Cortical homunculus

Biological: Behavioural genetics · Evolutionary psychology · Neuroanatomy · Neurochemistry · Neuroendocrinology · Neuroscience · Psychoneuroimmunology · Physiological Psychology · Psychopharmacology (Index, Outline)

Basic Definition[]

Specifically: A physical representation of the primary sensorimotor cortex, i.e., the portion of the human brain directly responsible for the movement and exchange of sense and motor information (namely touch: sensitivity, cold, heat, pain etc.) of the rest of the body.

The resulting image is a grotesquely disfigured human with diproportionately huge hands, lips, and face in comparison to the rest of the body. Because of the fine motor skills and sense nerves found in these particular parts of the body they are represented as being larger on the homunculus. A part of the body with fewer sensory and/or motor connections to the brain is represented to appear smaller.

The Cortical Homunculus is a visual representation of the concept of "the body within the brain" that one's hand or face exists as much as a series of nerve structures or a "neuron concept" as it does a physical form. This concept relates to many neuro-biological phenomena including "phantom limb".

Motor Activity	Sensory Activity
Toes	Toes
Ankle	Ankle
Leg	Leg
Knee	Knee
Hip	Hip
Trunk	Trunk
Shoulder	Shoulder
Elbow	Elbow
Wrist	Wrist
Fingers	Fingers
Thumb	Thumb
Neck	Neck
Brow	Brow
Eyelid	Eyelid
Nose	Nose
Lips	Lips
Tongue	Tongue
Larynx	Jaw

Images (external and probably copyrighted)[]

Sensorimotor Cortex, a diagram of the body mapped onto the brain
Sensory homunculus, a 3D model of the male human body with size proportional to sensory cortial area