Central Nervous System of Toad

• Brain is closely covered by meninges: inner pia mater and outer dura mater
• Both ventricles and central canal contain cerebrospinal fluid
• What is the ventricle within the olfactory bulb?

  rhinocoele
• Other name for telencephalon?

  cerebral hemispheres
• What separates the paired telencephalon?

  medial groove
• What is the ventricle within telencephalon?

  Lateral ventricles
• The lateral ventricles converge posteriorly into the foramen of Monro
• What is the ventricle within the diencephalon?

  3rd ventricle
• On the dorsal side of diencephalon is the pineal gland or epiphysis which is an endocrine gland
• In intact brains, the diencephalon is covered by heavily-vascularized anterior choroid plexus, consisting of cerebrospinal fluid-producing ependymal cells
• mesencephalon

  • marked by paired ovoid structures protruding dorsally called optic lobes
• What is the ventricle within the mesencephalon?

  optic ventricles or opticoele
• At the ventral side of the mesencephalon, remnants of optic nerves are seen
• A fairly wide point of convergence of optic nerves found at the mid-ventral side is optic chiasma
• Immediately posterior to the optic chiasma is the bi-lobed infundibulum
• What is the extension of the diencephalon?

  Infundibulum
• Posterior to the infundibulum is small pituitary body or hypophysis
• Posterior to mesencephalon is the metencephalon or cerebellum
• Metencephalon houses the aqueduct of Sylvius
• Aqueduct of sylvius

  • connects the optic ventricles with the fourth ventricle
• Myelencephalon has a dorsal triangular opening leading to the fourth ventricle
• Other name for myelencephalon: medulla oblongata
• The dorsal triangular opening of myelencephalon is covered with posterior choroid plexus
• Filum terminale

  • tapered posterior end
• The mid-dorsal groove along the spinal cord is the dorsal median sulcus while the ventral median fissure is the counterpart
• Two enlargements present along the cord:

  • anterior brachial enlargement
  • posterior lumbar enlargement
• The brachial enlargement and lumbar enlargement serves as the points of emergence of spinal nerves for forelimbs and hindlimbs
• The filum terminale and the elongated roots of the posterior spinal nerves form feather-like cauda equina