Anatomy Flashcards
At what level does the the upper respiratory tract become the lower respiratory tract?
C6 at the lower border of the larynx
True or False: During development, growing lung buds grow inside the pleural cavity
False, they grow into but not inside the pleural cavity
What are the 2 layers of the pleura?
1) Parietal pleura - adherent to the structures of the mediastinum and the internal aspects of the chest wall 2) Visceral pleura - adherent to the developing lung bud
How many lobes does the right and left lung have?
Right: 3 (superior, middle & inferior)
Left: 2 (superior & inferior)
At what level is the horizontal fissure (right lung only)?
Rib 4
At what level are the oblique fissures (both lungs)?
Rib 6
How many bronchopulmonary segements does each lung have, and what is each served by?
10 bronchopulmonary segments each served by their own segmental bronchi
Which rib attaches at the sternal angle, and what else is found at this level?
Second rib. Aortic arch and pulmonary bifurcation are also found here
How many pairs of ribs are there?
12
Which riba are the true ribs?
1-7
Which ribs are the false ribs?
8-10
Which ribs are the floating ribs?
11 & 12
How do ribs articulate with the sternum?
- Head of the rib: articulates with the body of the vertebra of the same number & the body of the vertebra superiorly)
- Rib Tubercle: articulates with the transverse process of the vertebra of the same number
Costal groove
Groove found inferiorly on deep surface of the ribs for the intercostal NVB
What are the 3 joints of breathing?
1) Costovertebral joins: rib to vertebrae
2) Costochondral joints: rib to costal cartilages
3) Sternocostal joints: sternum to costal cartilage
What are the 3 layers of muscles between the ribs and within the intercosta spaces?
- external intercostal muscles
- these muscle fibres are at the angle as if putting hands in pockets
- internal intercostal muscles
- innermost intercostal muscles
- Both of these are at right angles
How many intercostal spaces are there?
11
What is the arterial supply and venous drainage of the anterior and posterior parts of the intercostal spaces?
- Anterior parts:
- Internal thoracic artery and veins
- Course vertically either side of the deep surface of the sternum
- These give off the bilateral anterior intercostal arteries which supply the chest wall
- Posterior parts:
- Posterior intercostal arteries branching from the thoracic aorta
- Azygous vein
What is the nerve supply to the intercostal spaces?
Intercostal nerves give sensory, motor and sympathetic supply. They arise from the anterior ramus of that level eg. T1-11
The diaphragm has holes to permit the travel of which structures through it?
- Oesophagal opening (T10 level): Transmits the oesophagus, vagus nerves, and oesophageal branches of the left gastric vessels.
- Aortic opening (T12 level): Transmits the aorta, thoracic duct (a large lymphatic vessel) and azygous vein.
- Caval opening (T8 level): Transmits the inferior vena cava.
What is unusual about the tendon of the diaphragm?
It is a central tendon
Which dome of the diaphragm is more superior?
The right, due to the presence of the liver
What is the nerve supply of the diaphragm?
phrenic nerve (C3,4 & 5 anterior rami)
“C3,4,5 keeps the diaphragm alive”
Where does the muscular part of the diaphragm articulate?
- the sternum
- the lower 6 ribs & costal cartilages
- L1-L3 vertebral bodies
What is the pathway of the phrenic nerve?
- Formed in the cerival plexus from anterior rami of C3, 4 and 5
- Found in the neck on the anterior surface of scalenus anterior
- In the chest it descends over the lateral aspect of the fibrous pericardium
- Supplies somatic sensory and sympathetic axons to the diaphragm & fibrous pericardium
- Supplies somatic motor axons to the diaphragm, to each respective half
What are the mechanical steps of inspiration?
- The diaphragm contracts and descends, increasing the chest cavity vertically
- the intercostal muscles contract, elevating the ribs and pulling the ribs laterally/anteriorly, increasing the A-P and lateral chest cavity dimensions
- The chest walls pull the lungs outwards with them due to: surface tension between the parietal and visceral pleurae created by the pleural fluid
- The lungs expand: lung P1V1 = lung P2V2
- Air flows into the lungs down a pressure gradient (between atmosphere & lungs)
What are the mechanical steps of expiration?
