Thorax anatomy

Accessory muscles of respiration

Muscles recruited according to breathing demand

Diaphragm

Expands the chest by moving downward

External intercostals

Outer intercostal layer that helps lift the ribs

Innermost intercostals

Intercostal fibers deep to the main nerve and vessels

Internal intercostals

Middle intercostal layer with region-dependent actions

Moderator band

Right ventricular bridge carrying conduction tissue

Papillary muscles

Ventricular muscles that maintain chordal support

Pectinate muscles

Ridged atrial muscle concentrated in the appendages

Subcostal muscles

Variable deep slips that bridge several ribs

Trabeculae carneae

Ventricular ridges and bridges of working muscle

Transversus thoracis

Deep muscle slips behind the sternum

Bones

Bone

Sternum

Midline support for the front of the rib cage

Bone

Typical rib

A curved plate that links the spine to the chest wall

Bone

Nerves

Cardiac plexus

Autonomic and sensory routes entering the heart

Greater splanchnic nerve

Thoracic sympathetic fibers continuing to the upper abdomen

Intercostal nerves

Segmental nerves supplying the chest and abdominal walls

Phrenic nerve

Cervical nerve that drives each half of the diaphragm

Pulmonary plexus

Nerve connections around the lung roots

Sympathetic trunk

Linked ganglia extending along both sides of the spine

Thoracic splanchnic nerves

Visceral pathways whose fiber type depends on the named group

Vessels

Accessory hemiazygos vein

A variable collector of left mid-thoracic intercostal veins

Anterior cardiac veins

Right ventricular veins with direct atrial drainage

Anterior interventricular artery (LAD)

The anterior descending branch of the left coronary system

Aorta

The main arterial route from the left ventricle to the body

Aortic arch

The curved aortic segment supplying the head and upper limbs

Ascending aorta

The upward aortic route between the root and arch

Atrioventricular nodal artery

A small coronary branch serving atrioventricular conduction tissue

Azygos vein

The main right paravertebral venous channel

Brachiocephalic trunk

The usual common arterial stem for the right neck and arm

Brachiocephalic veins

The paired venous trunks joining upper-body drainage

Bronchial arteries

Systemic vessels supporting the airways

Circumflex artery

The left coronary route around the atrioventricular groove

Coronary sinus

A collecting channel for most cardiac venous blood

Great cardiac vein

A major venous route from the anterior heart to the coronary sinus

Hemiazygos vein

A lower left thoracic tributary of the azygos system

Internal thoracic artery

The parasternal artery of the anterior chest wall

Left coronary artery

The usual common stem of the left coronary branches

Left marginal (obtuse marginal) artery

Circumflex branches serving the lateral left ventricle

Lymphatic drainage of the breast

A variable network linking breast tissue to regional nodes

Middle cardiac vein

The venous channel in the inferior interventricular groove

Posterior intercostal arteries

Segmental arteries supplying the posterior chest wall

Posterior interventricular artery (PDA)

The descending artery in the inferior interventricular groove

Pulmonary arteries

Paired inflow vessels for the lungs

Pulmonary trunk

Right ventricular outlet to the pulmonary circulation

Pulmonary veins

Return pathway from lung capillaries to the left atrium

Right coronary artery

The coronary vessel following the right atrioventricular groove

Right lymphatic duct

A variable final lymphatic channel at the right neck base

Right marginal (acute marginal) artery

An acute-border branch to the right ventricular wall

Sinoatrial nodal artery

A variable coronary route to the sinus-node region

Small cardiac vein

A variable right-sided tributary of the cardiac venous system

Subclavian vein

The upper-limb venous route in front of the anterior scalene

Superior vena cava

The final upper-body venous channel to the right atrium

Thoracic (descending) aorta

The descending aortic segment behind the heart

Thoracic duct

The main lymphatic return route through the chest

Organs

Alveolus

Microscopic air space at the gas-exchange surface

Aortic valve

The valve at the left ventricular outlet

Atrioventricular bundle (of His)

Electrical passage through the atrioventricular insulation

Atrioventricular node

A controlled delay between atrial and ventricular activation

Auricles (atrial appendages)

