Human Anatomy: Thorax and Sternum

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Questions and Answers

Which anatomical landmark is considered the midpoint in locating the mammary line?

The jugular notch

The suprasternal notch

The sternal angle

The midpoint of the clavicle (correct)

What is the primary function of the mammary line in surgical reference?

To mark the location of the sternum

To provide a reference for surgery in the axillary area (correct)

To divide the abdomen into quadrants

To identify the midline of the body

What does the mammary line specifically divide on the chest wall?

The thoracic cavity into upper and lower sections

The chest wall into two unequal halves (correct)

The abdominal wall into two equal sections

The left lung from the right lung

Which structure is referred to as the broadest part of the sternum?

Gladiolus Signup and view all the answers

How many notches are present in the manubrium of the sternum?

Three notches Signup and view all the answers

What is unique about the 11th and 12th ribs in terms of their anatomical features?

They do not have a neck and tubercle. Signup and view all the answers

Which arteries are primarily responsible for supplying the intercostal spaces?

Intercostal arteries Signup and view all the answers

During which action does the intercostal space become wider?

Inspiration Signup and view all the answers

What structures pass through the aortic hiatus at T12?

Aorta, Thoracic Duct, and Azygos Vein Signup and view all the answers

Which nerve is responsible for innervating the diaphragm?

Phrenic nerve Signup and view all the answers

What is the location of the intercostal neurovascular structure in relation to the subcostalis muscle?

Superficial to the subcostalis muscle Signup and view all the answers

Which muscle is the innermost intercostal muscle separated from by intercostal nerves and vessels?

Internal intercostal muscle Signup and view all the answers

Which statement about the innermost intercostal muscle is true?

It connects ribs to ribs. Signup and view all the answers

What is a characteristic of the innermost intercostal muscle?

It is often incomplete or variable. Signup and view all the answers

How does the innermost intercostal muscle relate to the internal intercostal muscle?

They are separated by intercostal nerves and vessels. Signup and view all the answers

What structure is likely to be absent if the intercostal vessels are visible in the thoracic cavity?

Innermost intercostal muscle Signup and view all the answers

Where does the sternocostalis muscle originate?

From the sternum Signup and view all the answers

What artery supplies the anterior thoracic wall and branches from the internal thoracic artery?

Anterior intercostal artery Signup and view all the answers

What happens to the subclavian artery at the seventh rib?

It divides into the superior epigastric and musculophrenic arteries Signup and view all the answers

What is drained by the anterior intercostal vein?

Internal thoracic vein Signup and view all the answers

Which muscle is considered the most constant in the inner surface of the anterior thoracic wall?

Sternocostalis muscle Signup and view all the answers

Which artery is the first to supply the thoracic wall?

Anterior intercostal artery Signup and view all the answers

What structure is covered by the sternocostalis muscle?

Intercostal arteries Signup and view all the answers

What anatomical landmark lies in the same horizontal plane as the lower border of the body of the second thoracic vertebra (T2)?

Jugular notch Signup and view all the answers

Which ribs directly connect to the sternum through cartilage?

True Ribs Signup and view all the answers

At which level is the sternal angle corresponding to the second costal cartilage found?

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

Which ribs are referred to as floating ribs?

11th-12th ribs Signup and view all the answers

What is the name of the process that is the smallest and diamond-shaped structure at the lower part of the sternum?

Xiphoid Process Signup and view all the answers

Which of these ribs are categorized as vertebrochondral ribs?

8th-10th ribs Signup and view all the answers

What distinguishes the true ribs from the false ribs?

True ribs connect directly to the sternum Signup and view all the answers

How many sternebrae comprise the body of the sternum?

4 Signup and view all the answers

Which type of ribs are the longest in the human body?

7th ribs Signup and view all the answers

Which region of the body is defined as the area between the neck and the abdomen?

Thoracic region Signup and view all the answers

Study Notes

Mammary Line

Extends from the axilla to the pelvis on both sides
Divides the chest wall into two unequal halves
Reference point for surgery in the axillary area
Midpoint of the clavicle serves as a reference point

Bony Thorax

Region of the body between the neck and abdomen
Thorax:
- Jugular notch is in the same horizontal plane as the lower border of the body of the second thoracic vertebra (T2)
- Sternal angle corresponds to the second costal cartilage, is at the level opposite the intervertebral disc between the fourth and fifth thoracic vertebrae, used to count the ribs

Sternum

Manubrium:
- Broadest part of the sternum
- Three notches:
  - Two clavicular notches
  - One suprasternal (jugular notch)
Sternal angle:
- Also known as Angle of Louis or Ludwig
- Point of attachment for the 2nd rib
- Where the manubrium and body of the sternum meet
Body of the Sternum:
- Consists of four sternebrae
Xiphoid process:
- Smallest, diamond-shaped part of the sternum

Ribs

True ribs (Vertebrosternal ribs):
- First 7 pairs of ribs
- Connect directly to the sternum via cartilage
False ribs (Vertebrochondral):
- 8th-10th ribs
- Cartilages join the cartilage of the 7th rib before attaching to the sternum
Vertebral ribs:
- 11th and 12th ribs (floating ribs)
- Do not attach to the sternum

Superior Thoracic Aperture

Foramina:
- Aortic Hiatus (T12):
  - Aorta
  - Thoracic duct
  - Azygos vein
- Esophageal Hiatus (T10):
  - Right and Left vagus nerves
  - Esophageal branches of the left gastric artery
- Inferior Vena Cava Hiatus (T8):
  - IVC
  - Right phrenic nerve
  - Lymphatic vessel

Typical Ribs

Upper 9 intercostal spaces are closed by costal cartilage
Widest intercostal space is in the 3rd intercostal area
Intercostal space is wider during inspiration

Intercostal Spaces

External Intercostal Muscle:
- Located superficial to the subcostalis muscle
- Attaches to the thoracic vertebra
Innermost Intercostal Muscle:
- Passes from ribs to ribs
- Separated from the internal intercostal muscle by the intercostal nerve and vessels
- May be incomplete or absent in some people

Transverse Thoracic Muscle

Located on the inner surface of the anterior thoracic wall
Arises from the sternum and inserts at the rib above it
7th rib is the longest rib

Blood Vessels

Anterior Intercostal Arteries:
- First artery supplying the thoracic wall
- Branches of the internal thoracic artery, which is a branch of the subclavian artery
Posterior Intercostal Arteries:
- Second artery supplying the thoracic wall

Venous Drainage

Posterior Intercostal Vein:
- Drains to the anterior intercostal vein, which drains to the internal thoracic vein or the upper 6th anterior intercostal vein.

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Description

This quiz covers important anatomical features of the thorax, including the mammary line, bony structure, and sternum details. It focuses on reference points used in surgeries and anatomical landmarks essential for understanding human anatomy. Test your knowledge on these critical components!