Spinal cord

The spinal cord is the region of the Central Nervous System which is housed in the spinal canal and which is responsible for carrying nerve impulses to the 31 pairs of spinal nerves, communicating the brain to the body, with two basic functions.

These function are the afferent, which are sensory sensations carried from the trunk, neck and all four limbs to the brain, and efferent, which the brain directs via the effector organs to perform a certain action, carrying these impulses to the trunk, neck and limbs.  Its functions also find immediate movement control and vegetative, as the reflex, the sympathetic nervous system and the parasympathetic.

External Anatomy
The spinal cord nerve tissue is considered the largest in the human body and can reach its neurons up to a meter away.  Weighing approximately 30 grams in their development the spinal cord reaches the length of 45cm in men and 43cm in women.  The bone is asymmetrical in nearly 75% of humans.

This asymmetry is due to the presence of more fibers of the descending corticospinal on the larger side.  The spinal cord has four faces, one front, two sides and a rear face.  The anterior midline in the anterior median fissure presents and limited laterally by the side grooves above, the apparent origins of the motor or efferent nerve roots of spinal nerves and also separates it from the sides.

Two swellings, one cervical and one lumbosacral:  ‘C4′ a ‘T1′ cervical enlargement; this is thickening due to the roots of nerves to transmit sensation and motor action to and from the upper limbs (arm, forearm and hand).  And ‘L2′ a ‘S2′ intumescences lumbosacral: due to the nerve roots that let you transmit sensation and motor action to and from the lower limbs (thigh, leg and foot).

In its lower portion it tapers quickly to end in a point known as a cone terminal.  On the sides is binding to the dentate ligaments and at the bottom, terminal filum is related to coccygeal filament that is inserted into the bone coccyx.  Three membranes concentrically surround the spinal cord: the pia mater; arachnoid and dura mater.

The pia mater that surrounds it is directly introduced into the grooves.  On it and related to a loose part of the arachnoid is a cerebrospinal fluid-filled space called the subarachnoid space. Above this space is the most homogeneous and distinguishable from the arachnoid.

It’s like a fine net, transparent and loose that comes to be introduced into the grooves of the Medilas.  In some parts it is difficult to differentiate from the pia arachnoid.

Therefore, we sometimes use the term pia-arachnoid.  Finally, the dural meningeal layer is the outermost layer and is fibrous and strong.  Between the arachnoid and dura mater is a virtual space called the subdural space.
The spinal cord is attached to the medulla oblongata at the top with its continuity with the bulge in its middle by conjunctive extensions to adhere to the dura.  Flaps in the nerve roots as dependencies of the pia mater, form both types of extensions of the dentate ligaments.  At the lower end a prolongation of the dura surrounds the filum terminale that was fixed to the base of the coccyx.