Thoracic Anatomy and Functions

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Questions and Answers

What connects the vertebral body to the transverse processes in a vertebra?

Pedicle (correct)

Transverse process

Spinous process

Lamina

How do the transverse processes of thoracic vertebrae contribute to rib articulation?

They have demifacets for articulation.

They provide support to the ribcage structure.

They possess costal facets for the tubercles of the rib. (correct)

They attach muscles that connect to the ribs.

What is a characteristic of the spinous processes of thoracic vertebrae?

They slant inferiorly. (correct)

They are short and straight.

They extend laterally.

They curve anteriorly.

Which thoracic vertebrae typically have demifacets on their vertebral bodies?

T2-T9 Signup and view all the answers

What type of bone is the sternum classified as?

Flat bone Signup and view all the answers

What is the primary function of the thoracic cage?

Aids in respiration and protects major organs Signup and view all the answers

Which structures are located in the central mediastinum?

Heart and esophagus Signup and view all the answers

What defines the sternal angle?

The junction between the manubrium and body of the sternum Signup and view all the answers

Which structure separates the thoracic cavity from the abdominal cavity?

Diaphragm Signup and view all the answers

What is enclosed in the thoracic inlet?

Trachea, esophagus, nerves, and vessels Signup and view all the answers

Which is NOT part of the skeletal framework of the thoracic cage?

Lungs Signup and view all the answers

What is the anterior part of each thoracic vertebra called?

Vertebral body Signup and view all the answers

Which ribs are associated with the costal margins?

Ribs 7 to 10 Signup and view all the answers

What is the function of the left superior intercostal vein?

It drains into the internal thoracic vein. Signup and view all the answers

Which intercostal nerves are primarily distributed within their intercostal spaces?

The first six intercostal nerves. Signup and view all the answers

Which nerve is involved in mediating referred pain along the medial side of the arm in coronary artery disease?

The intercostobrachial nerve. Signup and view all the answers

What is the anterior ramus of the twelfth thoracic nerve commonly known as?

Subcostal nerve. Signup and view all the answers

Where do the seventh to ninth intercostal nerves exit their intercostal spaces?

By passing deep to the costal cartilage. Signup and view all the answers

What area does the lateral cutaneous branch of the second intercostal nerve supply?

The floor of the axilla. Signup and view all the answers

In acute coronary artery disease, pain is typically felt in which areas?

The left side of the arm and axilla. Signup and view all the answers

What is the primary role of the intercostal nerves?

To supply sensation to the thoracic cavity. Signup and view all the answers

Which anatomical landmark lies opposite the lower border of the body of the second thoracic vertebrae?

Suprasternal notch Signup and view all the answers

What is the primary muscle of respiration?

Diaphragm Signup and view all the answers

Which opening of the diaphragm is associated with the passage of the aorta?

Aortic opening Signup and view all the answers

At which intercostal space is the apex beat of the heart normally located?

Fifth intercostal space Signup and view all the answers

Which rib is used as a reference point for counting up to identify other ribs?

12th rib Signup and view all the answers

The midclavicular line runs vertically from which anatomical feature?

Midpoint of the clavicle Signup and view all the answers

What forms the lower boundary of the thorax?

Costal margin Signup and view all the answers

In which gender is the position of the nipple typically constant?

Male Signup and view all the answers

What is the term for the space between two adjacent ribs?

Intercostal space Signup and view all the answers

Which ribs are considered true ribs?

Ribs 1 through 7 Signup and view all the answers

Which of the following statements about the first rib is correct?

It has a scalene tubercle. Signup and view all the answers

What is the primary function of the external intercostal muscles?

Elevation of the ribs during inspiration Signup and view all the answers

Which ribs are categorized as atypical?

Ribs 10 to 12 Signup and view all the answers

How do the costal cartilages of the eighth to tenth ribs articulate?

With the costal cartilage of the seventh rib Signup and view all the answers

What is the primary anatomical feature that distinguishes the tenth, eleventh, and twelfth ribs?

They have pointed anterior ends and lack a tubercle. Signup and view all the answers

What are the primary arteries supplying the intercostal spaces?

Posterior intercostal and subcostal arteries Signup and view all the answers

Where do the intercostal veins drain?

Into the superior vena cava Signup and view all the answers

What is the function of the innermost intercostal muscle?

