Chest Wall and the Anatomy of Ventilation Flashcards
What are the boundaries of the thorax?
- Posterior: Vertebral column
- Anterior: sternum, manubrium, xiphoid process, costal cartilages
- Lateral: Ribs
- Inferior: Diaphragm
True ribs: 1-7
False: 8-10
Floating: 11 &12
Sternal angle/manubriosternal joint = 2nd rib (T4)
What are the 2 joints?
- Costotransverse joint – between transverse process and tubercle of rib
- Costovertebral joint - Joint of head of rib (between rib and costal facet) (costovertebral joint)
What is the thorax surface anatomy?
Infrasternal angle = angle for CPR
Sternal angle = 2nd rib (T4)
Auscultation of lungs
Auscultation assesses airflow
checks if lungs are filled with:
air (resonant sound) - normal
fluid (dull sound)
solid (flat sound)
What are the Divisions within the Thoracic Cavity?
Left and right pleural cavities = contain lungs
Mediastinum = the heart, blood vessels, airways (trachea), thorax innervation (vagus n. - parasympathetic, sympathetic trunk and phrenic nerves) and thorax lymphatics (nodes, thoracic duct)
Explain the pleura
- Parietal pleura: Adhered to the wall of the thoracic cavity, the diaphragm (thoracic surface) and neighbouring the borders of the mediastinum (e.g. pericardium). Sensitive to pain, temperature, touch and pressure (via intercostal nerves and phrenic nerves)
- Visceral pleura: Adhered tightly to the lungs (and lobar fissures). Sensitive to stretching (via autonomic nerves)
Pleura and rubs go above ribcage.
Costomediastinal recess
What is the diaphragm?
- Primary muscle of respiration. Skeletal muscle.
- Voluntary somatic.
- Forms barrier between the thorax and abdomen
- Several openings to allow vessels and GI tract to pass through
- Tendinous core containing vena caval opening
C3,4,5
What are the Openings Through the Diaphragm?
There are three main openings through the diaphragm:
1) Caval opening (through central tendon): T8
Passes the inferior vena cava and terminal branches of phrenic nerves
2) Oesophageal opening (through muscular part): T10
Passes the oesophagus, left and right vagus nerves and the lymphatic vessels of the lower third of the oesophagus
3) Aortic opening (through tendinous arch): T12
Passes the aorta, thoracic duct and azygos vein
Intercostal muscles
Occupy intercostal spaces
Three layers:
- External intercostal (hands in pocket direction) - elevate ribs
- Inner intercostal - depress ribs
- Innermost intercostal - depress ribs (probably)
Innervation: intercostal nerves. Intercostal nerves arise from the ventral rami of spinal nerves.
Blood supply: intercostal arteries and veins
Between the innermost intercostal muscles and internal intercostal muscles, triad of intercostal nerve, intercostal artery and intercostal vein sit there (at costal groove). Protected by ribs.
Dermatome distribution
dermatome distribution on the thorax follows the pattern of intercostal nerve supply
What is the blood supply of the intercostal muscles?
Arterial blood supply:
1) Posterior intercostal arteries = From the thoracic aorta via the posterior intercostal arteries and its lateral cutaneous branches
2) Anterior intercostal arteries = From the subclavian arteries via the internal thoracic arteries and the anterior intercostal artery
Posterior intercostal arteries and anterior intercostal muscles anastomose.
Venous drainage:
1) The posterior intercostal veins and their cutaneous branches drain to the azygos, hemiazygos and accessory hemiazygos veins.Ultimately, the ayzgos vein drains to the superior vena cava
2) The anterior intercostal veins drain to the internal thoracic vein and the subclavian veins
What are the thoracic lymphatics?
The chest wall and parts of the mediastinum drain first towards the:
-Paravertebral nodes
-Parasternal nodes
-Paramammary nodes
And then to the thoracic duct and the right lymphatic duct
What is the nervous and blood supply of the thoracic wall?
Intercostal vein, artery, and nerve travel through the costal groove
What are the muscles in inspiration and expiration?
1)Quiet inhalation:
Diaphragm
External intercostals
Scaleni
Active inhalation: accessory muscles (sternocleidomastoid, pectorals)
2) Quiet exhalation:
Passive event mostly
Relaxation of diaphragm
Internal intercostals
Active exhalation:
(singing, speech, exercise, sneezing, coughing)
Abdominal wall muscles
Internal intercostals
Breast
- Between 3rd and 7th rib, in the middle between sternum and axilla
- Lies on the pectoral fascia – can be moved out of resting position quite easily
- Anchored by suspensory ligaments of the breast in between the mammary gland lobules
- Fatty tissue (more extensive in women)
- Apocrine glandular tissue, producing milk
- Develops in both men and women from the same embryological tissue
- Breast = mammary glands. Mammary glands are modified sweat glands consisting of ducts and secretory lobules. The lobules drain into lactiferous ducts which open into the nipple. Lactiferous sinuses are reserves for breast milk.
