Page 387 - Clinical Anatomy

ECA6 7/18/06 6:54 PM Page 372

372 The central nervous system

fossa is the relatively large pterygopalatine ganglion. This receives its
parasympathetic or secretomotor root from the greater superficial petrosal
branch of VII, its sensory component from two pterygopalatine branches of
the maxillary nerve and its sympathetic root from the internal carotid plexus.
Its parasympathetic efferents pass to the lacrimal gland through a commu-
nicating branch to the lacrimal nerve. Sensory and sympathetic (vasocon-
strictor) fibres are distributed to nose, nasopharynx, palate and orbit.

V : The mandibular nerve (see Fig. 260)
3
This is the largest of the three divisions of the trigeminal nerve and the only
one to convey motor fibres. In addition to supplying the skin of the tempo-
ral region, part of the auricle and the lower face, the mucous membrane of
the anterior two-thirds of the tongue and the floor of the mouth, it also
conveys the motor root to the muscles of mastication and secretomotor
fibres to the salivary glands.
Passing forwards from the trigeminal ganglion, it almost immediately
enters the foramen ovale through which it reaches the infratemporal fossa.
Here it divides into a small anterior and a larger posterior trunk, but before
doing so it gives off the nervus spinosus to supply the dura mater and the
nerve to the medial pterygoid muscle from which the otic ganglion is suspended
and through which motor fibres are transmitted to tensor palati and tensor
tympani.
The anterior trunk gives off:
1◊◊a sensory branch, the buccal nerve, which supplies part of the skin of the
cheek and the mucous membrane on its inner aspect; and
2◊◊motor branches to the masseter, temporalis and lateral pterygoid
muscles.
The posterior trunk, which is principally sensory, divides into three
branches:
1◊◊the auriculotemporal nerve, which conveys sensory fibres to the skin of
the temple and auricle and secretomotor fibres from the otic ganglion to the
parotid gland;
2◊◊the lingual nerve, which passes downwards under cover of the ramus of
the mandible to the side of the tongue (Fig. 197), where it supplies the
mucous membrane of the floor of the mouth, the anterior two-thirds of
the tongue (including the taste buds by way of fibres which join it from the
chorda tympani), and the sublingual and submandibular salivary glands;
3◊◊the inferior alveolar (dental) nerve, which passes down into the mandibu-
lar canal and supplies branches to the teeth of the lower jaw. It then emerges
from the mental foramen to supply the skin of the chin and lower lip. This
branch also conveys the only motor component of the posterior trunk: the
nerve to the mylohyoid, supplying the muscle of that name and the anterior
belly of the digastric.

The otic ganglion

The otic ganglion is unique among the four ganglia associated with the