| Definition | Term |
| Between two structures. | |
| Toward the trunk or beginning of the structure. | |
| Away from the trunk or the source of a structure. | |
| Away from the centre. | |
| Middle of the structure. | |
| Away from the surface. | |
| Away from the front or toward the back. | |
| | Definition | Term |
| Near the surface. | |
| Toward the midline of the body. | |
| Away from the midline of the body. | |
| Toward the head or upper part of the structure. | |
| Toward the front. | |
| Toward the centre. | |
| Away from the head or toward the lower end of the structure. | |
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