- The diaphragm relaxes and ascends, decreasing the vertical chest cavity dimension
- The intercostal muscles relax, returning the ribs to the resting position, decreasing the A-P and lateral chest cavity dimensions
- The chest walls return to the resting position, relaxing the stretch on the lungs
- Surface tension decrease and the lungs are permitted to elastically recoil
- The lunhs defalte: lung P1V1 = lung P2V2
- Air flows out of the lungs down a pressure gradient (between lungs and atmosphere)
What are the 4 quadrants of the breast?
- Superolateral
- Superomedial
- Inferolateral
- Inferomedial
What are the main components of the exterior breast?
- Areola
- Nipple
- Axillary tail
What is the arterial supply and venous drainage of the breast?
Subclavian > internal thoracic artery and vein
What is the lymphatic drainage of the breast?
- 2 lateral quadrants drain towards the axillary nodes –unilateral drainage
- While the medial quadrants drain towards the sternum (parasternal nodes)
- They drain to both the ipsilateral and contralateral nodes of the sternum
- And so are referred to as bilateral drainage
Winged scapula
If the long thoracic nerve if parylysed or compressed, then the serratus anterior is no longer anchoring the scapula onto the posterior wall so it starts to ‘float’
What stimulates coughing?
Occurs with stimulation of sensory receptors in:
- oropharyngeal mucosa
- laryngopharyngeal mucosa
- laryngeal mucosa
- mucosa of LRT
Which nerves transmit the stimulation signals of coughing to the medulla?
glossopharyngeal (CNIX) or vagus (X)
Carotid sheath
- A protective “tube” of cervical (neck) deep fascia
- Attaches superiorly to the bones of the base of the skull
- Blends inferiorly with the fascia of the mediastinum
- It contains:
- the vagus nerve
- the internal carotid artery
- the common carotid artery
- the internal jugular vein
How the pulmonary visceral afferents connect to the CNS?
- travel from visceral pleura & respiratory tree to the plexus
- then follow the vagus nerve (hitch a ride) to the medulla of the brainstem
What makes up the pulmonary plexus?
Sympathetic axons, parasympathetic axons and visceral afferents
Which areas does the phrenic nerve supply somatic sensory and sympathetic axons to?
- Fibrous pericardium
- Mediastinal parietal pleura
- Diaphragmatic parietal pleura
- Diaphragmatic parietal peritoneum
Which areas does the phrenic nerve supply somatic motor axons to?
Diaphragm
What are the muscles of quiet breathing?
- Diaphragm
- Intercostal muscles
What are the muscles of active breathing?
- Diaphragm
- Intercostal muscles (but far more forcefully)
- Pectoralis major
- Pectoralis minor
- Sternocleidomastoid
- Scalenus anterior, medius & posterior
What are the attachments of pectoralis major?
Attaches between sternum/ribs & humerus
What are the attachments of sternocleidomastoid?
Attaches between sternum/clavicle & mastoid process of temporal bone
What are the attachments of scalanus anterior, middle and posterior?
Attach between cervical vertebrae & ribs 1 & 2
What are the attachments of pectoralis minor?
Ribs 3-5 and the coracoid process of the scapula
Which nerve is responsible for closing the rima glottis during coughing?
Vagus
Where do the vagus nerves descend in relation to the lung root?
posterior
What are the accessory muscles of forced expiration?
The right and left anterolateral abdominal muscles contract forcefully, increasing intra-abdominal pressure.
What are the anterolateral abdominal muscles, in order of superficial to deep?
Anterior vertical muscles:
- Rectus abdominus
- Pyramidalis
Lateral flat muscles:
- External oblique
- Internat oblique
- Transversus abdominus
What does the left and right external oblique aponeuroses blend to form?
Linea alba in the midline
What are the attachments of the external obliques?
