Test 3 Flashcards
Skeletal part of thorax
Bony enclosure formed by sternum, ribs and costal cartilages
Thoracic cage
Surrounds and protects organs in the thoracic cavity, provides support for upper limbs and plays a role in breathing
Superior thoracic aperture
Also known as thoracic inlet
Structures passing btwn the thoracic cavity and neck pass through it (trachea, esophagus etc.)
Inferior thoracic aperture
Also known as thoracic outlet
Structures passing btwn the thoracic cavity and abdominal cavity pass through it
12th Thoracic verterba
Bones of thoracic skeleton
Sternum and ribs
Sternum major regions and major surface features
a. manubrium (articulates with first and second ribs to form sternoclavicular joints)
b. body
c. xiphoid process
d. sternal angle
e. suprasternal (jugular) notch
f. clavicular notches (articulate with clavicles to form sternoclavicular joints)
True Ribs (vertebrosternal)
Pairs 1-7
Attach directly to sternum via costal cartilage
False ribs
Pairs 8-10
Attach indirectly to the sternum
Floating ribs
Pairs 11-12
Only attach posteriorly to the thoracic vertebrae, not sternum (no neck or tubercle)
Important surface features of the typical ribs
- head
- neck
- tubercle: both articular and non-articular parts
- body (shaft): costal angle and costal groove
Head of the ribs
Demifacets: superior and inferior
*TYPICAL RIB ONLY
Intercostal spaces
Spaces btwn neighbouring ribs
Typical ribs
3rd-9th
Atypical ribs
1st, 2nd, 10-12th
Single/complete costal facets
Absent transverse costal facets (11th-12th)
Function of the ribs
Provide attachment points to muscles of the back, thorax and proximal upper limb
Protect thoracic organs such as heart and lungs
Costovertebral joint articular surfaces
Costal demifacets on vertebrae T1-T9, full costal facets on vertebrae T1, T10, T11, T12; heads of ribs 1-12
Costotransverse joint articular surfaces
Tubercle and transverse costal facets on transverse processes of ribs 1-10
Ligaments of costovertebral joint
Fibrous capsule
Radiate ligament of head
Intra-articular ligaments (only joints 2-9)
Ligaments of costotransverse joint
Fibrous capsule
Medial costotransverse ligament
Superior costotransverse
Lateral costotransverse ligaments
Movements of costovertebral joints
Internal rotation and elevation of head of rib (gliding)
Movements of costotransverse joints 1-6
Internal rotation of neck of rib
Movements of costotransverse joints 7-10
Posteromedial translation of neck of rib
Neurovasculature of the thoracic cage
V: Intercostal veins (ant and post)
A: Intercostal arteries (ant and post)
N: Intercostal nerves
Internal thoracic artery
O: subclavian artery
Branches: Musculophrenic artery, superior epigastric artery, upper 6 anterior intercostal arteries
Anterior intercostal arteries
Origin: Internal thoracic artery (upper 6), musculophrenic artery (lower 3)
Posterior intercostal arteries
Origin: Supreme intercostal artery (upper 2), thoracic aorta (lower 10)
Subcostal artery
Origin: Thoracic aorta
Anterior intercostal veins
Drain into: Internal thoracic vein (which drains into the brachiocephalic veins) via the Venae Comitantes of the internal thoracic artery
Posterior intercostal veins
Supreme intercostal vein drains into: Brachiocephalic vein
Right 4th-11th drain into: Azygos vein
Left 4th-11th drain into: Hemiazygos veins
Subcostal vein
Drains into: Azygos vein
Thoracic Nerves
Anterior rami of spinal nerves T1-T11: Intercostal nerves
Anterior ramus of spinal nerve T12: Subcostal nerve
External intercostal muscles
*most superficial; fibres course inferomedially
O: Inferior border of one rib
I: superior border of immediate rib below
A: elevate the ribs during forced inspiration
N: anterior rami of spinal nerves T1-T11, i.e., the intercostal nerves of the corresponding intercostal space.
Internal intercostal muscles
*middle layer; fibres course inferolaterally
O: costal groove of one rib
I: superior border of immediate rib below
A: depress ribs during forced expiration
N: same as external
Innermost intercostal muscles
*deepest; fibres course inferomedially
O: costal groove of one rib, posterior to origin of internal intercostals
I: superior border of immediate rib below
A: depress the ribs during forced expiration.
