Thoracic Wall And Pectoral region Flashcards
Describe the inferior thoracic aperture boundaries
- 12 th thoracic vertebra
- 11th and 12th pair of ribs
- Costal cartilages of ribs 7th - 10th (costal margin)
- Xiphisternal joint
- Closed by the diaphragm
Describe the superior thoracic aperture
Boundaries:
-body of 1st thoracic vertebra
- 1st ribs and their costal cartilages
- jugular notch
What structures pass through superior thoracic aperture?
Structures passing through
-left Subclavian artery
- Subclavian (or SCV) vein
- Brachiocephalic trunk
What are the bones of the thoracic wall?
Vertebrae, ribs, sternum
What are the muscles of the thoracic wall?
Diaphragm, intercostal, pectoral, serratus anterior, latissimus dorsi
What are the nerves and blood vessels of the thoracic wall?
Intercostal neurovascular vessels
Aside from bones, muscles, nerves and bloood vessels, what other structures constitute the thoracic wall?
Skin, subcutaneous tissue, endothiracic fascia,parietal pleura
What are the three main parts of the sternum?
- Manubrium
- Body
- Xiphoid process
What does the sternum articulate with?
- Clavicle
- Costal cartilages I-VII
What is the jugular notch of the sternum?
Small indentation on the superior border if the manubrium
What is manubriosternal joint(angle of Louis) of the sternum?
-Anterior boundary of the transthoracic plane
Corresponds to:
- T4/5 intervertebral disc
- 2nd costal cartilage
Describe typical ribs
- head= 2 Articular facets
- tubercle= 1 Articular facet
- Angle
- Costal groove-for neurovascular bundle
- Sternal end-attached to costal cartilage
Summarize atypical ribs
Ribs 1,2,10, 11,12
- each atypical for their own reason
- Also correspond to the atypical vertebrae
Describe thoracic vertebrae
- small heart shaped body
- round vertebral foramen
- downward slanting spinous process
- Two demifacets on body for articulation with the head of the rib
- A facet on the transverse process for articulation with the tubercle of the rib
Describe the costovertebral joints
Synovial joints between rib and vertebrae
Typical rib articulates with!
-adjacent vertebral body and body of vertebrae above including disk (via Demi facets)
-adjacent transverse process (via facet)
Describe the sternocostal joint
- synovial joints between costal cartilage and sternum (1st rib is fibricartilaginous)
- true ribs attach with sternum directly (via costal cartilage)
- false ribs attach indirectly by joining costal cartilage of rib 7
- Floating ribs don’t attach to
Differentiate true ribs, false ribs and floating ribs
True ribs- 1-7- attach to sternum via own costal cartilage
False- 8-10 attach costal cartilage of rib above
Floating rib- no attachment anteriorly
How are external intercostal fibers oriented?
-fibers- down and medial “hands in front pockets”
How are internal intercostal fibers oriented?
-fibers-down and lateral “hands in back pockets”
How are the fibers of the innermost intercostal oriented?
Fibers- sane as internal
What is the neurovascular bundle of the intercostal muscles?
- intercostal artery, nerve, vein
- between internal and innermost
- innervation is segmental from intercostal nerves
What is the action of the intercostal muscles?
Action: elevation and depression of ribs and maintaining the intercostal space during respiration
Summarize the transverse Abdominis
Radiates from out the sternum
Innervated is segmental from intercostal nerves
Where are subcostal muscles of the deep muscles of the thoracic cage found? What is the innervation?
Subcostal muscles- found posteriorly near the angles of the ribs and span 1 or more intercostal spaces
Innervation is segmental from intercostal Space
What is the function and innervation of pectoralis major?
Innervation: medial & lateral nerve
Shoulder adduction, flexion & medial rotation of humerus
What is the function & innervation of serratus anterior?
Long thoracic nerve
Upward rotates scapula (allows for abduction beyond 90 degrees) keeps scapula against thoracic cage
What is the innervation & function of subclavius?
Nerve to Subclavius
Depressses clavicle
What is the function and innervation of pectoralis minor (in clavipectroral fascia)?
Medial pectoralis nerve
Depresses shoulder, protracts scapula
Describe rib movement during respiration
“Pump handle” increases anterior-posterior dimensions
“Bucket handle” -increases lateral
Contraction of diaphragm increases vertical dimension
What is the pleura?
Membranes consisting of two parts separated by a space (pleural cavity)
What are the divisions of the pleura?
Visceral-lines/added to the lungs
Parietal- lines/adhered to the. Thoracic cage
What are nerves in pleura named according to?
Names according to the thoracic cage innervation accordingly
- Costal: intercostal nerves
- mediastinal; phrenic nerves
- diaphragmatic: phrenic & intercostal
- cervical
What is the function of pleura?
