Thoracic Spine and Thorax/Chest Wall Flashcards
Function of the Thoracic Region
Stability
What serves the stability of the Thoracic region?
Due to structure:
-rib cage
-spinous processes
-vertebral bodies
-static restraints
Thoracic Body
Wedge-shaped Posterior height greater than anterior height
2 demifacets (half facets) for articulation with ribs
Peak anteroposterior height difference occurs…
at T7
What does the anterior wedging of the body produce?
The normal kyphotic posture of the TS
Arches of the TS vertebrae
Pedicles: face posteriorly
Laminae: short, thick, broad
Superior facets: thin, flat (face posterior, superior, lateral)
Inferior facets: thin, flat (Face anterior, inferior, medial)
Transverse processes: large, thickened ends (paired oval facets, decrease in length caudally)
Spinous processes: T1-10 (slope inferiorly, T11-12(triangular shape)
Vertebral foramen: small, circular
IVD of the TS vertebrae
Thinner
Smaller ratio of disc size: vertebral body size
Supports the function of stability over mobility
Annulus fibrosis (outer fibers)
Resists distraction, translation, and rotation of vertebral bodies
Anterior Long. Ligament
Limits extension
Reinforces anterolateral annulus, anterior aspect of IV joint
(thicker than at CS)
Posterior Long. Ligament
Limits forward flexion
Reinforces posterior annulus
Ligamentum Flavum
Limits forward flexion, particularly in lumbar region
(thicker than at CS)
Supraspinous Ligament
Limits forward flexion
Intertransverse Ligament
Limits forward flexion, CL flexion
Zygapophyseal Joint Capsule
Resists forward flexion, axial rotation
TS Interbody Joints
Between flat vertebral surfaces
Allow for translations in all planes
Discs allow for small amounts of tilting
TS Zygapophyseal Joints
Plane synovial joints
-Tighter joint capsule compared to CS and LS
Lie approx. 60 deg off the transverse plane and 20 deg off the frontal plane OVERALL
-Somewhat dependent on region of thoracic spine
Orientation of Zygapophyseal Joints of the TS
Inferior facets of SUPERIOR vertebrae: Anterior, inferior, medial
Superior facets of INFERIOR vertebrae: Posterior, superior, lateral
Each thoracic vertebra articulates with a set of paired ribs by way of two joints. What are they?
The costovertebral and the costotransverse joints.
What are the vertebral components of the costovertebral joints?
The demifacets located on most of the vertebral bodies
What are the vertebral components of the costotransverse joints?
The oval facets on the transverse processes
Thorax
Describes the bones of the rib cage, the fascia and muscles that attach to the rib cage, the visceral organs within the rib cage, and even the skin that covers the rib cage
Rib Cage (thoracic cage or the bony thorax)
Consists of the thoracic vertebrae, the ribs, and the sternum
What does the rib cage protect?
Heart, lungs and viscera
What does the process of ventilation, including inhalation/exhalation(inspiration/expiration) depend on?
Depends on the mobility of the rib cage and the ability of the muscles of ventilation to move it
Structure of the Rib Cage
Anterior Border: the sternum
Lateral Borders: the ribs
Posterior Border: formed by the thoracic vertebrae
Superior Border: formed by the manubrium of the sternum, superior borders of the first costal cartilages, and by the first ribs and their contiguous first thoracic vertebra
Inferior Border: formed by the xiphoid process, the shared costal cartilages of ribs 7-10, the inferior portions of the 11th and 12th ribs, and the 12th thoracic vertebra
True Ribs attaching directly to the sternum
Ribs 1-7
False ribs attaching indirectly to the sternum via rib 7
Ribs 8-10
Floating ribs that have no attachment to the sternum
Ribs 11th and 12th
What are the articulations that join the bones of the rib cage?
