OSCE book

Question 1

1 Picture page 1 book

Label the structures 1–5.

2. What are the proximal and distal borders of the trachea?
3. What forms the wall of the trachea?
4. Which type of mucosa lines the trachea?
5. What lies immediately posterior to the trachea?
6. Which major vascular structures traverse the trachea anteriorly?
7. What is the blood supply to the trachea?
8. What is the nerve supply of the trachea?

Answer 1

Answers
1. 1. Thyroid gland
2. Thyroid cartilage
3. Carotid sheath
4. Vagus nerve
5. Oesophagus
2. The trachea begins proximally at the lower border of the cricoid cartilage (C6) and
terminates distally at the sternal angle (T4) where it bifurcates into the two main bronchi.
3. The walls are composed of fibrous tissue reinforced by 15–20 incomplete semicircular
cartilaginous rings.
4. The trachea is lined by respiratory epithelium. Histologically, this is ciliated pseudostratified columnar epithelium.
5. The oesophagus lies posteriorly with the recurrent laryngeal nerve running in a groove
between the trachea and oesophagus.
6. The brachiocephalic artery and the left brachiocephalic vein traverse the trachea anteriorly. Abnormal vascular anatomy can potentially cause life-threatening bleeding if
not identified prior to tracheostomy.
7. The arterial supply is from the inferior thyroid artery, which arises from the thyrocervical
trunk. Venous drainage is via the inferior thyroid veins, which drain into the right and left
brachiocephalic veins.
8. The nerve supply is predominantly via the recurrent laryngeal branch nerves (branches of
the vagus nerve) with an additional sympathetic supply from the middle cervical ganglion.

Question 2

Questions

1. Label the structures 1–6.
2. What are the origins of the brachial plexus?
3. Describe the course of the brachial plexus until it reaches the clavicle.
4. What are the branches of the lateral cord?
5. What are the branches of the medial cord?
6. How would you perform a block of the plexus using an axillary approach?
7. Which nerves may be missed using the axillary approach?
8. What complications are associated with supraclavicular nerve blocks?

Answer 2

1. 1. Nerve to subclavius
2. Long thoracic nerve
3. Musculocutaneous nerve
4. Axillary nerve
5. Median nerve
6. Radial nerve
7. The brachial plexus arises from the anterior primary rami of C5, C6, C7, C8 and T1.
8. The plexus emerges as five roots lying anterior to scalenus medius
   and posterior to scalenus anterior.

The trunks lie at the base of the posterior triangle of the neck, where they are palpable, and pass over the first rib, posterior to the third part of the subclavian
artery, to descend behind the clavicle.
The divisions form behind the middle third of the
clavicle.
4. Branches of the lateral cord:

Lateral pectoral nerve to pectoralis major
Musculocutaneous nerve to corachobrachialis, biceps, brachialis and the elbow joint. It continues as the lateral cutaneous nerve of the forearm, supplying the radial surface of the forearm
Lateral part of the medial nerve
5. Branches of the medial cord:
Medial pectoral nerve
Medial cutaneous nerves of the arm and forearm
Ulnar nerve
Medial part of median nerve