-Folds to conform to the boundaries of the thoracic cavity reflection lines are formed.
- Contains two recesses to allow for movement of the lungs during breathing
- Costodiaphragmatic
- Costomedial
The lungs don’t fill the entire space to allow for movement during breathing
The Costcodiaphragmatic recess is ideal for thoracocentesis
Why can bones be used for landmarks for pleura?
Because the parietal pleura lines the thoracic cage bony landmarks can be used to identify its boundaries.
The inferior boundary corresponds to the location where the planes cross certain ribs. The visceral pleura at rest is 2 rib levels higher that the parietal
Describe the neurovascular bundle of the pleura
Travels in costal groove on inferior aspect of rib all incisions/tubes placed above rib to avoid VAN: Thoracocentesis
“Pleural tap” to sample fluid from pleural space:
Thoracostomy
Chest tube inserted to drain fluid or air from pleural cavity
Describe nerve supply to the thoracic wall
Ventral rami of spinal nerves (intercostal nerves):
- Motor innervation to muscles
- Sensory innervation to ribs, costal cartilages, skin, costal pleura and peritoneum (T7-12)
Dermatomes
-Cutaneous branches from the spinal nerves supply the skin segmentally
-Pain from the pleura is felt on the skin along the corresponding dermatome
Describe the dermatome of the thoracic wall
T4-nipple
T7-tip of the xiphoid
T10-umbilicus
T12- suprapubic region
L1-inguinal region
What does the costocervical trunk supply?
Supplies the first 2 posterior intercostal spaces
What does the Subclavian artery?
Gives internal thoracic artery, vertebral artery, and costocervical trunk
What does the descending thoracic aorta supply?
Supplies posterior intercostal arteries
What does the posterior intercostal artery supply?
Runs in costal groove
What does internal thoracic artery supply?
Gives anterior intercostal arteries and terminates into musculophrenic and superior epigastric
What does anterior intercostal artery supply?
Follows the inferior border of the rib and anastomoses with the posterior intercostal arteries
What does musculophrenic artery supply?
Continues along the costal margin supplies diaphragm, anterior and lateral walls
What does the superior epigastric artery supply?
Continues onto the anterior abdominal wall and anastomoses which inferior epigastric artery
What is the parietal pleura supplied by?
Supplied segmentally by the vessels associated with the adjacent wall
- Diaphragmatic is supplied by superior phrenic arteries
- Mediastinal portion is supplied by pericardiophrenic artery
Summarize veinous drainage of the thoracic wall
The veins from the upper 2 intercostal spaces posteriorly join together and May drain into the azygos and accessory hemiazygos or directly into the brachiocephalic vein
Describe lymphatic drainage of the thoracic wall
Drainage:
- Anteriorly to parasternal nodes
- Posteriorly to intercostal nodes
- Inferiorly to diaphragmatic nodes
Most lymph nodes from the thorax eventually drain into thoracic duct
-Upper part of right thorax into right brachiomediastinal
Summarize the thoracic duct(lymphatic drainage)
The thoracic duct is the continuation of the cisterna chyli superior to the diaphragm
-Thoracic duct pierces the diaphragm with the aorta
- Runs between the aorta and azygos vein
- Crosses to the left at T4/5
- Empties into venous system at junction between IJV & SCV
Describe the mammary gland
-Modified sweat glands that overlie the pectoralis major muscles
- Contains numerous connective tissue septa
- This compartmentalizes the breast tissue
- Some are condensed into ligaments = suspensory ligament (suspends the breast)
- Numerous secretory lobules
- The lobules increase in size during pregnancy and lactation
- 15-20 lactoferous ducts open onto the nipple
- Nipple is surrounded by the Areola
-Surrounding the secretory lobules are areas of adipose tissue
What is the retromammary space?
Space between the breast and the pec muscles
Allows for free movement of the breast
Breast is firmly attached to the pectoral fascia by the suspensory ligaments
What are the clinically divided quadrants?
Upper lateral: UL
Upper medial:UM
Lower lateral: LL
Lower medial:LM
This is important as it relates to lymph drainage and therefore cancer metastases
What is the significance of T4 cutaneous nerve to the breast?
Supply to the nipple corresponds to the T4 dermatome
Even in pendulous breasts
What is the sentinel node?
The first node into which lymph drains from any of the quadrants
Summarize lymph drainage in the breast
Lymph will drain first to the nearest group of nodes (typically anterior)
Continue to move from node to node until ultimately into the apical nodes
Eventually into Bronchomediastinal and Subclavian trunk
Joins the veinous system by left and right main duct
Contrast axillary and parasternal nodes
Axillary nodes- receives 75%
Parasternal nodes- receives only 25%. Some may cross to contralateral
