Central sulcus !

The central sulcus is the groove that separates the frontal and parietal lobes, dividing the motor strip in front from the sensory strip behind.

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What it is

The groove that separates the frontal and parietal lobes.

What it does

Divides the motor strip (in front) from the sensory strip (behind).

Key facts

Where: Runs from the top of the hemisphere down and forward towards the lateral sulcus
Function: Separates the frontal lobe (motor, precentral gyrus) from the parietal lobe (sensory, postcentral gyrus)

Relations

In front: Motor cortex (precentral gyrus), the thicker of the two banks
Behind: Sensory cortex (postcentral gyrus), the thinner bank
Above: Crosses the upper border onto the medial surface for a short way, into the paracentral lobule, just in front of the marginal ramus of the cingulate sulcus
Below: The subcentral gyrus, a bridge of cortex joining the two central gyri, which separates its lower end from the lateral sulcus
Deep: Primary motor area 4 covers its front wall and the touch and muscle-sense areas 3a and 3b its back wall, facing each other across the depth

How to find it

Runs down and forward from just behind the midpoint of the top edge; on MRI a long unbroken sulcus behind the hand knob, notching the top edge before the marginal ramus. Scalp: upper end about 2 cm behind the nasion–inion midpoint, sloping forward at about 70° (Krönlein: supraorbital horizontal at the mid-zygomatic vertical to the retromastoid vertical at the midline).

On imaging

Before surgery near the motor strip, functional MRI (finger tapping, lip and foot movement) and diffusion tractography of the corticospinal tract show where movement lies relative to the lesion. On high axial CT slices the hand knob can often be recognised as well.

Clinical notes

Lesions just in front of the sulcus weaken, those just behind it numb; a small stroke of the hand knob can give an isolated weak hand that mimics a radial or ulnar nerve palsy
Awake craniotomy with cortical mapping allows removal of tumours close to the motor strip while movement and speech are tested
Perirolandic tumours (gliomas, metastases, convexity or falx meningiomas) often first present with focal motor or sensory seizures

Anatomical variants

The hand knob is usually an inverted omega on axial images, sometimes a horizontal epsilon

Test yourself

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What does the central sulcus separate?

The frontal lobe (motor cortex, precentral gyrus) in front from the parietal lobe (sensory cortex, postcentral gyrus) behind.

How is the central sulcus found on axial MRI?

By the hand knob, a bulge of the motor cortex shaped like an inverted omega; the sulcus curves just behind it.

How is the central sulcus confirmed during surgery?

By phase reversal of the median nerve somatosensory evoked potential across a strip electrode, and by direct cortical stimulation of the motor strip.

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

Its names

Official Latin (TA2): sulcus centralis TA2 5435
Official Spanish (DeCS): Surco central
English (TA2): Central sulcus
Also called: fissure of Rolando · sulcus Rolandi

Sources: Terminologia Anatomica (TA2); Neuroanatomy, Precentral Gyrus; Neuroanatomy, Postcentral Gyrus; Anatomía humana (4.ª ed.), tomo 1, cap. 27: Relaciones del cerebro; 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.