The Central Nervous System

The __ __ terminates as a blind sac at the level of the second sacral vertebra, below the end of the spinal cord.

The _ attaches to the inside of the cranial cavity and forms the internal periosteum of the surrounding skull bones.

The sheath around the spinal cord is not attached directly to the vertebrae but is seperated by an __ __ which lies between the dural sheath and the bony walls. This space contains blood vessels, loose C.T. , and adipose tissue that provides a protective pad around the spinal cord.

The __ __ is thin and weblike. It lacks blood vessels and is located between the dura and pia maters. It spreads over the brain and spinal cord but generally does not dip into the grooves and depressions on their surface.

Interconnected cavities called __ are located within the cerebral heisphers and brainstem. These spaces are continuous with the central canal of the spinal cord and are filled with cerebrospinal fluid.

The largest ventricles are the __ __, which are the first and second ventricles. They extend anteriorly and posteriorly into the cerebral hemisphers.

The first lateral ventricle is located in the __ cerebral hemisphere.

The second lateral ventricle is located in the __ cerebral hemisphere.

A narrow space that constitutes the __ __ is located in the midline of the brain beneath the corpus callosum.

The __ __ is a bridge of axons that links the two cerebral hemispheres.

The third ventricle communicates with the lateral ventricles through openings called __ __ in its anterior end.

The __ __ is located in the brainstem just in front of the cerebellum.

A narrow canal, the __ __ __, connects the fourth ventricle to the third ventricle and passes lengthwise through the brainstem. This ventricle is continuous with the central canal of the spinal cord and has openings in its roof that lead into the subarachnoid space of the meninges.

Tiny, reddish cauliflower-like masses of specialized capillaries from the pia mater, called __ __ secrete cerebrospinal fluid. These structures project into the cavities of the ventricles.

Humans secrete nearly __ ml's of CSF daily. However, only about 140 ml's are in the nervous system at any time, because CSF is continuously reabsorbed into the blood.