[Durgical](https://durgical.com/en/) › [DurgiPedia](https://durgical.com/en/durgipedia/) › [Anatomy](https://durgical.com/en/anatomy/) › [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) › Pineal gland [Endocrine system](https://durgical.com/en/anatomy/system/endocrine-system/) · [Head and neck](https://durgical.com/en/anatomy/region/head-and-neck/) # Pineal gland The pineal gland is a tiny pine-cone-shaped gland deep in the brain; it makes melatonin, which helps set the sleep cycle. [See in 3D →](https://durgical.app/?from=durgipedia&lang=en#region=head_neck&select=pineal_gland&side=r) Opens in the Durgical app, no sign-up needed. ## What it is A tiny pine-cone gland at the back of the third ventricle. ## What it does Makes melatonin, which helps set the sleep cycle. ## Key points - Light pathway: [retina](https://durgical.com/en/anatomy/retina/), suprachiasmatic nucleus of the [hypothalamus](https://durgical.com/en/anatomy/hypothalamus/), [spinal cord](https://durgical.com/en/anatomy/spinal-cord/), superior cervical ganglion, then sympathetic fibres to the gland; darkness raises melatonin and light suppresses it - Pineal region tumours press on the tectum: Parinaud syndrome, with loss of upward gaze, pupils that react to near but not to light, eyelid retraction and convergence-retraction nystagmus - The same tumours squeeze the cerebral aqueduct beneath, causing obstructive hydrocephalus with headache and vomiting - Pea-sized (about 8 mm long); it calcifies with age ('brain sand'), making it a midline landmark on CT ## Key facts **Where** Behind the third ventricle, above the superior colliculi **Blood supply** Posterior choroidal arteries **Nerve** Sympathetic (light information via the retina and hypothalamus) **Function** Melatonin (sleep-wake rhythm) ## Relations **In front** Back wall of the [third ventricle](https://durgical.com/en/anatomy/third-ventricle/), with the pineal recess; its stalk carries the habenular commissure above and the posterior commissure below **Below** Superior colliculi of the [midbrain](https://durgical.com/en/anatomy/midbrain/) and the opening of the [cerebral aqueduct](https://durgical.com/en/anatomy/aqueduct-of-midbrain/) beneath them **Above** Splenium of the [corpus callosum](https://durgical.com/en/anatomy/corpus-callosum/) and the internal cerebral veins, which join above it **Behind** Quadrigeminal cistern with the great cerebral vein, which drains into the [straight sinus](https://durgical.com/en/anatomy/straight-sinus/); the cerebellar [vermis](https://durgical.com/en/anatomy/central-lobule/) below and behind ## How to find it Not palpable. On CT its calcification marks the midline just behind the third ventricle, above the superior colliculi; surgeons reach the region from behind, for example between the [cerebellum](https://durgical.com/en/anatomy/anterior-quadrangular-lobule/) and the [tentorium](https://durgical.com/en/anatomy/tentorium-cerebelli/) (supracerebellar infratentorial approach). ## Examination - Upward gaze and pupil checks: asking the person to look up and comparing pupil reactions to light and to a near target; upgaze palsy with light–near dissociation suggests a pineal region mass pressing on the tectum ## On imaging CT shows calcification in most adults; calcification in a young child is unusual and raises concern for a tumour. Sagittal MRI is the view for pineal masses and for small fluid-filled pineal cysts, a frequent incidental finding that is usually harmless. ## Clinical notes - Germinoma is the most common pineal tumour and occurs mainly in boys and young men; blood and CSF tumour markers help separate germ cell tumours from other types - Hydrocephalus from a pineal mass is relieved by a ventricular shunt or an endoscopic opening of the third ventricle floor - On CT or older skull radiographs, a calcified pineal pushed away from the midline points to a mass or swelling in one hemisphere - Germ cell tumours of the pineal region that secrete hCG can cause precocious puberty in boys ## Anatomical variants - Small pineal cysts are common incidental findings on MRI and are usually harmless ## Development It grows as an outpouching of the roof of the diencephalon (epithalamus), at the back of the third ventricle. ## Test yourself Think of the answer, then tap the question to see it. ## What hormone does the pineal gland make, and how does light affect it? Melatonin; darkness raises it and light suppresses it, via the retina, suprachiasmatic nucleus and sympathetic fibres from the superior cervical ganglion. ## What is Parinaud syndrome and what causes it? Loss of upward gaze, pupils reacting to near but not light, lid retraction and convergence-retraction nystagmus, from a pineal region tumour pressing on the tectum. ## Why can a pineal tumour cause obstructive hydrocephalus? It squeezes the cerebral aqueduct beneath the pineal gland. ## Which is the most common pineal tumour, and in whom? Germinoma, mainly in boys and young men. [Add to my cards (4)](https://durgical.app/estudiar/?add=/en/anatomy/pineal-gland/) Educational information, not medical advice. For any symptom, see a health professional. ## Its names **Official Latin (TA2)** glandula pinealis TA2 3862 **Official Spanish (DeCS)** Glándula Pineal DeCS D010870 **English (TA2)** Pineal gland **Also called** epiphysis cerebri · pineal body Sources: Terminologia Anatomica (TA2); [DeCS](https://decs.bvsalud.org/es/ths/resource/?id=11303); [Physiology, Pineal Gland](https://www.ncbi.nlm.nih.gov/books/NBK525955/); Tratado de anatomía humana (9.ª ed.), tomo II, Libro V, cap. VI: Cerebro (configuración exterior e interior, ventrículos, formaciones coroideas, epífisis). ## **Spotted a mistake?** We are always improving for the community. Tell us what is wrong and our team will review it. Report a mistake Representative model, for educational purposes only. --- Source: https://durgical.com/en/anatomy/pineal-gland/ License: CC BY 4.0 (https://creativecommons.org/licenses/by/4.0/). Cite as: DurgiPedia (durgical.com), https://durgical.com/en/anatomy/pineal-gland/