Atrial appendages beside the great-vessel roots

Bronchioles

Small airways without supporting cartilage

Bronchopulmonary segment

Bronchovascular subdivision of a lung lobe

Bronchopulmonary segments of the left lung

Left-lung territories with common segment combinations

Bronchopulmonary segments of the right lung

Ten standard named right-lung territories

Bundle branches

Paired routes from the His bundle into the ventricles

Carina

Internal ridge between the main bronchial openings

Crista terminalis

Right atrial ridge where pectinate muscles begin

Esophageal constrictions

Usual narrowing sites along the swallowing passage

Esophagus

Muscular passage from pharynx to stomach

Fibrous pericardium

The connective-tissue sac surrounding the heart

Fossa ovalis

Thin atrial depression left by a fetal passage

Heart

Connects the lung and body circulations

Interatrial septum

True partition and folds between the atrial chambers

Interventricular septum

Contractile partition shared by both ventricles

Left atrium

Posterior chamber receiving pulmonary venous return

Left inferior lobe

Left lobe behind the heart and above the diaphragm

Left lung

Two-lobed lung sharing the chest with the heart

Left main bronchus

Main airway beneath the aortic arch

Left superior lobe

Upper left lobe including the lingula

Left ventricle

Systemic-pressure pump forming the cardiac apex

Lingula

Two-segment projection of the left superior lobe

Lobar (secondary) bronchi

Airways assigned to individual lung lobes

Lymph node

Organized immune tissue along a lymphatic route

Mitral valve

A two-leaflet apparatus guarding the left atrioventricular opening

Parasternal (internal mammary) nodes

Lymph nodes following the vessels beside the sternum

Parietal pleura

Pleural lining attached to the thoracic boundary

Pulmonary valve

The semilunar outlet of the right ventricle

Purkinje fibers

Specialized muscle cells that distribute ventricular excitation

Right atrium

Receives systemic veins before the right ventricle

Right inferior lobe

Posterior and basal right lung lobe

Right lung

Three-lobed lung beside the right mediastinum

Right main bronchus

Short main airway entering the right lung

Right middle lobe

Anterior right lobe between two fissures

Right superior lobe

Upper right lobe containing the lung apex

Right ventricle

Anterior ventricle supplying the lungs

Segmental (tertiary) bronchi

Airways defining bronchopulmonary segments

Serous pericardium

Continuous parietal and visceral surfaces around the heart

Sinoatrial node

The usual starting point of each heartbeat

Thymus

A specialized environment for developing T cells

Trachea

Cartilage-supported airway between larynx and bronchi

Tracheobronchial lymph nodes

Mediastinal nodes around the central airway division

Tricuspid valve

The right atrioventricular valve and its supports

Visceral pleura

Thin pleural covering attached to the lung

Joints

Joint

Costovertebral joints

Rib-to-spine joints that permit breathing movement

Joint

Ligaments

Central tendon of the diaphragm

Mobile fibrous center of the breathing diaphragm

Chordae tendineae

Fibrous restraints for the atrioventricular leaflets

Fibrous skeleton of the heart

Connective support and electrical separation around cardiac junctions

Ligamentum arteriosum

The postnatal remnant of the fetal ductal connection

Suprapleural membrane

Fascial reinforcement over the cervical pleura

Spaces

Aortic hiatus

Posterior route beneath the median arcuate ligament

Aortic sinuses (of Valsalva)

The expanded root spaces beside the aortic cusps

Cardiac auscultation areas

Chest-wall regions for hearing transmitted cardiac sounds

Caval opening

Passage for the vena cava within tendon

Costodiaphragmatic recess

Pleural extension below the resting lung edge

Costomediastinal recess

Anterior pleural interval beside the mediastinum

Esophageal hiatus

Muscular opening around the lower esophagus

Horizontal fissure

Usual boundary between right superior and middle lobes

Intercostal space

Muscle and neurovascular layers between ribs

Mediastinum

The central thoracic region between the pleural sacs

Oblique fissure

Sloping pleural boundary beside the inferior lobe

Oblique pericardial sinus

A blind recess behind the left atrium

Pericardial cavity

The thin fluid-containing space between serous surfaces

Pleural cavity

Fluid-lined interval around each lung

Root of the lung

Structures connecting a lung to the mediastinum

Transverse pericardial sinus

A pericardial passage behind the arterial roots

Triangle of Koch

Surface landmarks around atrioventricular conduction tissue