The pineal gland is a small, tiny pine cone shaped (hence its name) structure considered to be part of the epithalamus. It typically measures 7 x 6 x 3mm in size and is situated in a grove between the laterally placed thalamic bodies 1-6. It is located above and behind the superior colliculi and behind and beneath and stria medularis.
The pineal gland arises during the seventh week of gestation from a thickening of the ependyma at the posterior most aspect of the third ventricle 5.
The pineal gland produces melatonin which affects the modulation of wake/sleep patterns and photoperiodic (seasonal) functions. Unlike much of the rest of the brain, it is not isolated from the body by the blood-brain barrier.
The pineal gland has a predilection for calcification which is invariably histologically present in adults but rarely seen below the age of 10 years 6. Calcification is visible on lateral skull x-rays in 50-70% of adults 6. The habenular commissure also calcifies and is visible as a small C-shaped (open part posteriorly) density above and infront of the pineal calcification.
With CT's far higher contrast resolution calcification is almost always visible in the adult pineal gland, sometimes visible as specs embedded in a small soft tissue nodule similar in density to grey matter. In children under the age of 5 years no calcification is present, but prevalence increases rapidly with age, reaching a plateau at about 30 years of age 5.
MRI is the modality of choice for evaluating the pineal region although its sensitivity to calcification on conventional sequences is poor (note: susceptibility weighted imaging (SWI) has sensitivity to calcification similar to CT).
The gland appears as a small nodule of tissue with similar intensity to grey matter. It enhances vividly during contrast administration as it is outside the blood brain barrier.
The pineal region is anatomically complex and plays host to a number of unique masses and tumours as well as potentially affected by many entities seen more frequently elsewhere in the brain.
- cystic non-neoplastic lesions
- pineal parenchymal tumours
- germ cell tumours
- tumours also encountered in the pineal region
- vascular lesions
- 1. Gray's anatomy. 40th edition. [Edinburgh] : Churchill Livingstone/Elsevier, 2008. ISBN:0443066841. Read it at Google Books - Find it at Amazon
- 2. Schünke M, Schulte E, Ross LM et-al. Thieme atlas of anatomy, head and neuroanatomy. George Thieme Verlag. (2007) ISBN:3131421215. Read it at Google Books - Find it at Amazon
- 3. Arendt J, Arendt J. Melatonin and the Mammalian Pineal Gland. Springer. (1994) ISBN:0412536005. Read it at Google Books - Find it at Amazon
- 4. Afifi A, Bergman RA. Functional Neuroanatomy: Text and Atlas, 2nd Edition, Text and Atlas. McGraw-Hill Medical. (2005) ISBN:0071408126. Read it at Google Books - Find it at Amazon
- 5. Sumida M, Barkovich AJ, Newton TH. Development of the pineal gland: measurement with MR. AJNR Am J Neuroradiol. 1996;17 (2): 233-6. AJNR Am J Neuroradiol (abstract) - Pubmed citation
- 6. Buttler P. Applied radiological anatomy. Cambridge University Press. (1999) ISBN:0521481104. Read it at Google Books - Find it at Amazon