Spinal Column: the series of connecting "vertebrae" that support and protect the "spinal cord." (Oxford) A flexibly bony column extending from the base of the skull to the small of the back. It encloses and protects the spinal cord, and provides attachment for the "muscles" of the back. It is made up of individual bones (vertebra) connected by discs of “fibrocartilage” and bound together by “ligaments.” (OxfordMed) Also referred to as  ‘spine,’  ‘backbone,’ and ‘vertebral column.’

Central Canal: “cerebrospinal fluid” filled canal that is ‘continuous’ with the “fourth ventricle” of the brain and extends along the entire length of the spinal cord. (Patestas, 56)

Coccyx: a bone of the spine. (MeSH) The small bone at the bottom of the spine. It is made up of 3-5 fused bones. (NCI1) The lowermost element of the (spinal column.) The ‘vestigial human tail.’ It consists of four vertebrae fused to form a triangular bone that articulates with the "sacral vertebrae." (OxfordMed) Also referred to as ‘tailbone.’

Intervertebral Disc: spongy discs located between the vertebrae of the spinal column. (NCIt) The flexible plate of fibrocartilage that connects any two adjacent vertebrae in the spinal column. They act like shock absorbers, protecting the brain and spinal cord from the impact produced by running and other movements. (OxfordMed)  Also referred to as “disc.”

Spinal Canal: the channel containing the spinal cord that runs down the centre of the spinal column. (Oxford) A cavity through which the spinal cord passes. (OxfordMed) In the adult, the spinal cord is much shorter than the (spinal) canal. (Patestas, 21) Also referred to as ‘spinal cavity,’  ‘vertebral canal,’ and ‘vertebral foramen.‘ 

Caudal Equina: (area that) contains "nerve roots" but no spinal cord." (Blumenfeld, 320) A loose conglomeration of nerve fibers within the ‘lumbar cistern.’ (Patestas, 55) The region of the (spinal canal) that is devoid of spinal cord. (An) accumulation of dorsal and ventral "rootlets." (Patestas, 21) Also referred to as ‘horse’s tail.’

Lumbar Cistern: a “cerebrospinal fluid” filed chamber that is accessible for ‘spinal taps,’ (thus) avoiding damage to the spinal cord. (Patestas, 56)

Vertebrae: any of the ring-shaped bony structures that constitute the spinal column and surround the spinal cord. (NCIt) Any of the bony or segments (of “cartilage”) that make up the spinal column and that have a short more or less cylindrical body whose ends articulate by pads of elastic or cartilaginous tissue with those of adjacent vertebrae and a bony arch that encloses the spinal cord. (GHR) The 33 bones of which the (spinal column) is composed. Each vertebra typically consists of a body from the back of which arises an arch of bone enclosing the spinal canal. (OxfordMed) Singular - ‘vertebra.’

Cervical Vertebrae: the seven bones making up the neck region of the backbone. (OxfordMed) Any one of the seven vertebrae that start with C1, connecting the skull to the spine, and end with C7, which joins the cervical with the thoracic spine. (NCIt)

Lumbar Vertebrae: one of the five bones situated between the thoracic vertebrae and the sacrum in the lower part of the spine. (NCIt) They are the largest of the unfused vertebrae and have stout “processes” for attachment of the strong muscles of the lower back. (OxfordMed)

Sacral Vertebrae: one of the usually five fused vertebrae forming the triangular bone just below the lumbar vertebrae. (NCIt) A curved triangular element consisting of five fused vertebrae. It (joins) with the last lumbar vertebra above, the coccyx below, and the hip bones laterally. (OxfordMed) Also referred to as the ‘sacrum.’

Thoracic Vertebrae: one of 12 vertebrae in the human vertebral column. The thoracic vertebrae are situated between the seventh cervical vertebra down to the first lumbar vertebra. (NCIt) The twelve bones to which the ribs are attached. They lie between the neck and lower back vertebrae and are characterized by the presence of “facets” for (joining) with the ribs. (OxfordMed)