QUICK SEARCH:   [advanced] Author: Keyword(s):
Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents

First published online November 19, 2004
Journal of Experimental Biology 207, 4427-4438 (2004)
Published by The Company of Biologists 2004
doi: 10.1242/jeb.01282

This Article Summary Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Dunbar, D. C. Search for Related Content PubMed PubMed Citation Articles by Dunbar, D. C.

Stabilization and mobility of the head and trunk in vervet monkeys (Cercopithecus aethiops) during treadmill walks and gallops

Donald C. Dunbar

Department of Anatomy and Caribbean Primate Research Center, School of Medicine, University of Puerto Rico, PO Box 365067, San Juan, PR 00936-5067, USA

View larger version (14K): [in a new window]   Fig. 1. Measured axes and angles in the pitch plane. Head axis was a line passing through the external auditory meatus and the apex of the mouth. Trunk axis was a line passing through the hip and shoulder joints. Head angle relative to space () and trunk angle relative to space (ß) were measured in reference to earth horizontal. Head-to-trunk angle () was calculated from the head-to-space and trunk-to-space angles.

View larger version (22K): [in a new window]   Fig. 2. Cine film tracing of (A) a diagonal-sequence walk with the head oriented between 45° and 90° to the trunk while rotating downwards and upwards, (B) a rotary gallop with no head rotation in the yaw plane, and (C) a rotary gallop with a large head rotation to the right of more than 90° in the yaw plane.

View larger version (17K): [in a new window]   Fig. 3. Ranges and mean positions of the head and trunk during treadmill walks and gallops (N=10 cycles/gait). Vervet head range is plotted against trunk range (A). The circles depict walks and the crosses depict gallops. A comparable head range-trunk range plot (B) based on overground locomotor data for two other species (Macaca radiata or bonnet macaque, Semnopithecus entellus or hanuman langur) is provided for comparison (Dunbar et al., 2004). The circles depict walks and the crosses depict gallops by bonnet macaques, whereas the squares depict walks and the inverted triangles depict gallops by hanuman langurs. In A and B, the horizontal and vertical dashed lines indicate the 20° threshold for stabilization of the head and trunk, respectively. Mean head (C) and trunk (D) positions are plotted against locomotor velocity. In A and C, the clusters of symbols to the left (lower velocities) are for walks, whereas the clusters to the right (higher velocities) are for gallops.

View larger version (22K): [in a new window]   Fig. 4. Segmental angular displacements and instantaneous angular velocities during single representative cycles of a diagonal sequence walk (left column) and a rotary gallop (right column) at treadmill speeds of 1.68 m s–1 and 2.56 m s–1, respectively. Note that in this gallop cycle (B), the head is pitching through less than 20° and is not rotating in any other plane. The (A,B) segmental displacement graphs depict changes in head-to-space (H–S,), trunk-to-space (T–S), and head-to-trunk (H–T) angles. Earth horizontal is indicated by 0° (dashed horizontal line), and negative values indicate a nose-down angle of the head axis and a shoulders-down angle of the trunk axis. The horizontal lines depict the support phases of the left hind limb (LH), left forelimb (LF), right forelimb (RF) and right hind limb (RH). The remaining graphs depict instantaneous angular velocity changes of (C,D) the head relative to space, (E,F) the trunk relative to space and (G,H) the head relative to the trunk. In (C,D) the head-to-space velocity graphs, the solid horizontal lines indicate 350° s–1 that, at least in humans, is the saturation velocity for the vestibulo–ocular (VOR) reflex (Pulaski et al., 1981).

View larger version (22K): [in a new window]   Fig. 5. Segmental angular displacements and instantaneous velocities during single representative cycles of rotary gallops at treadmill speeds of 2.57 m s–1 (left column) and 3.03 m s–1 (right column). Note that in left gallop cycle (A), both the head and trunk are rotating through more than 20° in the pitch plane, but that the head has just surpassed this threshold. Note also that in the right gallop cycle (B), head rotation in the pitch plane exceeds 20° by several degrees, but that trunk rotations have dropped to below 20°. In both cycles, however, head rotations do not occur in any other plane. The (A,B) segmental displacement graphs depict changes in head-to-space (H–S), trunk-to-space (T–S) and head-to-trunk (H–T) angles. Earth horizontal is indicated by 0° (dashed horizontal line), and negative values indicate a nose-down angle of the head axis and a shoulders-down angle of the trunk axis. The horizontal lines depict the support phases of the left hind limb (LH), left forelimb (LF), right forelimb (RF), and right hind limb (RH). The remaining graphs depict instantaneous angular velocity changes of (C,D) the head relative to space, (E,F) the trunk relative to space, and (G,H) the head relative to the trunk. In (C,D) the head-to-space velocity graphs, the solid horizontal lines indicate 350° s–1 that, at least in humans, is the saturation velocity for the vestibulo–ocular (VOR) reflex (Pulaski et al., 1981).