Nervous system · Head and neck

Lateral sulcus !

The lateral sulcus is the deep groove on the side of the brain above the temporal lobe; the middle cerebral artery runs in it and the insula lies hidden inside.

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What it is

The deep groove on the side of the brain above the temporal lobe.

What it does

The middle cerebral artery runs in it; the insula lies hidden inside.

Key facts

Where

Sylvian fissure: deep cleft on the lateral surface of the hemisphere

Function

Separates the temporal lobe from the frontal and parietal lobes; insula in its depth; middle cerebral artery runs in it

Relations

Above

Frontal and parietal opercula: pars opercularis and pars triangularis (Broca's area on the dominant side), the lower ends of the motor cortex and sensory cortex, and the supramarginal gyrus

Below

Superior temporal gyrus of the temporal lobe; on its hidden upper surface, Heschl gyrus and, behind it, the planum temporale

Deep

Insula, outlined by the circular sulcus; beneath it the extreme capsule, claustrum, external capsule and putamen

In front

Its stem lies along the lesser wing of the sphenoid bone (sphenoid ridge), between the frontal lobe and temporal lobe, opening medially toward the anterior perforated substance

Contents

Middle cerebral artery and its branches, the superficial middle cerebral (sylvian) vein draining toward the sphenoparietal or cavernous sinus, and CSF of the sylvian cistern

How to find it

The deepest, longest cleft of the lateral surface, running back and slightly up from the temple; its front part lies roughly deep to the pterion. Scalp line: from about 3 cm behind the frontozygomatic suture, back almost parallel to the zygomatic arch. At surgery it is split along the superficial sylvian vein to expose the middle cerebral artery and the insula (transsylvian approach).

On imaging

On CT, blood in the sylvian fissure suggests a ruptured middle cerebral artery aneurysm; a bright dot in the fissure (dot sign) marks a clotted M2 branch. Wide sylvian fissures go with brain atrophy and, with tight sulci over the vertex, are typical of normal pressure hydrocephalus.

Clinical notes

• Middle cerebral artery aneurysms, usually at the main bifurcation, sit inside the fissure; rupture can cause a temporal lobe haematoma as well as subarachnoid blood
• The transsylvian approach opens the fissure to reach aneurysms of the circle of Willis, insular tumours and the region above the sella
• Conduction aphasia: fluent speech and good comprehension with poor repetition, from damage to the arcuate fasciculus beneath the supramarginal gyrus at the back of the fissure
• Congenital bilateral perisylvian syndrome: polymicrogyria around both fissures with weak face, tongue and throat movements (pseudobulbar palsy) and often epilepsy

Anatomical variants

• Usually asymmetric: the left fissure is longer and flatter and the right posterior ramus ends higher, matching the usually larger left planum temporale

Development

One of the first sulci to form in the fetus; the opercula then grow over the insula, which stays exposed in very preterm brains and in lissencephaly, where the fissures are shallow.

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Educational information, not medical advice. For any symptom, see a health professional.

Its names

Official Latin (TA2)

sulcus lateralis TA2 5436

Official Spanish (DeCS)

Surco lateral

English (TA2)

Lateral sulcus

Also called

Sylvian fissure · fissura Sylvii

Related

• Middle cerebral artery

Sources: Terminologia Anatomica (TA2); Neuroanatomy, Sylvian Fissure; Tratado de anatomía humana (9.ª ed.), tomo II, Sistema nervioso central: cerebro, núcleos grises centrales, vías de conducción y circulación cerebral.

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Representative model, for educational purposes only.