Page 295 - Clinical Anatomy

ECA5 7/18/06 6:50 PM Page 280

280 The head and neck

derived from the lingual, ascending palatine and ascending pharyngeal
arteries.
The venous drainage passes to the pharyngeal plexus. An important
constant vein, the paratonsillar vein, descends from the soft palate across the
lateral aspect of the tonsillar capsule. It is nearly always divided in tonsil-
lectomy and may give rise to troublesome haemorrhage.
Lymph drainage is via lymphatics which pierce the superior constrictor
muscle and pass to the nodes along the internal jugular vein, especially the
tonsillar or jugulodigastric node at the angle of the jaw. Since this node is
affected in tonsillitis it is the most common lymph node in the body to
undergo pathological enlargement.
Embryologically, the tonsil derives from the second internal branchial
pouch (Fig. 194).

Clinical features

1◊◊Tonsillectomy may be carried out by dissection or by the guillotine; both
depend on removing the lymphoid tissue and underlying fascial capsule
from the loose areolar tissue clothing the superior constrictor in the floor of
the tonsillar fossa. In dissection, an incision is made in the mucosa of the
anterior pillar immediately in front of the tonsil; the gland is then freed by
blunt dissection until it remains attached only by its pedicle of vessels near
its lower pole. This pedicle is then crushed and divided by means of a wire
snare.
In the second method, the guillotine is applied so that the tonsil bulges
through the ring in the instrument. The tonsil is then removed by closing
the blade of the guillotine.
Unless there have been repeated infections, the superior constrictor lies
separated from the palatine tonsil and its capsule by loose areolar tissue
which prevents the pharyngeal wall being dragged into danger during
tonsillectomy.
Similarly, the internal carotid artery, although only 1in (2.5cm) behind
the tonsil, is never injured in this operation since it lies safely freed from the
pharynx by fatty tissue around the carotid sheath.
2◊◊A quinsy is suppuration in the peritonsillar tissue secondary to tonsilli-
tis. It is drained by an incision in the most prominent part of the abscess
where softening can be felt.

The laryngopharynx
The laryngopharynx extends from the level of the tip of the epiglottis to the
termination of the pharynx in the oesophagus at the level of C6.
The inlet of the larynx, defined by the epiglottis, aryepiglottic folds
and the arytenoids, lies anteriorly. The larynx itself bulges into this part of
the pharynx leaving a deep recess anteriorly on either side, the piriform
fossa, in which sharp ingested foreign bodies (for example, fish bones), may
lodge.