Paper authors: Jonathan Morley, Ana Bucchi, Carlos Lorenzo, Thomas A. Püschel Link to preprint

Corresponding author: Thomas A. Püschel Contact: Email: thomas.puschelrouliez@anthro.ox.ac.uk Web: thomas.puschel.com


Landmark collection

3D landmarks were collected to quantify the MC1’s morphology. Eight curves comprising 20 equidistant landmarks each were placed at pre-defined points on the MC1 (Figure 1). These landmarks were chosen to provide a good representation of the shaft of the bone. The first and last landmarks from each one of the eight curves were treated as fixed (i.e., 16 fixed landmarks), whereas all the rest of them (i.e., 144 landmarks) were considered as semi-landmarks.

Figure 1. Illustration of the 16 landmarks (yellow spheres) and 144 semi-landmarks (red spheres) used in this study. The numbers of the 16 fixed landmarks and eight semi-landmark curves (C1-C8) are also plotted

Landmark and semi-landmark definitions

Landmarks_and_semilandmarks Definition
Fixed landmarks
1 Most dorsal point on the distal articular border along the midline of bone
20 Most dorsal point on the proximal articular border along the midline of bone
21 Most palmar point on the distal articular border along the midline of bone
40 Most palmar point on the proximal articular border along the midline of bone
41 Dorsopalmar point on the distal border of the dorsal radial epicondyle
60 Dorsopalmar midpoint along the lateral border of the proximal articular surface
61 Dorsopalmar midpoint along the medial border of the proximal articular surface
80 Dorsopalmar midpoint along the medial border of the distal articular surface
81 Most medial point on the dorsal border of the distal articular surface
100 Most medial point on the dorsal border of the proximal articular surface
101 Most lateral point on the dorsal border of the distal articular surface
120 Most lateral point on the dorsal border of the proximal articular surface
121 Most proximal point on the border of the palmar radial epicondyle
140 Most lateral point on the palmar border of the proximal articular surface
141 Most proximal point on the border of the palmar ulnar epicondyle
160 Most medial point on the palmar border of the proximal articular surface
Semi-landmark curves
C1 18 coordinates between landmarks 1 and 20
C2 18 coordinates between landmarks 21 and 40
C3 18 coordinates between landmarks 41 and 60 on the crest for the insertion of the opponens pollicis muscle
C4 18 coordinates between landmarks 61 and 80
C5 18 coordinates between landmarks 81 and 100
C6 18 coordinates between landmarks 101 and 120
C7 18 coordinates between landmarks 121 and 140
C8 18 coordinates between landmarks 141 and 160

Visualize landmarks and semi-landmarks

The model closest to the mean shape was previously warped to match the multivariate mean using the thin plate spline method. The landmarks and semi-landmarks are plotted on the surface of this average 3D model. The 16 fixed landmarks correspond to the yellow spheres, whereas the 144 semi-landmarks correspond to the smaller red spheres. Please notice that the 3D model was decimated to an extremely small size (as compared to our original models) to avoid long computational times when rendering with rgl.