Biomedical Engineering Reference
In-Depth Information
vertebrae, the relationship between the vertebral column
and bony pelvis, and the vascular supply of the tail.
Morphological features associated with obtaining samples
of cerebrospinal fluid are discussed in the section on
“Clinically significant features of head and neck
morphology” above. With this one exception, most of the
bony landmarks used to locate internal structures in the
cervical, thoracic, and abdominal regions are on the ventral
surface and are discussed with the thorax, abdomen, and
pelvis (see the sections “Thoracic morphology” and
“Abdominal and pelvic morphology” below).
In the vertebral column the spines of the middle thoracic
vertebrae, in particular, angle sharply caudally and the tip
of a spine may actually be dorsal to the body of the vertebra
caudal to it ( Figure 4.8A ). The spines of the lumbar
vertebrae are very broad in a cranial
vervet (Cercopithecus pygerythrus) and perhaps other
species as well, the lateral veins anastomose with the
median vein and artery at each tail segment
presumably
an arrangement which minimizes heat loss through the tail
( Hongo and Luck, 1953 ). The lateral caudal veins of the tail
are tributaries of the inferior gluteal veins. In species with
short tails, these vessels are more commonly referred to as
the superficial lateral coccygeal veins.
e
LIMB MORPHOLOGY
Overview of Limbs
The limbs of all primates follow the generalized mamma-
lian pattern, including five digits on each of the four
extremities. Modification of this basic pattern in primates is
rarely a change in the number of elements but rather species
differences in the relative curvature, robustness, and length
of bones as well as migration of the positions of muscle
attachments. Usually these differences in limb morphology
are not based solely on evolutionary relationships but
instead can be correlated with functional similarities, or
differences, in locomotor behavior and habitat use ( Ashton
and Oxnard, 1964 ) which are reflected in different housing
requirements (see the sections “Introduction” (above) and
“Clinically significant
caudal direction and
are easily palpated except those bracketed by the ilia. The
ilia project cranially from the sacroiliac joints and the iliac
crests usually lie approximately parallel to the inferior part
of the second to the last lumbar vertebrae. Although most
nonhuman primate anatomy is more similar to human
anatomy than to other mammals, the bony pelvis and its
relationship to the vertebral column is an exception. In this
case the nonhuman primate bony anatomy is similar to that
of other quadrupeds rather than to the human biped. The
soft tissue, as discussed in the sections on the abdomen,
pelvis, and perineum (see the sections “Abdominal and
pelvic morphology” and “Perineal morphology” below),
however, is more similar to humans in many respects.
Nonhuman primates are susceptible to the same age- or
trauma-related degenerative diseases of the spine as
humans. These include osteoporosis and the full spectrum
of degenerative joint diseases such as osteoarthritis (OA),
spondyloarthropathy, diffuse idiopathic skeletal hyperos-
tosis (DISH), calcium phyrophosphate dihydrate (CPPD or
pseudo-gout), etc. ( DeRousseau, 1985; Gahunia et al.,
1995; Rothschild et al., 1999; Rothschild, 2005 ). With
increased age and disease progression the spine becomes
more rigid and/or develops the kyphosis characteristic of
osteoporosis ( Cerroni et al., 2000 ).
In most mammals, the tail veins are frequently used for
accessing the circulation in obtaining blood and for intra-
venous injection. In Old and New World monkeys, the tail
is supplied with arterial blood via the caudal artery, a direct
branch leaving the dorsal aspect of the abdominal aorta just
proximal to its terminal bifurcation. It is the larger equiv-
alent of the median (middle) sacral artery of humans and
apes. This artery is initially accompanied by two caudal
veins which unite more distally to become the central vein
of the tail. Larger, more superficial, lateral veins also run
the length of the tail and are easily accessible for ven-
epuncture, but have unusually thick muscular walls capable
of vigorous constriction believed to assist the venous return
against gravity during sleep ( Hongo and Luck, 1953 ). In the
e
features of
limb morphology”
(below)).
The relative lengths of forelimbs, hindlimbs, and trunk,
and resultant body proportioning are commonly used to
morphologically characterize species. All higher primates
except the Callitrichidae have at least one pair of limbs
longer than their trunk. As discussed in the section on back
morphology above (see sections “Overview of back and
tail” and “Skeleton”), there is considerable variability in the
vertebral columns of primates, particularly in the lumbar
region. Short vertebral columns are frequently found in the
lesser and great apes and in species highly dependent on
suspensory locomotion. Long vertebral columns are found
most frequently in leaping species. In general, long limbs
relative to trunk length are found among terrestrial
quadrupedal primates, whereas relatively short limbs which
lower the center of gravity are common among arboreal
quadrupeds. However, arboreal species whose locomotion
emphasizes suspensory activities (brachiation, semi-
brachiation, or arm swinging) generally have relatively
long forelimbs while species who engage in extensive
vertical clinging and leaping usually have relatively long
hindlimbs.
The relative lengths of forelimbs and hindlimbs (inter-
membral index
¼
length humerus
þ
radius
100/length
femur
tibia) also vary considerably and can be correlated
to specific locomotor patterns ( Fleagle, 1999; Schultz,
1969 ). Limb length proportioning among mammals,
including primates, appears to result from differences in the
þ
Search WWH ::




Custom Search