Functional cervicothoracic boundary modified by anatomical shifts in the neck of giraffes

Abstract

Here we examined the kinematic function of the morpho-logically unique first thoracic vertebra in giraffes. The first thoracic vertebra of the giraffe displayed similar shape to the seventh cervical vertebra in general ruminants. The flexion experiment using giraffe carcasses demonstrated that the first thoracic vertebra exhibited a higher dorsoventral mobility than other thoracic vertebrae. Despite the presence of costovertebral joints, restriction in the intervertebral movement imposed by ribs is minimized around the first thoracic vertebra by subtly changes of the articular system between the vertebra and ribs.