Generality
The thoracic vertebrae are the 12 vertebrae that make up the thoracic segment of the vertebral column, interposing between the 7 thoracic vertebrae and the 5 lumbar vertebrae.
The thoracic vertebrae have the task of protecting the thoracic spinal cord and contribute to the formation of the thoracic cage, through the anchoring of the ribs.
Identified by the capital letter T and a number from 1 to 12 depending on the cranio-caudal position, the thoracic vertebrae are vertebrae whose dimensions are greater than those of the cervical vertebrae, but smaller than those of the lumbar vertebrae.
The thoracic vertebrae can be protagonists of a medical condition called hypercyphosis or pathological kyphosis.
What are thoracic vertebrae?
The thoracic vertebrae are the 12 vertebrae that follow the 7 thoracic vertebrae and precede the 5 lumbar vertebrae .
The thoracic vertebrae are the constituent elements of the so-called thoracic tract (or segment ) of the spine.
The thoracic vertebrae are identified with the capital letter T (which stands for "thoracic"), plus a number between 1 and 12, which indicates its cranio-caudal positioning along the vertebral column (clearly, the number 1 identifies the first vertebra thoracic, number 2 the second thoracic vertebra etc.).
To understand: revision of the Vertebral Column and Vertebrae
- The spine, or spine, is the bone structure that:
- It runs vertically along the center of the back;
- It is the backbone of the human body;
- It houses and protects the spinal cord (which, along with the brain, makes up the central nervous system ).
- Starting from the apex, the vertebral column can be divided into 5 segments (or sections): the cervical segment, the s. thoracic, the s. lumbar, the s. sacral and the s. coccygeal;
- The vertebral column is composed of 33-34 overlapping irregular bones, called vertebrae, which are separated from each other by a thin fibrocartilage structure called the intervertebral disk;
- Of the 33-34 vertebrae forming the spine, 7 belong to the cervical tract, 12 to the thoracic tract, 5 to the lumbar tract, 5 to the sacral tract and 4/5 to the coccygeal tract;
- Although their specific anatomy varies in relation to the tract of spine considered, all the vertebrae present:
- A cuboid-shaped element in a ventral position, called a vertebral body ;
- An arched formation in dorsal position, called vertebral arch ;
- A hole between the arch and the body, whose name is a vertebral hole ;
- A prominence in the center of the outer edge of the arch, called the spinous process ;
- A prominence for each external side of the vertebral arch, called the transverse process .
Anatomy
The thoracic vertebrae are vertebrae whose size is somewhere between that of the cervical vertebrae and that of the lumbar vertebrae; if it is observed carefully, it is possible to notice that they are gradually larger as they approach the lumbar spine (in other words, starting from the top, they become progressively larger).
The thoracic vertebrae take part in the constitution of the thoracic cage, together with the 12 pairs of ribs - which emerge at the sides of the same thoracic vertebrae - and at the sternum .
What is the function of the rib cage?
Consisting of the 12 thoracic vertebrae, the sternum and the 12 pairs of ribs (or ribs), the thoracic cage is the skeletal structure of the upper part of the trunk, which has the task of:
- Enclose and protect vital organs, such as the heart, lungs, esophagus and spinal cord;
- Enclose and protect important blood vessels, such as the aorta, the first branches of the aorta, the superior vena cava and the inferior vena cava;
- Support the weight of the body, especially through the vertebral component;
- Allow the expansion of the lungs during the breathing process through the movement of the ribs.
The thoracic vertebrae belong to the particular category of vertebrae, which, in addition to the classic transverse and thorny processes, also presents the two upper joint processes and the two lower joint processes.
The thoracic vertebrae differ not only from a dimensional point of view: as will be seen later, the thoracic vertebrae T1, T9, T10, T11 and T12 (the so-called atypical thoracic vertebrae ) present a vertebral body different from the thoracic vertebrae of section T2-T8 (ie the thoracic vertebrae from T2 to T8).
The thoracic vertebrae constitute the segment of the vertebral column responsible for protecting the thoracic portion of the spinal cord, a section from which the 12 pairs of thoracic spinal nerves emerge.
Localization of Thoracic Vertebrae
- The spine section that includes the thoracic vertebrae begins more or less at shoulder height (back base of the neck) and ends just below the diaphragm .
