Thorax Flashcards
Pectoral region, vessels and nerves in superior mediastinum, heart and posterior mediastinum, anterior neck and thyroid, pharynx and larynx, nasal sinuses and oral cavity.
How does contraction of pectoralis major assist in breathing?
Pectoralis major contracts during active inspiration to pull the ribs outwards
Which bony structures lie subcutaneously in the anterior chest wall?
sternum (manubrium, body, xiphi sternum)
clavicle
what are the articulations of the clavicle?
medial end: synovial joint with the clavicular notch of the manubrium (sternoclavicular joint).
lateral end: articulates with the acromial process of the scapula via the acromioclavicular joint.
acromion process of scapula
what forms the anterior axillary fold?
lower edge of pectoralis major muscle
what lies deep to the pectoralis minor muscle
axilla
where does lymph from the upper outer quadrant of the breast drain?
Axillary lymph nodes receive 75-90% of breasts’ lymph.
10-25% of the breasts’ lymph will drain into the internal mammary lymph nodes.
Which costal cartilage connects to sternum at the sternal angle
second costal cartilage
What are the 4 pectoralis muscles?
- pectoralis major
- pectoralis minor
- serratus anterior
- subclavius
On it’s distal end, pec major attaches to where on the humerus?
Intertubercular sulcus
what is the primary function of pec major?
adduct and medially rotate the upper limb (eg. throwing a ball) and brings the scapula antero-inferiorly
What ribs does pec minor span and where does it attach? what is pec minors main function?
3-5th ribs and inserts onto the coracoid process of the scapula.
Main function = stabilise the scapula by bringing it antero-inferiorly against the thoracic wall.
Where is subclavius located?
small muscle located directly underneath the clavicle, running horizontally.
what ribs does serratus anterior span? where does it insert? what is it’s main function?
1-10 ribs and inserts onto the anterior surface of the scapula.
It’s main function is to rotate the scapula, lift the arm above 90 degrees and hold the scapula against the rib cage.
A ‘winged’ scapula can occur due to damage to what nerve? What muscle does this nerve innervate?
Long thoracic nerve - it innervates serratus anterior
What ribs does external oblique span? What is the main function?
From lower 8 (4-12) ribs to iliac crest and pubic tubercle
Function: pull the chest downwards and compress the abdominal cavity, which increases the intra-abdominal pressure and performs ipsilateral bending and contralateral rotation.
Which nerves carry sensation from the parietal and visceral pleura?
Parietal pleura = spinal nerves T1-12
Visceral pleura = vagus nerve and sympathetic nerve
At what level does the trachea commence and terminate?
C6 - level of the cricoid cartilage
Terminates at Angle of Louis - T4/5 where it bifurcates into left and right
Does the oesophagus lie anterior or posterior to the trachea?
Posterior
External intercostal muscles facilitate in forced inspiration or expiration?
forced inspiration
internal intercostals facilitate in forced inspiration or forced expiration?
forced expiration
Which direction do external intercostal fibres run?
anteriorly and inferiorly (hands in pockets)
Which direction do internal intercostal muscle fibres run?
postero-inferiorly from the sternum towards the angle of ribs at the back
What are the 2 main muscles used in the process of normal inspiration? What do they do & how does the air move into the lungs?
Diaphragm - flattens
External intercostal muscles - elevates ribs
Increase in thevolumeof the thoracic cavity. As the lungs are held against the inner thoracic wall by the pleural seal, they also undergo an increase in volume
Boyle’s law - an increase in lung volume results in a decrease in thepressurewithin the lungs. The pressure of the environment external to the lungs is nowgreaterthan the environment within the lungs, meaning air moves into the lungsdown the pressure gradient.
How many lobes are there in the right and left lungs? What fissures separate the lobes?
Right: 3 lobes (superior, middle and inferior) separated by the horizontal and oblique fissure
Left: 2 lobes (superior and inferior) separated by the oblique fissure
What are the 3 surfaces of the lungs?
Costal
Mediastinal
Diaphragmatic
What structures pass through the hilum of the lung?
- principle bronchus
- lobar bronchi
- 1 pulmonary artery
- 2 pulmonary veins
- bronchial arteries and. veins
- pulmonary nerve plexus
- lymphatics
- pulmonary lymph nodes
What is a broncho pulmonary segment?
How many broncho-pulmonary segments are there in each lung?
Portion of the lung supplied by a specific segmental bronchus, lymphatics and arteries.
10 broncho-pulmonary segments in each lung.
Which main bronchus is shorter, wider and takes a more vertical course? Why is this clinically relevant?
Right bronchus, inhaled foreign bodies will usually end up in the right middle / lower lobe bronchi.
What are the main divisions of the main bronchi in left and right lungs?