N: same
Transverse thoracic muscle
O: Inferoposterior surface of body of sternum and xiphoid process; sternal ends of costal cartilages of ribs 4-7
I: internal surface of costal cartilages of ribs 2-6
A: depressor of the ribs during forced expiration; Supports intercostal spaces and thoracic cage
Diaphragm origin
- Sternal part: xiphoid process
-Costal part: lower costal cartilages and ribs 7-12
-Lumbar part: Medial and lateral arcuate ligaments, bodies of vertebrae L1-L3, anterior longitudinal ligament
Diaphragm Insertion
Central tendon of diaphragm
Openings of diaphragm
- Aortic hiatus
- Esophageal hiatus
- Caval foramen
- Openings for greater & lesser splanchnic nerves, and superior epigastric vessels
What travels through the aortic hiatus?
Aorta, azygos vein, thoracic duct
What travels through the esophageal hiatus?
Esophagus, branches of the left gastric artery and vein, anterior and posterior vagal trunks
What travels through the caval foramen?
Inferior vena cava, branches of the right phrenic nerve
Recesses of diaphragm
- Costo-diaphragmatic recess (posteromedial)
- Costo-mediastinal recess (anteromedial)
Innervation of diaphragm
- Phrenic nerves (C3-C5)
- Sensory innervation of peripheries via 6th-11th intercostal nerves
Blood supply to diaphragm
- lowest 5 intercostal arteries
- Subcostal arteries
- Superior phrenic arteries
Function of diaphragm
- Main muscle responsible for respiration
- Increases abdominal pressure during defecation, vomiting, and voiding
- Applies pressure on the esophagus to prevent acid reflux
Abdominal surface of diaphragm parts
- Skeletal muscle (sternal, costal, and lumbar parts)
- Central tendon
Musculotendinous structures of abdominal surface of diaphragm
- Right and left crus of the diaphragm
- Median, medial and lateral arcuate ligaments
The heart
A hollow, cone-shaped organ that is about the size of a person’s closed fist
Location of the heart
- Located between the lungs in the mediastinum
- Two thirds of the heart’s mass lies to the left of the body’s midline.
Apex of the heart
Lower, pointed end (4th-5th intercostal space at midclavicular line)
Base of the heart
Broader, upper portion (2nd inercostal space and 2nd-6th costal cartilages to the right of the midline)
Surfaces of the heart
i. anterior surface (deep to sternum)
ii. inferior surface (resting on diaphragm)
iii. right surface (faces the right lung)
iv. left surface (faces the left lung).
Surface projection
outlining the dimensions of an organ on the surface of the body
Surface projection of the heart to the anterior surface of chest
i. superior right point
ii. superior left point
iii. inferior right point
**those are base
iv. inferior left point (apex)
Pericardium
Sac that surrounds and protects the heart
Portions of the pericardium
- Fibrous pericardium
- Serous pericardium
Fibrous pericardium
*superficial
Tough, inelastic dense irregular connective tissue prevents overstretching of the heart, provides protection, and anchors the heart in the mediastinum
Serous pericardium
*deep
Thin delicate mesothelial membrane
Layers of the serous pericardium
- Outer parietal layer lines the inside of the fibrous pericardium
- Inner visceral layer adheres to the heart’s surface
Pericardial cavity
Contains pericardial fluid, a lubricating fluid that reduces friction between the membranes as the heart moves.
Layers of the heart wall
a. Outer epicardium
b. Middle myocardium
c. Innermost endocardium
Outer epicaridum
Visceral layer of serous pericardium
Middle myocardium
Composed of thick cardiac muscle tissue
Innermost endocardium
Composed of connective tissue covered by endothelium that is continuous with the endothelium of the blood vessels
Upper/receiving chambers
- Right and Left atria
Auricle
Anterior pouch-like structure in the atria that allows them to hold a larger volume of blood; receive blood from major systemic (superior & inferior venae cavae) veins (right atrium) and pulmonary veins (left atrium).