Attachment superiorly with the superficial aspects of the lower ribs and inferiorly to the anterior part of the iliac crest and the pubic tubercle
What is th linea semulunaris?
Wheer emuscle fibres end and the aponeurosis begins of the external oblique.
What is the fibre direction of the external oblique?
Direction of hands in pockets
What are the attachments of the internal oblique?
Inferior boarder of the lower ribs to the iliac crest and thoracolumbar fascia of the lower back.
What is the fibre direction of the internal oblique?
Anterolateral (Opposite to external oblique/same as internal intercostals)
What are the attachments of the transversus abdominus?
Deep aspects of the lower ribs to the iliac crest and the thoracolumbar fascia of the lower back
What is the rectus sheath composed of?
Formed by the aponeuroses of the three flat muscles, and encloses the rectus abdominus and pyramidalis muscles
What is the somatic motor, somatic sensory and sympathetic nerve supply of the anterolateral abdominal muscles?
Conveyed within the thoracoabdominal nerves:
- The 7th to the 11th intercostal nerves travel anteriorly then their terminal branches leave the intercostal spaces, in the plane between the internal oblique & the transversus abdominus, as the thoracoabdominal nerves
- the subcostal nerve
- (T12 anterior ramus)
- the iliohypogastric nerve
- (half of L1 anterior ramus)
- The ilioinguinal nerve
- (the other half of L1 anterior ramus)
What are the functions of the anterolateral abdomincal muscles?
- 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
What are the stages of coughing?
- Occurs with stimulation of sensory receptors in the mucosa of the: Oropharynx (CN IX). Laryngopharynx (CN X), Larynx (CN X) and Respiratory tree: Visceral afferents
- The CNS responds by rapidly coordinating the following:
- A DEEP (forced) inspiration using the diaphragm, intercostal muscles & “accessory muscles of inspiration”.
- Adduction of the vocal cords to close the rima glottides
- Contraction of the anterolateral abdominal wall muscles 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, causing expiration
Why do we cough?
To protect and clear the respiratory tract:
- Protects the lungs against aspiration (inhalation of foreign bodies)
- Enhances clearance of excess mucus produced by inflamed respiratory mucosa
Which lung are foreign bodies more likely to get stuck in and why?
Right lung, because at the bifurcation at the carina, the right bronchus is more vertical, straighter, has a greater diameter and is shorter
What are the possible general causes of pneumothorax?
penetrating trauma, fractured rib or pathology eg. boula (blister/bubble in the lung)
What happens when air enters the pleural cavity in a pneumo thorax?
the vacuum is lost, the elastic lung tissue recoils towards the lung root and a pneumothorax results.
Size of the pneumothorax depends on the amount og air entering the pleural cavity:
- Small = < 2cm gap between lung & parietal pleura
- Large = >2 cm gap
What are the signs of a pneumothorax?
- Reduced chest expansion
- Reduced breath sounds
- Hyper-resonance on percussion
What does a pneumothorax look like on CXR?
- Absent peripheral lung markings
- It looks all black as there is just air in the cavity as the lung has collapsed
- Can also sometimes see the outline of the collapsed lung, i.e. a visible lung edge
Tension pneumothorax
A pneumothorax but the difference is that the hole in the lung becomes valvular
This means when you breath in, the air escapes into the pleural space, but when you breath out the valve closes so air cant escape (Unlike in normal pneumothorax where air enters but also escapes).
Means that it grows much faster and is much faster
What can tracheal deviation be a sign of?
Tension pneumothorax (due to mediastinal shift). It deviates away from the collapsed side
Why can mediastinal shift result from tension pneumothorax?
Eventually the build up of air in the pleural cavity applies tension (pressure) to the mediastinal structures
What are the clinical consequences of mediastinal shift?
SVC compression reduces venous return to the heart leading to hypotension (low arterial blood pressure
What is the managment for a pneumothorax?
