Skeletal Ribcage, Ribs, Sternum and Scapula

Skeletal Ribcage

• The skeletal ribcage consists of ribs, vertebrae, and the sternum.
• Twelve thoracic vertebrae correspond to the rib number.
• All ribs attach posteriorly to vertebrae T1-T12.

Ribs

• True ribs (1-7) attach directly to the sternum via costal cartilage.
• False ribs (8-10) indirectly attach to the sternum.
• Floating ribs (11-12) are not connected to the sternum.

Sternum

• The sternum has three parts: Manubrium, Body and Xiphoid Process.

Vertebral Articulations

• Costovertebral articulation describes the rib head and vertebral body connection.
• Costotransverse articulation describes the rib tubercle and transverse process.

Scapula

• The scapula has several bony landmarks including Acromion Process, Coracoid Process, Glenoid Cavity/Fossa, Lateral Border, Medial Border, Superior Border, and the Inferior Angle.
• Other bony landmarks are the Scapular Spine, Superior Angle, Scapular Notch, Supraspinous Fossa, Infraspinous Fossa, and Subscapular Fossa.

Thorax Compartments

• The thorax is divided into three compartments.
• There are two lateral compartments referred to as pulmonary cavities, containing the lungs and pleural sac.
• There is one central compartment referred to as the mediastinum containing the heart.

Muscles of the Thorax

• There are both intrinsic and extrinsic muscles of the thorax.
• The external intercostals are intrinsic muscles involved in inspiration, raising the ribs.
• The internal intercostals are intrinsic muscles involved in forced expiration lowering the ribs.
• The extrinsic muscles include the Pectoralis Major, Pectoralis Minor, the Serratus Anterior, and the Scalenes.
• The Pectoralis major is a large chest muscle.
• The Pectoralis minor is a smaller chest muscle.
• The serratus anterior looks like a serrated knife.
• There are three Scalenes; Anterior, Middle and Posterior.

Pectoralis major

• Inserts on Anterior Humerus.
• Originates on the Medial 1/3rd of the clavicle, sternum, & ribcage.
• Performs Horizontal Adduction of Humerus.

Pectoralis minor

• Inserts on the Coracoid Process.
• Originates on Ribs 3-5.
• Performs inspiration(elevates ribcage).

Serratus Anterior

• Inserts on the Medial Border of Scapula.
• Originates on Ribs 1-8 or 1-9
• Holds the Scapula to the ribcage. -Protracts the scapula to allow Upward Rotation.
• The long Thoracic Nerve Innervates it.

Scalenes

• The Anterior Scalene inserts on the 1st Rib .
• The Middle Scalene insertss on the 1st Rib.
• The Posterior Scalene inserts on the 2nd Rib.
• All originate on the Transverse Processes.
• They elevate ribs to assist with according to the insertion points.

Respiration

• Respiration involves the exchange of Oxygen and Carbon Dioxide.

Quiet and Forced Inspiration

• During Quiet Inspiration, the diaphragm contracts and flattens, enlarging the vertical dimension of the cavity
• During Forced Inspiration, the primary muscle used is the Diaphragm, along with the External Intercostals, Scalenes, & Pectoralis Minor.
• During inspiration the ribs and sternum are elevated also contributing to expansion.

Quiet and Forced Expiration

• During Quiet Expiration, the Diaphragm Relaxes and arches.
• During Forced Expiration, the Abdominal Muscles contract to push air out of the lungs by compressing the thoracic cavity,
• The Internal Intercostals also contract during forced expiration.

Diaphragm

• It is a Musculotendinous sheet dividing the Thoracic Cavity from the Abdominal Cavity.
• Functions as the Primary muscle of respiration.
• It inserts at the Central Tendon.
• It originates at the Ribs, Vertebrae, and Xiphoid Process.
• Movement of the thorax increases during inspiration by flattening the diaphragm.
• It is Innervated by the Phrenic Nerve (C3-C5).
• The Caval Aperture passes the Inferior Vena Cava.
• The Esophageal Aperture passes the Esophagus.
• The Aortic Aperture passes the Aorta.

Phrenic Nerve

• The Phrenic Nerve innervates the Diaphragm and is composed of spinal nerves C3-C5.

Lungs

• The lungs facilitate respiration for the exchange of gases into/out of blood,
• They communicate with the tracheobronchial tree and heart

Lung Characteristics and Layers

• The Right Lung has 3 lobes, while the Left Lung has 2 and a lingula.
• Pleura is the layer surrounding the lungs.
• The lung layers are the Visceral and Parietal Pleura.
• The Pleural Cavity contains Serous Fluid.

Left/Right Lung

• The right lung is larger and heavier, but it is shorter and wider.
• The left lung is lighter and narrower, but it is longer than the right.
• The left lung has 2 lobes (superior, inferior) and a cardiac notch to accommodate the heart, while the right has 3 lobes.
• The lingula moves into the costomediastinal recess during inspiration.