Lower/pumping chambers
Right and left ventricles
Pump blood into systemic (aorta; left ventricle) and pulmonary (right ventricle) arteries
Pulmonary pump
Right atrium and right ventricle
Pumps deoxygenated blood towards the lungs
Systemic pump
Left atrium and left ventricle
Pumps oxygenated blood towards rest of the body
Three major sulci on surface of the heart
i. coronary sulcus (atrioventricular (AV) sulcus)
ii. anterior interventricular sulcus
iii. posterior interventricular sulcus
Where does the right atrium receive deoxygenated blood from?
Three veins
i. superior vena cava (SVC)
ii. inferior vena cava (IVC)
iii. coronary sinus
Superior vena cava
Brings blood from most parts of the body superior to the heart
Inferior vena cava
Brings blood from all parts of the body inferior to the diaphragm
Pectinate muscles (musculi pectinate)
Internal parallel ridges on anterior and lateral walls of the right atrium
Crista terminalis
- Smooth muscular ridge in the superior portion of the right atrium
- Divides the musculi pectinati and the right atrial appendage from the smooth surface of the right atrium
- Provides anatomical separation of the orifices of the IVC and the Coronary sinus
Interatrial septum
separates the atria
has an oval depression (fossa ovalis)
Part of right atrium
Right atrioventricular valve (tricuspid valve)
How blood flows from right atrium into right ventricle
Consists of three cusps (or leaflets)
Trabeculae carnae
Irregular surface of ridges on the internal surface of the right ventricle
Chordae tendineae and papillary muscles
Located in right ventricle
Ensure that the cusps of the tricuspid valve permit blood to flow into the right ventricle but prevent backflow of blood into the right atrium
Interventricular septum
Separates the two ventricles
Pulmonary valve
Allow the right ventricle to pump blood into pulmonary trunk which divides into the right and left pulmonary arteries which carry blood to the lungs
How does the left atrium receive oxygenated blood?
Four pulmonary veins; a pair of two pulmonary veins (one superior and one inferior) drain blood from each lung
Atrioventricular valve (bicuspid valve)
Allows blood flow from left atrium into left ventricle (2 cusps)
Left ventricle
Forms apex of heart
Also has trabeculae carneae, chordae tendineae and papillary muscles to ensure that the cusps of the bicuspid valve permit blood to flow into the left ventricle but prevent backflow of blood into the left atrium.
Aortic valve
Allows oxygenated blood flow from the left ventricle to the ascending aorta
Right and left coronary arteries
Arise from ascending aorta
Deliver blood to walls of heart
Ascending aorta
continuous with the arch of the aorta, which is followed by the descending aorta (which consists of the thoracic aorta and the abdominal aorta).
Branches of the aorta deliver blood throughout the systemic circulation
Ligamentum arteriosum
Fibrous remnant of the fetal ductus arteriosus vessel
Attached to the left pulmonary artery near its root and the inferior part of the aortic arch
Myocardial wall thickness and function
Atria: thin bc they pump low pressure blood into adjacent ventricles.
Ventricles: thick bc they pump higher pressure blood greater distances; the wall of the left ventricle is much thicker than that of the right ventricle
Fibrous skeleton of the heart
Consists primarily of four dense connective tissue rings that surround the four heart valves:
a. right atrioventricular fibrous ring
b. left atrioventricular fibrous ring
c. pulmonary fibrous ring
d. aortic fibrous ring
Function of fibrous skeleton of heart
provides a structural foundation for the heart valves, helps prevent overstretching of the valves, forms point of insertion for cardiac muscle bundles, and electrically insulates the atria and ventricles to ensure proper action potential propagation.
