s will look
almost vertically towards the pharyngeal pouch. When the juggler is
about to "swallow the sword," he throws the head back so as to bring the
mouth and fauces in a straight line with the pharynx and oesophagus. And
when the surgeon passes the probang or other instruments into the
oesophagus, he finds it necessary to give the head of the person on whom
he operates the same inclination backwards. When instruments are being
passed into the oesophagus through the nasal fossa, they are not so
likely to encounter the rima glottidis below the epiglottis, 9, as when
they are being passed into the oesophagus by the mouth. The glottis may
be always avoided by keeping the point of the instrument pressing
against the back of the pharynx during its passage downwards.

When in suspended animation we endeavour to inflate the lungs through
the nose or mouth, we should press the larynx, 10, 11,12, backwards
against the vertebral column, so as to close the oesophageal tube.

DESCRIPTION OF PLATES 20 & 21.

PLATE 20.

A A. The dura-matral falx; A*, its attachment to the tentorium.

B. Torcular Herophili.

C. Dura-mater lining the spinal canal.

D D*. Axis vertebra.

E E*. Atlas vertebra.

F F*. Basilar processes of the sphenoid and occipital bones.

G. Petrous part of the temporal bone.

H. Cerebellar fossa.

I I*. Seventh cervical vertebra.

K K*. First rib surrounding the upper part of the pleural sac.

L L*. Subclavian artery of the right side overlying the pleural sac.

M M*. Right subclavian vein.

N. Right common carotid artery cut at its origin.

O. Trachea.

P. Thyroid body.

Q. Oesophagus.

R. Genio-hyo-glossus muscle.

S. Left tonsil beneath the mucous membrane.

T. Section of the lower maxilla.

U. Section of the upper maxilla.

V. Velum palati in section.

W. Inferior spongy bone.

X. Middle spongy bone.

Y. Crista galli of oethmoid bone.

Z. Frontal sinus.

2. Anterior cartilaginous part of nasal septum.

3. Nasal bone.

4. Last molar tooth of the left side of lower jaw.

5. Anterior pillar of the fauces.

6. Posterior pillar of the fauces.

7. Genio-hyoid muscle.

8. Opening of Eustachian tube.

9. Epiglottis.

10. Hyoid bone.

11. Thyroid bone.

12. Cricoid bone.

13. Thyroid axis.

14. Part of anterior scalenus muscle.

15. Humeral end of the clavicle.

16. Part of posterior scalenus muscle.

[Illustration: Head and neck, in section, from front