Module 1: The Thoracic Wall Flashcards
Diaphragm
Thin musculotendinous septum that separates the thoracic and abdominal cavities
Diaphragm function
Respiration
Contracts and its dome flattens to increases volume in thoracic cavity
Features of the diaphragm
Right dome
Left dome
Central tendon
Right and left crus
Right dome
Rises to upper border of fifth rib
Left dome
Rises to lower border of fifth rib
Central tendon
Where the peripheral muscle fibres of diaphragm attach to inferior margin of thoracic cage and lumbar vertebrae
Right crus
Originates from anterolateral surface of upper 3 lumbar vertebrae
Left crus
Originates from anterolateral surface of upper 2 lumbar vertebrae
Apertures of the diaphragm
Caval opening
Esophageal hiatus
Aortic hiatus
Caval opening
In central tendon at T8
Opening for IVC
Esophageal hiatus
In right crus at T10
Opening for esophagus
Aortic hiatus
Btwn left and right crus, anterior to T12
Opening for abdominal aorta
External intercostals
Fibres run anteroinferiorly from lower border of rib
Elevate ribcage during inspiration
Internal/innermost intercostals
Fibres run posteroinferiorly from upper border of rib
Depress rib cage during expiration
Injury to intercostal muscles
Results from twisting and reaching upwards causing swelling, pain and muscle tightness
Manubriosterbal joint
Sternal angle or angle of Louis
In line w 4th and 5th vertebrae
Easily palpable forming a clinical landmark
Xiphoid process
Attaches to sternal body at xiphisternal joint
In line w T9
Intervertebral discs
Annulus fibrosus
Nucleus pulposus
Annulus fibrosus
Outer ring of disc made of fibrocartilage
Resists shear forces
Nucleus pulposus
Gelatinous structure that resists compressive forces
DDx: Herniated (slipped) disc
Results from bulging of nucleus pulposus through weak spots of the annulus fibrosus
Symptoms: localized back pain, numbness and weakness along lower thoracic cage
What happens to the intervertebral disc if the annulus fibrosus ruptures completely?
The protruding nucleus pulposus can compress contents of the intervertebral foramen (spinal nerves)
Possible injuries to ribs
Rib fracture
Bruising
Inflammation of costal cartilage
DDx: Fractured rib
Crack or break in ribs caused by a direct blow to the chest
**break in costal cartilage can be considered a rib fracture
Symptoms: injury to internal organs, localized chest and back pain, pain associated with inhalation/exhalation
Thoracic apertures
Thoracic inlet (superior)
Thoracic outlet (inferior)
Thoracic inlet
Formed by manubrium, rib 1, body of T1
Allow for passage btwn thorax and neck
Thoracic outlet
Formed by xiphoid process, costal margin, rib 11 and 12 and body of T12
Allows for passage btwn thorax and abdomen
DDx: Thoracic outlet syndrome
A conditon when blood vessels/nerves passing through the thoracic inlet are compressed causing pain in the neck and shoulders and numbness in fingers
Common causes of thoracic outlet syndrome
Physical trauma, repetitive injuries, anatomical defects, pregnancy
Internal thoracic arteries
Paired (right and left) arteries that run on either side of sternum and supply the anterior thoracic wall
Where do anterior intercostal arteries arise from and travel?
Arise from internal thoracic arteries
Travel in costal grooves of ribs and anastomose with posterior intercostal arteries
Posterior intercostal arteries
Branch of thoracic aorta
Travel anteriorly to anastomose w anterior intercostal arteries
Subcostal arteries
12th pair in intercostal space
Run inferior to costal margin
Veins of thoracic region
Anterior and posterior intercostal veins, subcostal veins
Drain deoxygenated blood into heart
Inferior vena cava
Principal vessel draining lower body
Travels through caval opening at T8
Hemothorax
Accumulation of blood in the pleural cavity due to damage to intercostal artery
Thoracic spinal nerves
Rami and branches
Rami of thoracic spinal nerves
After exiting the intervertebral foramen each thoracic spinal nerve divides into a dorsal (posterior) ramus and a ventral (anterior) ramus
Ventral rami
Intercostal nerves
Run in costal grooves of corresponding ribs
Dorsal rami
Supply deep muscles of back and skin
Branches of thoracic spinal nerves
Cutaneous branches
Muscular branches to intercostal and anterolateral muscles
Cutaneous (sensory) branches
Branch from intercostal nerves
Lateral cutaneous branch and anterior cutaneous branch
Intercostal nerves 1-6
Innervate intercostal muscles of the thoracic wall and overlying skin
Intercostal nerves 7-12 (and subcostal nerve T12)
Supply abdominal muscles and overlying skin
Phrenic nerves
Left and right
Formed by union of C3, C4, C5