6. Perform a PDEQ check:
   Patient: procedure explained, full consent obtained, intravenous access, supine with a
   pillow under the head, arm abducted with elbow flexed and shoulder rotated so that the
   hand lies next to the head on the pillow
   Drugs: local anaesthetic (skin and injectate); full resuscitation drugs should be available
   Equipment: nerve stimulator and 50-mm insulated nerve stimulator needle. Full
   monitoring as per AAGBI guidelines
   Note: ultrasound-guided regional blocks are becoming more popular due to
   improved efficacy and safety profiles; opt for ultrasound if you have been trained to
   use it.
   Position the patient appropriately and identify the axillary artery. Draw a line down
   from the anterior axillary fold (insertion of pectoralis major) crossing the artery
   After cleaning and draping the skin, infiltrate local anaesthetic subcutaneously
   Fix the artery between your index and middle finger and insert a needle to pass above
   or below the artery
   Pass the needle 45 degrees to the skin, angled proximally to a depth of 10–15 mm,
   aiming either above the artery (median, musculocutaneous nerves), below the artery
   (ulnar nerve) or below and behind the artery (radial nerve)
   Section 1: Anatomy – Brachial plexus
   4
   If using a nerve stimulator, adequate proximity to each nerve is indicated by motor
   responses produced at 0.2–0.4 mA
   If using ultrasound, the proximity of the needle to the correct nerve can be clearly
   visualised. Most anaesthetists would use an in-plane approach for this purpose
   After negative aspiration, inject 30–40 mL of levobupivicaine, ropivicaine or lignocaine depending on your desired onset and duration of the block
   Do not inject if blood is aspirated or resistance is felt on injection
7. The axillary approach may miss the intercostobrachial nerve supplying the superomedial
   surface of the arm and the musculocutaneous nerve. The intercostobrachial nerve can be
   blocked by subcutaneous infiltration.
8. Complications include:
   Intravascular injection of local anaesthetic
   Temporary and permanent nerve damage
   Bleeding
   Failure
   Phrenic nerve palsy
   Recurrent laryngeal nerve palsy
   Pneumothorax
   Brachial plexus anatomy may be tested by asking how you would perform a brachial plexus
   block on a human subject or manikin. Being able to draw a schematic diagram of the plexus
   in 10 seconds will not help if the question asks about the anatomical relationships of the
   plexus in the neck. Detailed knowledge of the neck and upper limb anatomy is vital for safe
   anaesthetic practice and this will be expected by the examiner.

Question 3

The axillary approach may miss the

Answer 3

intercostobrachial

Question 4

1. Label the structures 1–8. page 7
2. Which sinuses combine to form the internal jugular vein?
3. What is the relationship between the internal jugular vein and the carotid artery?
4. Where does the internal jugular vein terminate?
5. Which veins combine to form the external jugular vein?
6. Where do the anterior and external jugular veins join?

Answer 4

Page 7

1. 1. Facial vein
2. Anterior jugular vein
3. Right internal jugular vein
4. Right brachiocephalic vein
5. Right subclavian vein
6. Right vertebral vein
7. External jugular vein
8. Posterior auricular vein
9. The sigmoid sinuses and inferior petrosal sinuses combine to form the internal jugular
   vein, which then passes through the jugular foramen at the base of the skull.
10. The internal jugular vein lies posterior to the carotid artery at the level of C2, posterolateral at C3, and then lateral to the artery at C4. The vein and artery are contained within
    the carotid sheath along with the vagus nerve.
11. The internal jugular vein terminates behind the sternoclavicular joint as it unites with the
    subclavian vein to form the brachiocephalic vein.
12. The external jugular vein arises from the junction of the posterior auricular vein and the
    posterior division of the retromandibular vein. It lies within the superficial tissues of the
    neck.
13. The external and anterior jugular veins pierce the deep fascia of the neck, usually posterior
    to the clavicular head of sternocleidomastoid, and unite before draining into the subclavian vein behind the midpoint of the clavicle.

Question 5

Picture page 8

1-8

Answer 5

1. 1. Biceps
2. Radial nerve
3. Brachial artery
4. Median nerve
5. Radial artery
6. Ulnar artery
7. Pronator teres
8. Brachialis

Question 6

2. What are the borders of the antecubital fossa?
3. What are the contents of the antecubital fossa?
4. What is the path of the radial nerve through the antecubital fossa?
5. Where does the ulnar nerve traverse the elbow joint?
6. How would you block the median nerve at the elbow?

