1) Medial 2) Median 3) Sagittal 4) Towards the midline 1) Medial 2) Sagittal 
towards or on the middle of a part
middle
• (a.) Middle; median; in, or in the region of, the mesial plane; internal; -- opposed to lateral.
Nearer the middle line of the body or the surface of a tooth nearer the center of the dental arch.
Forward or front. For example your cuspid is mesial to you bicuspid. The mesial surface of your bicuspid is the part of the bicuspid closest to your cuspid.
is the surface of the tooth nearest the midline of the dental arch.
Towards the front of the mouth. For example a central tooth is mesial to a lateral tooth.
towards the midline.
<dentistry> Forward or front. For example your cuspid is medial to you bicuspid. The medial surface of your bicuspid is the part of the bicuspid closest to your cuspid. ... (08 Jan 1998) ... 
(me´ze-әl) situated in the middle; median; nearer the middle line of the body or nearer the center of the dental arch.
Me'sial adjective [ Greek 
The side of the tooth towards the middle of the jaw.
Type: Term Pronunciation: mē′zē-ăl, mes′ē-ăl Definitions: 1. Nearer to the midline or most anterior part of the dental arch.
Mesial: 1. Toward the middle. As, for example, a mesial temporal lobe structure. 2. In dentistry, toward the middle of the front of the jaw.
towards or on the middle of a part
[adj] - (anatomy) being in or directed toward the midline or mesial plane of the body
mesial Nearer or nearest the midline in the dental arch; a reference especially of the surface of a tooth.
adjective being in or directed toward the midline or mesial plane of the body
adjective - medial, used in dental anatomy.