Motor innervation to diaphragm, sensory innervation to central tendon
Internal structures of the breast
- Lobes
- Suspensory ligaments
- Lactiferous ducts
Lobes of the breast
Each breast divided into 15-20 lobes that contain mammary glands
Suspensory ligaments of Cooper
Separate lobes and support breast
DDx: Mammary duct ectasia
Condition in which lactiferous ducts widens causing duct walls to thicken leading to nipple discharge, breast tenderness and breast lumps
Symptoms: can be asymptomatic
**more common in perimenopausal women
DDx: Torn pectoralis muscle
Can occur due to the placement of an implant during breast augmentation surgery
Symptoms: localized swelling at breast, weakness, reduced range of motion of shoulder
Arterial supply of lateral breast
Lateral thoracic arteries (branches of axillary artery)
Blood supply of medial breast
Branches of internal thoracic artery
DDx: Paget’s disease of the breast
Rare form of breast cancer that can spread via arterial vessels or lymphatic system
Symptoms: nipple changes in shape and crusting of lactiferous products
Regions of the thorax concentrated with lymph nodes
- Axillary nodes (lateral)
- Parasternal nodes (medial)
- Supraclavicular nodes (superior)
DDx: Intraductal papilloma
Small benign palpable tumor in lactiferous duct proximal to nipple
Symptoms: swollen axillary and/or parasternal lymph nodes
Pericardium
Sac surrounding heart and vessels
DDx: Pericarditis
Inflammation of the pericardium causes abnormal buildup of fluid in pericardial cavity
Symptoms: diaphragmatic spasms, shortness of breath and chest
**idiopathic
Innervation of the heart
The phrenic nerve provides sensory innervation to the fibrous pericardium and serous parietal pericardium
Pericardial layers of the heart
**Outer to inner
Fibrous
Parietal layer
Serous fluid in pericardial fluid
Visceral layer
DDx: Referred pain in a heart attack
Pain associated with the heart is felt in shoulder and neck region due to cervical nerves C3, C4, C5 (phrenic nerves)
Left ventricular outflow tract
Aortic orfice
Aortic valve: 3 semilunar cusps and 3 aortic sinuses
Right ventricular outflow tract
Infundibulum or conus arteriosus–> leads to pulmonary trunk
Pulmonary orfice–> pulmonary valve which consists of 3 semilunar cusps
DDx: Hypertrophic cardiomyopathy
Long excessive endurance exercise leads to enlargement of the muscle in the left ventricular walls
Symptoms: shortness of breath, chest pain during exercise, fainting
DDx: Mitral valve prolapse
Backflow of blood from left ventricle to left atrium
Associated with heart palpitations
Cause of mitral valve prolapse
Mitral valve cusps dont close properly due to abnormally long or short chordae tendinae or malfunctioning papillary muscles
The interventricular septum
Divides left and right ventricles
Separates oxygenated and deoxygenated blood
Parts of interventricular septum
- Thick muscular part
- Thin upper membranous part
What is a ventricular septal defect?
Incomplete formation of interventricular septum, leaving an opening btwn right and left ventricles
Most common site for a interventricular defect?
Membranous part of interventricular septum
Symtoms/causes of interventricular septum defect
Thickened ventricular walls and interventriculular septum
Left to right shunting of blood flow
Calcified aortic stenosis
Fibro-calcific remodelling and thickening of the aortic valve leaflets that evolve over years causing obstruction to cardiac outflow
Symptoms of calcified aortic stenosis
Shortness of breath, chest pain, feeling faint or dizzy when exercising
Three main branches of the aorta
- Brachiocephalic
- Left subclavian
- Left common carotid
Brachiocephalic trunk
Ascends 4-5 cm before it bifurcates into right common carotid and right subclavian arteries
DDx: Aortic aneurysm
Balloon like buldge in aorta
Interferes w oxygenated blood delivery to body from heart
Symptoms of aortic aneurysm
*Symptoms only present when dilation is sufficiently large
Chest or back pain
Difficulty breathing
Shortness of breath
What is the flow of blood from the left ventricle?
Aorta->brachiocephalic artery->left common carotid artery->left subclavian artery
Origin of right internal thoracic artery
Right subclavian
Origin of left internal thoracic artery
Left subclavian artery
What arteries do the left and right sinuses of the aorta give rise to?
Left and right coronary arteries
What arteries does the posterior aortic sinus give rise to?
None
What do the left and right coronary arteries create?
An anastomoses to form a circle in the coronary sulcus (atrioventricular sulcus)
Loop in the interventricular sulcus btwn the ventricles
Why is a circle/loop arrangement of arteries advantageous?
