Thoracic Wall Anatomy

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Questions and Answers

Which of the following structures define the boundaries of the thorax?

Heart and lungs

T1 vertebra, rib 1, and manubrium (correct)

R & L pleural cavities

Diaphragm and costal margin (correct)

The thoracic wall consists solely of soft tissues.

False

What are the two main spaces located within the thorax?

R & L pleural cavities and mediastinum

The inferior thoracic aperture is bounded by the muscular ______.

diaphragm Signup and view all the answers

Match the thoracic structures with their associated levels:

Inferior vena cava = T8 Esophagus = T10 Aorta = T12 Nipples = Level of 4th rib Signup and view all the answers

What is located in the mediastinum?

Heart Signup and view all the answers

The thoracic wall mainly consists of the lung structures.

False Signup and view all the answers

List the two major outlets of the thorax.

Superior and inferior thoracic apertures Signup and view all the answers

How many thoracic vertebrae are present in the human body?

12 Signup and view all the answers

The rib cage consists of 12 pairs of ribs.

True Signup and view all the answers

What is the name of the structure located at the top of the sternum?

manubrium Signup and view all the answers

The __________ are known as the ribs that do not attach to the sternum.

floating ribs Signup and view all the answers

What type of nerve innervates the pectoralis major muscle?

Medial pectoral nerve Signup and view all the answers

Match the following types of ribs with their descriptions:

True ribs = 7 pairs that attach directly to the sternum False ribs = 3 pairs that attach indirectly to the sternum Floating ribs = 2 pairs that do not attach to the sternum Signup and view all the answers

The xiphoid process is located at the bottom of the sternum.

True Signup and view all the answers

The __________ is the notch located at the top of the sternum.

jugular notch Signup and view all the answers

Study Notes

Thoracic Wall - Learning Objectives

Define the boundaries, spaces, and contents of the thorax
Describe the osteology of the thoracic wall
Describe the intercostal muscles of the chest wall
Understand the blood supply to the chest wall
Understand the intercostal neurovascular structures

Anatomy of the Thorax

Thorax (Chest):
- Boundaries: Chest wall (bony structures), superior/inferior outlets
- Spaces: Right and left pleural cavities, mediastinum
- Contents: Heart, lungs, and others

Definition of the Thorax

Thoracic Inlet: Superior border, bounded by T1 vertebra, rib 1, and manubrium
Thoracic Diaphragm and Costal Margin: Inferior border

Surface Anatomy

Surface Anatomy Landmarks: Jugular notch, clavicle, anterior axillary fold, manubrium, sternal angle and manubriosternal joint, body of sternum, intermammary cleft, xiphisternal joint, epigastric fossa, costal margin, midclavicular line, xiphisternal angle, ribs, and costal arch

Anatomical Planes

Anterior view
Lateral view
Posterior view

Anatomy of the Thorax - Thoracic Inlet

Superior thoracic aperture (Thoracic inlet):
- Boundaries: Posteriorly – first thoracic vertebra (T1), Laterally – first pair of ribs & costal cartilages, Anteriorly – superior border of the manubrium
- Contents: Esophagus, brachial plexus, subclavian artery and vein, trachea

Anatomy of the Thorax - Inferior Thoracic Aperture

Inferior thoracic aperture (Thoracic outlet):
- Boundaries: Posteriorly – 12th thoracic vertebra, Laterally – 11th and 12th pairs of ribs, Anteriorly – costal cartilages of ribs 7-10, xiphisternal joint.
- Closure: Closed by the diaphragm

Anatomy of the Thorax - Inferior Thoracic Aperture - Musculature of the Diaphragm

T8: Inferior vena cava
T10: Esophagus
T12: Aorta

Thorax/Abdomen Relationship

Nipples: Level of the 4th rib, diaphragm elevation upon full expiration (4th intercostal space)

