Preferred Label : rib endochondral element;
Uberon definition : A rib bone or its cartilage or pre-cartilage precursor.;
Uberon synonym : rib element;
Uberon broad term : rib skeletal element;
Uberon Taxon note : Humans have 24 ribs (12 pairs). The first seven sets of ribs, known as 'true ribs',
are directly attached to the sternum through the costal cartilage. The following five
sets are known as 'false ribs', three of these sharing a common cartilaginous connection
to the sternum, while the last two (eleventh and twelfth ribs) are termed floating
ribs (costae fluitantes) or vertebral ribs. They are attached to the vertebrae only,
and not to the sternum or cartilage coming off of the sternum. Some people are missing
one of the two pairs of floating ribs, while others have a third pair. Rib removal
is the surgical excision of ribs for therapeutic or cosmetic reasons. In fish, there
are often two sets of ribs attached to the vertebral column. One set, the dorsal ribs,
are found in the dividing septum between the upper and lower parts of the main muscle
segments, projecting roughly sideways from the vertebral column. The second set, of
ventral ribs arise from the vertebral column just below the dorsal ribs, and enclose
the lower body, often joining at the tips. Not all species possess both types of rib,
with the dorsal ribs being most commonly absent. Sharks, for example, have no dorsal
ribs, and only very short ventral ribs, while lampreys have no ribs at all. In some
teleosts, there may be additional rib-like bones within the muscle mass. Tetrapods,
however, only ever have a single set of ribs which are probably homologous with the
dorsal ribs of fishes. In the early tetrapods, every vertebra bore a pair of ribs,
although those on the thoracic vertebrae are typically the longest. The sacral ribs
were stout and short, since they formed part of the pelvis, connecting the backbone
to the hip bones.[1] In most subsequent forms, many of these early ribs have been
lost, and in living amphibians and reptiles, there is great variation in rib structure
and number. For example, turtles have only eight pairs of ribs, which are developed
into a bony or cartilagenous carapace and plastron, while snakes have numerous ribs
running along the full length of their trunk. Frogs typically have no ribs, aside
from a sacral pair, which form part of the pelvis.[1]. In birds, ribs are present
as distinct bones only on the thoracic region, although small fused ribs are present
on the cervical vertebrae. The thoracic ribs of birds possess a wide projection to
the rear; this uncinate process is an attachment for the shoulder muscles.[1]. Mammals
usually also only have distinct ribs on the thoracic vertebra, although fixed cervical
ribs are also present in monotremes. In marsupials and placental mammals, the cervical
and lumbar ribs are found only as tiny remnants fused to the vertebrae, where they
are referred to as transverse processes. In general, the structure and number of the
true ribs in humans is similar to that in other mammals. Unlike reptiles, caudal ribs
are never found in mammals.;
Origin ID : 0015019;
part of
A rib bone or its cartilage or pre-cartilage precursor.
