Anatomy Module 6 SG PDF

**[Module 6]** **[Thoracic Wall ]** - **Thorax:** the part of the body between the neck and abdomen - **Chest:** more extensive than the thorax including shoulders and breasts - **Thoracic Cavity:** walls have the shape of a truncated cone, contains [pleural cavity], [pericardial...

**[Module 6]** **[Thoracic Wall ]** - **Thorax:** the part of the body between the neck and abdomen - **Chest:** more extensive than the thorax including shoulders and breasts - **Thoracic Cavity:** walls have the shape of a truncated cone, contains [pleural cavity], [pericardial cavity], and [mediastinum] **Functions of the Thoracic Wall** - Protects vital thoracic organs - Resist the negative pressures generated by inspiratory movements - Provide attachment for and support the weight of the upper limbs - Provide the anchoring attachment of many of the muscles that move and maintain the position of the trunk and upper limbs **Thoracic Wall Structure** - **Wall** of thoracic cavity is thin and made from: - Thoracic cage (rib cage) - Ribs - Costal cartilages - Sternum - Thoracic vertebrae - The **floor** of the thoracic cavity is made by thoracic diaphragm **Types of Ribs** - **True (vertebrosternal) ribs (1^st^-7^th^ ribs):** Attach directly to the sternum through their own costal cartilages. - **False (vertebrochondral) ribs (8^th^, 9^th^ & usually 10^th^ ribs):** Their cartilages are connected to the cartilage of the rib above them. Their connection with the sternum is indirect. - **Floating (vertebral, free) ribs (11^th^, 12^th^ & sometimes 10^th^ ribs):** the rudimentary cartilages of these ribs do not connect even indirectly with the sternum. They end in the posterior abdominal musculature. E:\\Spring 2018\\5014 lectures\\thorax\\1.jpeg - **Typical Ribs (3^rd^-9^th^) Components:** - **Head** make a joint with bodies of two thoracic vertebrae - **Neck** between the head and tubercle - **Tubercle** located at the junction of the neck and body. Articulates with the corresponding transverse process of vertebrae - **Body (shaft)** thin, flat, and curved part. It has a costal groove along the inferior border that provides some protection for the intercostal nerve and vessels.  - **Atypical Ribs (1^st^-2^nd^ and 10^th^-12^th^):** - **1^st^ rib** - Widest, nearly horizontal, shortest and most sharply curved - Has a **single facet** on its head - Has two transversely directed grooves crossing its superior surface for the subclavian vein and artery - **2^nd^ Rib** - Articulates with the bodies of the T1 and T2 vertebrae - Main atypical feature is a rough area on its upper surface tuberosity for **serratus anterior** - **10^th^-12^th^ Ribs** - Have only one facet on their heads and articulates with a single vertebra - Short and have no neck or tubercle Ribs - Physiopedia **Thoracic Vertebrae** - Long, inferiorly slanting spinous processes - Bilateral costal facets (demifacets) on vertebral bodies articulates with heads of ribs - Costal facets on transverse processes articulates with tubercles of ribs (except for the inferior two or three thoracic vertebrae) **The Sternum (sternon, chest)** - Flat, elongated bone that forms the middle of the anterior part of the thoracic cage - Consists of three parts: - Manubrium - Body - Xiphoid process - **Jugular notch** (suprasternal notch) concave center of the superior border of the manubrium - **Clavicula notches** receive clavicle forming the *sternoclavicular (SC) joints*  **Thoracic Apertures** - **Superior Thoracic Apertures** is bounded as follows: - **Posteriorly** by vertebra T1 - **Laterally** by 1^st^ pair of ribs and their costal cartilages - **Anteriorly** by the superior border of the manubrium - **Inferior Thoracic Aperture,** *the anatomical thoracic outlet,* is bounded as follows: - **Posteriorly** by the 12^th^ thoracic vertebra - **Posterolaterally** by the 11^th^ and 12^th^ pairs - **Anterolaterally** by the joined costal cartilages of