Answer 6

2. The borders are as follows:
   Proximally – a line between the humeral epicondyles
   Laterally – brachioradialis
   Medially – pronator teres
   The floor – supinator and brachialis
   The roof – deep fascia with median cubital vein and median cutaneous
   nerve on top
3. The antecubital fossa contains the median, radial and posterior interosseous nerves, the
   brachial artery (dividing into radial and ulnar arteries) and the biceps tendon.
4. The radial nerve descends in the upper arm, lying between the medial and long heads of
   the triceps, and enters the antecubital fossa between the lateral epicondyle of the humerus
   and the musculospiral groove. It runs just lateral to the biceps tendon and under
   brachioradialis before dividing into its superficial and deep branches.
5. The ulnar nerve arises medial to the axillary artery and continues medial to the brachial
   artery, lying on corachobrachialis, to the midpoint of the humerus. Here it leaves the
   anterior compartment by passing posteriorly through the medial intermuscular septum
   with the superior ulnar collateral artery. It lies between the intermuscular septum and the
   medial head of triceps, passing posterior to the medial humeral epicondyle, and enters the
   forearm between the two heads of flexor carpi ulnaris.
6. Once you have explained the procedure to the patient and have prepared your drugs and
   equipment:
   Flex the elbow and mark the elbow crease
   Identify the brachial artery on this line and mark a point just medial to the artery
   Clean and drape the area and use a fully aseptic technique
   Direct your insulated stimulator needle 45 degrees to the skin, aiming proximally
   At 10–15 mm, a pop or click will be felt (bicipital aponeurosis)
   Electrical stimulation with 0.2–0.4 mA should elicit finger flexion (pronation alone is
   inadequate)
   Slowly inject 5 mL of your chosen local anaesthetic solution to block the nerve
   Again note that modern anaesthetic practice may well employ the use of ultrasound for a
   median nerve block. If you have been trained in its use and are happy with the technique,
   then use that approach.

Question 7

Questions

1. Label the structures 1–11.

Answer 7

1. 1. Anterior cerebral artery
2. Ophthalmic artery
3. Superior cerebellar artery
4. Basilar artery
5. Vertebral artery
6. Anterior spinal artery
7. Pontine arteries
8. Posterior communicating artery
9. Internal carotid artery
10. Middle cerebral artery
11. Anterior communicating artery

Question 8

2. Which arteries supply the Circle of Willis?
3. Where do they enter the skull?
4. What is normal cerebral blood flow?
5. How does the blood flow to white matter and grey matter differ?
6. List the factors affecting cerebral blood flow.

Answer 8

2. The Circle of Willis is formed from both internal carotid arteries and both vertebral
   arteries (which form the basilar artery).
3. The internal carotid arteries enter via the carotid canal while the vertebral arteries enter
   through the foramen magnum.
4. Normal cerebral blood flow is around 15% of the cardiac output = 750 mL/min. This
   equates to roughly 50 mL/100 g/min.
5. Grey matter receives a higher proportion of blood flow than white matter, 70 mL/100 g/
   min and 20 mL/100 g/min, respectively.
6. The factors influencing cerebral blood flow are legion and include:
   Mean arterial pressure
   Arterial PO2
   Arterial PCO2
   Cerebral metabolic rate
   Body temperature
   Anaesthetic agents – volatiles, ketamine, propofol.

Question 9

7. Describe the production and circulation of the cerebrospinal fluid (CSF).

Answer 9

7. There is approximately 150 mL of CSF, which is in constant circulation from brain to spinal cord. It is produced in the choroid plexuses of the lateral, third and fourth ventricles at a rate of around 500 mL/24 hours. It passes from the lateral ventricle to the third
   ventricle via the foramen of Munro, from the third to fourth ventricle via the Sylvian aqueduct and leaves the fourth ventricle through the foramina of Luschka laterally and foramen of Magendie medially. It is absorbed by the arachnoid villi, mainly in the brain,
   but it is also absorbed via the spinal arachnoid villi.

Question 10

Page 17 aortic trunk

Answer 10

1. 1. Left common carotid artery
2. Left subclavian artery
3. Left coronary artery
4. Right coronary artery
5. Brachiocephalic trunk
6. Right subclavian artery
7. Right common carotid arter

Question 11

Page 18 coronary

Answer 11

1. Left coronary artery (main stem)
2. Circumflex artery
3. Right coronary artery
4. Left interventricular (anterior descending) branch
5. Right marginal branch

Question 12

3. Where do the left and right coronary arteries arise from?
4. Describe the venous drainage of the heart?
5. What is the innervation of the heart?
6. What signs and symptoms might arise from reduced blood flow to the right coronary
   artery?

