Session 1 to 5 of cardiorespiratory anatomy Flashcards
How many percent of blood does the ductus venosus shunt directly from the umbilical veins to the inferior vena cava?
about 30%
What ribs do the body of the sternum articulate with?
Ribs 2-7. Rib 7 articulates with the superior end of the xiphisternum.
Which ribs are true ribs, false ribs and floating ribs? Why are they called these terms?
- Ribs 1-7 are true ribs as they articulate directly with the sternum (sternocostal joint)
- Ribs 8-12 are false ribs as they do not articulate directly with the sternum, (Ribs 8-10) join the 7th costal cartilage
- Ribs 11 and 12 are considered floating because they are short and do not articulate with the sternum. They only articulate with the vertebrae at the costovertebral joints
The costal cartilages of which ribs form the costal margin?
The costal cartilages of ribs 7-10 form the costal margin
What are typical and atypical ribs and Which are typical and atypical ribs?
Typical ribs - Ribs that look similar and share common anatomical features.
Atypical ribs - Look different to typical ribs and lack some of the features of typical ribs.
Ribs 3-9 are typical ribs as they have a head, neck and tubercle and body (shaft)
Ribs 1, 2, 10, 11, 12 are atypical for various reasons, e.g. they are much shorter than typical ribs.
In the vertebral column, what are the 5 vertebral sections and how many parts do they have?
Cervical - 7 vertebrae (C1 - C7)
Thoracic - 12 vertebrae (T1-T12)
Lumbar - 5 vertebrae (L1-L5)
Sacral - 5 vertebrae (S1- S5)
Coccygeal - 4 vertebrae (Co1-Co4)
What forms the boundaries of the superior thoracic aperture? (bones)
The manubrium, first rib and the first thoracic vertebrae
What do the heads and the tubercle of the ribs articulate with?
The head articulates with the vertebral body and the tubercle of the rib articulates with the transverse process of the vertebra.
What rib lies at the level of the sternal angle?
The second rib
What spinal nerves innervate the skin of the thoracic wall? What do the somatic sensory fibres do? What do the somatic motor fibres of the thoracic wall do?
- The skin of the thoracic wall is innervated by T1-T12 spinal nerves
- Sensation from the skin reaches our conscious perception via somatic sensory fibres in the spinal nerves.
- Somatic motor fibres innervate the skeletal muscles of the thoracic wall and controls voluntary movement.
What is a dermatome?
An area of skin innervated by a single spinal nerve. Each pair of thoracic spinal nerves supplies a ‘strip’ around the corresponding body part (thoracic spinal nerves supply strips around the chest wall). (picture in google docs)
What are the 5 components in the breast?
- Fat –> Variable amounts just under the skin
- Lobules of glandular tissue
- Ducts which converge on the nipple. (areola is the region of pigmented skin surrounding the nipple)
- Connective tissue and ligaments
- Blood vessels and lymphatics
What arteries supply the breast with oxygen?
The internal thoracic artery, axillary artery and anterior intercostal arteries
What are the 5 lymph nodes in the axilla? Which part do they drain?
Central- Breast
Pectoral- Upper limb
Humeral- Chest wall
Subscapular- Scapular region
Apical- Abdominal wall
Where is the apical node located and what is its significance?
The apical node is located in the apex of the axilla.
They receive lymph from all other lymph nodes in the axilla. Because they drain most of the lymph from the breast, they are usually involved in the spread of breast cancer.
How many layers of intercostal muscles are there and what is their function?
- External, internal and innermost intercostal muscles.
They move the ribs and alter the dimensions of the thoracic cavity for inspiration and expiration.
What are the 3 main muscles of the anterior thoracic wall and what are they attached to?
- Pectoralis major- Most superior muscle of the anterior chest wall. It is attached to the upper humerus, clavicle and ribs 1-6.
- Pectoralis minor- lies deep to the pectoralis major. It is attached to ribs 3-5 and the scapula.
- Serratus anterior- A layer of superficial muscle that lies jagged around the lateral aspect of the thoracic cage. It attaches to ribs 1-8.
What is the prime function of the pectoralis major, pectoralis minor and serratus anterior and how do they carry it out?
- The prime function of these muscles is to move the upper limb.
- Pectoralis major adducts the humerus while pectoralis minor and the serratus anterior abducts the scapula.
What are the accessory muscles of breathing and why is it possible for them to carry out this function? What is this a sign of (if you use accessory muscles for breathing)?
Pectoralis major, pectoralis minor and serratus anterior can also function as accessory muscles of breathing as they attach to the ribs and hence can move the ribs. HOWEVER, in patients, use of these muscles is a sign of respiratory distress. (the sternocleidomastoid can also function as an accessory muscle)
What are the spaces in between the ribs called and what do they contain?
- Intercostal spaces
It contains the - Intercostal muscles (3 layers and associated membranes)
- Intercostal neurovascular bundle (comprising of an intercostal, artery, vein and nerve)
The different layers of intercostal muscles have their fibres running in different directions and thus act on the ribs in different ways.
How are the 3 layers of intercostal muscles orientated?