Characteristics of the components of thoracic vertebrae
VERTEBRAL BODY
The vertebral body, or simply body, of the thoracic vertebrae is a bone formation that, when viewed from above, looks like a heart.
Flat both above and below, the vertebral body of the thoracic vertebrae is convex anteriorly and concave posteriorly.
Analyzing the thoracic segment of the vertebral column in a cranio-caudal direction (ie from top to bottom), it is possible to notice that the diameter of the vertebral bodies of the thoracic vertebrae increases progressively, reaching its largest dimension at the level of the thoracic vertebra T12.
In a completely unique way with respect to the vertebral bodies of the other vertebrae, on the sides of the vertebral body of the thoracic vertebrae find space of circular depressions ( facets ) or semi-circular ( semi-facets ), covered with cartilage, whose destiny is to anchor the head of the ribs (ie the initial portion of the ribs). In particular:
- From the thoracic vertebra T2 to the thoracic vertebra T8, the vertebral body hosts, at the upper border and at the lower border of both its sides, two semi-circular depressions ( upper and lower half-facets ), which complete the circumferential aspect with some similar semicircular depressions present on the body of the vertebral element above and on the body of the underlying vertebral element.
From this particular arrangement of the semi-facets, it results that, for the thoracic vertebrae from T2 to T8, the anchoring seat for the head of the ribs, specifically of the ribs from II to IX, is included between two adjacent vertebral bodies (ie involves two overlapping vertebral bodies).
It is important to note that such an architecture also involves the vertebral bodies of the thoracic vertebrae T1 and T9, as they border respectively with T2 and T8 (this explains the involvement of ribs II and IX);
- In the T1 thoracic vertebra, the vertebral body has, on both sides, a circular depression in a central position (facet) and a semi-circular depression at the lower border (lower half-facet), which completes its circumferential aspect with the depression semi-circular located at the upper border (upper half-facet) of the vertebral body of the thoracic vertebrae T2.
The circular depression in a central position fixes the head of the rib (therefore, the vertebra-rib ratio, in this situation, is not shared with other vertebral elements), while the semi-circular depression at the lower fixed border, with the help of upper semi-circular depression present on the thoracic vertebra T2, the head of the II rib (in this case, the affirmation of the thoracic vertebrae from T2 to T8 is repeated);
- In the T9 thoracic vertebra, the vertebral body has, on the side, only a semi-facet, the upper one, whose destiny is to collaborate with the lower half-facet of the vertebral body of the T8 thoracic vertebra when fixing the head of the IX rib;
- In the thoracic vertebrae T10, T11 and T12, the vertebral body is equipped, on both sides, more or less in a central position, with a single circular facet.
This architecture means that, for the thoracic vertebrae T10, T11 and T12, the attachment of the head of the ribs occurs totally in correspondence of the vertebral bodies (and not between the bodies of the adjacent vertebrae); specifically, T10 houses the head of the X rib, T11 the head of the XI rib and T12 the head of the XII rib.
Simplifying ...
- The vertebral bodies of the thoracic vertebrae fix the head of the 12 pair of ribs in correspondence with appropriate cartilage-covered depressions;
- For some specific ribs, fixation to the thoracic vertebrae occurs entirely on a vertebral body ; for the remaining ribs, instead, it takes place on the vertebral bodies of two adjacent thoracic vertebrae ;
- To determine the place of attachment is, in fact, the particular arrangement, on the bodies of the thoracic vertebrae, of depressions covered with cartilage: where the depression belongs to a single vertebral body, the costal attachment takes place entirely on the latter; where instead the depression is shared with two vertebral bodies, the costal fixation takes place on two vertebral bodies;
- The vertebral body of T1 fixes the head of the I rib and part of the head of the II rib;
- The vertebral bodies from T2 to T9 fix the head of the ribs from II to IX;
- The vertebral bodies of T10, T11 and T12 fix, respectively, the head of the X rib, the head of the XI rib and the head of the XII rib.
VERTEBRAL ARCH
As a rule, the vertebral arch of a generic vertebra consists of:
- The two peduncles, which constitute the point of connection between the arch and the vertebral body,
- The two intervertebral holes, which are the channels used for the passage of the spinal nerves exiting the spinal cord, and
- The lamina, which is the curved bony segment that runs from a peduncle to a peduncle and from which the transverse processes originate, just after the aforementioned peduncles, and, halfway, the spinous process.
