Biomedical Engineering Reference
In-Depth Information
A common site for venepuncture in some animal
species is the external jugular vein. Although this vessel is
accessible in higher primates, it is usually easier to obtain
blood samples from either the femoral or saphenous veins.
The external jugular vein in higher primates is relatively
short and drains blood almost exclusively from the region
of the face. The brain and deep face are drained by the
internal jugular vein which joins the external jugular vein
near the root of the neck. In Old World monkeys with cheek
pouches the exploration of the extent of these recesses
should precede venepuncture of the external jugular vein.
Samples of cerebrospinal fluid from higher primates are
readily obtainable by entering the subarachnoid space
either between the base of the skull and the first cervical
vertebra or between the first and second cervical vertebrae
(C1 and C2). Marked flexion of the head and neck opens up
spaces between the posterior (dorsal) arch of C1 and both of
the adjacent bones. The nuchal ridge of the skull and the
spine of C2 are easily palpable bony landmarks
(
Figure 4.11
). Withdrawal of cerebrospinal fluid lower in
the vertebral canal is obstructed by the broad articular
processes of the lumbar vertebrae and the cranial placement
of the iliac blades of the pelvis.
Nonhuman primates are models for both induced and
naturally occurring gingivitis and periodontitis (
Schou
et al., 1993
). The human oral region is similar to that of
nonhuman primates thus supporting the latter's use as
models examining the regulatory mechanisms for induction
of periodontal tissue regeneration (
Ripamonti et al., 2009
)
and evaluating factors contributing to successful peri-
odontal ligament formation around various types of dental
implants (
Warrer et al., 1993; Watzak et al., 2005
).
Increasingly, nonhuman primates are being recognized
for their value in studying human cognitive development
and decline, as well as the prevention, consequences, and
possible rehabilitation from stroke. Not surprisingly, given
their close evolutionary relationship to humans, nonhuman
higher primate brains conserve much of the structural basis
of cortical organization found in humans (
Dehaene et al.,
2005
). CNS myelination follows the same schedule in
humans and rhesus macaques (
Gibson, 1991
), suggesting
that this same sequence might characterize most higher
primates. However, the extent of myelination at birth and
its postnatal speed and duration appears correlated with the
length of the pre-adult part of the life cycle (
Gibson, 1991
).
FIGURE 4.11
Skeletal components of the nuchal region with the
head flexed ventrally (dorsal view of the skull and the first and second
cervical vertebrae of an Old World monkey, Macaca mulatta). Note
the thin dorsal (posterior) arch of the first cervical vertebra and the short
spine of the second cervical vertebra. Flexion of the head increases the
spaces between the occipital bone of the skull and C1 as well as the space
between C1 and C2. (Drawings by Nancy Hong.)
conduit of arterial blood to the brain. In nonhuman primates
the relative size of these two vessels is the reverse of that in
humans.
The innervation to structures in the head and neck
region of nonhuman primates in general is the same as in
humans (
Christensen, 1933; Howell and Straus, 1933b;
Kuntz, 1933
) and is supplied via the eight cervical spinal
nerves and the 12 cranial nerves. The cranial nerves include
both somatic and autonomic (parasympathetic) fibers and
ganglia and carry postganglionic fibers of the sympathetic
nerves following the basic patterns described in topics on
human anatomy.
Clinically Significant Features of Head and
Neck Morphology
Clinically significant features of head and neck
morphology include the approaches for obtaining samples
of blood and cerebrospinal fluid, the use of dental eruption
for aging immature animals (see also the section “Dental
and skeletal maturation” above), and their use as models for
studying pathology and normal development of the brain.
BACK AND SPINE MORPHOLOGY
Overview of Back and Tail
The vertebral column of higher primates typically has
26
31 vertebrae, exclusive of the tail, with most variability
occurring in the lumbar and sacral regions (
Shapiro, 1993
).
The functional components of the back, however, are more
e
