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The ear
upper part of the neck, directly or indirectly (but there are no lym-
The ear is subdivided into the outer ear, the middle ear and the inner ear.
phatics in the cranial cavity).
• The lower deep cervical nodes (jugulo-omohyoid nodes): in the
The outer ear mandible and also deep to sternomastoid. They drain the head and the
The outer third of this is cartilaginous and the inner two-thirds is bony. posterior triangle between the lower end of sternomastoid and the clav-
Lined by skin with ceruminous (wax) glands. icle. They drain the lower part of the neck and also receive lymph from
the upper deep cervical nodes, from the breast and some of the lymph
The middle ear from the thorax and abdomen. The efferents from this group drain into
This has four walls, a roof and a floor. It can therefore be represented the thoracic or left lymph duct via the jugular trunk.
diagrammatically by an opened-out box (Fig. 70.1). • Smaller groups of nodes are shown in Fig. 70.3.
• The lateral wall: • The lymph drainage of the tongue: the tip of the tongue drains into
• The tympanic membrane (Fig. 70.2)athe handle of the malleus the submental nodes. The rest of the anterior two-thirds drains into the
embedded in its middle layer. This is crossed by the chorda tym- submandibular nodes, some crossing the midline and some passing
pani, above which is the pars flaccida. The ‘cone of light’ is the directly to the upper deep cervical nodes. The posterior two-thirds
reflection of the light from the auriscope. drains directly into the upper deep cervical nodes.
• The epitympanic recess (attic)athe part of the middle ear cavity • The lymph drainage of the larynx: above the vocal cords the larynx
above the tympanic membrane. drains into the infrahyoid nodes and thence to the upper deep cervical
• The ossicles: the malleus, incus and stapesathe stapes engages group. Below the cords, drainage is to the paratracheal and inferior
with the oval window. The ossicles transmit vibrations of the mem- deep cervical nodes.
brane to the inner ear.
• The medial wall: Surface anatomy of the head and neck
• The promontoryaa bulge produced by the first turn of the cochlea. • The middle meningeal artery: the anterior branch may be exposed
• The oval windowaleads into the inner ear. at a point 4 cm above the midpoint of the zygomatic arch. The posterior
• The facial nervearuns backwards and then downwards in a bony branch may be represented on the surface by a pencil placed behind the
canal in the medial wall. It bears the geniculate ganglion and gives ear.
off the chorda tympani.
• The anterior wall: the pharyngotympanic (Eustachian) tube opens The face
onto the anterior wall and leads down to the nasopharynx. Its function • The supraorbital, infraorbital and mental nerves: all lie on a ver-
is to equalize the pressure between the middle ear and the pharynx. tical line passing between the two premolar teeth.
• The posterior wall: the aditus leads backwards into the mastoid • The facial artery can be felt on the mandible at the anterior border of
antrum, a cavity in the mastoid bone which, in turn, leads into the mas- the masseter.
toid air cells. • The superficial temporal artery is just in front of the tragus of the
• The roof: the tegmen tympani, a thin plate of bone that separates the ear.
middle ear from the middle cranial fossa. • The parotid duct follows the middle part of a line from the tragus of
• The floor: separates the middle ear from the internal carotid artery the ear to the middle of the upper lip. It hooks over the anterior border
and the internal jugular vein. of the masseter where it can be easily felt.

The inner ear The neck
The inner ear is involved in both hearing and balance. It consists of two • The sternomastoid muscle (with the external jugular vein on its sur-
components: face) may be made to contract by asking the patient to turn his head to
• The osseous labyrinth: comprises the vestibule, the semicircular the opposite side against resistance.
canals and the cochlea. The labyrinth itself consists of spaces in the • The trunks of the brachial plexus can be palpated in the angle
petrous temporal bone and it contains the membranous labyrinth. between the sternomastoid and the clavicle.
• The membranous labyrinth: comprises the utricle and saccule (in • The subclavian artery is palpable by deep pressure behind the
the vestibule), the semicircular ducts (in the semicircular canals) and middle of the clavicle. A cervical rib may also be palpable.
the duct of the cochlea (in the cochlea). The utricle and saccule are con- • The hyoid bone, and the thyroid and cricoid cartilages are easily
cerned with the sense of position and the semicircular ducts are con- felt. The larynx, and any swellings associated with it, move upwards
cerned with the sensation of motion. The cochlear duct is the organ of on swallowing, as does the thyroid gland. Thyroglossal cysts move
hearing. All are supplied by the vestibulocochlear (auditory) nerve. upwards when the tongue is protruded.
• The trachea is palpable in the suprasternal notch.
The lymphatics of the head and neck (Fig. 70.3) • The common carotid artery can be felt in front of sternomastoid
• Upper deep cervical nodes (jugulodigastric nodes): these are situ- and can be compressed against the transverse process of the 6th cer-
ated between the upper end of sternomastoid and the angle of the vical vertebra (carotid tubercle).

The ear, and lymphatics and surface anatomy of the head and neck 157