Root (Hilum)

• The root or hilum is the passageway into/out of the lung tissue.
• It connects the lung to the mediastinum.
• Contains pulmonary vessels, nerves & bronchi.

Bronchopulmonary Segments

• These are discrete pyramidal units of lobes divided by visceral pleura.
• They are anatomically & functionally independent units.

Pleura

• This is the Fibroserous membrane surrounding each lung & lining pulmonary cavities.
• The two continuous layers form the pleural sac that contains the pleural cavity.

Parietal and Visceral Pleura

• The Parietal Pleura is more superficial and close to the ribcage.
• The Visceral Pleura is more deep and close to the lungs.

Pleural Cavity

• The Pleural Cavity is a potential space within the pleural sac between the parietal and visceral pleura.
• It contains a thin layer of serous fluid and lubricates pleural surfaces to maintain surface tension and facilitate movement of the lungs.

Pathway of Air

• Air can follow the Nose or Mouth Route.
• Pathway through the Nose Route is External Nares, Nasal Cavity, internal nares, nasopharynx, then oropharynx.
• Pathway through the Mouth Route is Oral Cavity to the oropharynx.
• The common pathway involves the laryngopharynx larynx (past hyoid bone, thyrohyoid membrane, thyroid cartilage, cricothyroid membrane, cricoid cartilage, cricotracheal ligament, and associated membranes.
• Next the air travels to the trachea which Splits at carina.
• Then it Reaches the Primary bronchi to the secondary bronchi to tertiary bronchi finally reaching the conducting bronchiole.
• It continues to the terminal bronchiole to the respiratory bronchiole and ultimately the alveolar sac alveolus

Larynx

• The larynx contains the Epiglottis (Elastic Cartilage), Glottis, and Hyoid Bone.
• It has several cartilages including the Thyroid, Cricoid and Tracheal (aka Tracheal Rings).
• There are several Membranes and/or Ligaments such as the Thyrohyoid, Cricothyroid, Cricotracheal, and Tracheal.
• There are Muscles such as the Thyrohyoid.

Vocal Folds

• True vocal cords produce sound and are more inferior.
• False vocal cords are more superior.

Trachea

• Large membranous tube with cartilage rings spanning from Larynx to Tracheal Bifurcation.
• C-shaped cartilaginous rings prevent collapse of lumen. Muscular membrane connects rings posteriorly.

Air Pathway

• The carina internally bifurcates splitting the trachea into the right and left bronchus.
• This splitting is the external bifurcation of the trachea into right and left bronchus.

Tracheobronchial Tree

• Starts in the Trachea, the largest airway.
• Then splits to the Primary (Main) Bronchi and bifurcates at the carina.
• Next is the Secondary (Lobar) Bronchi, where One lobar bronchus enters each lobe of the lung.
• Then are the Tertiary (Segmental) Bronchi, each entering each bronchopulmonary segment.
• Next the Connecting Bronchioles are the Airway Network without cartilage.
• Then the Terminal Bronchioles complete the Final part of the conducting airway.
• Afterward are the Respiratory Bronchioles then the Alveolar Sacs and Alveoli.

Alveoli

• Air conduction & gas exchange occurs in Alveoli.
• Alveoli are found in Respiratory Bronchioles and Alveolar Sacs.
• Pulmonary Artery transports deoxygenated blood from the heart to the lungs
• Pulmonary Vein transports oxygenated blood from the heart to the body
• Bronchus = has cartilage
• Bronchiole = has smooth muscle
• Alveolar Duct = hole between alveoli
• Alveolus = 1 bubble (where gas exchange happens)
• Visceral Pleura = layer directly surrounding the lungs
• Cartilage appears blue
• Smooth Muscle has Salmon Colored Rings

Alveolar Model and its components

• Venules, Arterioles, and Elastic Fibers makeup the Alveolar Model.
• Capillaries are composed of individual endothelial cells.
• Type I Pneumocytes absorb surfactant.
• Type II Pneumocytes produce & secrete surfactant.
• Alveolar Pores are holes.

Type I Pneumocytes.

• Absorb surfactant.
• Are Flat, thin cells that pressed against the alveoli.

Type II Pneumocytes.

• Produce & distribute surfactant.
• Are Circular/larger cells, in between Type I pneumocytes.

Artery Components

• Pulmonary Artery (PA) facilitates Branches of pulmonary trunk and moves Deoxygenated blood to lungs.
• Bronchial Artery (BA) facilates Supply to bronchial tree.

Veins

• Pulmonary Vein moves oxygenated blood to heart.
• Bronchial Vein (BV) terminates in azygos & hemiazygos vein.

Asthma

• This is caused by Obstructed Bronchioles that needs to be treated with an inhaler for bronchodilation.

Emphysema

• Caused by Destroyed or damaged alveoli (reduces surface area for gas exchange).
• Treatable by Related to slowing the damage. Occurs in chronic obstructive pulmonary disease (COPD).

Choking

• Obstruction of upper airway due to object must be removed with heimlich or Dechoker.

