Lecture 7: thoracic wall Flashcards
what is thorax aka
rib cage
what is thorax bounded by
thoracic vertebrae t1-12 posteriorly, sternum and ribs
describe thorax - gen functions
osteo cartilagenous (bones+cartilage) structure (chunks of cartilage linking ribs to sternum)
encloses thoracic cavity and protects content (lungs, heart, and associated structures)
frame for attachment of upper limb and its muscles (all bones=scaffold, respiration muscles)
describe thorax - sealed by
thoracic wall and floor sealed off by muscles and connective tissues with a few key passages for neurovascular structures
describe superior thoracic aperture
thoracic inlet
not sealed = open
structures for continuity = trachea, common carotid (arteries)
describe inferior thoracic aperture
thoracic outlet = floor
mostly closed off by diaphragm muscle (but still has openings for structures to get in/out)
name and describe boundaries of thoracic wall
posterior boundary = thoracic (spine - vertebral column)
lateral boundaries = ribs
anterior boundaries = sternum (breastbone)
describe vertebrae of posterior boundary - gen
t1-t12
describe vertebral body
all vertebrae have
demi facets = stacking thoracic vertebrae together to make complete articulation for costovertebral joint
describe transverse process of vertebrae
articulates with ribs
costal facet = only t1-12
describe spinous process of vertebrae
large
Attachment of muscles of back - sticks out - see in lateral view, poke at midline, sagittal plane
describe superior articular process of vertebrae
articulates with superior vertebra
describe inferior articular process of vertebrae
articulates with inferior vertebra
describe vertebral foramen of vertebrae
passage of spinal cord
each opening = spinal nerves
what else do thoracic vertebrae have in addition to normal processes and articular facets
unique - have 3 additional articular surfaces for articulations with ribs
what distinguishes types of ribs
Depends on how articulates with sternum
describe true ribs
1-7
direct insertion onto sternum via costal cartilage (links directly to sternum)
describe false ribs
8-10
indirect insertion onto sternum via costal margin
10->9->8->7->sternum
converge on costal cartilage of 7 then meets sternum
cartilagenous ridge
describe floating ribs
11-12
no insertion on sternum
describe anatomy of typical rib - head
connects to vertebrae
describe anatomy of typical rib - neck
after head
describe anatomy of typical rib - costal angle
changes direction
starts c shape
more visible in some ribs than others
describe anatomy of typical rib - body
big
after costal angle
describe anatomy of typical rib - tubercle
bump
posterior
articulates with transverse process
describe anatomy of typical rib - articular facets
2 articular facets on head
slot into demi facets on vertebrae
describe anatomy of typical rib - c shape
connects posterior (vertebral) and anterior (sternum wall)
what does rib 5 articulate with
articulates with t5 and t4
same rib and one above it
describe entirely the 3 articulations of typical rib
1- posterior - rib head with bodies of 2 thoracic vertebrae (head with vertebral bodies = same level and superior)
2 - posterior - rib tubercle with thoracic transverse process of same level
3 - anterior - costal cartilage with sternum (ribs 1-7), no bone on bone, always have costal cartilage
describe posterior joints - gen
rib articulations with thoracic vertebrae
costovertebral joint
costotransverse joint
describe costovertebral joint - posterior joints
head of rib articulates with 2 demi facets = superior demi facet on vertebral body of same number vertebrae AND inferior demi facet of vetebral body above
joint type = complex synovial (3 bones), plane/gliding synovial movements
describe costotransverse joint - posterior joints
tubercle of rib articulates with costal facet on transverse process of same number vertebrae - between rib and transverse process
joint type = synovial plane/gliding
what are atypical ribs
lack one or more articulations
describe ribs 1,10-12 - atypical
lack costovertebral articulation with superior vertebral body (only articulate with own level)
no demi facet, joint surface shifts = now only on vertebral body
describe ribs 11-12 - atypical
no neck tubercle so no costotransverse joints
describe sternum and parts - 6
jugular notch
manubrium = top
manubriosternal joint = sternal angle, fused in adults
body of sternum = main part
xiphisternal joint - fused in adults
xiphoid process = little sharp point, sticks out, can feel it, palpable landmark
describe sternum - facets for true ribs
7 joints on either side
at which level is jugular notch of sternum- also rib
level of t2
rib 1
at which level is manubriosternal joint of sternum - also rib
t4/5
rib 2
at which level is xiphisternal joint of sternum - also rib
t9
rib 7
describe rib tilt
ribs tilted inferiorly from post to ant
so ribs at level of sternum do not coincide with thoracic vertebral levels
drop down as move forwards
describe anterior joints - 4
rib articulations with sternum
costochondral
sternocostal
1st sternocostal
interchondral
describe costochondral joint - anterior joints
ribs 1-10 only
ribs and costal cartilage
no movement under physiological conditions
synchondrosis - do not move, fused
describe sternocostal joint - anterior joints
ribs 2-7 only
costal cartilage and sternum
limited movement (synovial plane/gliding type, some movement, respiration)
