Superficial Structures

  1. The largest portion of the brain is the cerebrum, which is divided into two hemispheres. The outer layer of the cerebrum is the cerebral cortex. 


  1. Just posterior to the cerebrum is the cerebellum with its folded outer cortex. The gyri and sulci of the cerebellum are smaller and arranged in a more uniform pattern. 


  1. The spinal cord extends from the posterior portion of the brain, just inferior to the cerebellum 


  1. The surface of the cerebrum is covered with ridges called gyri and grooves called sulci


  1. The two cerebral hemispheres are divided by a large, deep groove called the longitudinal fissure


  1. The central sulcus divides the frontal lobe from the parietal lobe and runs from the longitudinal fissure vertically towards the inferior surface. It can be challenging to locate until the midsagittal cut is made. 


  1. On the inferior surface, an x shaped structure called the optic chiasm can be seen where the two optic nerves cross over each other on their way to the occipital lobe


  1. The olfactory lobes are relatively large structures below the frontal lobe


  1. The frontal lobes are much smaller in sheep than in humans


  1. The parietal lobes are posterior to the frontal lobes


  1. The occipital lobes are the most posterior lobes of the cerebrum


  1. The temporal lobes are located inferior to the parietal lobes on each side of the cerebrum