Primary motor cortex

Looks like

A strip of grey matter running over the top of the brain just in front of its central groove, one on each side.

What it does

Sends the commands for voluntary movement to the opposite side of the body.

Keeping it well

Its blood supply is what matters: sudden weakness of face, arm or leg on one side is a stroke until proven otherwise — call an ambulance.

Related conditions

• Acute liver failure
• ADHD
• African trypanosomiasis (sleeping sickness)
• Alcohol withdrawal and delirium tremens
• Altitude sickness
• Alzheimer's disease
• Amyloidosis (AL and ATTR)
• Amyotrophic lateral sclerosis
• Autism spectrum disorder
• Bipolar disorder
• Birth asphyxia (hypoxic-ischaemic encephalopathy)
• Body dysmorphic disorder
• Botulism
• Brain abscess
• Brain aneurysm
• Brain tumour (glioma & meningioma)
• Cerebral palsy
• Chickenpox (varicella)
• Chronic insomnia
• Chronic neuropathic pain
• Chronic pain syndrome
• Cluster headache
• Concussion (mild TBI)
• Congenital hypothyroidism
• Cryptococcal meningitis
• Delirium
• Dementia with Lewy bodies
• Down syndrome (trisomy 21)
• Drowning
• Eating disorders
• Encephalitis
• Epilepsy
• Essential tremor & dystonia
• Fainting (syncope)
• Febrile seizures
• Fibromyalgia
• Fragile X syndrome
• Frailty & falls in older age
• Frontotemporal dementia
• Functional (somatic) symptom disorder
• Generalised anxiety disorder
• Guillain-Barré syndrome
• Haemorrhagic stroke
• Heat exhaustion & heatstroke
• Hepatic encephalopathy
• Huntington's disease
• Hydrocephalus
• Hypoglycaemia (low blood sugar)
• Intellectual disability
• Ischaemic stroke
• Japanese encephalitis
• Lead poisoning
• Long COVID (post-viral syndrome)
• Lyme disease
• Major depressive disorder
• ME/chronic fatigue syndrome
• Measles
• Medication-overuse headache
• Meningitis
• Migraine
• Multiple sclerosis
• Myasthenia gravis
• Narcolepsy
• Neurocysticercosis
• Normal pressure hydrocephalus
• Parkinson's disease
• Peripheral neuropathy
• Phenylketonuria (PKU)
• Poisoning & overdose
• Post-traumatic stress disorder
• Postnatal depression
• Postpartum psychosis
• Rabies
• Restless legs syndrome
• Roseola (sixth disease)
• Schizophrenia
• Self-harm and suicidal crisis
• Shingles (herpes zoster)
• Subdural haematoma
• Substance use disorder
• Tension-type headache
• Tetanus
• Thrombotic thrombocytopenic purpura (TTP)
• Tick-borne encephalitis
• Tics and Tourette syndrome
• Toxoplasmosis & CMV
• Transient ischaemic attack
• Traumatic brain injury (moderate to severe)
• Tuberous sclerosis complex
• Vascular dementia
• Vitamin B1, C and other deficiencies