Anatomy of the Thorax and Anterior Neck pt. 1 Flashcards
The thorax is a region of the torso bounded superiorly by:
the 1st ribs and thoracic inlet
The thorax is a region of the torso bounded anteriorly by:
the sternum
The thorax is a region of the torso bounded laterally by
the costae (ribs 12 pairs) and intercostal spaces
The thorax is a region of the torso bounded posteriorly by:
the vertebral column (12 thoracic vertebrae)
The thorax is a region of the torso bounded inferiorly by:
the diaphragm
Pleural spaces contain:
pulmonary cavities, the pleurae, and the lungs
Mediastinum contains:
pericardium and heart, great vessels, portions of the airway, esophagus, lymphatics, and various neurovascular elements
Intercostal spaces
(between ribs) are occupied by layers of muscle and the neurovasculature which serves the muscle and overlying skin.
Generally, the intercostal muscle is divided into 3 layers:
- external intercostal
- internal intercostal
- innermost intercostal
External intercostal mm
pull ribs upwards and outwards, to slightly increase the volume of the thoracic cavity (inspiratory) present anteriorly as aponeuroses.
Internal intercostal mm
pull ribs downwards and inwards, to slightly decrease the volume of the thoracic cavity (expiratory). Distributed from the sternum to costal angle (only present posteriorly as aponeuroses)
Innermost intercostal mm
function akin to internal intercostal mm
Anterior intercostal brs. 1-6
typically arise directly from internal thoracic
Anterior intercostal brs 7-9
typically arise from musculophrenic br.
Posterior intercostal aa.
branch off thoracic aorta-posterior intercostal brs. are typically the dominant source of blood to the intercostal spaces
What arteries create anastomoses for intercostal spaces?
anterior and posterior intercostal arteries
Where are intercostal aa. found?
subcostal groove of the rib forming the superior boundary of the intercostal space; accompanied by an intercostal v. and n.
Where is the neurovascular serving the intercostal spaces found?
between the internal intercostal mm. and innermost intercostal mm.
How are the parts of the subclavian artery delimited?
Conceptually divided into three parts, with respect to the vessel’s relationship to the anterior scalene m.
First part of the SCA
found medial to the anterior scalene m.
Second part of the SCA
posterior to the anterior scalene m.
Third part of the SCA
lateral to the anterior scalene
Beyond the ________________, the subclavian a. transitions into the axillary a.
lateral border of the first rib
What are the boundaries of the mediastinum?
- superiorly by the thoracic inlet and first ribs
- inferiorly by the diaphragm
- laterally by the pleura
- anteriorly by the sternum and pleurae
- posteriorly by the vertebral column
What are the two layers of the pericardium?
fibrous pericardium and serous pericardium
The fibrous pericardium is made up of
dense connective tissue
What are the functions of the pericardium?
- anchor to diaphhragm and surrounding structures
- inflexible and provides heart from overfilling during diastole
- reduce friction
- protect heart from infection
The serous pericardium is composed of:
- parietal layer
- visceral layer (epicardium)
Parietal and visceral serous layers are separated by:
the fluid-filled pericardial cavity
Borders of the heart
- superior: atria
- right border: r. atrium
- left border (obtuse margin): L. ventricle + L. auricle
- Apex
- Inferior border (acute margin): ventricles
Sternocostal surface (anterior)
formed predominantly by the R. ventricle with small contributions from the R. atrium and L. ventricle. The coronary and anterior interventricular sulcus are visible on this surface
Diastole
ventricular filling
systole
ventricular emptying
Heart sounds
created by the shutting of valves (to prevent backwards flow)
Lub (1st sound; S1)
AV valves close
Dub (2nd sound; S2)
semilunar valves closure
Where is the heart found?
The heart is found in the middle mediastinum of the thoracic cavity, surrounded by the pericardium
Atria
receive blood that will be pumped into ventricles; weak contraction
Ventricles
discharge blood either into pulmonary trunk or ascending aorta; more powerful contraction