Depression of ribs Signup and view all the answers

Which rib is significantly shorter and broader compared to other ribs?

First rib Signup and view all the answers

What is the relationship between the costal cartilages of ribs three to seven and the sternum?

They form synovial joints with the body of the sternum. Signup and view all the answers

What is a common feature of typical ribs?

They possess a costal groove. Signup and view all the answers

Study Notes

Thoracic Cage & Thorax

The thorax is the region between the neck and abdomen, containing the thoracic cavity and thoracic wall.
The thoracic cavity is divided into three compartments: right and left pulmonary cavities (containing lungs and pleurae), and the central mediastinum (containing the heart, major vessels, trachea, esophagus, thymus, and lymph nodes).
The thoracic wall comprises the bony rib cage and muscular tissues.
The thorax functions in respiration, protects major organs, provides attachment for the upper limb, and anchors the upper limb, abdomen, neck, and back.

Thoracic Inlet & Outlet

The thoracic inlet (superior thoracic aperture) is the superior opening into the ribcage, bounded by the T1 vertebrae posteriorly, the 1st ribs and costal cartilages laterally, and the superior border of the manubrium anteriorly. It allows passage for the trachea, esophagus, nerves, and vessels.
The thoracic outlet (inferior thoracic aperture) is the inferior opening, separated from the abdominal cavity by the diaphragm, bounded by the 12th vertebrae posteriorly, 11th and 12th ribs posterolaterally, costal margins anterolaterally, and the xiphisternal joint anteriorly. It allows passage for the esophagus, inferior vena cava, and aorta.

Skeletal Framework

The rib cage is composed of the sternum anteriorly, ribs laterally, and the thoracic vertebrae with intervertebral discs posteriorly.

Thoracic Vertebrae

Each thoracic vertebra consists of a body, vertebral arches, and processes.
The body is the anterior, weight-bearing portion.
The spinous process projects posteriorly from the arch.
The transverse processes extend laterally and posteriorly.
The lamina connects the transverse and spinous processes.
The pedicle connects the vertebral body to the transverse processes.
Thoracic vertebrae have characteristically long, inferiorly slanting spinous processes that are prominent and palpable.
They also possess costal facets on the transverse processes (articulation with rib tubercles) and demifacets on the vertebral bodies (superior and inferior facets for rib articulation).

Sternum

The sternum is a flat, elongated bone composed of three parts: manubrium (top), body (middle), and xiphoid process (bottom).
The manubrium is located at vertebral levels T3-T4, contains the jugular notch (suprasternal notch), and forms sternoclavicular joints with the clavicles.
The sternal angle, or angle of Louis, is the junction between the manubrium and the body of the sternum, located at vertebral level T4-T5.
The body is located at vertebral levels T5-T9.
The xiphoid process is the smallest and most inferior part.

Ribs

There are 12 pairs of ribs.
True ribs (first seven pairs) are connected to the sternum by costal cartilages.
False ribs (eighth, ninth, and tenth pairs) attach to the costal cartilages of the rib above.
Floating ribs (eleventh and twelfth pairs) have no anterior attachment.
Intercostal spaces are the spaces between the ribs, numbered according to the rib bordering the upper margin.
Typical ribs (third to ninth) have a head with two facets, a neck, a tubercle, a body with an angle and a costal groove.
Atypical ribs: the first rib is short and broad, has a single articular facet, and grooves on the upper surface for the subclavian vein and artery. The second rib is longer than the first, has two facets for articulation, and a roughened area for the serratus anterior muscle. The tenth, eleventh, and twelfth ribs have a single facet on the head, lack a tubercle and neck, and are tipped with cartilage.

Costal Cartilages

Hyaline cartilages cap the anterior rib tips, provide flexible attachment, and form costochondral junctions.
They are avascular, which makes healing slow following trauma.

Intercostal Muscles

Intercostal muscles are located in the intercostal spaces and function in respiration.
Three layers of muscles are:
- External intercostal muscle (most superficial): fibers extend downward and forward; elevates ribs during inspiration.
- Internal intercostal muscle: fibers extend upward and forward; depresses ribs during forced expiration.
- Innermost intercostal muscle: deepest layer, thin, vestigial muscle with three groups: anterior (transverse thoracis), lateral (innermost intercostal), and posterior (subcostal). These all depress ribs.
They are innervated by intercostal nerves.

