Page 335 - Kinesiology of the musculoskeletal system foundations for physical rehabilitation

Chapter 9 Axial Skeleton: Osteology and Arthrology 311

TABLE 9-2. Major Parts of a Midthoracic Vertebra Primary Function
Part Description

Body Large cylindric mass of trabecular bone lined by a thin Primary weight-bearing structure of each
cortex of bone. The multidirectional trabecular core is vertebra.
Intervertebral disc lightweight while still offering excellent resistance against
Interbody joint compression. Shock absorber and spacer throughout
the vertebral column.
Pedicle Thick ring of fibrocartilage between vertebral bodies of C2
Lamina and below. Primary bond between vertebrae.

Vertebral canal A cartilaginous joint joint formed between the superior and Connects the vertebral body to the
Intervertebral foramen inferior surfaces of an intervertebral disc and adjacent posterior elements of a vertebra.
Transverse process vertebral bodies.
Costal facets (on body) Protects the posterior aspect of the spinal
Short, thick dorsal projection of bone from the mid-to- cord.
Costal facets (on transverse superior part of the vertebral body.
process) Houses and protects the spinal cord.
Thin vertical plate of bone connecting the base of the
Spinous process spinous process to each transverse process. (The term Passageway for spinal nerve roots exiting
Superior and inferior laminae refers to both right and left laminae.) the vertebral canal.

articular processes, Central canal located just posterior to the vertebral body. Attachments for muscles, ligaments, and
including articular facets The canal is surrounded by the pedicles and laminae. ribs.
and apophyseal joints
Lateral opening between adjacent vertebrae. Attachment sites for the heads of ribs
(costocorporeal joints).
Horizontal projection of bone from the junction of a
lamina and a pedicle. Attachment sites for the articular tubercle
of ribs (costotransverse joints).
Rounded impressions formed on the lateral sides of the
thoracic vertebral bodies. Most thoracic vertebral bodies Midline attachments for muscles and
have partial superior and inferior facets (called demifacets). ligaments.

Oval facets located at the anterior tips of most thoracic Superior and inferior articular facets form
transverse processes. paired apophyseal joints. These
synovial joints guide the direction and
Dorsal midline projection of bone from the laminae. magnitude of intervertebral movement.

Paired vertical articular processes arising from the junction
of a lamina and pedicle. Each process has smooth
cartilage-lined articular facets. In general, superior
articular facets face posteriorly, and inferior articular
facets face anteriorly.

tubercle (Figure 9-6). The head and tubercle articulate with a parts: the manubrium (Latin, meaning “handle”), the body,
thoracic vertebra, forming two synovial joints: costocorporeal and the xiphoid process (from the Greek, “sword”) (see Figure
(also called costovertebral) and costotransverse, respectively 9-7). Developmentally, the manubrium fuses with the body of
(see Figure 9-5, B).188 These joints anchor the posterior end the sternum at the manubriosternal joint, a cartilaginous (syn-
of a rib to its corresponding vertebra. A typical costocorporeal arthrodial) articulation that often ossifies later in life.188 Just
joint connects the head of a rib to a pair of costal demifacets lateral to the jugular notch of the manubrium are the clavicular
that span two adjacent vertebrae and the intervening interver- facets of the sternoclavicular joints. Immediately inferior to the
tebral disc. A costotransverse joint connects the articular tuber- sternoclavicular joint is a costal facet that accepts the head of
cle of a rib with a costal facet on the transverse process of a the first rib at the first sternocostal joint.
corresponding vertebra.
Osteologic Features of the Sternum
The anterior end of a rib consists of flattened hyaline ••••••
cartilage. Ribs 1 through 10 attach either directly or indirectly Manubrium for sternoclavicular joints
to the sternum, thereby completing the thoracic rib cage Jugular notch sternocostal joints
anteriorly. The cartilage of ribs 1 to 7 attaches directly to the Clavicular facets
lateral border of the sternum via seven sternocostal joints Body
(Figure 9-7). The cartilage of ribs 8 to 10 attaches to the Costal facets for
sternum by fusing to the cartilage of the immediately superior Xiphoid process
rib. Ribs 11 and 12 do not attach to the sternum but are
anchored by lateral abdominal muscles. Intrasternal Joints
••
STERNUM Manubriosternal joint
The sternum is slightly convex and rough anteriorly, and Xiphisternal joint
slightly concave and smooth posteriorly. The bone has three