Parasagittal magnetic resonance image of the equine brain at the level of the pretectal area.

acn: accumbens nucleus, ah: adenohypophysis, Ans: ansate sulcus, ans: ansiform lobule, bcr: brachium of the rostral colliculus, cam: ammon’s horn, cc: corpus callosum, ccp: caudal cerebellar peduncle, chp: choroid plexus, cig: cingulate gyrus, cin: cingulum, cmf: commissure of fornix, cn: caudate nucleus, crc: cerebral crus, Cru: cruciate sulcus, cst: corticospinal tract, ectm: ectomarginal gyrus, fmt: mammilo-thalamical fasciculus, Fp: primary fissure, ftp: transverse fibres of the pons, lal: lateral lemniscus, lgb: lateral geniculate body, lmi: internal medullary lamina, mar: marginal gyrus, mgb: medial geniculate body, mtn: motor nucleus of the trigeminal nerve, nd: dentate nucleus, nip: interpositus nucleus, no: nodulus of the vermis, npo: nuclei of the pons, ob: olfactory bulb, olf: olfactory fibres, oli: olivary nucleus, op: olfactory peduncle, ot: optic tract, otb: olfactory tubercle, pdt: thalamic peduncle, pml: paramedian lobule, poa: preoptic area, ppd: parapeduncular nuclei, pta: pretectal area, pyr: pyramidal tract, qdr: quadrangulare lobule, rc: rostral commissure, rcp: rostral cerebellar peduncle, rst: rubrospinal tract, smt: medullary stria of the thalamus, snr: substantia nigra, stn: subthalamic nucleus, stt: terminal stria, tb: trapezoid body, th: thalamus, zi: zona incerta, II: optic nerve, III: oculomotor nerve, VII: facial nerve. asterisk: blind ending medullary branches, uncovered with cortex.