Anatomy of the Thoracic Cavity Quiz

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Questions and Answers

Which muscle is primarily responsible for inspiration?

Internal intercostals

Diaphragm (correct)

External intercostals

Transversus thoracis

What is the main function of the internal intercostal muscles during expiration?

Increase AP and transverse diameter

Stabilize the rib cage

Lower the ribs and reduce thoracic volume (correct)

Elevate the ribs superiorly

The caval opening in the diaphragm is located at which vertebral level?

T8 (correct)

T10

T12

Which nerve is responsible for the motor supply of the diaphragm?

Phrenic nerve Signup and view all the answers

Where are the neurovascular bundles located in the intercostal space?

Between the internal and innermost intercostal muscles Signup and view all the answers

The aortic opening, which is not a true opening, is located at what vertebral level?

T12 Signup and view all the answers

What is the function of the subcostal muscles?

May depress ribs Signup and view all the answers

To which structure is the pericardium directly attached within the diaphragm?

The central tendon Signup and view all the answers

Which nerve provides sensory innervation to the skin and parietal pleura of the thoracic wall?

Intercostal nerves Signup and view all the answers

Which blood vessel is secured by the transversus thoracis muscle?

Internal thoracic artery Signup and view all the answers

Which anatomical structure is NOT part of the boundaries of the thoracic cage?

Lumbar vertebrae Signup and view all the answers

What is the function of the visceral pleura?

To cover the surface of the lungs Signup and view all the answers

At what vertebral level is the sternal angle located?

Opposite T4-T5 intervertebral disc Signup and view all the answers

Which of the following is a characteristic of the inferior border of a typical rib?

Sharp and thin with a costal groove Signup and view all the answers

What is the primary distinguishing feature of the 1st rib?

It has a subclavian groove rather than a costal groove Signup and view all the answers

Which type of rib is attached to the sternum via its own costal cartilage?

True ribs Signup and view all the answers

What is the typical shape of the body of a thoracic vertebra?

Heart shaped Signup and view all the answers

Where is the costal groove located on a rib?

Inferior internal surface of the body Signup and view all the answers

What is the significance of the angle of the rib?

Where the body sharply turns Signup and view all the answers

Which structure articulates directly with the manubrium of the sternum?

Clavicle and 1st costal cartilage Signup and view all the answers

Which joint is located at the sternal angle?

Manubriosternal joint Signup and view all the answers

Which ribs articulate with the vertebrae via a single joint?

Ribs 1, 10, 11, 12 Signup and view all the answers

Which structure does not pass through the superior thoracic aperture?

Brachial plexus Signup and view all the answers

What is the primary anatomical boundary of the inferior thoracic aperture?

Costal margin Signup and view all the answers

Compression of which nerve roots are associated with thoracic outlet syndrome?

C5, C6, C7, C8 and T1 Signup and view all the answers

Which test for thoracic outlet syndrome involves the examiner moving the patient's shoulder down and back?

Costoclavicular maneuver Signup and view all the answers

What is the action of the levatores costarum muscles?

Elevate ribs during inspiration Signup and view all the answers

Which muscles are located within the intercostal space?

External, internal, and innermost intercostals Signup and view all the answers

Which of the following is a characteristic of the external intercostal muscles?

Fibers pass down and forward Signup and view all the answers

What nerve innervates the diaphragm?

Phrenic nerve Signup and view all the answers

Which ribs typically have a synovial plane joint with the sternum?

2nd to 7th ribs Signup and view all the answers

What is the origin of the diaphragm?

Xiphoid process, lower 6 costal cartilages, 1-3 lumbar vertebrae Signup and view all the answers

Which test involves the patient turning their head away from the tested arm?

Allen test Signup and view all the answers

Which muscle is primarily involved in raising the lower ribs during inspiration?

Diaphragm Signup and view all the answers

The costal groove contains which structures?

Intercostal nerves, veins and arteries Signup and view all the answers

Study Notes

Thoracic Wall Structure and Function

Thorax: Also known as the chest or breastplate, it's the region between the neck and abdomen. The thoracic cage is a bony framework of the thorax. It's flat anteriorly and posteriorly, but rounded laterally.
Boundaries: The thorax is bordered anteriorly by the sternum and costal cartilages, posteriorly by the thoracic vertebrae, and laterally by the intercostal spaces. It communicates superiorly with the neck. The superior thoracic aperture is defined by T1, the first rib, and the manubrium. The inferior border is separated from the abdomen by the diaphragm.
Functions: The thorax houses and protects the heart and lungs. It also acts as a conduit for structures passing between the neck and abdomen. It plays a crucial role in breathing and supports the upper limbs (UE).
Lines of Orientation: Critical for anatomical references, these lines include midsagittal, midclavicular, anterior and posterior axillary, midaxillary, vertebral, and scapular lines.
Spaces: Anteriorly, there are infraclavicular, supraclavicular, precardiac, and Traube's spaces. Posteriorly, there are interscapular, suprascapular, and intrascapular spaces.