Manubriosternal, xiphisternal, costovertebral, costotransverse, costochondral, chondrosternal, and the interchondral joints
Manubriosternal Joint
Manubrium and body of sternum
“sternal angle” or Angel of Louis”
Asynchondrosis and has a fibrocartilaginous disc between the articulating ends of the manubrium and the body of the sternum
Xiphisternal Joint
Xiphoid process and body of sternum
Asynchondrosis
Costovertebral Joint
Synovial joint
Head of rib + two adjacent vertebral bodies + intervertebral disc
Typical costovertebral joints
Ribs 2-9:
Head of ribs fit snugly into the surface formed by the adjacent demifacets
Atypical costovertebral joints
Ribs 1, 10, 11, 12
Articulate with only one vertebral body
Numbered by that body
More mobile
Inert tissue support (regional differences) of the Costovertebral joint
Fibrous joint capsule
Intra-articular ligament: attach to annulus fibrosus
Radiate ligament: firm attachment to anterolateral portion of capsule
Costotransverse Joints
Synovial joint
Costal tubercle of rib + costal facet on TP of corresponding vertebrae
10 pairs: T1-T10 with rib of same number
Inert tissue support of Costotransverse Joint
Thin, fibrous joint capsule
3 Major ligaments:
lateral costotransverse: short, stout band
costotransverse: short fibers that run within the costotransverse foramen
superior costotransverse: crest of the neck of the rib to the inferior border of the cephalad transverse process
Costochondral Joint
Synchondroses
1-10th ribs articulate anterolaterally with costal cartilages
Chondrosternal Joints
Costal cartilages of ribs 1-7 articulate anteriorly with sternum
-Rib 1 with lateral facet of manubrium
-Rib 2 with 2 demifacets at manubriosternal junction
-Ribs 3-7 with lateral facets of sternal body
Joints at ribs 1, 6, 7: synchondroses
Joints at ribs 2-5: synovial
Interchondral Joints
Synovial joints
Costal cartilages of ribs 7-10 articulate with the cartilage immediately above
Sagittal Plane
Flexion: ribs approximate (exhalation)
Extension: ribs separate (inhalation)
Frontal Plane
Lateral flexion:
Ipsilateral rib approximation
Contralateral rib separation
Transverse Plane
Rotation:
Ipsilateral rib separate
Contralateral rib approximation
Kinematics of the ribs and manubriosternum
Based on:
Types and angles of the articulations
Movement of manubriosternum
Elasticity of costal cartilage
Costovertebral and costotransverse joints are mechanically linked
Upper ribs: Frontal axis / Sagittal plane motion
Lower ribs: Sagittal axis / Frontal plane motion
Kinematics of the ribs and manubriosternum forms a closed chain with connections to vertebrae __________ and costal cartilages ____________
posteriorly; anteriorly
Rib 1
Anterior articulation is large and thicker
First costal cartilage stiffer
Chondrosternal joint is synchondrosis
Lies just inferior and posterior to SC joint (very lil movement ant. at manubrium)
Costovertebral joint has a single facet (Increase mobility post., can elevate w/inhalation as a result)
Ribs 2-7
Increase in length and mobility caudally
Most movement occurs anteriorly due to frontal axis
Pump-handle motion
Pump-handle Motion
Elevation of the upper ribs at the costovertebral and costotransverse joints
Results in anterior and superior movement of the sternum
Increases AP diameter of thorax
Ribs 8-10
Have a more angles shape
Indirect attachment to the sternum
Sagittal axis
Bucket-handle motion
Bucket-handle Motion
Elevation of the lower ribs at the costovertebral and costotransverse joints
Results in lateral motion of the rib cage (lateral and inferiorly)
Ribs 11-12
Only have one posterior articulation with a single vertebrae
Do not participate in closed chain motion of thorax
Ventilation - Primary muscles of inhalation
Diaphragm: Primary; 70-80% of inhalation force at rest
Intercostals (parasternals, external intercostals)
Scalenes
Ventilation - Primary muscles of exhalation
N/A
Passive function
Tidal Breathing
During inhalation, the diaphragm contracts, the dome descends from its resting position, compressing the abdominal contents. The resulting increase in intra-abdominal pressure limits further descent of (i.e., stabilizes) the central tendon of the diaphragm so that continued contraction of the costal fibers of the diaphragm on the stabilized central tendon results in expansion (bucket-handle motion) of the lower ribs
Ventilatory Sequence During Breathing
The diaphragm contracts and the central tendon moves caudally.
The parasternal, external intercostals, and scalene muscles elevate the ribs and move the sternum anteriorly and superiorly. The muscles also stabilize the anterior upper chest wall to prevent a paradoxical inward movement caused by the decreasing intrapulmonary pressure.
As intra-abdominal pressure increases, the abdominal contents are displaced so that the anterior epigastric abdominal wall is pushed anteriorly. Further outward motion of the abdominal wall is countered by the abdominal musculature, with that resistance allowing the central tendon to stabilize on the abdominal viscera.
With continued shortening of the appositional (costal) fibers of the diaphragm, the lower ribs are pulled cephalad and laterally, which results in the bucket-handle movement of the lower ribs.
With continued inhalation, the parasternal, scalene, and levatores costarum muscles actively rotate the upper ribs and elevate the manubriosternum, which results in an anterior (pump-handle) motion of the upper ribs and sternum.
The lateral motion of the lower ribs and anterior motion of the upper ribs and sternum can occur simultaneously.
Exhalation during breathing at rest is mostly passive, using the elastic recoil properties of the lungs and the cessation of inspiratory muscle contraction.
Skeletal changes that occur with aging impact pulmonary function
Interchondral and costochondral joints can fibrose
Manubriosternal and xiphisternal joints ossify
Overall chest wall compliance decreases with age
Affects length-tension relationship of muscles of ventilation
With age, pulmonary compliance ______and elastic recoil of lung tissue ______.
increases; decreases
Age Net effect:
The lungs retain more air at the end of exhalation
Inspiratory capacity decreases
Ventilation becomes less energy-efficient