- Left: bronchus enters hilum, divides into superior and inferior lobar bronchi
- Right: bronchus enters hilum, divides into superior, middle and inferior lobar bronchi
- Each lobar bronchi divides into segmental bronchi
- Each segmental bronchi enters a broncho-pulmonary segment
What is the pleural cavity? Are there one or 2 pleural cavities?
What is the pleura?
Fluid filled space that surrounds the lungs, there are 2 pleural cavities for each lung (prevents infection spreading)
It separates the lungs from the surrounding structures (thoracic cage, intercostal spaces, mediastinum, diaphragm)
The pleura is a double layered serous membrane made of squamous cells which surrounds the lungs. Visceral pleura is the more delicate inner layer of pleura that covers the lungs, parietal pleura is thicker and more durable and lines the inner aspect of the thoracic cavity.
What is a pleural recess, why are they important?
When 2 parietal pleura are close to each other and form a space (eg. at the side of the diaphragm between the costal pleura)
Important as we can look for them on an X-ray, we look for sharp angles, if fluid is collecting in the lungs (pleural effusion) it will appear as a blunt angle in the recess.
What is a pneumothorax? How is it treated?
‘Collapsed lung’ - air or gas enters the pleural space (rib fracture) and this removes the surface tension and reduces lung extension.
Treatment is via a chest drain into the pleural cavity to remove the air inside the lungs.
What is the most common carcinoma in men in the UK?
Bronchial carcinoma
Function of the diaphragm?
Blood supply to the diaphragm?
Primary muscle involved in inspiration
Contraction of the muscle facilitates expansion of the thoracic cavity to increase the volume of the cavity, decreasing intrathoracic pressure and allowing lungs to expand and inspiration to occur.
Blood supply
- Inferior phrenic arteries is the main vascular supply
- Superior phrenic arteries supply superior surface of the diaphragm
How does contraction of the diaphragm assist in returning blood to the heart?
Contraction of the diaphragm decreases intra-thoracic pressure and increases intra-abdominal pressure. The net effect is for blood to flow from the abdomen into the chest.
What is the sensory and motor nerve supply to the diaphragm?
Phrenic nerve is the motor and sensory nerve of the diaphragm. It originates from the cervical nerves in the neck (c3,c4,c5) and descends through the thorax to innervate the diaphragm. It is the only source of motor innervation to the diaphragm and therefore, plays a crucial role in breathing.
What is the surface markings of the lowest extent of the lungs?
At the midclavicular line to lowest part of the lung lies at the tip of the 6th rib, at the midaxillary line the 8th rib and posteriorly the 10th rib
What is intercostal recession?
When you have a partial blockage in your upper airway or the small airways in your lungs, air can’t flow freely and the pressure in this part of your body decreases. As a result, your intercostal muscles pull sharply inward. These movements are known as intercostal retractions, also called intercostal recession.
What is the developmental significance of the ligamentum arteriosum?
The ligamentum arteriosum is a small ligament that is the remnant of the ductus arteriosus formed within 3 weeks after birth. At the superior end, the ligamentum attaches to the aorta and at the inferior end it attaches to the pulmonary artery. The ligamentum arteriosum acts as a tether that holds the aorta and pulmonary artery close to each other. While this is a vestigal structure in an adult, during foetal development, the ductus arteriosus’ function is to bypass the lungs.
What are the main branches of the following arteries and what organs/tissues do these vessels supply:
(a) Left common carotid artery
(b) Left subclavian artery
Left common carotid: Ascends from the arch of the aorta directly up the neck and head, lateral to the trachea and oesophagus.
- It does not give off any branches. It supplies blood to the face and brain.
Left subclavian: left arm, chest, shoulders, back and CNS.
- It gives rise to 3 major branches - internal thoracic artery (supplies thymus, pericardium of heart, anterior chest wall), the vertebral artery (passes through the vertebral foramen in the cervical vertebrae and then through the foramen magnum to supply the brain and spinal cord) and the thyrocervical artery (thyroid, cervical region of the neck and upper back and shoulder)
What are the nerve roots of the phrenic nerve? Why is this clinically important?
The phrenic nerve is mostly composed of motor fibres which supply the diaphragm. They also supply sensory fibres to the pericardium, mediastinal pleura, peritoneum and the central part of the diaphragm. This means that upper abdominal pathology such as a perforated duodenal ulcer often results in shoulder tip pain.
What structures are supplied by the vagus nerve?
Vagus nerve has sensory, motor and parasympathetic functions.
- Sensory: innervates skin of external acoustic meatus and internal surfaces of laryngopharynx and larynx and provides visceral sensation to the heart and abdomen viscera
- Special sensory: taste to epiglottis
- Motor: innervation to majority of muscles of the pharynx, soft palate and larynx
- Parasympathetic: smooth muscle of trachea, bronchi and GI tract and regulated heart rhythm
What are the eight vessels which connect the heart to other structures?
aorta pulmonary artery 4 pulmonary veins superior vena cava inferior vena cava