1- anatomy & consequences of coughing

Question 1

sensory receptors are stimulated in mucosa of what areas?

Answer 1

1. oropharynx
2. laryngopharynx
3. larynx
4. respiratory tree (trachea to bronchioles)

Question 2

what does the CNS do in response to sensory receptors from mucosa?

Answer 2

1. a DEEP inspiration using the diaphragm (phrenic nerves), intercostal muscles (intercostal nerves) & “accessory muscles of inspiration”
2. adduction of the vocal cords to close the rima glottidis (vagus nerves)
3. contraction of the anterolateral abdominal wall muscles (intercostal nerves) to build up intra-abdominal pressure which pushes the diaphragm superiorly and builds up pressure in the chest/respiratory tree inferior to the adducted vocal cords
4. the vocal cords suddenly abduct to open the rima glottidis (vagus nerves)
5. the soft palate tenses (CN V) and elevates (vagus nerves) to close off the entrance into the nasopharynx and direct the stream of air (at ~100mph!!) through the oral cavity as a cough rather than through the nasal cavity as a sneeze!

Question 3

what nerves are associated with relaying action potential of sensory receptors in nasopharynx & oropharyngeal region?

Answer 3

CN IX, glossopharyngeal

Question 4

what nerves are associated with relaying action potential of sensory receptors in laryngopharynx & larynx region?

Answer 4

CN X, vagus nerve

Question 5

what results in stimulation of sneeze?

Answer 5

cranial nerve V, trigeminal nerve can relay action potential of sensory receptors in nasal mucosa triggering sneeze

Question 6

what are carotid sheaths?

Answer 6

they are tubes of deep cervical fascia that extend within neck to base of skull - contain variety of structures including internal carotid artery, common carotid artery, internal jugular vein & vagus nerve

*glossopharyngeal nerve doesn’t fully travel in carotid sheath but does enter superior part of carotid sheath to then relay info to skull

Question 7

how is sensory information relayed from visceral pleura & respiratory tree?

Answer 7

post synaptic sympathetic nerves & vagus nerves (carrying parasympathetic fibres) both contribute to pulmonary plexus which distributes both sympathetic & parasympathetic motor nerves out to respiratory tree, mucous glands and smooth muscle within bronchioles

additionally within pulmonary plexus = some sensory nerves (visceral afferents) - these extend from various aspects of respiratory tree and relay to pulmonary plexus where the visceral afferents follow vagus nerve back to brain →stimulating cough

Question 8

what are the accessory muscles for deep (forced) inspiration?

Answer 8

• pectoralis major
• pectoralis minor
• sternocleidomastoid
• scalenus anterior, medius, posterior muscles

Question 9

what does pectoralis major attach? and what does it do?

Answer 9

sternum & ribs & humerus

• mainly adducts and medially rotating humerus
• but if upper limb in fixed position then can pull ribs up & out so increase volume in thoracic cavity by pulling ribs up & out therefore used as accessory muscles

Question 10

what does pectoralis minor pull?

Answer 10

• can pull ribs 3-5 superiorly towards the coracoid process of scapula
  
  • fixed upper limb = moves ribs = increased volume of cavity

Question 11

what is sternocleidomastoid?

Answer 11

neck muscle attaching between sternum/clavicle and mastoid process of temporal bone (on base of skull)

Question 12

what do the scalenus (anterior, medius & posterior) muscles attach?

Answer 12

cervical vertebrae & ribs 1&2

Question 13

what is the rima glottidis?

Answer 13

narrowing within larynx between vocal cords

Question 14

what is on either side of rima glottidis?

Answer 14

vocal cords extending between 2 posterior arytenoid cartilages & cartilage anterior (thyroid cartilage)

Question 15

what makes vocal cords open & close?

Answer 15

vocal cords open & close based on movement of cartilages they’re attached to

→cartilages move due to contraction of muscles that attach to these cartilages = intrinsic muscles of larynx

Question 16

what are the intrinsic muscles of larynx? (not the names, just type & location of muscles)

Answer 16

skeletal muscles under voluntary control that connect to cartilage of larynx and their contraction can open & close vocal cords

= they are all supplied by (somatic) motor branches of vagus nerve CN X

Question 17

what is the route of vagus nerve?

Answer 17

• connect with cranial system at medulla oblongata and pass through skull via jugular foramen
• pass down through neck within carotid sheath - giving off branches to larynx - supply majority of thoracic passing posterior root of lung and passing through diaphragm on oesophagus and distributes to viscera in abdominal cavity

Question 18

what fibers of vagus nerve supply parts of larynx?

Answer 18

somatic sensory = to mucosa of larynx
somatic motor = to muscles of larynx

Question 19

what are the accessory muscles of deep (forced) contraction?

Answer 19

anterolateral abdominal wall muscles:

• anteriorly right & left rectus abdominis

lateral layers of muscles (from superficial to deep)
- external oblique
- internal oblique muscle
- transversus abdominis

Question 20

what happens in deep, forceful expiration?

Answer 20

• the diaphragm relaxes
• the right & left anterolateral abdominal wall muscles contract forcefully increasing intra-abdominal pressure
• the diaphragm is forced superiorly by the compressed abdominal contents
• intra-thoracic pressure increases… increasing the pressure within the respiratory tree inferior to the vocal cords

Question 21

what direction do fibres of external oblique move?

