Thorax

Thoracic vertebrae

Thoracic vertebrae


General plan of a vertebra Features of thoracic vertebrae Spinous process palpation Articulations

General plan of a vertebra

A vertebra in general is formed of a body and a vertebral arch

Vertebral arch

Encloses the vertebral foramen (= hole L.)

Vertebral arch

is formed of two pedicles (little feet, pes = foot L.)

Vertebral arch

is formed of two pedicles (little feet, pes = foot L.) and two laminae (thin plates).

Vertebral arch

The arch has several processes

Vertebral processes

The processes are 4 articular

Vertebral processes

The processes are 4 articular 2 transverse

Vertebral processes

The processes are 4 articular 2 transverse 1 spinous

Features of thoracic vertebrae

Costal facets vertebral canal body processes

Costal facets

The essential characteristic feature of a thoracic vertebra is the presence of a costal facet (place for articulation with the rib) on the body of the vertebra

thoracic

cervical
lumbar

Costal facets

The presence of the costal facet on the body of the thoracic vertebra distinguishes it from vertebrae of other regions in the vertebral column

Costal facets

A thoracic vertebra has costal facets on the body and transverse processes

Costal facets

A thoracic vertebra has costal facets on the body and transverse processes except T11 and T12, which has no costal facets on their transverse processes

Costal facets

In vertebrae from T2 to T9, two demi- (half) facets are located on each side of the body


X
X

Costal facets

The superior facet is for articulation with the head of its own rib

X
X
X+1

Costal facets

The inferior facet is for articulation with the head of the rib inferior to it

Costal facets, T1

Since the head of the first rib carries a single facet



Costal facets, T1

the body of T1 has a single costal facet on each side for the head of the first rib

Costal facets, T1

In addition, it carries a demi-facet for the head of the second rib

Costal facets, T10 - T12

Each side of the body of T10-T12 has a single facet for the head of the corresponding rib

Costal facets



In other words, the heads of ribs 1, 10, 11, & 12 articulate solely with the body of the vertebra to which they correspond numerically

Small & triangular

Large & triangular
Cervical
Lumbar

Vertebral canal

The vertebral canal of a thoracic vertebra is circular

Vertebral canal

Note the size of the vertebral canal



Vertebral body

The body of a thoracic vertebra is heart-shaped

Vertebral body


The body of a thoracic vertebra is heart-shaped, meaning a player’s card heart or lover’s heart rather than the anatomical heart

Kidney-shaped

Transversly elongated
Cervical
Lumbar
Thoracic

Vertebral body

Comparison

Vertebral body


In vertebrae of the middle of the series (T5-T8), the left side of the body is slightly flattened

Vertebral body, T5 - T8

In this region, the descending thoracic aorta is directly in contact with the bodies to the left of the midline

Spinous process

The spinous processes of thoracic vertebrae are long and tapered They vary in their obliquity

T1, T2, T11, and T12 have spinous processes that are almost horizontal

T3, T4, T9, and T10 have oblique spinous processes

Spinous process

In vertebrae of the middle of the series (T5-T8), the spinous processes are almost vertical

Spinous process, palpation

The spinous processes of thoracic vertebrae are palpated in the midline posteriorly

Spinous process, palpation

However, since the thoracic spines run downwards are joined by thick supraspinous ligaments are covered by fairly thick skin they are not easy to examine individually

Spinous process, palpation

If the index finger of the examining hand is moved downwards at the back of the neck while the vertebral column is flexed, the spines project much more

Vertebra prominans

The first spinous process that is visible and palpable is that of C7. Therefore, C7 is called the vertebra prominans although the spinous process of T1 may be more prominent

Spine levels

The spine of T2 lies against the superior angle of the scapula

Spine levels

The spine of T3 lies against the spine of the scapula

Spine levels

The spine of T7 lies against the inferior angle of the scapula

Articulations

Thoracic vertebrae articulate with each other by means of a secondary cartilaginous joint between the bodies

Articulations

Thoracic vertebrae also articulate with each other by means of a plane synovial joint on each side between superior and inferior articular processes

Intervertebral disc

The disc between the bodies has an outer circular fibrous part called anulus fibrosus (anulus = ring L.), and an inner softer part called nucleus pulposus.

Site of prolapse

Disc prolapse


If the anulus is torn (most frequently posteriorly), the nucleus may bulge out and press on spinal nerves

Site of prolapse

Disc prolapse

Intervertebral foramen


When two adjacent vertebrae are articulated, an intervertebral foramen is formed bounded above and below by the pedicles

Intervertebral foramen

A spinal nerve emerges from the foramen.

Thoracic spinal nerves

In the thoracic region T1 spinal nerve emerges between the 1st and 2nd thoracic vertebra and T12 spinal nerve between the 12th thoracic vertebra and the 1st lumbar vertebra

Thoracic spinelateral projection - dried specimen

Note superior articular process inferior articular process pedicle body of vertebra spinous process transverse process inferior vertebral notch

Thoracic spine, lateral projection

Note superior articular process inferior articular process site of intervertebral disc pedicle body of vertebra rib transverse process inferior vertebral notch

Thoracic spineantero-posterior projection - dried specimen

Note superior articular process inferior articular process pedicle spinous process transverse process

Thoracic spineantero-posterior peojection

Note transverse process pedicle body site of intervertebral disc spinous process ribs