describe 1st sternocostal joint - anterior joints
costal cartilage with sternum (manubrium) at rib 1
no movement synchondrosis - fused
describe interchondral joint - anterior joints
between costal cartilage
ribs 7-10
another pair present between ribs 6-7 (variable tho) - cartilage bridge, sometimes not present
unique type of synovial joint - plane/gliding, limited
name movements of thoracic wall - respiration
pump handle movement
Bucket handle movement
describe pump handle movement - respiration - generally
sagittal plane
volume of thoracic cavity - changes in an anterior to posterior diameter
as lifts ribs on either side in sagittal plane
describe pump handle movement - respiration - joints
at costotransverse (posteriorly) and costovertebral (anteriorly) joints (between 2)
ribs 2-7 (those with sternocostal joints)
describe pump handle movement - respiration - movement visibility
Smaller movement superiorly
larger movement inferiorly
increasingly visible as get to lower ribs
describe pump handle movement - respiration - what is pump handle
rib - not sternum
ribs move around axis of rotation
describe bucket handle movement - respiration - generally
volume of thoracic cavity changes in mediolateral diameter - side to side,
describe bucket handle movement - respiration - joints
at costotransverse and costovertebral joints (between), ribs 6-12 and sternocostal joint of 7&7, (recall - 8-10 have no sternocostal joints)
describe bucket handle movement - respiration - direction
mediolateral direction (lift bucket handle)
describe bucket handle movement - respiration - movement visibility
smaller superiorly and larger movements inferiorly (since less mobility)
what do intercostal muscles do
move vertebrae between ribs
describe external intercostals - direction
sup –>inf, down and medial
from ribs to costal cartilages anteriorly (membrane)
describe external intercostals - fiber orientation
from attachment on sueprior rib - obliquely towards anterior and inferior (hands in jacket pockets)
describe external intercostals - function
elevates ribs and sternum during forceful inspiration
bring out - in bucket handle motion
describe external intercostals - external intercostal membrane
attachment to costal cartilage on medial aspect = covered by membrane
describe internal intercostals - direction
“deep to external intercostal membrane
from sternum anteriorly to costal angle posteriorly”
describe internal intercostals - fiber orientation
perpendicular to external intercostals
describe internal intercostals - function
depresses ribs and sternum during forceful expiration (exercise and coughing)
when are intercostal muscles used
Accessory muscles of respiration - used during forceful movements of thoracic wall and are mostly relaxed during normal respiration
describe emg of intercostal muscles
“electromyography
muscle activation of external intercostals at different inspiration intensities
= more activity during forceful resp”
name and describe accessory muscles of thoracic wall
“deepest muscles
inside surface of thoracic wall
innermost intercostal muscles
transversus thoracis”
describe innermost intercostal muscles - fiber orientation
from superior rib = postero inferior (like internal intercostals)
describe innermost intercostal muscles - function
“like internal intercostals - same orientation
depresses ribs and sternum during forceful expiration”
describe transversus thoracis muscles -direction
from sternum body an xiphoid process to costal cartilage of ribs 2-6
describe transversus thoracis muscles - function
“depresses ribs, forceful expiration
pulls ribs down, sternum will not move towards rubs - opposite
so back towards sternum = bucket handle motion”
what are main muscles of respiration
Diaphragm
describe diaphragm - generally
“Separates thorax from abdomen (floor thoracic=roof abdomen)
dome shaped muscle, thin
seals off inferior thoracic aperture”
describe diaphragm - peripheral attachments
“along circumference of inferior thoracic aperture (outlet)
stretches all around periphery, runs along costal margin, xiphoid process
ribs 6-12, l1-l3 vertebrae”
describe diaphragm - innervation
“phrenic nerves (anterior rami of c3-5) to each hald
hiatuses for Inferior vena cava, esophagus and aorta (3 holes, not fully sealed off)
c3,4,5 keep diaphragm alive”
describe diaphragm - function
when fibers contract - resting respiration = depresses to increases thoracic cavity volume along superior inferior axis (dome becomes smaller and tighter, moves towards abdominal cavity)
describe diaphragm - clinical correlate
“damage to one phrenic nerve (2 phrenic - one on either side) can cause unilateral (hemis) paralysis of diaphragm
Can be seen on X Ray by paradoxical Rise of paralyzed side during inspiration, as abdominal viscera are pushed into it from depression of functional side (active side pushes abdominal viscera–>so the other side Rises: uneven movement of diaphragm & viscera (how diagnosed)”
describe vascular supply to thorax - gen
blood supply to intercostals and thoracic wall comes from intercostal arteries
describe vascular supply to thorax - anterior intercostal arteries
“arise from internal thoracic arteries (ica), 1st branches of subclavian arteries
running on posterior aspect of the anterior thoracic wall on either side of sternum
left and right internal thoracic artery (branch of subclavian) –> ant arteries”