Answer 21

in same direction as external intercostal muscle fibers
= from superiorly inferiorly , from laterally to medially (like hands in pockets)

Question 22

where does external oblique superiorly and inferiorly attach?

Answer 22

• to lower ribs
• inferiorly attaches to anterior part of iliac crest & the pubic tubercle

Question 23

what is aponeurosis?

Answer 23

flattened tendon that comes from both right & left sides and meets in middle making linea alba (white line)

= external oblique, internal oblique and transverse abdominus all have aponeurosis in middle with muscle attachments at sides

Question 24

what is linea semilunaris?

Answer 24

line differentiating muscle from aponeurosis

Question 25

what is linea alba?

Answer 25

part where flattened tendon called aponeurosis met in middle

Question 26

what muscle fibre direction in internal oblique?

Answer 26

same as internal intercostal muscle = opposite of external so medially from laterally and travelling superiorly from inferiorly

Question 27

where does internal oblique attach?

Answer 27

superiorly attached to lower ribs and inferiorly attached to iliac crest and posteriorly to thoracolumbar fascia

Question 28

what direction is muscle fibre of transverse abdominus?

Answer 28

transversely

Question 29

what does transverse abdominus attach to?

Answer 29

superiorly attach to lower ribs, inferiorly iliac crest and posteriorly the thoracolumbar fascia (of lower back)

Question 30

what is the rectus abdominus?

Answer 30

= known as six pack muscle
- long muscle is divided into tendinous intersections = give 6 pack appearance
- rectus abdominis surrounded by sheath formed by aponeurosis of external, internal oblique & transverse abdominis

Question 31

what aponeurosis completely surrounds rectus abdominis?

Answer 31

all of external & internal oblique and transverse abdominis form the sheath that surround it but aponeurosis of internal oblique actually splits (bifurcates) to completely surround rectus abdominis

Question 32

what are the functions of the anterolateral abdominal muscles?

Answer 32

• tonic (continuous low level) contractions maintain posture and support the vertebral column
  
  • (mechanical back pain can be improved by abdominal muscle exercises depending on aetiology)
• contractions produce movements of the vertebral column (spine):flexion; lateral flexion; rotations
• “guarding” contractions protect the abdominal viscera
• contractions increase intra-abdominal pressure to assist: defecation; micturition; labour
• contractions aid forced expiration

Question 33

what is consequence of chronic cough?

Answer 33

build up of air trapped in alveoli →rupture of lung, specifically visceral pleura eventually resulting in pneumothorax (air escaping into pleural cavity)

Question 34

what are reasons that can cause pneumothorax?

Answer 34

a) penetrating injury that disrupts parietal pleura

OR

b) rupture of the visceral pleura then the vacuum between visceral & parietal pleura is lost. this means the elastic lung tissue recoils towards the lung root and results in a pneumothorax

Question 35

what defines
a) a small pneumothorax?
b) a large pneumothorax?

Answer 35

a) defined as gap between the pleura is less than 2cm gap between lung & parietal pleura
b) defined as gap between the pleura is greater than 2cm gap between lung & parietal pleura

Question 36

what examination can be done to help diagnose pneumothorax?

Answer 36

• reduced ipsilateral chest expansion
• reduced ipsilateral breath sounds
• hyperresonance on percussion

Question 37

what does pneumothorax look like on radiograph?

Answer 37

absent lung marking peripherally (lung edges would be visible on xray)

Question 38

what is tension pneumothorax?

Answer 38

• the torn pleura (on either pleura) can create a one-way valve that permits air to enter the pleural cavity on each inspiration but prevents air escaping again on expiration
• means with each inspiration more air enters the pleural cavity but can’t escape so the pneumothorax expands & the lung collapses towards its root
• eventually the build up of air in the pleural cavity applies tension (pressure) to the mediastinal structures →may cause mediastinal shift (if extensive)

Question 39

what is consequence of mediastinal shift?

Answer 39

• deviation of trachea away from side of unilateral pneumothorax (can investigate by palpating trachea in jugular notch)
• compression of superior vena cava (resulting in reduced venous return to heart→hypotension)

Question 40

what is management of large pneumothorax?

Answer 40

needle aspiration:
- needs to be done in safe area with no surrounding damage
- via 4th or 5th intercostal space at mid axillary line in “safe triangle”

Question 41

what is safe triangle? (in context of large pneumothorax needle aspiration)

Answer 41

• the anterior border of latissimus dorsi
• the posterior border pectoralis major
• axial line superior to the nipple

Question 42

why should you not put needle aspiration for large pneumothorax too close to top or bottom of rib?

Answer 42

needle just wants to go through skin, fascia and muscle layers before going into pleural cavity, you don’t want it to touch any nerves so should go through midpoint of intercostal space (not directly above or below as has neurovascular bundle just below amd collateral neurovascular bundle just above)

Question 43

what would you do for emergency management of tension pneumothorax?

Answer 43

large gauge cannula inserted into the pleural cavity via the 2nd or 3rd intercostal space in the midclavicular line on the side of the tension pneumothorax. immediately hear hissing sound where excess air being relieved

Question 44

what would cannula pass through in emergency tension pneumothorax?

Answer 44

• skin
• superficial/deep fascia
• probably through pectoralis major muscle
• 3 layers of intercostal muscles
• parietal pleura