ribs 7-10, forming the costal margins - **Anterolaterally** by **xiphisternal joint** **Joints of Thoracic Wall** - **Intervertebral** (of vertebrae T1-T12) - **Costovertebral** - Joints of head of rib - Costotransverse - **Costochondral** - Lateral end of costal cartilage with sternal end of rib - **Sternocostal** - **Sternoclavicular** - Sternal end of clavicle with manubrium of sternum - **Manubriosternal** - **Xiphisternal** A table of muscles of thoracic wall Description automatically generated **Nerves of Thoracic Wall** - Nerves go to costal rooves and go from back to anterior. Accessory (dermatomes sensory) and motor (give the muscle fxn in that area intercostal muscles) branches - T2 -- T12 - Intercostal nerves run in intercostal grooves with arteries and veins making a bundle in the intercostal groove. **Veins of Thoracic Wall** - **Posterior intercostal veins** anastomose (connect) with the **anterior intercostal veins** (tributaries of **internal thoracic veins**) - The **intercostal veins** accompany the intercostal arteries and nerves and lie most superior in the costal grooves - Most posterior intercostal veins (4-11) end in the **azygos/hemi-azygos venous system**, which conveys venous blood **to the superior vena cava (SVC)**  **[Lungs and Pleura ]** **Compartments of Thoracic Cavity** - **Right & Left Pulmonary Cavities** contain the lungs and pleurae - **Central Mediastinum** compartment intervening between the two pleural cavities, which contain all other thoracic structures - Extends vertically from the superior thoracic aperture to diaphragm **Pleurae** A serous sac that consist of two continuous membranes: - **The Visceral Pleura** invests all surfaces of the lungs forming their shiny outer surface - **The Parietal Pleura** Lines the pulmonary cavities - **The Pleural Cavity** potential space between the layers of pleura containing pleural fluid, which lubricates the pleural surfaces and allows the layers of pleura to slide smoothly over each other during respiration. **Extensions of Pleura** - **The Visceral Pleura** - is continuous with the parietal pleura at the **hilum** of the lungs. - Where structures make up the **root** of the lung and covers the **outside** of the lungs. - **The Parietal Pleura** (lines inside of cavity -- wall of thorax) consist of three parts: - **Costal** covers the internal surfaces of the thoracic wall. - Separated from the internal surface of the thoracic wall by **endothoracic fascia** - Between costal and inside surface of ribs/intercostal muscles - **Mediastinal** covers the lateral aspects of the mediastinum - **Diaphragmatic** covers the superior (thoracic) surface of the diaphragm on each side of mediastinum - Does NOT cover along the costal attachments origins and where the diaphragm is fused to the pericardium - **The Cervical Pleura** - Covers the apex of the lung (the part of the lung extending superiorly through the superior thoracic aperture into root of neck) - Reinforced by fibrous extension of endothoracic fascia, the suprapleural membrane (**Sibson Fascia**) - **Pleural Reflections** - Abrupt lines along which the parietal pleura changes direction as it passes (reflects) from one wall of the pleural cavity to another - **Costodiaphragmatic Recesses** - Potential pleural spaces, pleura-lined "gutters" which surround the upwards convexity of the diaphragm inside thoracic wall - Increase in fluid in pleural cavity goes into the costodiaphragmatic recess **[Lungs]** - **Apex** blunt superior end of the lungs ascending above the levels of the 1^st^ and is covered by cervical pleura - **Base** concave inferior surface of lung, resting on diaphragm - **Right lung** divided by two **horizontal** and **oblique fissures** in three **superior, middle,** and **inferior lobes** - **Left Lung** divided by **oblique fissure** to two **superior** and **inferior** lobes **Lungs have:** - **Three Surfaces:** - **Costal** faces inside surface