Lecture Notes: External and Internal Anatomy of the Sheep Brain

External View

• Meninges:

  • Pia mater is present (shiny sheen observed).
  • Arachnoid and dura mater are removed, except some dura mater visible on the inferior aspect.

• Cerebrum:

  • Divided into left and right hemispheres by the longitudinal fissure.

• Cerebellum:

  • Located directly posterior to the cerebrum in the sheep brain.
  • In human anatomy, the cerebellum is more inferior to the cerebrum.

• Brainstem (Inferior view):

  • Midbrain, pons, and medulla are visible.
  • Spinal cord extends beyond the brainstem.

• Other Structures:

  • Optic nerve, pituitary gland, and trigeminal nerves removed for better view.

Brain Lobes

• Frontal Lobes:
  • Anterior aspect of the cerebrum.
• Parietal Lobes:
  • Located posterior to the frontal lobes.
• Temporal Lobe:
  • Visible from the lateral view.
• Occipital Lobes:
  • Located at the posterior aspect.
• Insula:
  • Not visible in this view.
  • Refer to additional pictures for the insula.

Internal Anatomy (Mid-sagittal Section)

• White Matter:

  • Becomes visible once deep into the cerebrum.
  • Corpus Callosum:
    • Large region of white matter.
    • Contains lateral ventricles.

• Septum Pellucidum:

  • Tissue film covering the tip of the pointer.

• Fornix:

  • Seen posterior to the septum pellucidum.

• Thalamus:

  • Central commissure visible.

• Hypothalamus:

  • Inferior to thalamus.
  • Optic chiasma located anterior to it.

• Third Ventricle:

  • Space around the thalamus.

• Pineal Gland and Corpora Quadrigemina:

  • Posterior to the third ventricle.
  • Superior and inferior colliculi present.

• Midbrain:

  • Part of the corpus quadrigemina.
  • Cerebral Aqueduct:
    • Drains into the fourth ventricle.

• Fourth Ventricle:

  • Space visible in the posterior aspect.

• Pons and Medulla:

  • Contained within the brainstem.

• Arbor Vitae:

  • White matter within the cerebellum.

Study Recommendations

• Review the functions of the mentioned brain regions and structures.
• Utilize additional images for better understanding of the insula and other structures.