Thalamic Connections Mnemonic

Structure of Thalamus

A vertical “Y” shaped white mater – internal medullary lamina divides thalamus into:

1. Anterior nuclear groups
2. Medial nuclear groups
3. Lateral nuclear groups

In anatomical position:

• Dorsal surface of brain: faces towards sky
• Ventral surface of brain: faces towards floor

Pulvinar = Posterior end or posterior pole of thalamus

Thalamic Connections

Picture mnemonic

Remember the schematic diagram drawn below showing important parts of thalamus in an anticlockwise fashion:

1. Anterior nucleus
2. Ventral nuclear group:
   • Anterior
   • Lateral
   • Posterior
     • Medial
     • Lateral
3. Lateral and Medial geniculate body
4. Medial-Dorsal nucleus

Now, we assign alphabets “A, B, C, D, E, F” sequentially to these important structures in anticlockwise fashion starting from anterior nucleus.

“A” for Anterior nucleus

A for:

• Alertness
• Attention
• Affect
• Acute memory

These are the functions of limbic system – Papez circuit:

• Afferent: Mamillary body
• Efferent: Cingulate gyrus

“B” for Ventral-anterior nucleus

B for: Basal ganglia

• Afferent: Globus pallidus and Substantia nigra
• Efferent: Brodmann Area 6 (Prefrontal and premotor cortex)

“C” for Ventral-lateral nucleus

C for: Co-ordination and Cerebellum

• Afferent: Cerebellum (Dentate nucleus) and Basal ganglia
• Efferent: Brodmann Area 4 (Primary motor cortex)

“D” for Ventral-Posterior nucleus

D for: Dermatome (Sensory)

• Afferent:
  • Ventro-postero-medial (VPM) nucleus: Trigemino-thalamic tract, Solitario-thalamic tract
    • Medial = Mask (face)
    • Taste (Nucleus tractus solitarius)
  • Ventro-postero-lateral (VPL) nucleus:
    • Lateral = Limbs
    • Spinothalamic tract
    • Medial lemniscus
• Efferent:
  • Brodmann Area 3, 1, 2 (Sensory cortex)

Thalamic pain syndrome: Involvement of primary somatosensory thalamic nucleus (ventral posterior lateral [VPL]/ventral posterior medial thalamus [VPM]) and the anterior pulvinar, a major spinothalamic target gives rise to thalamic pain syndrome. Approximately 25% of patients with a sensory stroke due to a thalamic lesion will develop central post-stroke pain. Thalamic pain is a severe, treatment-resistant pain syndrome. The pain is often described as burning or constrictive and is frequently accompanied by evoked pain (allodynia/hyperalgesia), paresthesias, or summation hyperpathia. 1http://www.ahcmedia.com/articles/137528-thalamic-pain-who-is-likely-to-develop-this-disorder

“E” for Geniculate Bodies

E for: Eyes and Ears

• Lateral geniculate body = Light (Eyes)
  • Afferent: Optic tract
  • Efferent: Primary visual cortex (Area 17)
• Medial geniculate body = Music (Ears)
  • Afferent: Inferior colliculus
  • Efferent: Primary auditory cortex (Area 41, 42)

“F” for Medial-Dorsal Nucleus

F for: Feelings (Limbic system)

• Afferent:
  • Amygdala
  • Olfactory cortex
• Efferent:
  • Prefrontal cortex
  • Limbic system

Thiamine deficiency in alcoholics (Wernicke-Korsakoff syndrome) results in degeneration of the medial-dorsal nucleus of thalamus, mamillary bodies, hippocampus and vermis of cerebellum.

Other mnemonics:

1. Lateral geniculate nucleus (LGN) = Light (Visual pathway)
2. Medial geniculate nucleus (MGN) = Music (Auditory pathway)
3. Ventral postero-lateral nucleus (VPL) = Very Painful Limbs (Spinothalamic tract and Dorsal column)
4. Ventral postero-medial nucleus (VPM) = Very Painful Mouth (Trigeminal and Gustatory pathway)
5. Ventrolateral nucleus (VL) = Victory Lap (Motor)
6. Dorsomedial nucleus (DMN) = Dog’s Memory and Nose (Memory, smell and emotions)

Dr. Sulabh Kumar Shrestha, MS Orthopedics

He is the section editor of Orthopedics in Epomedicine. He searches for and share simpler ways to make complicated medical topics simple. He also loves writing poetry, listening and playing music.