Premotor cortex

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Brain: Premotor cortex
Image of brain with Brodmann areas numbered
Brodmann area 6
NeuroNames	ancil-44

The premotor cortex is an area of motor cortex lying within the frontal lobe of the brain. It extends 3 mm anterior to the primary motor cortex, near the Sylvian fissure, before narrowing to approximately 1 mm near the medial longitudinal fissure, which serves as the posterior border for the prefrontal cortex. The premotor cortex is largely equivalent to Brodmann area 6. Activity within this region is critical to the sensory guidance of movement and control of proximal and trunk muscles of the body.

Anatomy and structure

The premotor cortex is dysgranular (a transition between the agranular motor cortex and the granular eulaminate frontal cortex), which means that there is only a faint granular lamina IV. This corresponds to Brodmann area 6, with the exception that the medial surface of this area is the site of the accessory motor cortex (also known as the supplementary motor area, or SMA).

Afferents

Subcortical

Cortical

Through "U fibers" (short cortico-cortical axons) the premotor cortex receives many axons from the motor cortex in an horizontal manner respecting the somatotopic map of the motor cortex.

Efferents

Subcortical

Cortico-spinal

The axons of the premotor cortex contribute to the pyramidal bundle

Striatum

Axons of the Vth layer contribute to the corticostriate connection ; a massive connection involving almost all parts of the cortex

Thalamus

The premotor cortex sends axons to the motor thalamus. This (see thalamus) comprises a part receiving cerebellar axons (nucleus Ventralis Intermedius Vim or VL), a part receiving pallidal axons (nucleus Ventralis oralis VO) and a part receiving nigral axons (nucleus Ventralis anterio VA). The Vim is separated into two parts one ventrolateral and one mediodorsal VImM. The premotor cortex sends axons electively to VImM and VO

Central complex

Subthalamic nucleus

Cortical

Physiology

Mirror neurons are cells located in the premotor cortex, the part of the brain relevant to the planning, selection and execution of actions. It is a part of the Cerebral cortex.