Osteology of the Thorax

Components: Thoracic vertebrae (12), Ribs (12 pairs), Sternum

Osteology of the Thorax - Ribs

Typical Ribs: Long, twisted, and flat bone with a rounded superior border and a sharp inferior border. Consists of a head, neck, tubercle, shaft, and angle. The head articulates with the vertebral body and the vertebra immediately above.
The Neck: A constricted portion between the head and the tubercle.
The Tubercle: A prominence on the outer surface, articulates with the transverse process of the corresponding vertebra.
The Shaft: Thin, flat, and curved. The inferior border forms the costal groove, housing intercostal vessels and nerves.
Angle: The anterior end of each rib is attached to the corresponding costal cartilage. Ribs 3rd-9th are typical ribs.
Atypical Ribs:
- 1st rib: Broadest, most curved, shortest, flattened from above downward, articulates only with T1, clinically important for brachial plexus and subclavian vessels.
- 2nd rib: Prominent tuberosity for serratus anterior muscle, similar curvature to 1st rib.
- 10th, 11th, 12th ribs: Short, lack a neck or tubercle, 12th rib lacks a costal groove or angle, 10th rib articulates only with T10.

Rib Articulations

The spinous processes of T5-T8 are nearly vertical, T1, T2, T11, and T12 are horizontal, and T3, T4, T9, and T10 slope inferiorly

Costal Cartilages

Hyaline cartilage bars: More rounded, extends from the anterior ends of the ribs
Costal margins: 7th to 10th costal cartilages join to form cartilaginous costal margins.
Infrasternal angle: Formed by the right and left costal margins

Sternum

Components: Manubrium, body, xiphoid process
Landmarks: Jugular notch, sternal angle, transverse ridges, articular facets

Sternocostal Joints

1st to 7th costal cartilages: With the sternum (1st pair - primary cartilaginous (synchondrosis); 2nd to 7th - Synovial.
Costochondral joints: Between costal cartilage and anterior end of the rib (primary cartilaginous joint - synchondrosis)
Interchondral joints: Between adjacent borders of ribs (synovial)
Manubriosternal joint: Between manubrium and body of sternum (secondary cartilaginous joint - symphysis)
Xiphisternal joint: Between xiphoid process and body of sternum (primary cartilaginous joint - synchondrosis)

Muscles of the Anterior Thoracic Wall

Intercostal muscles: External, internal, and innermost intercostal muscles.
- Pectoralis major
- Pectoralis minor
- Deltoid (part superficial)
- Cephalic Vein

Superficial Thorax: The Breast

Breast components: breast, nipple, areola, suspensory ligaments (Cooper's), gland lobule, lactiferous duct, and fat.
Axillary tail (of Spence): Found along superior edge of the axilla

Intercostal Muscles

External intercostal muscle
Internal intercostal muscle
Innermost intercostal muscle
Collateral branches

Layer of the Thoracic Wall

Superficial and deep fasciae
External intercostal muscle
Internal intercostal muscle
Innermost intercostal muscle (or transversus thoracis muscle)
Endothoracic fascia
Pleura (not seen)
Intercostal nerve

Blood Supply to the Thoracic Wall

Posterior intercostal artery
Internal thoracic (mammary) artery
Site of anastomosis (allows collateral flow)
Anterior intercostal artery

Diaphragm

Dome-shaped musculotendinous partition between thorax and abdomen
Principal muscle of respiration
Pierced by structures passing between thorax and abdomen
Descends during contraction, ascends during relaxation. Only the dome moves.
Openings:
- Caval opening (T8): Inferior vena cava and terminal branch of right phrenic nerve
- Esophageal opening (T10): Esophagus, vage nerve parts, vessels, lymph
- Aortic opening (T12): Aorta, thoracic duct, azygos vein
- Other minor openings: Sympathetic trunk, superior epigastric vessels, left phrenic nerve, neurovascular bundles of lower sixth intercostal spaces

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Description

This quiz covers the anatomy of the thoracic wall, including its boundaries, osteology, intercostal muscles, and neurovascular structures. Understanding these components is essential for comprehending the thorax's role in respiratory function. Test your knowledge on the key features and functions of this vital region!