Page 323 - Clinical Anatomy

ECA5 7/18/06 6:51 PM Page 308

308 The head and neck

enlarged in tonsillitis and is therefore the commonest swelling to be
encountered in the neck.
2◊◊Block dissection of the neck for malignant disease is the removal of the
lymph nodes of the anterior and posterior triangles of the neck and their
associated lymph channels, together with those structures which must be
excised in order to make this lymphatic ablation possible. It is sometimes
combined with en-bloc removal of the primary tumour.
The usual incision is Y-shaped, its centre being at the level of the upper
border of the thyroid cartilage, its lower limb running downwards to the
midpoint of the clavicle, its anterior limb extending to the symphysis menti
and its posterior limb to the mastoid process. The block of tissue removed
extends from the mandible above to the clavicle below and from the
midline anteriorly to the anterior border of the trapezius behind. It consists
of all the structures between the platysma and pretracheal fascia enclosed
by these boundaries, preserving only the carotid arteries, the vagus trunk,
the cervical sympathetic chain and the lingual and hypoglossal nerves. The
sternocleidomastoid, omohyoid and digastric muscles are removed in the
dissection. Excision also includes the external and internal jugular veins,
around each of which lymph nodes are intimately related, and the sub-
mandibular gland and the lower pole of the parotid gland, since these both
contain potentially involved lymph nodes.
The accessory nerve, passing across the posterior triangle, is usually
sacrificed.
3◊◊Tuberculous disease of the neck usually involves the upper part of the
deep cervical chain (from tonsillar infection). These infected nodes may
adhere very firmly to the internal jugular vein which may be wounded in
the course of their excision.

The cervical sympathetic trunk

The sympathetic chain continues upwards from the thorax by crossing the
neck of the first rib, then ascends embedded in the posterior wall of the
carotid sheath to the base of the skull (Fig. 220). It bears three ganglia:
1◊◊the superior cervical ganglion (the largest) lies opposite C2 and 3 vertebrae
and sends grey rami communicantes to C1–4 spinal nerves;
2◊◊the middle ganglion lies level with C6 vertebra and sends grey rami to C5
and 6 nerves;
3◊◊the inferior ganglion lies level with C7 and is tucked behind the vertebral
artery. Frequently, it fuses with the first thoracic ganglion to form the stellate
ganglion at the neck of the first rib. Grey rami pass from it to C7 and 8
nerves.
Note that these ganglia receive no white rami from the cervical nerves;
their preganglionic fibres originate from the upper thoracic white rami and
then ascend in the sympathetic chain.
As well as somatic branches transmitted with the cervical nerves, the