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Arterial Supply and Sensory Innervation of the Temporomandibular Joint _____ 31^
Arterial Supply and Sensory Innervation of the Temporomandibular Joint
The arterial blood supply of the temporomandibular joint is
provided primarily by the maxillary artery and the superficial
temporal artery (Boyer et al. 1964). Both of these arteries
are also the principle supply for the muscles of mastication.
Apart from the network of arteries surrounding it, the
condyle is also supplied from the inferior alveolar artery
through the bone marrow (Okeson 1998). The venous
drainage is through the superficial temporal vein, the maxillary
plexus, and the pterygoid plexus. The sensory
innervation of the joint capsule and its receptors has already
been addressed briefly on page 27. The tem-
poromandibular joint is innervated predominantly by the
auriculotemporal, masseter, and temporal nerves (Klineberg
et al. 1970, Harris and Griffin 1975). Proprioception occurs
through four types of receptors (Thilander 1961, Clark and
Wyke 1974, Zimny 1988): Ruffini mechanoreceptors (type I),
pacinian corpuscles (type II), Golgi tendon organs (type III),
and free nerve endings (type IV). These receptors are located
in the joint capsule, the lateral ligament, and in the bilaminar
zone and its genu vasculosum. The anteromedial portion
of the capsule contains relatively few pain receptors, of
type IV (Thilander 1961).
72 Arterial supply
Diagram of the arterial blood supply
of a left temporomandibular
joint (modified after Voy and Fuchs
1980). The condyle is supplied with
blood from all four sides. In addition,
there are anastomoses with
the inferior alveolar artery within
the marrow spaces. Because of the
abundant blood supply, avascular
necrosis is rarely found in the
condyle (Hatcher etal. 1997). Compression
of the anterior vessels by
anterior disk displacement (Schellhas
et al. 1992) will not interfere
with the condyle's blood supply.
73 Sensory innervation of a left
temporomandibular joint
The afferent nerve fibers arise from
the mandibular branch of the
trigeminal nerve and exhibit four
types of nerve endings. In rats, free
nerve endings (type IV), which are
potential pain receptors, have been
found in the capsule, lateral ligament,
bilaminar zone, and in the
pars anterior and pars posterior of
the disk (Ichikawa et al. 1990, Kido
et al. 1991). This has not been verified
for human disk structures,
however.
74 Innervation in the capsule
region
Schematic diagram of the different
areas of innervation (modified from
Ishibashi 1974, Schwarzer 1993).
Activation of the type-IV receptors
in the capsule increases the activity
of sympathetic efferent fibers
(Roberts and Elardo 1985). Because
of the sympathetic innervation of
the intrafusal muscle fibers (Grassi
et al. 1993), a secondary rise in
muscle tone is brought about by
activation of the afferent fibers of
the muscle spindles and the efferent
α-motoneurons (Schwarzer
1993).