Thoracic Cage Flashcards
What 3 parts are sternum composed of:
Manubrium, body, xiphoid process
What is the angle of Louis/ sternal angle
The point where the manubrium and body articulate at a manubriosternal joint- level of 2nd rib/T4
Suprasternal (jugular) notch
Notch in superior border of manubrium
How many pairs of ribs
12 angled downwards from back to front
What is the costal margin
The 7, 8, 9, 10th costal cartilage join to one another
Costochondral joint
Point where rib and costal cartilage articulate
Sternocostal joint
Costal cartilage and sternum articulate
Costovertebral joint
Ribs and thoracic vertebrae articulate
Typical ribs
Thin, flat, curved in a spiral
Ribs 3-9
Have a head, neck, body, tubercle
Number of thoracic vertebrae
12
Which ligaments hold the joints of the vertebrae together
Radiate ligament and superior costotransverse ligament
Synovial joints between vertebrae
- Head of rib articulates with vertebral body - head has 2 articular facets
• Tubercle of rib articulates with transverse process of vertebra (costotransverse joint)
3 types of intercostal muscle
External, internal, innermost
External intercostal muscle
fibres are orientated antero-inferiorly
• contraction pulls ribs superiorly- most active in inspiration
• In anterior part of intercostal space, muscle becomes membranous and forms the external intercostal membrane
Internal intercostal muscle
fibres run perpendicular to external intercostal in a postero-inferior direction
• Contraction pulls ribs inferiorly- most active in expiration
• Internal intercostal becomes membranous in posterior path of intercostal space and forms the internal intercostal membrne
Innermost intercostal muscle
lies in posterior part of intercostal space
• Fibres orientated in same direction of internal intercostal
Endothoracic fascia
Lies deep to innermost intercostal but superficial to parietal pleura
Where does the intercostal neurovascular bundle lie
In between the internal and innermost intercostal muscle
Lies along the inferior border of the rib superior to the space in a shallow costal groove on deep surface of rib
Intercostal nerves
Somatic and contain motor and sensory fibres
Also carry sympathetic fibres
Innervate the intercostal muscles, the skin of the chest wall and the parietal pleura
What is the anterior intercostal artery branched from
Internal thoracic artery (branches from subclavian artery)
What is the posterior intercostal artery branched from
Descending aorta in posterior thorax
What do anterior thoracic veins drain into
Internal thoracic vein
What do posterior thoracic veins drain into
Azygos system of veins
What does the intercostal neurovascular bundle supply
intercostal muscles, overlying skin and underlying parietal pleura
Thoracic cage is semi-rigid
costal cartilage that forms a flexible, springy ridge
Superior thoracic aperture
Manubrium, first ribs and first thoracic vertebra form boundary of superior thoracic aperture- passageway through which structures pass between neck and thorax
The suprasternal notch is a feature of which bone?
Manubrium
Intervertebral discs
The bodies of adjacent vertebrae are separated and united by an intervertebral disc, which provides padding and allows for movements between adjacent vertebrae.
The disc consists of a fibrous outer layer called the anulus fibrosus and a gel-like center called the nucleus pulposus.
Anulus fibrosus
Outer fibrous layer of intervertebral disc
Chondrocytes present
In the outer casing strong bands of collagen fibres are evident
Nucleus polposus
Gel-like centre of intervertebral disc
Chondrocytes present
at the centre the collagen is more evenly dispersed.
What are the articular surfaces of the vertebra covered by
Hyaline cartilage
Where do the posterior intercostal arteries originate from
originate from the superior (supreme) intercostal artery, a branch of the costocervical trunk. Third to eleventh posterior intercostal arteries arise directly from the posterior surface of the thoracic aorta.
what feature of the rib protects the neurovascular bundle
Costal groove
Number of posterior intercostal arteries
11
Number of anterior intercostal arteries
9
Where do anterior intercostal arteries originate from
The 1st to 6th anterior intercostal arteries arise directly from the lateral aspect of the internal thoracic artery. The 7th to 9th arise from the musculophrenic artery, a branch of the internal thoracic artery.
Importance of the sternal angle
RATPLANT
Rib - 2nd
Aortic arch
Trachea bifurcation
Pulmonary trunk bifurcation
Left recurrent laryngeal loops under aorta + Ligamentum arteriosum
Azygos vein drains into superior vena cava
Nerve- cardiac plexus
Thoracic duct empties into left subclavian vein
Parts of scapula from top to bottom
Acromion
Coracoid process
Glenoid fossa
Supraspinous fossa
Infraspinous fossa
Dermatome of suprapubic region
T12
Muscles of thoracic wall superficial to deep
Pectoralis major
Pectoralis minor
Serratus anterior
External intercostal
Internal intercostal
Innermost intercostal
Dermatome level of shoulder
C5
Action of serratus anterior muscle
Protract the scapula
Serratus anterior is supplied by which nerve
Long thoracic nerve
Which vein drains the posterior thoracic wall into the superior vena cava?
Azygos