Sets up a backup blood supply
If theres plaque buildup in a vessel, the blood can reroute via an alternate path
Ensures constant blood supply
DDx: Coronary artery disease
A blockage in the coronary artery circle and loop arrangement of the heart that arises from an aortic sinus
Symptoms of coronary heart disease
Chest pain and shortness of breath
What happens if there is a complete blockage of a coronary artery?
Heart attack
Coronary bypass surgery
Arteries/veins from other areas of body are transplanted to heart to divert blood flow around an occluded section of blocked artery
Angioplasty
Balloon catheter inserted into blocked artery and inflated to dilate it
Pleural recesses
Potential spaces of pleural which are not filled with lung tissue during expiration
Types of pleural recesses
- Costomediastinal recess
- Costodiphragmatic recess
DDx: Pleural effusion
Buildup of excess pleural fluid in the pleural cavity btwn the parietal and visceral pleura of the lungs
Impairs ability of lungs to expand
Symptoms of pleural effusion
Difficulty breathing and pain extending into shoulder/neck region due to phrenic nerve irritation
What can pleural effusions be caused by?
Underlying heart failure or cirrhosis
Costomediastinal recess
Right and left
In anterior thorax btwn the costal and mediastinal parietal pleura
Left costomediastinal recess
Larger and overlies heart
Why is it imp to distinguish btwn the right and left costomediastinal recesses?
To determine site of pleural effusion
Costodiaphragmatic recesses
Located btwn costal and diaphragmatic pleura, below inferior part of lungs
Clinically significant landmarks in pleural effusion
Innervation of parietal pleura
Intercostal nerves and phrenic nerves
Innervation of visceral pleura
Autonomic innervation
Not sensitive to pain, temp or touch but it is sensitive to stretch
Root of the lungs (hilum)
Collection of structures that enter and exit the lungs
Connect lungs to trachea and heart
DDx: Pulmonary arterial hypertension (PAH)
Condition in which patient has high blood pressure in the pulmonary arteries
Structural changes resulting from PAH
Pulmonary artery walls become stiff, swollen and thick causing scarring, clots and build up of plaque
Changes to blood flow caused by PAH
Impedes or occludes blood flow to lungs, increasing pressure in pulmonary arteries and veins and compressing adjacent bronchi
Consequences of PAH on the heart
Heart is required to generate a greater force to direct deoxygenated blood through pulmonary arteries to lungs
Cardiac dysfunction resulting from PAH
Prolonged exertion weakens the cardiac muscle resulting in tightness in thoracic wall, shortness of breath, fatigue and fainting
Where do brachiocephalic veins drain into?
Superior vena cava
Where does the azygos vein travel and drain into?
Enters thorax through aortic hiatus (T12), ascends to right of thoracic vertebral bodies, drains into SVC
Where do the posterior intercostal veins drain into?
Directly into azygos vein
Tributaries of the azygos vein
Hemiazygos veins
Acessory hemiazygos veins
Right posterior intercostal veins
Right bronchial veins
Hemiazygos veins
Lies left to thoracic vertebrae and drains the left posterior intercostal veins
Acessory hemiazygos veins
Lie left of thoracic vertebrae, superior to hemiazygos vein and drains the left posterior intercostal veins
Right posterior intercostal veins
Drain directly into the azygos vein
Right bronchial veins
Remove deoxygenated blood from lungs
What area of the body does the thoracic duct drain lymph from?
Left side of head, neck, thorax, left upper limb and all structures below diaphragm
What area of the body does the right lymphatic duct drain lymph from?
Right side of head, neck, thorax and right limb
Types of lymph nodes
- Pulmonary
- Bronchopulmonary (hilar)
- Tracheobrachial
- Paratracheal
- Bronchomediastinal trunks
DDx: Sarcoidosis
Inflammatory disease causing abnormal masses to form in pulmonary, bronchopulmonary and paratracheal lymph nodes
These enlarged lymph nodes compress airways
Symptoms of sarcoidosis
Persistant dry cough, fatigue, shortness of breath, tightness in chest
Rarely pain
Arterial supply of lung
Descending aorta provides oxygenated blood to thorax and bronchial arteries supply the lungs
DDx: Anxiety and Dyspnea
Anxiety (fight or flight) can lead to the constriction of bronchial arteries resulting in decreased blood supply to lungs
Symptoms of anxiety and dyspnea
Shortness of breath (dyspnea), tightness in chest, hyperventilation, fainting, nausea
Compartments of the mediastinum
Superior and Inferior
Inferior is divided into anterior, middle and posterior
Superior mediastinum
Posterior to manubrium and sternum, anterior to first 4 thoracic vertebrae
Inferior mediastinum
Superior border is the superior mediastinum, inferior border is diaphragm
Anterior mediastinum
Extends from sternum to anterior border of pericardium
Middle mediastinum
Btwn anterior and posterior borders of pericardium
Posterior mediastinum
Extends from posterior pericardium to posterior thoracic wall
