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The thorax is the area of the body bounded by the ribcage, or bony thorax, and lies between the head and abdomen.
In mammals, the thorax is the region of the body formed by the sternum anteriormedially, the thoracic vertebrae posteriormedially, the ribs laterally and the diaphragm inferiorly. It extends from the neck to the diaphragm, and does not include the upper limbs, which are considered to be another region. The heart and the lungs reside in the thoracic cavity, as well as many blood vessels. The inner organs are protected by the rib cage and the sternum.
It contains three potential spaces lined by mesothelium; the paired plural cavities, which surround the lungs, and the pericardium, which surrounds the heart.
Contents of the thorax
editViscera
- Heart (see cardiovascular system)
- Lungs, trachea and bronchi (see respiratory system)
- Oesophagus (see digestive system)
- Thymus gland (see endocrine system)
- Lymphatics
Bones
- Sternum- manubrium, sternum and xiphoid process
- Ribs and costal cartilages
- Thoracic vertebrae T1-12
Muscles
Anterior
- Pectoralis major
- Pectoralis minor
- Rectus abdominis
Posterior
- Subclavius
- Serratus anterior
- Levator scapulae
- Trapezius
- Latissimus dorsi
- Rhomboids- major and minor
- Serratus posterior superior
- Serratus posterior inferior
- Erector spinae (sacrospinalis)
Lateral
- External oblique
Vasculature
- Superior vena cava
- Inferior vena cava
- Aorta, including ascending and descending aorta and the aortic arch
- Pulmonary artery
- Azygos vein
Surface anatomy
Bony landmarks
- Suprasternal or jugular notch
- Sternal angle or the angle of Louis
- Xiphisternal joint
- Costal cartilage
- Ribs
- Thoracic vertebral spines
Soft tissues
- Nipples
- Apex beat
- Trachea
- Midclavicular or mammary plane
- Midaxillary line
- Scapular line
The Mediastinum
editThe mediastinum [1] consists of all the structures lying inside the bony cavity, and is surrounded by loose connective tissue. The mediastinum can by divided into superior and inferior mediastinum by the Plane of Louis, and imaginary line drawn between the sternal angle and the intervertebral disc between T4 and T5 vertebrae.
The inferior mediastinum can be further divided into:
- Anterior mediastinum, which lies between the posterior aspect of the sternum to the anterior pericardium
- Middle mediastinum, which contains the pericardium and, more importantly, the heart
- Posterior mediastinum, which lies from behind the pericardium to the anterior face of the spine.