The thoracic spine consists of 12 vertebrae located between the cervical and lumbar regions. Each thoracic vertebra has costal facets for articulating with ribs, forming the thoracic cage which protects the heart, lungs, and esophagus. Unique joints connect the vertebrae to each other and to the ribs. The thoracic spine is strengthened by ligaments and allows only limited movement to support respiration. Kyphosis is an excessive curvature of the thoracic spine causing a hunched appearance.

1. Thoracic Vertebrae
Dr M Idris Siddiqui

2. The thoracic spine
• The thoracic spine is the second segment of
the vertebral column, located between the
cervical and lumbar vertebral segments.
• It consists of twelve vertebrae, which are
separated by intervertebral discs.
• Along with the sternum and ribs, the thoracic
spine forms part of the thoracic cage.
• This bony structure helps protect the internal
viscera – such as the heart, lungs and
oesophagus.

3. Thoracic Cage
• Thoracic Cage is a skeletal framework which supports
the thorax. Muscles of thorax, upper extremities, back and
diaphragm are given connection by this cage.
• It’s nature is osteocartilaginous and elastic. It has a
significant role play for raising or reducing the intrathoracic
pressure to ensure mechanism of respiration.
• The thoracic vertebrae, ribs, costal cartilages,
and sternum form the thoracic cage.
• It gives protection for the internal organs of the thoracic
cavity and supports the superior trunk, pectoral girdle, and
upper limbs.

4. THE THORACIC SPINE
• The vertebral column in an adult typically
consists of 33 vertebrae arranged in five
regions:
– 7 cervical,
–12 thoracic,
–5 lumbar,
–5 sacral, and
–4 coccygeal

5. • The vertebrae gradually become
larger as the vertebral column
descends to the sacrum and then
become progressively smaller
toward the apex of the coccyx.
• The change in size is related to the fact that
successive vertebrae bear increasing amounts of
the body's weight as the column descends.

6. Typical vertebra
• A typical vertebra consists of a vertebral
body, a vertebral arch, and seven processes.
• The vertebral body is the more massive,
roughly cylindrical, anterior part of the bone
that gives strength to the vertebral column
and supports body weight.
• The size of the vertebral bodies increases as the
column descends, most markedly from T4 inferiorly,
as each bears progressively greater body weight.

7. • The vertebral body consists of
vascular, trabecular (spongy,
cancellous) bone enclosed by a thin
external layer of compact bone
• In life, most of the superior and
inferior surfaces of the vertebral body
are covered with discs of hyaline
cartilage (vertebral end plates), which
are remnants of the cartilaginous
model from which the bone develops

8. • The succession of vertebral foramina in
the articulated vertebral column forms
the vertebral canal (spinal canal), which
contains the spinal cord and the roots
of the spinal nerves that emerge from
it, along with the membranes
(meninges), fat, and vessels that
surround and serve them.

9. Vertebral notches
• The vertebral notches are indentations observed in
lateral views of the vertebrae superior and inferior
to each pedicle between the superior and inferior
articular processes posteriorly and the
corresponding projections of the body
anteriorly.The superior and inferior vertebral
notches of adjacent vertebrae and the IV discs
connecting them form the intervertebral foramina,
in which the spinal (posterior root) ganglia are
located and through which the spinal nerves
emerge from the vertebral column with their
accompanying vessels.

10. 7 processes
• Seven processes arise from the vertebral arch of a
typical vertebra :
• One median spinous process projects posteriorly
(and usually inferiorly, typically overlapping the
vertebra below) from the vertebral arch at the
junction of the laminae.
• Two transverse processes project posterolaterally
from the junctions of the pedicles and laminae.
• Four articular processes (G. zygapophyses)two
superior and two inferior also arise from the
junctions of the pedicles and laminae, each
bearing an articular surface (facet).

11. • The former three processes, one spinous and two transverse,
afford attachments for deep back muscles and serve as levers,
facilitating the muscles that fix or change the position of the
vertebrae.
• The latter four (articular) processes are in apposition with
corresponding processes of vertebrae adjacent (superior and
inferior) to them, forming zygapophysial (facet) joints . Through
their participation in these joints, these processes determine
the types of movements permitted and restricted between the
adjacent vertebrae of each region. The articular processes also
assist in keeping adjacent vertebrae aligned, particularly
preventing one vertebra from slipping anteriorly on the
vertebra below.

12. Thoracic Vertebrae
• The thoracic vertebrae lie in the
upper back and provide attachment
for the ribs .
• Thus the primary characteristic
features of thoracic vertebrae are
the costal facets for articulation with
ribs.

