Spinal column or Rachis
The spine is composed of a series of bones called vertebrae odd and short. Each vertebra has extensions called processes, spinous in the dorsal median position, and two transverse on both lateral sides, four joints, two on each side (cranial and caudal) and others that are found in the dorsal and lumbar vertebrae.
Subdivision of the spine:
Seven cervical vertebrae, already described in previous issues of AAC
Thirteen dorsal vertebrae (or thoracic)
Seven lumbar vertebrae
Three sacral vertebrae (welded together),
16 to 22 coccygeal vertebrae.
Pectoral girdle
Its anatomical basis is the scapula the only uneven bone, already described in previous numbers of AAC for both its anatomical characteristics and for its importance in the movement.
Pelvic girdle
The anatomical basis consists in the ileus, pubis and bilateral ischium, which are welded together at an early stage to form the coxal, a single bone in the shape of an airplane propeller, which is crucial in the movement.

The chest in the Chihuahua, viewed laterally, reaches the elbow, should never be as a barrel.
We can argue that the chest is well down in the chihuahua breed, indeed dogscience teaches us that if the lower profile of the chest reaches the elbow can be defined as a well down chest.
The depth or length is measured from the tip of the sternum to the penultimate asternal rib, the depth is due to the intercostal spacing. The greater the distance between the ribs, the greater the depth of the chest.

Breast
The anatomical base of the chest is given by the front of the sternum (dumbbell) and the pectoral muscles.
In the chihuahua the chest should never be too narrow, and a underdeveloped transverse diameter of the chest causes the approach of the top of the scapulae, flat ribs, weakens the muscles of the region with consequent decreased strength.

Ribs
Unequal region has as anatomical base the thirteen pairs of ribs and the intercostal muscles:
The ribs are divided into:
• Nine sternal pairs
• Four pairs of which the last one floating (asternal)
In the chihuahua, long and well arched ribs are to be found, their tilt is greater in the front to the back, the widest part of the chest should be slightly caudal at the elbows. the widest part of the chest should be slightly caudal to the elbows. This feature of the chest also helps a correct and typical chihuahua gait.

Sternum:
Uneven bone that delimits the ventral median rib cage
The sternum is composed of eight uneven segments called sternebrae with which the sternal ribs articulates by means of their costal cartilage.
The first cranial sternebrae is called the sternum dumbbell, at the tail ends with a cartilage called xiphoid cartilage.
In the chihuahua the direction of the xiphoid appendix is horizontal and encourages a belly slightly tucked up and avoids the effect of "pipe trunk". In the Xiphoid apophysis the abdominal muscles take origin.

Back
The anatomical base consists of the last eight thoracic vertebrae and muscles of the region.
In the chihuahua the back is short and taut.
The spinous processes of thoracic vertebrae have a cranial -caudal direction up to the eleventh caudal vertebra, called anticlinal, that, with the exception of the first, have a almost vertical direction .
One possible flaw is lordosis, also known as sway-back or saddle-back, found in the dorsal region and determining a large concave curve. In the saddle-back the spinous processes are arranged incorrectly, converging at their ends. In this case, the back can be technically called a celoide(concave) profile , resulting in fatigue and poor resistance to movement. In this region you can also find another kind of profile fault, technically called cirtoide , which is a convex arch on the back, also known as kyphosis. This type of profile starts from the tenth dorsal vertebra continuing up to the arch of the loins. There is no flexibility of the spine: and as a consequence there is a change in the motion.

In the next issue will analyze other regions of the trunk, back, loins, and tail.