Osteology of the Thoracic Cage

Framework: Formed by the thoracic vertebrae, ribs, intercostal spaces, sternum, and costal cartilages. It's divided into the mediastinum (central) and the pleurae and lungs (lateral).
Visceral Pleura: Thin membrane covering the lungs.
Parietal Pleura: Inner surface of the chest wall.
Pleural Cavity: Space between the visceral and parietal pleurae.

Osteology of the Sternum

Structure: Flat bone with three parts: manubrium, body, and xiphoid process.
Manubrium: Articulates with the clavicle and first and upper costal cartilages. Located opposite T3-T4 (thoracic vertebra 3 and 4).
Body: Articulates with costal cartilages 2-7.
Xiphoid: Hyaline cartilage that ossifies in adulthood.
Sternal Angle: A noticeable landmark. Opposite the intervertebral disc of T4-T5. Rib 2 is attached at this point.

Osteology of the Ribs

Structure: 12 pairs of ribs attached posteriorly to the thoracic vertebrae.
Types:
- True Ribs (1-7): Attach directly to the sternum.
- False Ribs (8-10): Attach to the costal cartilage of the 7th rib, not directly to the sternum.
- Floating Ribs (11-12): Have no attachment to the sternum.
Parts: Head (posterior vertebral end), neck, tubercle (prominence for articulation with transverse process), shaft (body), and angle.
Costal Groove: Located on the inferior aspect of the rib. Passageway that contains intercostal vessels and nerves.

Osteology of the Thoracic Vertebrae

Structure: 12 thoracic vertebrae are found in the main facet (superior facet) region. Heart-shaped; they have costal facets for articulation with ribs, which are critical for attachment points.

Atypical Ribs

1st Rib: Flat, short, connects to T1 only, and features a subclavian groove instead of a typical tubercle for muscle attachment.
2nd Rib: Flat but longer than the first rib. Atypical articulation.
10th, 11th, and 12th Ribs: Have reduced articulation (head only).

Costal Cartilages

Structure: Hyaline cartilage connecting ribs 1-7 to the sternum and ribs 8-10 to the 7th costal cartilage. Provide elasticity and mobility.

Joints

Sternal Joints: Manubriosternal and xiphisternal joints are primarily cartilaginous.
Costovertebral Joints: Synovial plane joints (two joints in most cases) between ribs and vertebrae.
Rib-Costal Cartilage Joints: Cartilaginous joints (1st rib-sternum is cartilaginous, rest are synovial plane).

Thoracic Openings

Superior Thoracic Aperture: Communicates with the root of the neck. Defined by T1, rib 1, and the manubrium sterni.
Inferior Thoracic Aperture: Large, expandable opening communicating with the abdomen. Closed by the diaphragm. This opening is crucial for passing structures such as esophagus, major blood vessels, and nerves.

Clinical Notes (Thoracic Outlet Syndrome)

Thoracic outlet syndrome is a condition involving compression of brachial plexus nerves (C5-T1), subclavian artery, and vein.
- Symptoms: Vascular (swelling, bluish discolouration, heaviness, pulsating lump, fatigue, pain) and neurologic (paresthesia, muscle weakness, atrophy, cramps, pain)
- Causes: Cervical rib, scalene syndrome, costoclavicular syndrome, hyperabduction syndrome.
- Tests: Allen test, Adson's test, costoclavicular maneuver.

Respiratory Muscles

Intercostal Muscles: Located between ribs, these muscles (external, internal, innermost) are critical for inspiration and expiration. They stabilize the rib cage and vary in function based on their position in relation to the other intercostal muscles and their positioning relative to other ribs on the rib cage.
Diaphragm: Dome-shaped muscle that separates the thorax and abdomen.
- Attachments: Xiphoid process, costal margin, ribs (11 and 12), lumbar vertebrae.
- Sections: Sternal, costal, vertebral parts.
- Crura (Right and Left): Parts of the diaphragm, attaching to the lumbar vertebrae.
- Central Tendon: Point of convergence for the diaphragm's muscles. Located in alignment with the xiphisternal junction.
- Openings: Caval (vena cava), esophageal, aortic openings.
- Nerve Supply: Phrenic nerve (C3-C5), critical because impingement will damage breathing functions.
- Action: Primary muscle of inspiration; also involved in increasing intra-abdominal pressure for actions like straining.

Neurovascular Bundle

Organization: Vein, artery, and nerve occur in a triad-like or bundle structure. Crucial for placement and avoiding injury during procedures.

Intercostal Nerves

Origin: Anterior rami of T1-T11 spinal nerves; T12 is the subcostal nerve.
Function: Somatic motor innervation to the thoracic wall, sensory innervation to skin and parietal pleura, and postganglionic sympathetic fibers.
Relationship: Anterior rami of T1 contribute to the brachial plexus; lower intercostal nerves innervate abdominal wall.

Arteries and Veins

Intercostal Arteries: Supply the intercostal spaces.
Intercostal Veins: Drain the intercostal spaces.

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Description

Test your knowledge about the anatomy and functions of the thoracic cavity. This quiz covers key concepts related to the diaphragm, intercostal muscles, and pleura. Perfect for students studying anatomy or related fields!