Chest X-ray Anatomy
Bones

Key points

  • Assess the bones on every chest X-ray
  • Check for abnormalities of single bones and for diffuse bone disease
  • The bones are helpful landmarks in assessing chest X-ray image quality

Bones are the densest structures visible on a normal chest X-ray. Despite this it is easy to overlook important abnormalities of the bones which may be very subtle.

The bones visible on a chest X-ray include the clavicles, the ribs, the scapulae, the spine, and the proximal humeri (upper arms). The sternum is also included on a frontal view but it overlies other midline structures and so is obscured.

The bones are used as useful markers of chest radiograph quality. They are used to assess patient rotation, adequacy of inspiration and X-ray penetration.

Clavicles / Spinous processes / Ribs

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Clavicles / Spinous processes / Ribs

  • The spinous processes of the vertebrae (posterior structures) and the medial ends of the clavicles (anterior structures) are landmarks to assess rotation
  • The ribs should be checked on every chest X-ray
  • The right 5th rib is highlighted (roll-over image)

Clavicle / Scapula / Humerus

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Clavicle / Scapula / Humerus

  • The clavicles, scapulae, and humeri are often clearly seen on a chest X-ray
  • Occasionally you will see evidence of important disease such as metastases in these bones

Key

  • 1 - Clavicle
  • 2 - Acromioclavicular joint
  • 3 - Acromion process of scapula
  • 4 - Body of scapula
  • 5 - Glenoid fossa of scapula
  • 6 - Head of left humerus
  • 7 - Glenohumeral joint
  • 8 - Coracoid process of scapula

Clavicle / Ribs

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Clavicle / Ribs

  • The clavicle and ribs act as landmarks when assessing the adequacy of inspiration taken by the patient
  • The anterior end of approximately 5-7 ribs should be visible above the point at which the mid-clavicular line intersects the diaphragm
  • Less than 5 ribs indicates incomplete inspiration
  • More than 7 ribs suggests lung hyper-expansion
  • On this normal X-ray the anterior end of the 7th rib (asterisk) intersects the diaphragm at the mid-clavicular line
  • The subcostal grooves are visible on the underside of the ribs (red highlights)
  • These grooves contain the subcostal nerves and vessels that accompany each rib
  • Note: To avoid damaging the subcostal nerves or vessels the superior edge of a rib is used as the landmark during procedures such as chest drain insertion
  • The spine can be seen through the heart indicating adequate X-ray penetration

Assessing the bones

Bones are useful for the initial assessment of chest X-ray image quality, and offer useful information regarding rotation, inspiration and penetration.

Acute rib fractures are often invisible, therefore chest X-rays are not helpful if there is clinical suspicion of a rib injury unless a complication such as pneumothorax is suspected.

Occasionally you will see an important abnormality of the bones on a chest X-ray such as bone metastases. Bone abnormalities may be very subtle, so always look carefully at all the bones when viewing a chest X-ray.

Page author: Salisbury NHS Foundation Trust UK (Read bio)

Last reviewed: February 2020