describe vascular supply to thorax - posterior intercostal arteries
“arise directly from thoracic aorta or subclavian arteries (superior 2)
Branches - moves out laterally –> post arteries”
describe vascular supply to thorax - meet
“anterior and posterior intercostal arteries in an intercostal space from an anastomosis
along thoracic cavity, runs parallel to ribs
post meets ant
Alternative pathways if something blocking one of 2 pathways (ant or post)”
describe vascular supply to thorax - blood supply to thoracic side of diaphragm
“2 branches of internal thoracic arteries =
musculophrenic = splits and artery runs into gutter formed where diaphragm attaches
pericardiophrenic = 1st branch, runs with phrenic nerve, also provides blood to pericardium
(and from lower intercostal arteries)”
describe somatic innervation of thoracic wall - gen
“somatic innervation = spinal nerves t1-12
runs as intercostal nerves but t12 = subcostal since last rib = no rib under”
describe somatic innervation of thoracic wall - runs where
“in costal groove of same numbered rib
with that levels intercostal artery and vein
runs from back to front”
describe somatic innervation of thoracic wall - branches of spinal nerves
“intercostal nerve (motor/sensory)
lateral cutaneous nerve (sensory)
anterior cutaneous nerve (sensory)
*cutaneous = to skin, meet so all has sensory coverage from same spinal level”
describe thoracic dermatomes - gen
in thorax spinal nerves create regular bands of skin receiving sensory innervation - from cutaneous branches of intercostal nerves at each level
what is dermatome t4 innervated by
t4 nerve
describe thoracic dermatomes - dermatome level and approx skin areas
“t4=nipple
t6=xiphoid process
t10=umbilicus”
describe thoracic dermatomes - clinical correlate
“Rashes can spread along thoracic nerve Roots
Ex: Reactivation & Spread of Chicken pox virus (V. zoster
causes Shingles = painful Rash in bands along one or
more dermatomes (likely T5/Th in pic)
along intercostal nerves-irritates infects nerves supply
(band as Rash)”
what runs in costal groove - describe
“intercostal nerve and a and v run as bundle in costal groove of rib at same thoracic level
bundle runs between innermost and internal intercostal muscles at that level”
describe VAN
“V = ant/post intercostal vein
A = ant/post intercostal artery
N = intercostal nerve
van = order, sup, mid, inf”
describe clinical correlate - relevance of bundle
“must be careful when insert chest tube or make nerve block
chest tube (e. g. to drain pleural cavity) = want to insert close to superior border of Rib below (if get close to inferior border = bad = risk damaging bundle running in costal groove)
if want nerve block = be closest to inf border of level you want to anesthetize”
describe lateral walls of thorax - sealed
lateral walls sealed off by muscles of respiration
describe diaphragm - central attachments
to itself via a central tendon (fibers to top of dome, converges on itself)
What is main functions of thorax
Enclose thorax
Protects its contents
Functions as frame to anchor upper limb skeleton = attachment sites for muscles of upper limb, back and those related to respiration
What is different about lower thoraci vertebrae
Have less articular surfaces = less articulations with ribs
What makes up zygopophyseal joints
Superior articulate process, articulates with superior vertebra
Inferior articular process, articulates with inferior vertebra
Describe costal angle
Coronal to Sagittal plane = marks transition
Body of rib runs in sagittal plane
What are articulations with rib
Head with 2 vert
Facet on tubercle with transverse process of same level
And with sternum anterioly
Describe atypical ribs
Ribs 1, 10-12 = lack costovertebral articulation with superior vertebrae (only articulate with same level)
Ribs 11-12, = have no neck/tubercle so no costotransverse joint
Lower vert = articular facet shifts, no split between levels, entirely contained in one vertebra
Describe bucket handle and pump handle movements
Bucket handle= v shape widen
Pump handle = sternum moves out towards us
= increase vol thoracic cavity
What are external intercostals function
Elevates ribs and sternum during forceful expiration
Bucket handle and pump handle motion
Describe mor accessory muscles of respiration - Genn
Cross from a vertebra or sternum to attach onto ribs at a diff level
= act in elevation/depression of ribs
Describe scalenes
Attached to first 2 ribs
RIB ELEVATION
Pull upper 2 ribs into neck, for inspiration
Describe innermost intercostal muscles
Rib depression - same direction as internal intercostal
Describe transversus thoracic
Upper ribs to sternum body
Rib depression
Describe deep intrinsic back muscles for respiration
Levatores costarum =
Rib elevation (deep intrinsic muscles help)
Describe deep extrisnic back muscles for respiration
Serratus posterior superior = rib elevation, pulls upper ribs up, forceful inspiration
Serratus posterior inferior = rib depression, forceful expiration
Describe somatic innvertaion of thoracic wall - gen
Provides by spinal nerves t1-t12
Run as intercostal nerves (*t12= subcostal)
In costal groove
Below same number rib
Describe somatic innvertaion of thoracic wall - SPECIFICS
Ant rami = intercostal nerves only in that region
= gives off cutaneous branches = sensory, lateral and anterior cutaneous nerves
Post rami = intrinsic muscles of back
