Page 1155 - Equine Clinical Medicine, Surgery and Reproduction, 2nd Edition

1130 CHAPTER 11

VetBooks.ir 11.5 11.6

Figs. 11.5, 11.6 Palpebral response. Gently tapping the medial (11.5) or lateral (11.6) canthus will stimulate
the sensory branches of CN V and generate the afferent stimulus. The efferent motor branch of the reflex is
mediated by CN VII.

11.7 11.8

Fig. 11.7 Menace response. A threatening gesture 11.9
is made near the eye; the expected response is eyelid
closure, often accompanied by movement of the head
away from the stimulus. You must be careful to avoid
producing air currents or inadvertently touching the
vibrissae while performing this test.

Figs. 11.8, 11.9 Pupillary light reflex. (11.8)
Normal pupil in ambient light. (11.9) Pupil under
effect of direct bright light stimulus. The retina, CN
II and the midbrain mediate the afferent arm of this
reflex, whereas the efferent motor pathway is through
CN III and the iris sphincter muscle.