to-intermediate signal with expansion or mass effect

    • Hemorrhage (subacute): High signal from methemoglobin

    • Atrophy: Sulcal widening and cortical thinning

T2-weighted images:

  • Cortex: Intermediate-to-bright signal

  • White matter: Darker than cortex

  • CSF: Bright

  • Lesions:

    • Edema or gliosis: Bright hyperintensity extending through cortex and subcortical white matter

    • Encephalomalacia: Hyperintense cystic change replacing cortical tissue

    • Low-grade glioma: Mildly hyperintense infiltrative lesion with poor margins

FLAIR (Fluid-Attenuated Inversion Recovery):

  • Normal cortex: Intermediate signal

  • White matter: Slightly darker

  • CSF: Dark (suppressed)

  • Pathology:

    • Cortical infarct or gliosis: Bright hyperintensity with cortical swelling

    • Tumor infiltration: Patchy or nodular FLAIR hyperintensity

    • Cortical dysplasia: Subtle thickening and blurring of gray-white junction

    • Encephalitis: Confluent cortical-subcortical hyperintensity with mild mass effect

DWI (Diffusion-Weighted Imaging):

  • Normal cortex: Isointense to brain parenchyma

  • Acute infarct: Bright restricted diffusion with low ADC signal

  • Tumor or abscess: May show variable diffusion restriction depending on cellularity or pus content

  • Cytotoxic edema: Prominent restricted diffusion during acute ischemia

T1 Fat-Sat Post-Contrast:

  • Normal cortex: Minimal enhancement

  • Enhancing lesions:

    • High-grade glioma/metastasis: Irregular or ring enhancement with surrounding FLAIR hyperintensity

    • Meningioma: Intense homogeneous enhancement along temporal convexity

    • Infection or encephalitis: Patchy gyral or leptomeningeal enhancement

    • Subacute infarct: Mild gyral enhancement in reperfusion phase

CT Appearance

Non-Contrast CT:

  • Gray matter: Intermediate attenuation (denser than white matter)

  • White matter: Hypodense relative to cortex

  • CSF: Low attenuation

  • Pathology:

    • Acute infarct: Early loss of gray-white differentiation in temporal lobe

    • Hemorrhage: Hyperdense cortical/subcortical region in superior temporal area

    • Calcified tumor (oligodendroglioma, meningioma): Focal high-attenuation deposits

    • Atrophy: Widened Sylvian fissure and temporal sulci

Post-Contrast CT:

  • Normal cortex: Minimal enhancement

  • Enhancing lesions:

    • Meningioma: Strong homogeneous enhancement with dural attachment

    • Glioma/metastasis: Irregular or ring enhancement with surrounding hypodense edema

    • Infection/abscess: Peripheral rim enhancement with central low attenuation

    • Subacute infarct: Gyral or cortical enhancement reflecting reperfusion

MRI images

Superior temporal gyrus mri 3t axial image

MRI images

Superior temporal gyrus mri 3t sagittal image

CT image

Superior temporal gyrus CT sagittal cross sectional anatomy radiology image