Topic 9: Bones, joints and muscles of the thoracic cage Flashcards
How many pairs of ribs are there?
12
How many true ribs are there?
7
how many false ribs are there?
3
how many floating ribs are there?
2
What are the 3 parts of the sternum?
- manubrium
- body
- xiphoid
How many thoracic vertebrae?
12
what else makes up the bones of the thorax?
costal cartilages
What are the boundaries for the thoracic inlet?
Rib 1, T1, Manubrium, costal cartilages
What are the boundaries for the thoracic outlet?
inferior
costal cartilages, lower 3-4 thoracic vertebrae
What are the 2 joints of the sternum?
- manubriosternal
- xiphisternal
What are the 2 joints of the anterior ribs?
- sternocostal (1st & 2-7)
- costochondral
* chondral = ribs
What are the 2 joints of the posterior ribs?
- costovertebral
- costotransverse
Classify the Manubriosternal joint
secondary cartilaginous- symphysis
how moveable is the manubriosternal joint?
slightly
classify the xiphisternal joint
secondary cartilaginous- symphysis
How moveable is the 1st sternocostal joint?
immovable (lots of imp structures around there)
how moveable is the xiphisternal joint?
slightly moveable but ossifies in middle age
Classify the 1st sternocostal joint
primary cartilaginous- synchondrosis
Classify the 2nd-7th sternocostal joints
synovial, multi-axial, plane
How moveable are the 2nd-7th sternocostal joints?
small range of twist & glide (for breathing)
Classify the costochondral joints
primary cartilaginous - synchondrosis
How moveable are the costochondral joints?
immovable
Classify the interchondral joints
synovial, multiaxial, plane (except 9&10- fibrous)
Which ribs have interchondral joints?
ribs 6-10
explain where the interchondral joints lie
between borders of costal cartilages of ribs 6-10 and lower border of cartilage above
What are the 3 bony landmarks on the ribs which articulate with the vertebrae?
- head
- neck
- tubercle
What bony landmark on the vertebrae does the head of the rib articulate with?
demi facets
What bony landmark on the vertebrae does the tubercle of the rib articulate with?
transverse processes
Classify the costovertebral joint
synovial, multi-axial, plane
What movements are allowed at the costovertebral joint?
small range of twist and glide
Classify the costotransverse joint
synovial, multi-axial, plane
what movements are facilitated at the costotransverse joint?
small range of twist and glide
articular surfaces of the costovertebral joints
- head of rib
- (demi) facet on the body of the thoracic vertebra
What thoracic vertebra does rib 1 articulate with in the costovertebral joints?
T1
Which thoracic vertebrae does rib 2 articulate with in the costovertebral joints?
T1 and T2
Which thoracic vertebrae does rib 9 articulate with in the costovertebral joints?
T8 & T9
Which thoracic vertebra does rib 10 articulate with in the costovertebral joints?
T10
Which thoracic vertebra does rib 11 articulate with in the costovertebral joints?
T11
Which thoracic vertebra does rib 12 articulate with in the costovertebral joints?
T12
Costotransverse joints- articular surfaces
- tubercle of rib
- facet on the transverse process of the thoracic vertebra
Which ribs have no costotransverse jt and why?
ribs 11 &12 - no costal cartilage and transverse process articulation (floating)
What are the 2 ligaments of the costovertebral joints?
- radiate
- intra-articular
What are the 3 ligaments of the costotransverse joints?
- costotransverse
- lateral costotransverse
- superior costotransverse
COSTOVERTEBRAL LIGAMENTS
Where does the radiate ligament span?
From the head of the rib – to the body of the vertebra above, the vertebra of the same number and the intervening IV disc
Function of the radiate ligament
- limit movement in all directions
- attaches head of rib to vert
Intra-articular ligament
Where does it go?
From the head of the rib– to the IV disc, divides the cavity into 2
Function of the intra-articular ligament
keeps head of rib in place
COSTOTRANSVERSE JT LIGAMENTS
1. superior costotransverse ligament
Where does it go?
