Gland
Pineal gland
Epithalamic source of the nightly melatonin signal
High-yield
The main regulatory pathway links the suprachiasmatic nucleus, hypothalamus and upper thoracic sympathetic outflow to the superior cervical ganglion, whose fibers reach the pineal.
Overview
The pineal projects from the posterior third-ventricular region, below the splenium and above the dorsal midbrain. Pinealocytes produce melatonin from serotonin. Retinal light information influences this secretion through circadian brain circuits and a sympathetic relay, rather than through a direct retinal projection to the gland.
Reference facts
- Location
- Midline epithalamus, attached near the posterior third ventricle and lying above the superior collicular region.
- Hormones
- Melatonin, normally with greater secretion during the biological night.
- Blood supply
- Chiefly posterior choroidal arterial branches; anatomical studies also show variable anterior-circulation contributions.
- Innervation
- Predominantly postganglionic sympathetic fibers from the superior cervical ganglia, traditionally called nervi conarii.
- Function
- Conveys information about biological night and helps coordinate circadian timing, including sleep-wake rhythms.
Clinical correlation
A pineal-region mass may disturb upward gaze and pupillary responses by affecting the dorsal midbrain, or obstruct the cerebral aqueduct. Pineal calcification is often physiological, but its amount and visibility vary with age and cannot alone establish disease.
Frequently asked questions
Where is the pineal gland located?
The pineal gland lies midline epithalamus, attached near the posterior third ventricle and lying above the superior collicular region.
What does the pineal gland secrete?
The pineal gland secretes melatonin, normally with greater secretion during the biological night.
What does the pineal gland do?
Conveys information about biological night and helps coordinate circadian timing, including sleep-wake rhythms.
What is the blood supply of the pineal gland?
Chiefly posterior choroidal arterial branches; anatomical studies also show variable anterior-circulation contributions.