The spinal cord does not have the same diameter throughout its length. Instead, it has two thicker regions called the enlargements, and both correspond to the nerve plexuses that innervate the upper and lower limbs. The spinal cord contains the following enlargements:

• Cervical enlargement - located at the C5 to T1 segmental levels, and it is associated with the brachial plexus (Read more!) that innervates the upper limb on each side;
• Lumbosacral enlargement - situated at the T11 to L1 segmental levels, and it corresponds to the lumbar (Read more!) and sacral plexuses (Read more!) that provide innervation to the lower limbs.