From the neck of the rib to the transverse processes of the vertebra above
What is the function of the superior costotransverse ligament
limits separation of the ribs
- lateral costotransverse ligament
Where does it go?
strong band between tip of transverse processes and the costal tubercle (same level)
Function of the lateral costotransverse ligament
keeps rib & thoracic vert together
- costotransverse ligament
Length of fibres
short fibres
where does the costotransverse ligament go?
from the back of the neck of the rib – to the front of the transverse process
DIAMETERS OF THE THORAX
What happens to ALL dimensions of the thoracic cage (TC) with each inspiration?
increase
DIAMETERS OF THE THORAX
What happens to the vertical diameter of the TC with each inspiration and how?
Increased by descent of diaphragm
DIAMETERS OF THE THORAX
What happens to the antero-posterior diameter with each inspiration and how?
increased by movement of the sternum and anterior parts of ribs
DIAMETERS OF THE THORAX
What happens to the lateral diameter with each inspiration and how?
increased by movements of the lateral parts of the ribs
What are the 2 mechanisms for movement of the ribs?
- pump handle
- bucket handle
Which ribs does the pump handle mechanism involve?
upper ribs 2-5
What axis diameter does pump handle mechanism increase?
AP diameter
What is the movement axis for pump handle mechanism?
along neck of rib
Which ribs does the bucket handle mechanism involve?
lower ribs 8-10
Where does the diameter increases in the bucket handle mechanism?
lateral
what is the movement axis for the bucket handle mechanism?
through the costovertebral and sternocostal joints
MUSCLES OF THE THORACIC CAGE:
1. diaphragm
What does it cover?
the thoracic outlet
Attachments of the diaphragm
- bodies & intervening discs L1-L3
- inner surface of the ribs 7-12 and their costal cartilages (lat &ant)
- posterior surface of the xiphoid process of the sternum
- central tendon
what is the prime role of the diaphragm
prime mover for inspiration
What 2 areas does the diaphragm separate?
the thorax & abdo
What happens to the thoracic cage when the diaphragm contracts?
- increase volume
- decrease pressure
What happens to the abdo when the diaphragm contracts?
- decrease volume
- increase pressure
What are the 3 apertures of the diaphragm?
- Abdominal aorta (T12)
- Oesophagus (T10)
- Inferior Vena Cava (T8)
Where is the abdominal aorta aperture of the diaphragm located?
behind the diaphragm
Is the abdominal aorta aperture affected by diaphragm contraction?
no
Where is the oesophagus aperture located?
through the muscle of the diaphragm
what happens to the oesophagus aperture when diaphragm contracts?
closed
Where is the inferior vena cava aperture located?
through the central tendon
What happens to the inferior vena cava aperture when diaphragm contracts?
opens
OTHER MUSCLES OF THORAX
1. intercostals
where do they go?
from the lower border of one rib to the upper border of the rib below
Three layers of intercostals:
- external
- internal
- innermost
Role of the intercostals
- stiffen the space between the ribs
- role in breathing & in posture
direction of external intercostal fibres?
hands in pockets
direction of innermost & internal intercostal fibres?
opposite to hands in pockets
What is an accessory muscle of inspiration?
any muscle attaching to the ribs from above can lift the ribs and increase thoracic volume (inspiration)
e.g. of inspiratory muscles (upper limb)
serratus anterior, pec major & minor, sternocleidomastoid
e.g. inspiratory muscles of the vertebral column
- scalenes group
- serratus posterior superior
Are expiratory muscles largely active or passive in awake humans?
passive
what happens with the diaphragm at the start of expiration?
contracts eccentrically for a short period to slow expiratory rate
Muscles used in FORCED expiration
- abdominal muscles
- any other muscle that can pull the ribs down e.g. serratus posterior, QL
What happens to the diameter of the rib cage in forced expiration
decreases
4 phases of respiratory cycle
- quiet inspiration
- forced inspiration
- quiet expiration
- forced expiration
Muscles responsible for quiet inspiration
diaphragm, external intercostals
Muscles responsible for forced inspiration
diaphragm, pec maj & min, skelinis, sternoclydomastoid, serr ant, lat dorsi, ser post sup
Muscles responsible for quiet expiration
diaphragm – eccentric initially – relaxes after
Muscles responsible for forced expiration
abd muscles, serratus post, longissimus, lat dorsi, ext/int obliques, iliocostalis, transversus abdominus, serr post inf, QL