In the vertebral arch of the lumbar vertebrae, the two peduncles are oriented slightly upwards and have a large lower surface; the lamina is thick and imbricata with the lamina of the underlying vertebral element (with an example, "imbricata" means that it is arranged like the tiles of the roofs); finally, the intervertebral holes are small and circular.
To this it must be added that the vertebral arch of the lumbar vertebrae also houses the two so-called upper articular processes and the two so-called lower articular processes: these 4 bony projections emerge from the lamina, roughly where transverse processes are born.
What is the intervertebral hole? Some more details
The intervertebral hole is an even lateral opening of the vertebral column, which originates from the superposition of two vertebrae.
The very first segment (the so-called root) of the spinal nerves passes through the intervertebral holes.
SPINY PROCESS
Originating from the lamina of the vertebral arch, the spinous process of the thoracic vertebrae is a long and direct bone projection, with an oblique, downward direction. It should be noted that the spinous processes of the thoracic vertebrae T5, T6, T7 and T8 are imbricate, that is, arranged like the roof tiles.
The spinous process of the thoracic vertebrae serves, as in all vertebrae, to anchor the muscles and / or ligaments of the back .
TRANSVERSE PROCESSES
Located posterior to the upper articular processes, the transverse processes of the thoracic vertebrae are thick, long and very resistant formations, oriented backwards and slightly obliquely towards the outside.
Unlike the transverse processes of the other vertebrae, the transverse processes of the thoracic vertebrae have, at the ends, concave areas covered with cartilage, whose task is to anchor the so-called tubercle of the ribs .
What is the tubercle of the ribs?
The tubercle of the ribs is a squat-looking bone process, present in all the ribs, except for the XI and XII ribs, which comes to life immediately after the tract called head.
UPPER JOINT PROCESSES
The upper joint processes of the thoracic vertebrae are two rather defined bone formations, which project upwards with respect to the peduncles, from which they originate;
At the free end, the two upper joint processes of the thoracic vertebrae are provided with a smooth region, covered with hyaline cartilage, which serves to anchor a thoracic vertebra to the immediately superior vertebral element.
LOWER JOINT PROCESSES
The inferior articular processes of the thoracic vertebrae are two less defined bony growths of the upper articular processes, which develop downwards with respect to the lamina, from which they emerge.
At the free end, the two lower joint processes of the thoracic vertebrae have a smooth region, whose fate is to fix a thoracic vertebra to the immediately lower vertebral element.
VERTEBRAL HOLE
The thoracic vertebrae form a vertebral hole with a smaller diameter than the lumbar and cervical vertebrae.
The thoracic section of the spinal cord is located in the vertebral hole formed by the thoracic vertebrae.
- In the T9 thoracic vertebra, the vertebral body has, on the side, only a semi-facet, the upper one, whose destiny is to collaborate with the lower half-facet of the vertebral body of the T8 thoracic vertebra when fixing the head of the IX rib;
- In the thoracic vertebrae T10, T11 and T12, the vertebral body is equipped, on both sides, more or less in a central position, with a single circular facet.
This architecture means that, for the thoracic vertebrae T10, T11 and T12, the attachment of the head of the ribs occurs totally in correspondence of the vertebral bodies (and not between the bodies of the adjacent vertebrae); specifically, T10 houses the head of the X rib, T11 the head of the XI rib and T12 the head of the XII rib.
Function
The thoracic vertebrae cover two functions:
- Contribute to the supporting action carried out by the spine towards the weight of the body;
- They protect the thoracic portion of the spinal cord.
Did you know that ...
The vertebrae that contribute most to supporting the weight of the body are the lumbar vertebrae. This explains why these vertebrae are the most voluminous of all.
diseases
The thoracic vertebrae may be the protagonists of a medical condition known properly as hypercyphosis or pathological kyphosis .
In anatomy, the term " kyphosis " identifies the physiological curve formed by the thoracic vertebrae, along the thoracic tract of the spine.
What is the Hypercosis and what causes it?
Hypercifosis is the excessive accentuation of the curvature normally present along the vertebral column section including the thoracic vertebrae.
Wrongly called kyphosis (kyphosis is a natural curvature), hyperciphosis causes a person's spine back to appear abnormally curved.
Hypercifosis recognizes various causes; in fact, it may be due to aging, osteoporosis, poor posture, some disease that alters the morphology of the vertebral bodies of the thoracic vertebrae, or some congenital anomaly affecting the vertebral column.
