Anatomy of the Sternum

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Questions and Answers

What is the primary function of the sternal angle?

To ossify the ribs

To serve as an attachment point for the costal cartilages

To facilitate movements of the rib cage (correct)

To provide structural support to the thoracic vertebrae

What is the meaning of the Latin word 'manus' in the context of the sternum?

Sharp point or sword

Dagger or blade

Main part or body

Hand or holder (correct)

Which of the following is NOT a part of the sternum?

Thoracic vertebrae (correct)

Manubrium sterni

Body of sternum

Xiphisternum (Xiphoid process)

What is unique about the 1st rib compared to other ribs?

It is flatter and has grooves and tubercles not seen on the others Signup and view all the answers

Why do the costal cartilages fail to complete ossification?

Because ossification starts posteriorly Signup and view all the answers

Which of the following ribs do not have tubercles and do not attach to anything anteriorly?

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

Who is credited with the discovery of the sternal angle?

Antoine Louis Signup and view all the answers

What is the function of the superior facet on the body of a thoracic vertebra?

To articulate with the head of the rib Signup and view all the answers

What is the term for the xiphoid process in ancient Greek?

Xiphos Signup and view all the answers

Which of the following ribs has two facets on its head?

2nd rib Signup and view all the answers

What happens to the sternal angle in the elderly?

It ceases to function Signup and view all the answers

Who revealed the significance of the sternal angle in the 19th century?

Pierre-Charles Alexandre Louis Signup and view all the answers

What is the term for the joint formed between a rib and a thoracic vertebra?

Costovertebral joint Signup and view all the answers

Which of the following ribs may occasionally articulate with the T10 vertebra only?

10th rib Signup and view all the answers

What is the function of the tubercle on the 1st rib?

To attach to the scalenus anterior muscle Signup and view all the answers

Which of the following statements is true about the 11th and 12th ribs?

They only have a single facet on their head Signup and view all the answers

What is the primary reason why the fractured ends of the ribs in both children and adults are rarely displaced?

Due to the presence of periosteum, connective tissues and muscles Signup and view all the answers

What is the potential complication of a fractured rib?

Lung collapse Signup and view all the answers

What is the main topic of the lecture series?

Respiratory System Signup and view all the answers

After completing Part 2 of this lecture, what should you be able to do?

Name the parts of a rib, know which ribs are typical and which are atypical, and know which thoracic vertebrae are typical and which are atypical Signup and view all the answers

What is the focus of Part 3 of the lecture series?

The basic arrangements of blood vessels, lymphatics and innervation of the chest Signup and view all the answers

Why is the baby mentioned in the introduction?

To express relief that the baby is now safe in a foster home Signup and view all the answers

What is the key characteristic of atypical ribs?

They have a different structure than typical ribs Signup and view all the answers

What is the benefit of learning about the osteology of the chest wall?

It allows for a better understanding of respiratory system function Signup and view all the answers

What is the primary source of blood supply to the pectoral region of the thoracic wall?

Branches of the axillary artery Signup and view all the answers

What is the origin of the internal thoracic arteries?

Subclavian artery Signup and view all the answers

Where do the internal thoracic veins drain into?

Brachiocephalic veins Signup and view all the answers

What is the location of the posterior intercostal arteries in the intercostal space?

Between the 2nd and 3rd layer of intercostal muscles Signup and view all the answers

What is the destination of the venae comitantes in the internal thoracic vessels?

Brachiocephalic veins Signup and view all the answers

What is the branch of the internal thoracic artery that supplies the diaphragm and pericardium?

Pericardiacophrenic branch Signup and view all the answers

What is the location of the thymus gland in the thoracic cavity?

Anteriorly in the thoracic cavity Signup and view all the answers

How do the anterior and posterior intercostal arteries interact in the intercostal space?

They anastomose with each other Signup and view all the answers

What is the ultimate drainage point for the posterior set of lymph nodes?

Thoracic duct Signup and view all the answers

What type of muscles do the posterior rami of the thoracic spinal nerves supply?

Post-vertebral muscles of the chest Signup and view all the answers

What is the safest place to insert needles into the chest wall, according to traditional consideration?

Above a rib Signup and view all the answers

What is the correct location to perform intercostal nerve blocks?

As far posteriorly as possible, but above and below the rib Signup and view all the answers

What is the function of the collateral branches of the neurovascular bundle?

To run along the lower margin of the intercostal space Signup and view all the answers

What is the significance of the interconnections between the anterior and posterior sets of lymph nodes?

They allow for the drainage of infection and cancers from one territory to another Signup and view all the answers

What is the anatomical structure that lies in the subcostal groove between the 2nd and 3rd layers of muscles?

Neurovascular bundle Signup and view all the answers

Each intercostal nerve supplies:

A single dermatome Signup and view all the answers

Study Notes

The Sternum

The sternum consists of three parts: manubrium, body, and xiphisternum (or xiphoid process)
These parts are linked together by secondary cartilaginous joints
The manubrium is the handle of the dagger, and manus translates as hands, with a manubrium being a handle or holder
The joint between the manubrium and the body is the sternal angle, also known as the angle of Louis

The Rib Cage

The rib cage comprises the sternum, costal cartilages, ribs, and thoracic vertebrae
The costal cartilages are the unossified parts of the ribs
Ossification starts posteriorly but fails to complete the task

Osteology: Atypical Ribs

The 1st rib is short, strong, flat, and very curved, with a tubercle for scalenus anterior, a single facet on the head, and grooves for subclavian vessels
The 2nd rib has a tubercle for scalenus posterior and serratus anterior
The 10th rib is only sometimes atypical, as it may occasionally articulate with the T10 vertebra only
The 11th and 12th ribs do not have tubercles and have no anterior attachments, with only a single facet on their head

Articular Facets on Vertebra

Superior facet for the head of the rib
Inferior facet for the rib below
Each typical rib articulates with the superior facet on the body at that level and the inferior facet of the vertebra above

Vasculature of the Chest Wall

The thoracic wall receives blood supply from at least three sources: axillary artery, internal thoracic arteries, and thoracic aorta
Internal thoracic arteries give rise to anterior intercostal arteries, whilst the aorta gives rise to posterior intercostal arteries
These anastomose with each other within the intercostal space

Internal Thoracic (Mammary) Vessels

Internal thoracic arteries arise as branches of the subclavian artery
Veins drain into the brachiocephalic veins at the root of the neck
Veins lie either side of the artery as a venae comitantes, which unite before entering the brachiocephalic veins

Lymphatics of the Chest Wall

The lower nodes on the right side drain into the thoracic duct
There are interconnections between the anterior and posterior sets of lymph nodes, allowing infection and cancers to spread
Mostly, the drainage is via the bronchomediastinal lymph trunks

Nerve Supply of the Chest Wall

Intercostal nerves are the anterior rami of the thoracic spinal nerves
Posterior rami supply the post-vertebral muscles of the chest and the skin overlying these
Anterior rami supply the intrinsic muscles of the chest and associated skin
The neurovascular bundle (vein, artery, and nerve) lies in the subcostal groove, between the 2nd and 3rd layers of muscles covering the space between the ribs

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Description

This quiz covers the different parts of the sternum, including the manubrium sterni, sternal angle, body of sternum, and xiphisternum. It also touches on the composition of the rib cage.