- External intercostal muscles have fibres running infero-medially (antero-inferiorly)
- Internal intercostal muscles and innermost intercostal muscles have fibres running perpendicular to the EIM (postero-inferiorly) to that and so away from the midline and inferiorly.
Function of the external intercostal muscles
When it contracts during inspiration, it pull the ribs superiorly to increase the volume of the thoracic cavity, thus decreasing pressure in the lungs and allowing inflow of air.
Function of internal intercostal muscles
When it contracts during expiration, it pulls the ribs inferiorly decreasing intrathoracic volume thus increasing pressure in the lungs and air is expelled from the lungs.
Where does the endothoracic fascia lie?
Deep to the innermost intercostal muscles and superficial to the parietal pleura.
Order of layers from the skin to the lungs
Skin, superficial fascia, serratus anterior, external intercostal muscles, internal intercostal muscles, innermost intercostal muscles, endothoracic fascia, parietal pleura, pleural cavity, visceral pleura, lung.
Where is the neurovascular bundle?
They lie along the inferior border of the ribs, superior to the intercostal space.
It lies in a shallow costal groove on the deep surface of the rib. (They are located in the plane between the internal and innermost intercostal muscle)
(That is why when you need to pierce the intercostal space you usually cut at the middle or lower part of the intercostal space to avoid damaging the neurovascular bundle)
What does the neurovascular bundle supply?
It supplies the intercostal muscles, the overlying skin, and the underlying parietal pleura.
Where do the anterior and posterior intercostal arteries branch from?
- Anterior intercostal arteries- branches of the internal thoracic artery (a branch of the subclavian artery)
- Posterior intercostal arteries- branches from the descending aorta (in posterior thorax).
Where do the anterior and posterior intercostal veins drain into?
- The anterior intercostal veins drain into the internal thoracic vein.
- The posterior intercostal veins drain into the azygous system of veins (carries blood back to the heart).
What does the two layers of pleura cover and what are they called.
What lies in between the 2 layers of pleura?
- They generally cover the lungs and structures passing in and out of the lungs (pulmonary blood vessels and the main bronchi)
- The parietal pleura lines the inside of the thorax
- The visceral pleura adheres and covers the surface of the lungs, (and extends into the fissures)
- A thin pleural cavity lies between both layers of pleura. They contain pleural fluid made by pleural cells to aid mechanics of breathing.
Function of pleural fluid
- To create surface tension between the parietal pleural lining, the thoracic cavity and the visceral pleura.
- Surface tension allows the lung and thoracic wall to move together so when thoracic volume changes, lung volume changes as well.
- Pleural fluid also prevents the lungs from collapsing. If there is a puncture in the parietal pleura and air enters the pleural cavity, ventilation may become dysfunctionl.
What are the different borders of the parietal pleura?
- Cervical pleura- covers apex of the lungs
- Costal pleura- lies adjacent to the rib
- Mediastinal pleura- lies adjacent to the heart
- Diaphragmatic pleura- lies adjacent to the diaphragm.
Where is the costomediastinal and costodiaphragmatic recess?
Costomediastinal recess- Lies at the junction of the costal and mediastinal pleura.
Costodiaphragmatic recess- Where the costal parietal pleura becomes continuous with the diaphragmatic pleura
What nerves are the visceral and parietal pleura innervated by?
Visceral- Branches of the vagus nerve (Autonomic sensory fibres)
Parietal- Innervated by intercostal nerves that innervate the overlying layer of skin over the chest wall. SOMATIC sensory fibres carry sensations to our consciousness.
What separates the lobes of the lungs? (talk about both lungs)
- Both lungs have oblique fissures. In the left lung, it separates the superior and inferior lobe. In the right lung it separates the superior and middle lobe from the inferior lobe.
- The right lobe has a horizontal fissure as well separating the superior and the middle lobe.
What landmarks can you use to explain where the fissures of the lung extend to and from?
Oblique fissure- 4th rib posteriorly, 5th rib deeply and 6th rib anteriorly.
Horizontal fissure- at the level of the 4th rib, it intersects with the oblique fissure.
What is the hilum of the lung?
The region on the mediastinal surface of the lung where the pulmonary artery, pulmonary vein and the main bronchus enter and exit the lung.
Where do the pulmonary veins and main bronchus lie on the hilum of both lungs?
In both right and left lungs, the pulmonary veins are usually situated most anteriorly and inferiorly.
(essentially, the bronchus is located medially on both)
In the right lung, the main bronchus lies anterior to the pulmonary artery while in the left lung, the main bronchus usually lies inferior to the pulmonary artery.
What is the branching system of the bronchial tree?
1) Each main bronchus is divided into lobar bronchi- 3 in the right lung, two in the left lung.
2) Each lobar bronchi divide into segmental bronchi- 10 in each lung. (each supplying their own independent segment of the lung)
3) Segmental bronchi continue to divide into terminal bronchioles, respiratory bronchioles and alveolar ducts (where gas exchange occurs).
What is a difference between the walls of the trachea and main bronchus from the bronchioles?
The walls of the trachea and bronchi contain smooth muscle AND cartilage while the walls of the bronchioles only contain smooth muscle. (contraction and relaxation of the smooth muscle is controlled autonomically)
