Anatomists usually classify the thalamic nuclei according to their relation to the internal medullary lamina into 5 groups: anterior, medial (centromedian), lateral, intralaminar and reticular nuclei. The lateral nucleus is further divided into ventral and dorsal groups. The dorsal tier nuclei include the lateral dorsal, lateral posterior and pulvinar. The ventral tier nuclei include the ventral anterior, ventral lateral, ventral posterior and the metathalamus (medial and lateral geniculate bodies). On the other hand, physiologists divide the thalamic nuclei according to their connections (input and output) into specific and nonspecific nuclei. The medical students are usually puzzled between the 2 classifications.
To make it understandable and simple, I adopted a new classification based on their main function and connections so that medical students can easily recognize them and remember their function. I called this classification "Bondok’s Classification of the Thalamic Nuclei". I divided the thalamic nuclei into 5 groups:
- 2 Specific Motor Nuclei: ventral anterior nucleus and ventral lateral nucleus.
- 2 Specific Sensory Nuclei: ventral posterior nucleus and metathalamus (medial and lateral geniculate bodies).
- 2 Limbic System Nuclei: anterior nucleus and medial nucleus.
- 2 Reticular Activating System Nuclei: reticular nucleus and intralaminar nucleus.
- 3 Association Nuclei: the 3 dorsal nuclei (lateral dorsal, lateral posterior and pulvinar).
Prof Adel Bondok,
Professor of Anatomy and Neuroscience,
Faculty of Medicine, Mansoura University, Egypt
◊ An article contributed on (13 September 2008) for biologyonline.com.