13. Characteristic Features
• The thoracic vertebrae have four features which
distinguish them from other vertebrae:
• Vertebral body is heart shaped.
• Presence of demi-facets on the sides of each vertebral
body – these articulate with the heads of the ribs.
• Presence of costal facets on the transverse processes –
these articulate with the tubercles of the ribs. They are
present on T1-T10 only.
• The spinous processes are long and slant inferiorly. This
offers increased protection to the spinal cord,
preventing an object such as a knife entering the spinal
canal.

14. Superior and Inferior Costal Facets
• The superior and inferior costal facets are located
on the sides of each vertebral body. They consist
of cartilage lined depressions, which articulate
with the heads of the ribs. The superior facet
articulates with the head of the adjacent rib, and
the inferior facet articulates with the head of the
rib below
• In the majority of the vertebrae (T2-T9) these
facets are demi-facets. There are some atypical
vertebrae that possess whole facets.

15. Atypical Vertebrae
• The atypical thoracic vertebrae display variation in
the size, location and number of their superior and
inferior costal facets.
• T1 – Superior facet is not a demifacet, as this is the
only vertebrae to articulate with the 1st rib.
• T10 – A single pair of whole facets is present which
articulate with the 10th rib. These facets are located
across both the vertebral body and the pedicle.
• T11 and T12 – Each have a single pair of entire
costal facets, which are located on the pedicles.

16. Joints
• The joints of the thoracic spine can be divided into two
groups – those that are present throughout the
vertebral column, and those unique to the thoracic
spine.
• Present throughout Vertebral Column
• There are two types of joints present throughout the
vertebral column:
• Between vertebral bodies – adjacent vertebral bodies
are joined by intervertebral discs, made of
fibrocartilage. This is a type of cartilaginous joint,
known as a symphysis.
• Between vertebral arches – formed by the articulation
of superior and inferior articular processes from
adjacent vertebrae. It is a synovial type joint.

17. Unique to Thoracic Spine
• The articulations between the vertebrae and the ribs are
unique to the thoracic spine. For each rib, there are two
separate articulations – costovertebral and costotransverse.
• Each costovertebral joint consists of the head of the rib
articulating with:
• Superior costal facet of the corresponding vertebra
• Inferior costal facet of the superior vertebra
• Intervertebral disc separating the two vertebrae
• Within this joint, the intra-articular ligament of head of rib
attaches the rib head to the intervertebral disc. Only slight
gliding movements can occur at these joints, due to the close
articulation of their components.
• The costotransverse joints are formed by the articulation of
transverse processes of a thoracic vertebra and the tubercle
of the adjacent rib. They are present in all vertebrae except
T11 and T12.

18. Ligaments
• The thoracic spine is strengthened by the presence of
numerous ligaments.
• Present Throughout Vertebral Column
• Anterior and posterior longitudinal ligaments: Long
ligaments that run the length of the vertebral column,
covering the vertebral bodies and intervertebral discs.
• Ligamentum flavum: Connects the laminae of adjacent
vertebrae.
• Interspinous ligament: Connects the spinous processes of
adjacent vertebrae.
• Supraspinous ligament: Connects the tips of adjacent spinous
processes.
• (Note: In the cervical spine, the interspinous and supraspinous
ligaments thicken and combine to form the nuchal ligament).

19. Thoracic Vertebrae

20. Unique to Thoracic Spine
• A number of small ligaments also support the
costovertebral joints:
• Radiate ligament of head of rib – Fans outwards from
the head of the rib to the bodies of the two vertebrae
and intervertebral disc.
• Costotransverse ligament – Connects the neck of the
rib and the transverse process.
• Lateral costotransverse ligament – Extends from the
transverse process to the tubercle of the rib.
• Superior costotransverse ligament – Passes from the
upper border of the neck of the rib to the transverse
process of the vertebra superior to it.

24. Part Characteristics
Body Heart shaped; one or two costal facets for
articulation with head of rib
Vertebral
foramen
Circular and smaller than those of cervical and
lumbar vertebrae
Transverse
processes
Long and strong and extend posterolaterally; length
diminishes from T1 to T12 (T1 to T10 have facets
for articulation with tubercle of rib)
Articular
processes
Superior facets directed posteriorly and slightly
laterally; inferior facets directed anteriorly and
slightly medially; plane of facets lies on arc
centered about vertebral body
Spinous
processes
Long; slope posteroinferiorly; tips extend to level of
vertebral body below

25. Kyphosis
• Kyphosis is an excessive curvature of the thoracic
spine, causing the back to appear “hunched”. It may
occur for a number of reasons early in life. These
include poor posture, abnormally wedge-shaped
shaped vertebrae (Scheuermann’s kyphosis), and
fusing of vertebrae during development.
• Various diseases can also lead to kyphosis in adults.
The most common cause is osteoporosis – a
condition whereby bone mass is lost (mostly in
older people). This leaves the spine less able to
support the weight of the body, thus resulting in
characteristic kyphosis.