Heart valves
Open and close in response to pressure changes as the heart contracts and relaxes
Valves that prevent backflow of blood into the heart
Two atrioventricular valves: Right= tricuspid, Left= bicuspid
Two semilunar vales: pulmonary and aortic
Coronary (cardiac) circulation
Flow of blood through the blood vessels that penetrate the myocardium
Left coronary artery
Divides into the anterior interventricular branch (left anterior descending (LAD) artery) and circumflex branch
Right coronary artery
Divides into the posterior interventricular branch (posterior descending artery (PDA)) and the marginal branch
Coronary sinus
Where blood draining out of the myocardium travels
Empties into the right atrium
Principal tributaries of the coronary sinus
i. great cardiac vein (accompanies the LAD artery)
ii. middle cardiac vein (accompanies the PDA artery)
iii. small cardiac vein (runs parallel to the inferior margin of the right side of the coronary/AV sulcus)
iv. anterior cardiac veins (runs along the right inferior margin of the Rt ventricle)
Autorhythmic cells
Act as a natural pacemaker to set the rhythm for contraction of the entire heart
Form the cardiac conduction system to conduct action potentials throughout the myocardium, ensuring that the cardiac chambers contract in a coordination manner
Components of the cardiac conduction system
a. sinoatrial (SA) node which initiates each heartbeat and thus is the heart’s natural pacemaker
b. atrioventricular (AV) node
c. atrioventricular (AV) bundle or bundle of His
d. right and left bundle branches
e. Purkinje fibers
Nervous system and pace of contractions
NV can increase or decrease pace of contractions but not initiate contraction
Cardiac plexus
Sympathetic and parasympathetic nerves
Sympathetic: stimulate increased heart rate and cause dilation of coronary arteries
Parasympathetic: decreases heart rate
Systemic circulation
- Left side of heart receives oxygenated blood from the lungs and pumps blood into the aorta which branches into smaller systemic arteries that can carry blood to organs
- Arteries branch into arterioles, then into systemic capillaries where nutrients, wastes, gases, etc. are exchanged between the blood and the surrounding cells.
- Capillaries merge to deliver deoxygenated (oxygen-poor) blood into systemic venules which merge to form systemic veins that carry this blood to the right atrium of the heart
Pulmonary circulation
- Right side of the heart receives deoxygenated blood returning from the systemic circulation and pumps it into the pulmonary trunk which branches into pulmonary arteries that carry blood to the right and left lungs
- In the lungs, the pulmonary capillaries are the site of gas exchange, and the blood becomes oxygenated
- The oxygenated blood flows into pulmonary veins and returns to the left atrium
Mediastinum
Separates lungs into two distinct chambers
Pleural membrane and layers
Encloses and protects each lung
Two layers
1. Superficial parietal pleura: lines wall of thoracic cavity
2. Deeper visceral pleura: adheres to the lungs
Pleural cavity
Btwn the two pleurae
Contains a lubricating fluid secreted by the membranes
Lungs
Base: inferior portion
Apex: narrow superior portion
Surfaces of the lungs
- Costal surface
- Mediastinal (medial) surface
- Diaphragmatic
Costal surface of the lungs
lies against the ribs
Mediastinal surface of the lungs
Contains the hilum through which bronchi, pulmonary blood vessels, lymphatic vessels, and nerves enter and exit the lung
Cardiac notch
Found on medial surface of left lung
Heart rest against it
Left lung lobes
Superior (upper) lobe and Inferior (lower) lobe
Separated by oblique fissure
Right lung lobes
Superior and inferior lobe separated by upper part of oblique fissure
Inferior lobe and middle lobe separated by lower part of oblique fissure
Middle lobe bordered superiorly by horizontal fissure
Right main bronchus
Divides into the superior, middle, and inferior lobar (secondary) bronchi
Supplies lobes of right lung
Left main bronchus
Divides into the superior and inferior lobar (secondary) bronchi
Supply lobes of left lung
Lobar bronchi
Secondary bronchi
Conducting zone
Trachea
Main bronchi
Lobar(secondary bronchi)
Segmental (tertiary bronchi)
Bronchioles
Respiratory zone
Respiratory bronchioles
Alveolar ducts
Alveolar saccules
Segmental (tertiary) bronchi
Lobar bronchi divide into these in each lung
They supply air to the bronchopulmonary segments of each lung.
Lobules
lung unit distal to the respiratory bronchioles
composed of alveolar ducts, alveolar saccules and pulmonary alveoli
Respiratory bronchiole
divides into several alveolar ducts
Alveolar ducts
Each one terminates in a cluster of about 100 numerous alveolar saccule and pulmonary alveoli.
Alveolar saccule
terminal dilation of an alveolar duct and is composed of about 20–30 outpouchings called pulmonary alveoli.
