The thoracic wall and regions

THORAX ANATOMY AND PHYSIOLOGY STUDY NOTES

Clavicle: A bone in the upper chest, connecting the arm to the body.
Second rib: Used as a landmark for locating the sternal angle.
Sternal angle: The joint between the manubrium and body of the sternum, notable for its position at the second rib.
Twelfth rib: Indicates the inferior boundary of the thoracic cavity.

The thorax is the part of the body located between the neck and the abdomen, encompassing various critical structures.

Vertebral column: The spinal column located posteriorly.
Superior thoracic aperture: The top opening of the thoracic cavity.
Mediastinum: The central compartment of the thoracic cavity, containing the heart, esophagus, trachea, and major blood vessels.
Right pleural cavity: Contains the right lung.
Ribs: Bone structures protecting thoracic organs.
Diaphragm: The muscular organ separating the thorax from the abdomen and playing a key role in respiration.
Left pleural cavity: Contains the left lung.
Rib I: The first rib, which is shorter and involved in various anatomical landmarks.
Inferior thoracic aperture: The lower opening of the thoracic cavity.
Manubrium of sternum: The uppermost portion of the sternum.
Body of sternum: The long flat part of the sternum.
Xiphoid process: The small cartilaginous tip at the inferior end of the sternum.

Cervical pleura: The dome-shaped region of pleura over the apex of the lung.
Space for root of lung: The area where bronchi, blood vessels, and nerves enter and leave the lung.
Pulmonary ligament: A fold of pleura extending from the hilum of the lung to the mediastinum.
Costal part: The portion of the pleura that is adjacent to the rib cage.
Mediastinal part: The pleura facing the mediastinum.
Diaphragmatic part: The portion of pleura that covers the diaphragm.

Apex of right lung: The top part of the right lung.
Right main bronchus: The main airway that leads to the right lung.
Parietal pleura: The outer layer of pleura lining the thoracic cavity.
Visceral pleura: The inner layer of pleura closely covering the lungs.
Costodiaphragmatic recess: A potential space between the pleura at the lower aspects of the thoracic cavity.
Trachea: The main airway leading to the bronchi.

Vertebral column: Comprises individual vertebrae supporting the thoracic structure.
Rib cage: Formed by ribs, protecting essential organs.
Manubrium: The upper section of the sternum at the fulcrum.
Thoracic vertebrae: The twelve vertebrae located in the thoracic region.
Sternum: Comprising three parts: manubrium, body, and xiphoid process.
Xiphoid: The small and variable part of the sternum.

Jugular notch: A visible dip at the top of the sternum, differing slightly between males and females.
Sternoclavicular joint: The joint connecting the sternum to the clavicle.
1st rib: Notable in anatomical reference for various structures.
Sternal body: The central portion of the sternum.
Xiphoid process: The pointed end of the sternum where other muscles attach.
Costal cartilage: Cartilage connecting ribs to the sternum.

Pectoral branch of thoracoacromial artery: Supplies blood to the pectoral region.
Internal thoracic artery: Provides blood supply to the anterior thoracic wall.
Central axillary nodes, Lateral thoracic artery, Lateral axillary nodes, and Pectoral axillary nodes: Involved in lymphatic drainage and blood supply to the breast.
Axillary process: A portion of breast tissue extending towards the axilla.
Lymphatic and venous drainage passes from the lateral and superior part of the breast into the axilla.

Pectoralis major muscle: A large muscle covering the upper front of the chest.
Secretory lobules: Parts of the breast responsible for milk production.
Suspensory ligaments: Connect breast tissue to the skin, aiding its shape.
Lactiferous ducts: Tubes transporting milk to the nipple.
Lactiferous sinuses: Spaces where milk accumulates before exiting the nipple.
Retromammary space: A potential space allowing movement between breast tissue and the underlying muscle.
Parasternal nodes: Lymph nodes situated near the sternum involved in drainage from medial parts of the breast.

Pectoralis major muscle: A key muscle in arm movement and shoulder stability.
Serratus anterior muscle: Important for the movement of the scapula.
Pectoralis minor muscle: A smaller muscle beneath the pectoralis major, helping in arm movements.

External intercostal muscles: Elevate the ribs during inhalation.
Internal intercostal muscles: Depress the ribs during forced exhalation.
Innermost intercostal muscles: Assist in rib depression during exhalation.
External intercostal aponeurosis: A layer covering the external intercostals.

External intercostal muscles: Run in a downward and forward direction, assisting in inhalation.
Internal intercostal and innermost intercostal muscles: Run perpendicular to external intercostals, aiding in forced exhalation.

Intercostal bundles: Comprising the Intercostal Vein, Artery, and Nerve (V.A.N.), essential for thoracic innervation and blood supply.
Lateral branches: Offshoots of intercostal nerves supplying skin sensation.
Posterior ramus of spinal nerve: Supplies erector spinae muscles and skin.
Posterior intercostal arteries and veins: Ensure vascular supply to the thoracic wall.
Collateral branches: Extensions of intercostal nerves involved in structural support.

Coronal (frontal) view: Showing the diaphragm separating thoracic and abdominal cavities.
Right and Left domes of diaphragm: The right dome is higher due to underlying liver.
Central tendon: A structure allowing muscle fibers to attach and assist in contraction during breathing.
Caval opening and aortic hiatus: Openings allowing passage for major blood vessels and esophagus.

Inspiration: Contraction leads to inhalation, drawing air into the lungs.
Expiration: Relaxation facilitates exhalation, pushing air out of the lungs.

Phrenic nerve (C3, C4, and C5): Critical for diaphragm function, with the mnemonic "C3, C4 and C5 keep the diaphragm alive."