- needle aspiration (thoracentesis)
- chest drain
What is the site for a chest drain or thoracentesis?
the 4th or 5th intercostal space in the midaxillary line in the ‘safe triangle’:
- the anterior border of latissimus dorsi
- the posterior border pectoralis major
- axial line superior to the nipple
(NVB in the intercostal spaces are close to the ribs above in the costal groove and also below, so put it in the middle of the intercostal space to avoid damaging these)
What is the emegency management of a tension pneumothorax?
Insert a large gauge cannula (grey/orange) into the pleural cavity via the 2nd or 3rd intercostal space in the midclavicular line on the side of the tension pneumothorax
Hernia
A condition in which an internal part of the body is displaced and protrudes through the wall of the cavity of muscle containing it
What 2 factors are generally involved in the development of a hernia?
- Weakness of one structure: commonly a part of the body wall (can be a normal weakening e.g. diaphragm or umbilical, or an abnormal weakenign eg. congenital)
- Increased pressure on one side of that part of the wall (eg. due to chronic cough)
Hiatus hernia
The protrusion of an organ, typically the stomach, through the oesophageal opening in the diaphragm.
What are the 2 types of hiatus hernia?
- Paraoesophageal Hiatus Hernia
- the herniated part of the stomach passes through the oesophageal hiatus to become parallel to the oesophagus & in the chest
- Sliding Hiatus Hernia
- the herniated part of the stomach slides through the oesophageal hiatus into the chest with the gastro-oesophageal junction
Where do inguina hernias form?
In the medial half of the inguinal region
What contributes to the weakness and increased pressure factors in inguinal hernias?
- Weakness: presence of the inguinal canal in the inguinal part of the anterolateral abdominal wall.
- Increased pressure:
- Chronic cough
- Chronic constipation
- Occupational lifting of heavy weights
What is the inguinal canal, both embryologically and in adults?
- The inguinal canal is formed embryologically during the passage of the testes or the round ligament of the uterus into the perineum
- In the adult the canal contains the spermatic cord or the round ligament of the uterus
Where do the inguinal ligamanents attach?
Attach between the ASIS & pubic tubercle
True or False:
The inguinal ligaments are the inferior borders of the external oblique aponeuroses and the medial halves of form the floors of the inguinal canals and
True
Inguinal canal
~ 4 cm long passageways through the anterior abdominal wall in the inguinal regions.
Each canal runs between a deep ring (the entrance to the canal) and a superficial ring (the exit from the canal).
What is the pathway of the descending testes?
- Between the 3rd month of pregnancy and its end the testes become transferred from the lumbar area (ventro-medial to the mesonephros) into the future scrotum.
- A fibrous cord of tissue called the gubernaculum attaches the inferior portion of the gonad to the future scrotum, and guides them during their descent.
- Starts in between the peritoneum and the transverse abdominus - deep ring
- Also takes along the processus vaginalis - an outpouching of the parietal peritoneum which regressto the tunica vaginalis in the scrotum
- It moves down and misses out transverse abdominus and passes through transversalis fasica and internal oblique (forming cremasteric fascia) and then through a v-shaped deformity in the aponeurosis of the external oblique - superificial ring
- Then picks up a layer of the external oblique aponeurosis, superfical fascia and scrotal skin
What is the spermatic cord and what does it contain?
It is the 3 layers of “coverings” gained as the testis passes through the inguinal canal + the structures contained within. It contains:
- vas deferens
- testicular artery
- pampinform plexus
Direct inguinal hernia
A “finger” of peritoneum is forced through the posterior wall of the inguinal canal and directly out of the superficial ring into the scrotum
Indirect inguinal hernia
A “finger” of peritoneum is first forced through the deep ring into the inguinal canal and then out of the superficial ring into the scrotum
How do you differentiate a direct and indirect inguinal hernia?
- Reduce’ the hernia
- Occlude the deep ring with fingertip pressure
- Ask the patient to cough
- if it is a direct hernia, the lump will reappear
- if it is an indirect hernia, the lump will not reappear
What passes through the inguinal canal in females?
The round ligaments of the uterus pass through the inguinal canals into the labium majus
