Red nucleus

Looks like

A round, pinkish nucleus in the midbrain, coloured by iron, sitting in front of the cerebral aqueduct.

What it does

Relays signals from the cerebellum to the thalamus and spinal cord, and helps with arm movement and posture.

Keeping it well

Damage from a small midbrain stroke causes a coarse tremor of the opposite arm that worsens as the hand reaches out (Holmes or rubral tremor), sometimes with a droopy lid and weak eye movement on the side of the stroke (Benedikt syndrome).

Related conditions

• Acute liver failure
• ADHD
• African trypanosomiasis (sleeping sickness)
• Alcohol withdrawal and delirium tremens
• Altitude sickness
• Alzheimer's disease
• Amyloidosis (AL and ATTR)
• Autism spectrum disorder
• Bipolar disorder
• Birth asphyxia (hypoxic-ischaemic encephalopathy)
• Body dysmorphic disorder
• Botulism
• Brain abscess
• Brain aneurysm
• Brain tumour (glioma & meningioma)
• Cerebral palsy
• Chiari malformation and syringomyelia
• 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
• 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
• Sudden infant death syndrome
• 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)
• Trigeminal neuralgia
• Tuberous sclerosis complex
• Vascular dementia
• Vestibular schwannoma (acoustic neuroma)
• Vitamin B1, C and other deficiencies