This word refers to the shape of the body, or part of it. We may speak of external or internal body morphology. A An anatomical abnormality affecting the lowermost part of brain, where it joins the spinal cord, at the top of the neck. Various sub-types are described - see under their individual names. The term hindbrain hernia is sometimes used to incorporate all forms. refers to a morphological abnormality at the That part of the body where the base of the skull is joined to the top of the spine. Inside these bony enclosures, the craniovertebral junction is also where the brain stem continues downwards as the spinal cord..