of ribs - **Mediastinal** sides face each other -- inner sides - **Diaphragmatic** on tope of diaphragm - **Three Borders** Anterior, Posterior & Inferior - **The Hilum** - The lung is wedge-shaped on the mediastinal surface of each lung through which the structure form the root of the lung pass to enter or exit the lungs **[Tracheobronchial Tree]** - **Trachea** bifurcates at sternal angle into right and left main bronchi - Passing inferolaterally to enter the lungs at the hila - **The right main bronchus** is wider and shorter runs vertically (most objects go to Rt side) - **The left main bronchus** passes inferolaterally - inferior to arch of aorta - anterior to esophagus and thoracic aorta to reach hilum of lung A diagram of the trachea Description automatically generated **[Bronchopulmonary Segments ]** - Largest Pyramidal-Shaped subdivisions of a lobe of the lung - apices face the lung root and bases at pleural surface - Usually 18-20 in number (10 in Rt lung and 8-10 in left lung) - **Surgically resectable** - Supplied independently by a segmental bronchus and a tertiary branch of pulmonary artery - Named according to segmental bronchi supplying them - Primary bronchi (main bronchi) R&L largest bronchi - Secondary (lobar) bronchi three on Rt & two on left - Tertiary (segmental) bronchi "Bronchioles" -- little bronci, less than 1mm in diameter  **[The Respiratory Zone]** - Consists of air-exchanging structures - Respiratory bronchioles branch from terminal bronchioles - Lead to **alveolar ducts** - Lead to **alveoli sacks (air sacks)** **[Arterial Supply ]** - **Bronchial Arteries** supply blood for nutrition of structures making up root of lungs supporting lung tissue and visceral pleura - **Two Left Bronchial Arteries** arise directly from **thoracic aorta** - **Single Right Bronchial Artery** can arise from aorta but commonly arises indirectly from **posterior intercostal arteries** or a common trunk within **left superior bronchial artery** A diagram of a human body Description automatically generated **[The Bronchial Veins ]** - Drain only part of blood supplied to lungs by bronchial arteries - Remainder of blood drained by pulmonary veins - **Rt bronchial veins** drains into **azygos vein** - **Left bronchial vein** drains into **accessory hemi-azygous** **vein** or **left superior intercostal vein** - **Superficial Subpleural Lymphatic Plexus** (deep to visceral pleura) DRAINS into **Bronchopulmonary Lymph Nodes** (region of lung hilum) - **Deep Bronchopulmonary Lymphatic Plexus** (in submucosa of bronchi & peribronchial connective tissue) DRAINS initially into the **Intrinsic Pulmonary Lymph Nodes** - Lymph from BOTH the Superficial and Deep Lymphatic Plexuses DRAINS to the **Superior and Inferior Tracheobronchial Lymph Nodes** - Lymph from the Tracheobronchial Lymph Nodes passes to the **Right & Left Bronchomediastinal Lymph Trunks** TERMINATE on each side at the venous angles - Lymph from the **Parietal Pleura** DRAINS into the **Lymph Nodes of Thoracic Wall** (intercostal, parasternal, mediastinal, phrenic) **[Nerves of Lungs and Pleurae]** - Nerve fibers of pulmonary plexuses are **autonomic** - **Vagal Parasympathetic Fibers** (not stressful conditions) bronchoconstrictive, vasodilator and secretomotor - **Sympathetic Fibers** (fight or flight) bronchodilator, vasoconstrictor - **Visceral Afferent** (sensory for reflex and pain)  **[Clinical Correlates ]** - **Pneumothorax** (collapsed lung) a condition that occurs when air leaks from the lung into the space between the lung and chest wall. This buildup of air can cause the lung to collapse, making it difficult to expand when breathing in.  - ** Hemothorax** a serious condition in which blood collects in the pleural space. The pleural space is a hollow area (cavity) between lungs and rib cage. Without treatment, blood can continue to accumulate and put so much pressure on the outside of the lung that it can\'t fully inflate.