Neurovascular Bundle

The intercostal nerve, vein, and artery lie in the costal groove, partially covered by the innermost intercostal muscle.
The subcostal nerve (T12) runs inferior to the 12th rib.
The posterior rami of intercostal nerves supply the joints, deep back muscles, and skin of the back.
The neurovascular bundle is located just above the lower rib, which is clinically relevant for medical procedures involving needle insertion.

Arterial supply

The thoracic aorta supplies the intercostal spaces via posterior and subcostal arteries.
The subclavian artery provides the internal thoracic and supreme intercostal arteries.
The axillary artery contributes the superior and lateral thoracic arteries.
The internal thoracic artery (internal mammary artery) arises from the subclavian artery, descends along the sternum, and branches into the musculophrenic artery and superior epigastric artery.
The anterior intercostal arteries (1st-6th) branch from the internal thoracic artery. The 7th-9th are branches of the musculophrenic artery.
The inferior intercostal spaces are supplied by the posterior intercostal arteries.

Venous Drainage

Intercostal veins accompany the intercostal arteries, located most superior in the costal groove.
There are 11 posterior intercostal veins and 1 subcostal vein.
Posterior intercostal veins (4th-11th) drain into the azygos and hemiazygos systems, which ultimately empty into the superior vena cava.
The posterior intercostal vein of the 1st space drains into the brachiocephalic veins.
The 2nd and 3rd posterior intercostal veins unite to form the superior intercostal vein, which typically drains into the azygos vein on the right and the brachiocephalic vein on the left.
The internal thoracic (internal mammary) vein drains into the brachiocephalic vein.

Intercostal Nerves

Intercostal nerves are the anterior rami of the first 11 thoracic spinal nerves.
The anterior ramus of T12 becomes the subcostal nerve in the abdomen.
Intercostal nerves are distributed within their intercostal spaces (1st-6th) and pass deep to the costal cartilages into the anterior abdominal wall (7th-9th).
The 10th and 11th nerves pass directly into the abdominal wall.

Surface anatomy

Suprasternal notch/Jugular notch: the indentation at the top of the sternum, felt between the clavicles, opposite the lower border of the T2 vertebrae.
Sternal angle/ Angle of Louis: the junction of the manubrium and sternal body, located at the level of the T4-T5 intervertebral disc, and easily palpable as a bony prominence.
Xiphisternal joint: the point where the xiphoid process joins the body of the sternum, opposite the T9 vertebrae.
Subcostal angle: the angle formed by the inferior end of the sternum and the costal cartilages, opposite the level of the T10 vertebrae.
Costal margin: the lower boundary of the thorax, formed by the costal cartilages of the 7th-10th ribs and the ends of the 11th and 12th ribs. The 10th rib is the lowest point of the costal margin, located at the level of the L3 vertebrae.
Nipple: in males, typically located at the level of the 4th intercostal space.
Apex beat of the heart: the point where the lower portion of the left ventricle contacts the chest wall, typically at the 5th intercostal space, 3.5 inches from the midline.

Lines of Orientation

Midsternal line: a vertical line down the center of the sternum.
Midclavicular line: a vertical line down from the midpoint of the clavicle.
Midaxillary line: a vertical line down from a point midway between the anterior and posterior axillary folds.

Diaphragm

The diaphragm is a muscular and tendinous septum that closes the inferior opening of the thoracic cavity, separating it from the abdominal cavity.
It is the primary muscle of respiration.
It has three parts:
- Sternal part: arises from the posterior surface of the xiphoid process.
- Costal part: originates from the inner surfaces of the lower six ribs.
- Vertebral part: arises from the lumbar vertebrae.
The central tendon is a tough, aponeurotic structure located in the center of the diaphragm.
Openings of the diaphragm:
- Aortic opening: allows the passage of the aorta.
- Esophageal opening: allows the passage of the esophagus.
- Caval opening: allows the passage of the inferior vena cava.

Lymph Nodes

Lymph nodes are small, bean-shaped organs located along the lymphatic vessels throughout the body.
They serve as surveillance points for pathogenic invasion, filtering interstitial fluid returning to the general circulation to detect potentially harmful agents.

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Description

Explore the anatomy of the thoracic cage and thorax through this quiz. Learn about the thoracic cavity's compartments and the functions of the thoracic wall. Test your knowledge on the thoracic inlet and outlet, essential for understanding respiratory and circulatory systems.