Anatomy Of Thoracic Wall Flashcards
How many ribs are there?
12
What is included in the thoracic wall?
Thoracic cage
Muscles between ribs
Skin
Muscles which cover anterolateral wall
Which ribs are true ribs? What does this mean?
Ribs 1-7
Connected by costal cartilages to the sternum
Which ribs are false ribs? What does this mean?
Ribs 8-10
Connected to the cartilage of the rib above them
Which ribs are floating ribs? What does this mean?
Ribs 11 and 12
They end free in abdominal muscle
Which ribs are typical ribs?
3-9
Structure of typical ribs?
Head has two articular facets separated by a crest
The neck connects the head of the rib with the body
The tubercle is the at the junction of the neck and body.
The body/shaft has a concave surface with a costal groove
Function of the articular facets on the head of a true rib?
One facet articulates with the vertebra
The other articulates with the vertebra superior
What is the function of the tubercle on a typical rib?
Articulates with the transverse process of the vertebra
Attachment for costotransverse ligament
What is the function of the intercostal groove
Provides protection for the intercostal nerve and vessels
Which ribs are atypical?
1, 2, 10, 11, 12
What makes the first rib atypical?
Very short and board and curved
Has one facet
What makes the second rib atypical?
Poorly marked costal groove
Tuberosity for serratus anterior
What makes ribs 10, 11 and 12 atypical?
One facet on the head and articulate with a single vertebra
11 and 12 have no tubercle or neck because they are floating
What articulates at the costotransverse joint?
Tubercle of rib and transverse costal facet of corresponding vertebra
What articulates at the costovertebral joint?
Where head of rib articulates with superior costal facet of the corresponding vertebra and inferior costal facet of the vertebra above
So two for each rib
Name the three parts of the sternum
Manubrium
Body
Xiphoid process
Features of the manubrium?
Concave
Depression - jugular notch
Fossa lined with cartilage which articulate with clavicle
Facet for articulation with costal cartilage of first rib
Demifacet for second rib
Features of the body of the sternum?
Flat and elongated
Lateral edges have many facets
Which ribs does the body of the sternum articulate with?
3-6
Has demifacets for articulation with ribs 2 and 7
Features of the xiphoid process?
Smallest part of the sternum
Located at T10
Largely cartilaginous - ossified in later life
Articulates with cc of 7th rib
Name the intercostal muscles
External intercostals
Internal intercostals
Innermost intercostals
How many pairs of external intercostals are there?
11
What are the external intercostals continuous with?
The external oblique
Innervation of the intercostal muscles?
Intercostal nerves
Action of the external intercostals?
Increase volume of thoracic cage during forced inspiration
What direction do the external intercostals run?
Inferoanteriorly
What direction do the internal intercostals run?
Inferoposteriorly
Action of the internal intercostals?
Decrease volume of the thoracic cage during forced expiration
What are the innermost ICs and internal ICs separated by?
The intercostal neurovascular bundle
Action of the innermost intercostals?
Decrease volume of thoracic cage during forced expiration
Where do the transverse thoracic muscles attach?
Originate from lower manubrium and xyphoid process
Attach to costal cartilages of ribs 2-6
Innervation of transverse thoracics?
Intercostal nerve
Action of the transverse thoracic muscles?
Pull ribs down providing a weak expiratory function
Functions of diaphragm?
Separates thoracic cavity from the abdominal
Alters volume of thoracic cavity and lungs
Attachments of the diaphragm?
Lumbar vertebrae and arcuate ligaments (L1-3)
Costal cartilages of ribs 7-12
Xiphoid process of the sternum
Central tendon fuses sign inferior surface of fibrous pericardium
Actions of diaphragm?
Inspiration - contracts and flattens, increasing vertical diameter of the thoracic cavity
Expiration - diaphragm relaxes and turns to its dome shape
Innervation of the diaphragm?
Phrenic nerve (left and right) C3, 4, 5
Arterial supply of the diaphragm?
Inferior phrenic arteries
They arise from the abdominal aorta
Superior phrenic, pericardiacophrenic and musculophrenic arteries
Venous drainage of the diaphragm?
Inferior phrenic vein
Superior phrenic vein
Pericardiacophrenic vein
Musculophrenic vein
Movements of the ribcage?
Upper ribs move in a pump-handle movement to increase anterior-posterior diameter of the thorax
Lower ribs move in a bucket handle movement - increases lateral diameter of the thorax
What are the three major arteries supplying the thoracic wall?
Thoracic aorta
Subclavian artery
Axillary artery
In the neurovascular bundle, what is the order of structures from top to bottom?
Vein
Artery
Nerve
Where do most of the posterior intercostal veins drain into?
Azygous/hemiazygous venous system to the superior vena cava
Where do the two anterior and one posterior intercostal arteries arose from?
Posterior - aorta
Anterior - internal thoracic arteries
Where does the internal thoracic artery arise from?
Subclavian
Roots of the intercostal nerves?
Anterior rami of T1-T12
