Posterior horn of spinal cord
Cornu posterius medullae spinalis
- Latin synonym: Columna grisea posterior
- Synonym: Dorsal horn of spinal cord
- Related terms: Posterior horn; Dorsal horn
Definition
The posterior horn of spinal cord is part of the spinal gray matter which is situated dorsal to the central canal. It is sensory in function and is the place where information from the body surface and underlying tissues first reaches the central nervous system.
The posterior horn of spinal cord extends throughout the length of the cord. According to the old literature, it is divisible into various sub-parts, including an apex, a head, a neck and a base. The posterior horn can also be divided into distinct layers or laminae–called the Rexed laminae–based on the cytoarchitectural details of the cells in these regions:
Rexed Lamina | Corresponding sub-part of the posterior horn of spinal cord | ||
Rexed lamina I | Rexed lamina I is the thinnest of all and corresponds with the apex of the posterior horn. | ||
Rexed lamina II | Lamina II caps the head of the posterior horn (with some considering it to be a part of the head). | ||
Rexed lamina III, IV | Lamina III and IV correspond with the head of posterior horn. | ||
Rexed lamina V | It lies in the neck of the posterior horn. | ||
Rexed lamina VI | It lies in the base of the posterior horn. | ||
Rexed lamina VII | Some consider lamina VII (zona intermedia) as part of the base as well. | ||
The posterior horn of spinal cord contains different groups of sensory nuclei, which are positioned in dedicated Rexed laminae mentioned above. These nuclei include:
Nuclei | Corresponding laminae of the posterior horn of spinal cord | Type of sensory processing | ||
Marginal zone nucleus | Rexed lamina I. | |||
Substantia gelatinosa | Rexed lamina II. | Sensory information of pain and temperature is relayed into the substantia gelatinosa (and marginal zone) nuclei by first order neurons of spinothalamic pathway. | ||
Nucleus proprius | Rexed lamina III and IV (with slight projection into lamina V as well). | Sensory information pertaining to conscious proprioception, vibration, and 2-point discrimination gets transmitted to nucleus proprius by collaterals from first order neurons of dorsal column pathway. | ||
Dorsal nucleus of Clarke or posterior thoracic nucleus | Rexed lamina VII. | Subconscious proprioceptive information from cerebellum gets relayed into dorsal nucleus of Clarke. | ||
Visceral afferent nucleus | Rexed lamina VII. | The visceral afferent information gets transmitted to the visceral afferent nucleus in the posterior horn of spinal cord. | ||
Note: Every type of sensory information gets eventually relayed inside the thalamus, prior to reaching the primary sensory cortex.
References
Snell, R.S. (2010). ‘Chapter 4: The Spinal Cord and the Ascending and Descending Tracts’, in Clinical Neuroanatomy. (7th ed.) Philadelphia: Wolters Kluwer Health/Lippincott Williams & Wilkins, pp. 137-142.
Byrne, J.H. and Dafny, N. ‘Chapter 2: Anatomy of the Spinal Cord. [Content reviewed and revised 07 Oct 2020]. In Neuroanatomy Online, an open-access electronic laboratory for the neurosciences. McGovern Medical School at UTHealth; Accessed 2022 Oct 22. Available from: https://nba.uth.tmc.edu/neuroscience/m/s2/chapter03.html
Brown, A.G. (1982). Review article the dorsal horn of the spinal cord. Quarterly Journal of Experimental Physiology: Translation and Integration, 67(2), pp.193-212. https://doi.org/10.1113/expphysiol.1982.sp002630
Ganapathy, M.K., Reddy, V. and Tadi, P. Neuroanatomy, Spinal Cord Morphology. [Updated 2021 Oct 30]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK545206/
