Rad 320 Week 1 Chest Anatomy Intro To Positioning

Chest Anatomy and Radiography

  • Overview

  • The chest, also known as the thorax, is the upper part of the trunk between the neck and abdomen.

  • Chest radiographs are the most common type of radiographic procedures in medical imaging.

Components of the Chest

  • Clavicle and Sternum: Vital components of the bony thorax.

    • Sternum Parts:

      • Manubrium

      • Body

      • Xiphoid process

  • Scapula and Ribs: Form the protective walls of the thorax.

    • 12 pairs of ribs surround the thoracic cavity.

  • Thoracic Vertebrae: Support the structure and provide flexibility.

Thoracic Cavity

  • The thoracic cavity is bounded by the walls of the thorax, extending from the superior to the inferior thoracic aperture.

Thoracic Viscera

  • Comprises the lungs and mediastinum.

Respiratory System

Diaphragm

  • The diaphragm is the primary muscle of respiration, divided into left and right hemi-diaphragms.

  • It separates the thoracic cavity from the abdominal cavity.

  • Contraction of the diaphragm increases thoracic cavity volume, reducing intrathoracic pressure, allowing air influx to the lungs.

Bony Thorax

  • It consists of the thoracic spine, ribs, and sternum, providing a protective framework for thoracic organs.

  • The bony thorax is expandable because of the cartilaginous connections of the ribs.

Thoracic Viscera

  • Contains lungs and other key thoracic organs located in the mediastinum.

Sternum

  • The sternum has three parts: manubrium, body, and xiphoid process.

Clavicles

  • These bones articulate medially with the sternum and laterally with the scapula, contributing to the upper thoracic structure.

Ribs

  • Ribs segment the thoracic cavity and articulate posteriorly with the thoracic vertebra.

Respiratory System Anatomy

Components of the Respiratory System

  • The respiratory system facilitates gas exchange of O2 and CO2. It consists of:

    • Pharynx: Air passage connecting to the larynx.

    • Trachea: The windpipe leading to the bronchi.

    • Bronchi: Larger tubes leading to each lung.

    • Lungs: The site of gas exchange, containing alveoli.

Pharynx Structure

  • Divided into three parts:

    • Nasopharynx (associated with the nose)

    • Oropharynx (associated with the mouth)

    • Laryngopharynx (associated with the larynx)

Respiratory Tract

Larynx

  • A cartilaginous structure involved in voice production, located below the pharynx.

Trachea

  • A fibrous muscular tube covered with C-shaped cartilage rings measuring about 4.5 inches long and 0.5 inches in diameter.

Bronchial Tree

  • Comprises:

    • Primary Bronchi

    • Secondary Bronchi

    • Tertiary Bronchi

    • Bronchioles

    • Alveoli

Alveoli

  • Functional units of the lungs where gas exchange occurs, forming a large surface area for effective oxygen and carbon dioxide transfer.

Lungs

  • Right lung has three lobes (superior, middle, inferior); left lung has two lobes and features a cardiac notch.

Pleura

Pleura Structure

  • Parietal Pleura: Lines the thoracic cavity.

  • Visceral Pleura: Covers the lungs.

  • The space between these layers is known as the pleural cavity.

  • Conditions like pneumothorax (air) and hemothorax (fluid) occur within the pleural cavity.

Lung Base and Costophrenic Angle

  • The base of the lung rests on the diaphragm, and the costophrenic angle is the junction where the diaphragm meets the ribs.

Mediastinum

Mediastinal Structures

  • The mediastinum contains vital components including:

    • Thymus gland

    • Heart and major vessels

    • Trachea

    • Esophagus

Mediastinum Boundaries

  • Bounded by the sternum and spine, serving as a central compartment in the thoracic region.

Thymus Gland Functions

  • Central to immune function, producing the hormone thymosin, its size decreases post-puberty.

Positioning Landmarks for Radiography

Radiographic Positioning

  • Essential landmarks for consistent radiographic positioning include:

    • Jugular Notch (T2-3): Useful for identifying T7 (centering point for chest radiographs).

    • Vertebral Prominens (C7): The spinous process of the seventh cervical vertebra helps locate thoracic structures.

    • Xiphoid Process: Inferior tip of the sternum located at T9-T10, relevant for diaphragm location.

Chest Projections

  • PA Projection: Essential for visualizing lung fields and cardiac silhouette. Proper positioning maximizes image quality.

  • Lateral Projection: Often used in conjunction with PA to provide a complete view of thoracic anatomy.