The Heart

• The heart is a central compartment in the thorax known as the mediastinum

Heart Components

• External Structures: Auricles, Coronary Arteries & Veins, Great Vessels,
• Internal Structures: Valves, Cardiac Skeleton, Conduction System Chordae Tendineae
• Heart Muscles: Pectinate, Papillary Trabeculae Carneae, Myocardium
• Heart Layers: Endocardium, Myocardium and Epicardium
• Layers Surrounding the Heart: Serous Pericardium, and Fibrous Pericardium

Nerve Supply to the Pericardium and Thorax

• Supplied by the Phrenic Nerve (C3-C5).

Internal Heart Structures

• The heart is a hollow and muscular, pumping blood through the circulatory system.
• There are 4 chambers in the heart, 2 atria and 2 ventricles.

Arteries and Veins

• Arteries carry blood away from the heart.
• Veins carry blood towards the heart through pulmonary circulation.

Septums

• These are the myocardium layer in between chambers that forms the wall.
• There can be Interatrial (or Atrial) or Interventricular types.

Chambers of the Heart

• The upper chamberds are the Right and Left Atrium are smaller and thinner walled .
• The lower chambers are the the Right Ventricle and Left Ventricle.
• The Atrium is singular while the plural form being Atria.
• The Ventricle is singular and the plural form being Ventricles.

Atrioventricular Valves

• These are a Right Atrioventricular valve, (aka Tricuspid) that has 3 cusps. a And a Left Atrioventricular Valve(aka Bicuspid/Mitral) that has 2 cusps.
• Function to Prevent backflow of blood from ventricles to atria.

Semilunar Valves

• Right Semilunar = Pulmonic has 3 semilunar cusps.
• Left Semilunar = Aortic also has 3 semilunar cusps. Function Prevent outflow from ventricles as the chambers fill and to prevent backflow after expulsion

Atriocentricular and Semilunar valves

• Atrioventricular are between the atria & ventricles.
• Semilunar, are between ventricles & systemic blood vessels.

Valves

• Heart valves contain cusps.
• Cordae tendineae (heart strings) connect cusps of heat vales to the capillary muscle

Contraction

• Capillary muscles contact when valves close for the purpose of preventing prolapse of valve cusps.

Main blood vessels

• Arteries- Aorta, Pulmonary Trunk and Pulmonary Arteries/Veins.
• Veins- Superior Vena Cava/Inferior Vena Cava

Contraction muscles.

• Middle Layer of the heart- myocardium, creates myocardial contractility.
• Bump muscles that always have Chordae Tendineae - Papillary.
• Ridge- Pectinate a. found only in the Auricles.
• Ridge- Trabeculae b. Ridge like; only c. found in the Ventricles.

Auricles

• Extensions of Atria (pouch), also known as Elephants ears.
• Contains Pectinate Muscle which are rough walled pouches.

Heart Conduction system

• Def: Coordinated electrical transmission leading to contraction of atria & ventricles b.
• Moderated (Automaticity) specialization in cardiac muscle and tissue Autonomic n.
• Innervation Cardiac Plexuses and the Vagus Nerve Sinoatrial (SA) b. Node “Pacemaker” Atrioventricular (AV) Node Interatrial Bundle ( Bachmann's bundle) d. Internodal Bundle (aka Atrioventricular Bundle) Right Bundle Branch Azygos vei. Hemiazygos vei.-
• Thoracic o Purkinje Fibers (aka Atrioventricular Bundle).

Heart Function

• Cardiac Cycle = how blood moves thru the hear.
• Has two phases Diastole which is relaxation.
• Systole which is contraction Ventricular filling-
• Ventricular ejection
• Aorta, base, blood flow to left Atrium Right Atrium to left atrium (through tricuspid.

Heart Valves

Lub a.

• Closure of AV valves: tricuspid and mitral valves during.
• Ventricular contraction b. Dub - Closure semilunar valves: pulmonary are the aorta during ventricular.
• Relaxation Auscultation-best distinction in heart valves.
• Blood flow Cardiac cycle a.

1. First Initial diastole b. Atria & Ventricle relaxed are closed
2. Later D. Node open from A b & semiluna.
3. AV Bundles contraction, the Atria activated blood fills passively to help AV. Valves Close and are atrial in a slow systole.
4. Aortic Valve is at atria pressure higher.
5. Contraction of ventricles -Intra- 8. Is in relaxation - Seminal

• Diostole equals filling an area

Aortic Stenosis

• Clinical Issues: Aortic Valve Stenosis -Def: Failure of valve to open fully"
• Most common valve abnormality".
• Left Ventrical Narrowing =

Heart Failure

• Amount of blood pumped the total is low ejection in ventricular and there could be
• Ventricular Hypertrophy and reduced ejection fraction.

Heart Failure Solution

Solution = new to do heart transpants Heart Transplant TransMedics Biorad and new machine.

Conduction System

1. SA Node "Bachmanns Bundle"
2. Internodal Bundle/Pathway
3. AVNode
4. Bundle of His
5. Right & Left Bundle Branches
6. Purkinje Fibers