Thorax 1 Flashcards
what is the thoracic wall
a cage made of the thoracic skeleton (vertebrae, ribs, sternum), associated cartilages (costal cartilages) and muscles connected to thoracic skeleton (intercostal, transversus thoracics and serratus posteriors)
what is the superior thoracic aperture?
ring made up of the first thoracic vertebrae, first rib + costal catyilages and superior surface of manubrium
what is the inferior thoracic aperture?
more irregular shape closed off by diaphram
why are the true muscles of thoracic wall true?
-attach to skeletal structure of thoracic wall
-act to move these structures (ie elevate or depress)
what are the 6 true muscles of the thoracic wall
-external intercostal
-internal intercostal
-innermost intercostal
-transversus thoracis
-serratus posterior superior
-serratus posterior inferior
how does the external interocstal muscles run?
-inferomedially
how does the interal interocstal muscles run?
(deeper than external)
-superomedially
how does the innermost interocstal muscles run?
(deeper than inner but v similar)
-superomedially
role of external intercostal
increase intrathoracic volume by elevating and widening rib cage during forced inspiration
role of internal intercostal
decreasing intrathoracic vol (tf increasing pressure) by depressing and narrowing rib cage during forced expiration
role of innermost intercostal
similar role to internal intercostal muscle
role of intercostal VAN bundle
intercostal vein, artery and nerve bundle supllies blood supply and innervation to the intercostal muscles and skin in that region
where does intercostal VAN run?
runs between innermost and internal intercostal muscles, sit tucked under inferior border of each rib (costal groove)
if a needle needed to be inserted into the ribcage (ie drain air) where would it be inserted and why?
superior border of each rib as collateral branching of VAN is not as important to injure as the major intercostal VAN bundle
origin and insertion of external intercostal muscle
o: inferior borders of ribs
1-11
i: superior borders of ribs immediately below origin sites
their directions (where they run) is independent of their origin and ins
so superomedially
origin and insertion of internal intercostal muscle
o: inferior borders of T1-T11 ribs + costal cartilages
i: superior borders of ribs and costal cartilages immediately below origin sites
origin and insertion of innermost intercostal muscle
o: inferior borders of T1-T11 ribs
i: superior borders of ribs immediately below origin sites
innervation of external, internal and innermost intercostal muscles
adjacent intercostal nerves (anterior rami of thoracic nerves)
where does the transversus thoracis muscle lie?
deepest muscle on the interal surface of the thoracic cage
function of transversus thoracis
-assist forced expiration by depressing the ribs
-proprioception of position of ribcage
o and i of transversus thoracis
o: posterolateral aspects of body and xiphoid process of sternum
i: internal surface of costal cartialges and costal ends of adjacent ribs 2-6
what are the serratus posterior (infeior and superior) muscles of the back and their roles?
part of the intermidiate layers of the back with more of a role in proprioception of ribs (like transversus thoracis)
but superior: elevation
inferior: depression of ribs
o and i of serratus posterior superior
o: C7-T3
i: ribes 2-5
o and i of serratus posterior inferior
o: T11-L3
i: ribs 9-12
describe the arterial supply of the thorax
the subclavian artery branches into the internal thoracic artery (which branches into the pericardiacophrenic artery, perforating branches on internal thoracic artery and musculophrenic artery)
-then the internal thoracic artery continues as the superior epigastic artery (other branches of intenral thoracic supply the intercostal muscles)
internal thoracic artery runs where
parallel to sternum in wall of anterior thoracic cage (between transversus thoracis and internal intercostal)
pericadiacophrenic artery supplies?
-pericardium and diaphragm
perforating branches of internal thoracic artery supplies
-pec major
-breast
-overlying skin
muscolophrenic artery supplies?
-intercostal muscles
-diaphragm
-abdominal muscles
superior epigastric artery supplies
abdominal wall
what is the pectoral region
region superior to thoracic cage
what is the pectoral region made up of?
-superficial part (skin, fascia and breast tissue)
-deeper compartment (4 pairs of muscles anterior to thorax)
what is the deeper compartment of the pectoral region made up of?
4 muscles
-pectoralis major
-pectoralis minor
-serratus anterior
-subclavius
subclavius muscle function
stabilise clavicle during movement of upper limb
pectoralis major function
adduct humerus by putting it closer to body
pectoralis minor function
-downwardly rotate scapula during movement of shoulder joint
-somethimes assist with respiration
serratus anterior function
-stabilise scapular + hold it close tto thoracic wall (inferior angle of scap dont wing/stick out during movement of upper limb)
pectoralis major function
adduct humerus by putting it closer to body
what muscles are deepest in the deep compartment of the pectoral region
deepest: subclavius, pectoralis minor and serratus anterior
more superficial: pectoralis major
insertion and origin of pectoralis major
o: clavicular head (to medial 1/2 of clavical) + sternal head + some of the costal cartilages
i: greater tubercle of humerus
o and i of pectoralis minor
o: ribs 3, 4 and 5
i: coracoid process of scapular
o and i of subclavius
o: 1st costal cartilage
i: middle of clavicle
o and i of serratus anterior
o: ribs 3-8
i: deep anterior surface of scapular at its medial border
pectoralis major function
adduct humerus by putting it closer to body
what are extrinsic muscles?
origin in one region, insertion in another
what are intrinsic muscles in the back
origin+ insertion in back itself
what can the extrinsic muscles be categorised into?
superficial and intermediate muscles
what can the intrinsic muscles be categorised into?
deep muscles
what are the superficial muscles of the back
-trapezius muscle
-levator scapulae
-rhomboid minor
-rhomboid major
-latissimus dorsi
what are the intermediate muscles of the back
serratus posterior (superior and inferior)
what are the deep muscles of the back
-spinotransversales (splenius capitis and colli)
-erector spinae
-transversospinales (semispinalis and multifidus)
what are the erector spinae muscle made up of?
-iliocostalis lumborum
-iliocostalis thoracis
-longissimus thoracis
-spinalis thoracis
role of deep musscles
movement of vertebral column
role of superficial muscles
move shoulder joint
role of intermediate muscles
-elevate or depress ribs
-proprrioception in ribs
what does the first thoracic mixed spinal nerve of the spinal cord very quickly divide into?
posterior and anterior ramus of first thoracic nerve
role of posterior ramus of the thoracic nerve
innervating deep muscles of back
role of anterior ramus of the thoracic nerve
-supreficial + intermediate layers of brank
-brachial + lumbar plexues
(bigger than posterior due to mas sig role)
serratus anterior innervation
long thoracic nerve (c5-c7)
