The enigma of the ulna in the primate wristMarie Vanhoof

Evie Vereecke, Filip Stockmans , Koen NelissenJan Palfijn Anatomy Lab, Dept. Development & Regeneration, University of Leuven Campus Kulak Kortrijk, Belgium

The wrist is a highly complex structure, asit is a combination of differentarticulations that together constitute theoverall mobility of the wrist.

marie.vanhoof@kuleuven.be

ACKNOWLEDGEMENTS

We would like to thank the zoos and institutions that contributed by providing the primate cadaverand skeletal specimens, and AZ Groeninge (Kortrijk, Belgium) for CT-scanning. The research is fundedby KU Leuven.

REFERENCES

* © Kristiaan D’AoûtLewis, O.J., 1969, Am J Phys Anthropol 30, 251-267Almécija et al., 2015, The Anatomical Record 298(1), 212-229.Boyer et al., 2015, The Anatomical Record 298(1), 249-276.

GEOMETRIC

MORPHOMETRICS

Include the 3D bone models of both the skeletal and cadaver specimens dataset: > 400 specimens of a wide range of primate taxa Use dedicated scripts and toolboxes for analysis (e.g. Fig. 2 and Boyer et al. (2015))

Figure 2: Left hamate of Pan troglodytes illustrating

the 23 surface landmarks (Almécija et al., 2015)

Investigate the interrelationship betweendistal ulnar and carpal morphology andwrist mobility in primate species with adistinct phylogenetic position relative tomodern humans and a differentlocomotor behaviour.

GOAL METHODOLOGY

RADIOULNAR

RANGE OF MOTION

Skeletal specimens and fresh-frozen cadaver specimens of different locomotor groups

A self-designed rig to standardize the wrist (and elbow) positions

Each cadaver specimen is CT-scanned in five positions (neutral, maximal radial/ulnar deviation, maximal pro/supination)

All scans include the entire radius, ulna, carpal bones and third metacarpal

1. Quantify differences in ulnar and carpal morphology across primates

2. Correlation between morphology of carpal bones and distal ulna across primates?

3. Link between different morphology and different locomotor behaviour?

BONOBO SCAPHOID

GIBBON SCAPHOID

Figure 1: Proximal wrist joint in different primates. S: scaphoid, L: lunate, T: triquetrum, P:

pisiform, R: radius, U: ulna, d: os daubentonii (intrameniscal), m: menisus [adapted from Lewis

(1969)]

What is the precise contribution of thesearticulations in radial and ulnardeviation?

During primate evolution, there is areduction of the distal ulna in thehominoid lineage (Fig. 1).

suspensory/brachiators terrestrial knuckle-walkers terrestrial palmigrades/digitigrades

3. Wrist kinematics contribution of differentarticulations to radial/ulnardeviation?

BABOON SCAPHOID

2. Segmentation of CT-scans to create 3D surface models to measurethe maximal range of motion (ROM)

ROM

1. CT-scanning

*

(n = 5) (n = 19)