Pulmonary alveolus
cup-shaped outpouching lined by simple squamous epithelium and supported by a thin elastic basement membrane
Bronchopulmonary segment
Compartments of each lung (usually 10)
Each one is supplied by a tertiary/segmental bronchus
Blood supply to the lungs
Pulmonary arteries and bronchial arteries
Pulmonary arteries and veins
Pulmonary trunk splits into left and right pulmonary arteries which deliver deoxygenated blood to the lungs
Oxygenated blood is returned to the heart by four pulmonary veins (right and left superior and inferior pulmonary veins) which drain into the left atrium
Bronchial arteries
Branch from the aorta and deliver oxygenated blood to the bronchi and bronchioles
Innervation of the lungs
Pulmonary plexus formed by branches of vagus nerve and sympathetic trunks
Inhalation
Process of moving air into lungs
Occurs when alveolar pressure is lower than atmospheric pressure
Expanding lungs increases volume and decreases pressure
Muscles of inhalation
- Diaphragm (CONTRACTS DOWNWARDS)
- External intercostal muscles
Exhalation
Process of moving air out of lungs
Increased alveolar pressure due to decreased volume of thoracic cavity and lungs
Forced expiration (labored breathing)
involves the contractions of abdominal and internal intercostals muscles.
Mediastinum
A compartment of the thorax located in the midline of the body, that contains most of the thoracic viscera, apart from the lungs
Borders of the mediastinum
Superior: Thoracic inlet
Inferior: Diaphragm
Anterior: Sternum and costal cartilages of 1st-5th ribs
Posterior: Vertebral bodies of superior thoracic vertebrae
Lateral: Parietal pleura of each lung
The thoracic plane (of Ludwig)
Imaginary line extending from the sternal angle, anteriorly, to the T4-T5 intervertebral space, posteriorly
Divides the mediastinum into superior and inferior mediastinal divisions
Inferior division of mediastinum
further subdivided into anterior, middle, and posterior compartments by the pericardial sac
Anterior mediastinum
Posterior to the body of the sternum and anterior to the pericardium
Middle mediastinum
bounded by the pericardium, which encloses the heart and origins of the great vessels
Posterior mediastinum
posterior to the pericardium and anterior to the vertebrae
Pericardial sac
Structures located anterior to the pericardial sac belong to the anterior mediastinum
Structures located posterior to pericardial sac= posterior mediastinum.
Structures located in and around the pericardial sac= middle mediastinum
Structures that course longitudinally through the superior and inferior mediastinum
esophagus, azygos veins and vagus and phrenic nerves
Esophagus
courses longitudinally throughout the mediastinum, posterior to the trachea and main bronchi and anteromedial to the azygos vein.
Lymphatics of mediastinum
Most of the mediastinal organs drain into the thoracic duct
EXCEPT: the right side of the thorax with the right side of the head drains into the right lymphatic trunk
Contents of the superior mediastinum
Thymus, trachea, superior part of superior vena cava, aortic arch and its branches (brachiocephalic trunk, left common carotid artery and left subclavian artery), esophagus, vagus and phrenic nerves.
Contents of the anterior mediastinum
Remnants of the thymus
Contents of middle mediastinum
Pericardial sac and heart
Roots of superior and inferior vena cava
Pulmonary trunk, pulmonary arteries, and pulmonary veins
Root of aorta
Main bronchi
Phrenic nerves
Contents of posterior mediastinum
- Descending thoracic aorta and its branches.
- Azygos veins and hemiazygos venous systems
- Esophagus and esophageal plexus
- Thoracic duct & cisterna chyli
- Vagus nerves (left & right)
- Sympathetic trunk; greater and lesser splanchnic nerves
Function of abdominal wall
- Protection of the internal abdominal organs
- Stabilization and rotation of the trunk
- Increase of intra-abdominal pressure (involved in coughing, defecating, vomiting)
Layers of the abdominal wall
From superficial to deep:
- Skin
- Superficial fascia
- Muscles
- Transversalis fascia
- Extraperitoneal fat (extraperitoneal fascia)
- Peritoneum
Two main sections of the abdominal wall
Anterolateral wall and posterior abdominal wall
Anterolateral abdominal wall main layers
Four main layers
1. Skin
2. Superficial fascia
3. Muscles and associated fascia
4. Parietal peritoneum
Posterior abdominal wall
Formed by the lumbar vertebrae, pelvic girdle, posterior abdominal muscles and their associated fascia