Thorax

Internal Intercostal Muscle

Internal Intercostal Muscle The structure indicated is the internal intercostal muscle. The intercostal muscles are a set of three flat muscles which are located in each intercostal space. The three intercostal muscles, from superficial to deep are: External intercostal Internal intercostal Innermost intercostal Origin: Lateral edge of costal groove of rib directly above Insertion: Superiorly on rib directly below Innervation: Intercostal nerves (T1 – T11) Action: Forced expiration, movement of ribs inferiorly The muscle fibres of the internal intercostal muscles pass obliquely in the opposite direction to the external intercostal muscles, whose fibres pass anteroinferiorly (when the thoracic wall is viewed …

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Internal Intercostal

Right Main Bronchus

Right Main Bronchus The structure indicated is the right main bronchus. The trachea divides into two main bronchi – the right main bronchus and the left main bronchus (also referred to as primary bronchi). The trachea divides at the level of the sternal angle and the point at which it bifurcates is known as the carina – a cartilaginous ridge which runs between the left and right main bronchi. The main bronchi then divide into smaller and smaller airways in the following sequence: Lobar bronchi (secondary bronchi) Segmental bronchi (tertiary bronchi) Bronchioles Terminal bronchioles Respiratory bronchioles Alveolar ducts Alveolar sacs …

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Right Main Bronchus