Twelfth rib
Encyclopedia
The twelfth rib has a single articular facet
on the head
, which is of rather large size. It has no necks
or tubercles, and is pointed at its anterior ends.
The twelfth has angle
nor costal groove
; it is much shorter than the eleventh rib
, and its head is inclined slightly downward.
Sometimes the twelfth rib is even shorter than the first rib
.
Articular facet
An articular facet is a surface where two anatomical structures meet.-Structures with articular facets:* cricoid cartilage* lateral malleolus* medial malleolus* tubercle of rib...
on the head
Head of rib
The head of the rib is the end of a rib closest to the vertebral column, with which it articulates.It is marked by a kidney-shaped articular surface, divided by a horizontal crest into two facets for articulation with the depression formed on the bodies of two adjacent thoracic vertebrae; the upper...
, which is of rather large size. It has no necks
Neck of rib
The neck of the rib is the flattened portion which extends laterally from the head; it is about 2.5 cm. long, and is placed in front of the transverse process of the lower of the two vertebræ with which the head articulates....
or tubercles, and is pointed at its anterior ends.
The twelfth has angle
Angle
In geometry, an angle is the figure formed by two rays sharing a common endpoint, called the vertex of the angle.Angles are usually presumed to be in a Euclidean plane with the circle taken for standard with regard to direction. In fact, an angle is frequently viewed as a measure of an circular arc...
nor costal groove
Costal groove
The Costal groove is a groove between the ridge of the internal surface of the rib and the inferior border. It contains the intercostal vessels and intercostal nerve....
; it is much shorter than the eleventh rib
Eleventh rib
The eleventh rib has a single articular facet on the head, which is of rather large size.It has no necks or tubercles, and is pointed at its anterior ends.The eleventh has a slight angle and a shallow costal groove....
, and its head is inclined slightly downward.
Sometimes the twelfth rib is even shorter than the first rib
First rib
The first rib is the most curved and usually the shortest of all the ribs; it is broad and flat, its surfaces looking upward and downward, and its borders inward and outward....
.