Anatomy of Thorax/ Histology Flashcards
What are the differences between true, false and floating ribs?
True- Ribs 1-7- costal cartilage is attached directly to sternum
False- Ribs 8-10- Costal cartilage attaches to cartilage above it (cartilage creates costal margin)
Floating- Ribs 11, 12- Do not attach to sternum
What forms the superior thoracic aperture?
Superior margin of T1 ribs and manubrium of sternum
What forms the inferior thoracic aperture and what attaches to it?
Diaphragm attaches to it
Formed by inferior margin of floating ribs, costal margin and xiphoid process of sternum
How far up does the diaphragm sit?
Attached to T11
What does the diaphragm attach to?
Inferior thoracic aperture, xiphoid, lumbar vertebrae (1-3)
What innervates the digaphram?
Phrenic Nerve (C3-C5) C3, 4, 5, keep the phrenic nerve alive
What openings are in the diaphragm and what passes through at what level of the ribs?
Caval opening- inferior vena cava at T8, most anterior
Oesophageal Opening- Oesophagus T10
Aortic Hiatus- Aorta (most posterior) at T12
What muscles are in the thoracic wall, what movement does each muscle cause, and when is each set most active?
Internal intercostal- present anteriorly back to angle of ribs. Active during expiration. Pull ribs down
External- Active during inspiration. Pull inferior ribs upward and out.
Innermost intercostal- Incomplete and sparse, associated with internal layer
Where is the neurovascular bundles supplying the intercostal muscles found in terms of depth?
Between the internal and innermost intercostal muscles
What muscles are important for respiration?
Diaphragm moves down
External intercostal move ribs up and out
What accessory muscles aid in exhalation?
Internal intercostal muscles Transverse Thoracis External Obliques Internal Obliques Rectus Abdominus
What accessory muscles aid in inhalation?
Pectoralis minor (via fixing upper limb to help lift ribs)
Sternocleidomastoid
Scalene
Serratus Anterior
Where and what forms the intercostal neurovascular bundles, and where do the nerves stem from?
Run along costal grove at inferior posterior portion of rib.
VAN- Vein (superior- most protected)
Artery
Nerve
Anterior rami of T1-T11 form intercostal nerves
Anterior ramus of T12 forms subcostal (underneath rib 12)
Where do the intercostal arteries stem from?
Posterior- originates from aorta and travels along with nerve
Anterior- originates from internal thoracic artery (branch of subclavian aka mammary)
They will anastomose
Why is the anastomosing of the anterior and posterior intercostal arteries important?
Important in aiding in blood flow to the lower body if there is a blockage of the aorta (blockage can’t be sudden)
Blood will move into anterior intercostal artery, meet with posterior and down, then re-join with aorta lower down
What cavities are found in the thoracic cavity, and what is found in them?
2 Pulmonary- hold lungs, left is smaller
Mediastinum- hold heart, oesophagus, aorta, trachea and separates two pulmonary cavities
What layers of the heart and what are their purpose(s), starting most superficial?
Fibrous pericardium- protective, anchors heart in place
Parietal serous - secrete fluid to reduce friction
Pericardial cavity
Visceral serous pericardium (epicardium)- secrete fluid to reduce friction
Myocardium- contains myocytes for contraction
Subendocardium- Purkinje Fibres are here, connects myocardium and endocardium
Endocardium- Simple squamous cells, helps reduce friction in chambers reducing turbulence, helps form valves
Membranes are continuous
What layers surround the lungs and what are their purpose, starting most superficial?
Parietal Pleura- anchors lungs to thoracic cavity
Pleural cavity- has fluid secreted by serous membrane (pleura)
Visceral Pleura- surrounds lungs
Membranes are continuous
What is serous membrane?
Set of membranes (visceral and parietal) surrounding an organ that allows for lubrication between two membranes helping to reduce friction.
What are the pleural recesses?
Potential spaces between the costal and diaphragmatic pleura that the lungs can move into during inspiration.
Visceral, parietal, costal, diaphragmatic, mediastinal, cervical
What is the costodiaphragmatic recess?
Between costal and diaphragmatic pleura there is a sharp angle at dome of thorax
It is potential space for lung to extend into.
Most inferior part of cavity and where liquid will build
Where is the safest place for a draining chest tube placement, and why?
Just above the 10th rib.
This is where the costodiaphragmatic recess is (where fluid will accumulate), so best for drainage
Above 10th rib- intercostal nerves run along costal groove inferior to ribs, and are more important in function than collateral branches that run superior to ribs.
Can angle needle up to try and avoid collateral branches
What structures do you pass through in order to place a chest tube? Start most superficial.
Skin Subcutaneous fat and Fascia External, internal, innermost intercostal muscles (avoid collateral/ intercostal nerves) Endothoracic Fascia Costal parietal pleura Costodiaphragmatic recess
Starting at the sagittal plane of the body and moving laterally, what are surface landmarks?
Jugular notch at the manubrium down to sternal angle (where rib 2 attaches) Midclavicular line Anterior axillary line Midaxillary line Posterior axillary line
What fissures are found in the lungs?
Horizontal on right lobe- most superior, separating superior and middle lobes
Oblique- separates middle/ inferior right lobe, and superior/inferior left lobe
What is the cardiac notch and lingula?
Cardiac notch is in left lobe where the heart sits
Lingula is a lipping of the inferior medial aspect of the superior left lobe
What hold the lobes in place?
The trachea and structures entering the lobes through the hilum
How do the borders of the right and left lungs differ?
Right has larger posterior border and straight anterior (costal) border.
What structures are found in the hilum of the lungs?
Bronchi Pulmonary arteries Pulmonary veins Nerves Lymphatics (can be quite distinctive and black at the hilum)
What is the arrangement of the structures within the hilum?
Superior- Pulmonary arteries
Inferior- Pulmonary veins (2)
Posterior- Bronchus is posterior to the structures and more superior in right lobe- may also see cartilage around them