Answer 12

3. The left coronary artery arises from the left posterior aortic sinus while
   the right coronary artery arises from the anterior aortic sinus.
4. The majority of venous drainage occurs via the coronary sinus. It is the main vein of
   the myocardium running left to right in the posterior aspect of the coronary groove.
   It receives blood from the great, middle and small cardiac veins as well as from the
   left marginal and posterior ventricular veins. A smaller percentage (20%–30%) occurs
   via the anterior cardiac and Thebesian veins, which drain directly into the right
   atrium.
5. The innervation of the heart is via the autonomic nervous system from superficial and
   deep cardiac plexuses. The sympathetic supply is from presynaptic fibres of T1 – T5 and
   postsynaptic fibres from the cervical sympathetic chain ganglia. The parasympathetic
   supply is derived from the vagus nerve.
6. The right coronary artery supplies the right atrium and ventricle (in the majority of
   people) as well as some of the posterior wall of the left ventricle and the anterior twothirds of the interventricular septum. The right coronary artery also supplies much of the
   conducting system of the heart. Reduced blood flow will result in ischaemia to that area.
   The symptoms range from nothing to general malaise, sweating, fatigue and nausea and
   may progress to the classical symptoms of chest pain and shortness of breath. Signs would
   include anxiety, tachycardia, arrhythmias, hypotension, pulmonary oedema and
   tachypnoea.

Question 13

Page 21

1. Label the canals/foramina 1–8 and state which nerves pass through them.

Answer 13

1. Optic canal: 
optic nerve (II), ophthalmic artery, sympathetic nerves

2. Cribriform plate: 
olfactory nerve (I)

3. Foramen rotundum:
   maxillary division of the trigeminal nerve (V)
4. Foramen ovale:
   mandibular branch of the trigeminal nerve (V), accessory meningeal artery
5. Foramen spinosum:
   middle meningeal vessels,
   meningeal branch of the mandibular nerve

6. Internal auditory meatus: 
facial nerve (VII), vestibulocochlear nerve (VIII)

7. Hypoglossal canal
   : hypoglossal nerve (XII)
8. Foramen magnum:
   medulla oblongata, vertebral arteries, spinal arteries

Question 14

2. How would you test trigeminal nerve function?

Answer 14

2. The trigeminal nerve (cranial nerve V) is the largest of the cranial nerves.

It provides sensory supply to the face and much of the scalp in its three divisions, which are the ophthalmic, maxillary and mandibular nerves.

Testing of the trigeminal nerve, therefore, requires assessment of these three branches.

The ophthalmic branch leaves the trigeminal ganglion and travels through the superior orbital fissure. It is a sensory nerve, providing branches (lacrimal, frontal and nasociliary) to supply sensation to the anterior aspect of the scalp and the superior parts of the face
including the cornea.
The maxillary branch passes through the foramen rotundum and is the sensory supply to
the mid-face.
The mandibular branch has a mixed sensory and motor function. It exits the skull via the
foramen ovale. It has an extensive sensory innervation to the mandibular area, up to the
temporomandibular joint and temple as well as the buccal mucosa and anterior twothirds of the tongue. It also provides the motor supply to the masseter, temporalis and
pterygoid muscles.
Therefore, testing of the trigeminal nerve is as follows:
Test for light touch, pin-prick and temperature in the three separate nerve
distributions.
Test the corneal reflex (motor response via the facial nerve).
Ask the patient to clench his/her jaw and palpate the masseter and temporalis muscles
for volume and tone.
Open the mouth and observe for mandibular deviation.
Test lateral jaw movement against resistance

Question 15

3. What are the functions of cranial nerve VII?

Answer 15

3. The facial nerve has motor and sensory functions. It exits the skull via the internal
   auditory meatus along with the vestibulocochlear nerve (VIII).
   It is motor to most of the facial muscles, notably frontalis, orbicularis oculi and orbicularis oris, platysma and stapedius. Therefore, it is involved in providing innervation for
   blinking, frowning and smiling.
   Its sensory component is responsible for taste to the anterior two-thirds of the tongue as
   well as secretory function to the lacrimal gland, nose and mouth, submandibular and
   sublingual salivary glands.
   As well as being able to identify the different foramina, you need to know the structures they
   transmit. This knowledge may be tested in asking about specific signs and symptoms relating
   to intracranial pathologies.

Question 16

1. Label structures 1–4.

2. At what levels are the three diaphragmatic foramina?

Answer 16

1. 1. Central tendon of the diaphragm
2. Inferior vena cava (IVC) hiatus
3. Aorta/aortic hiatus
4. Oesophagus/oesophageal hiatus

The IVC hiatus is at the level of T8; the oesophageal hiatus at T10; the aortic hiatus
at T12

Question 17

3. What does each of them transmit?
4. What is the function of the diaphragm?
5. What is it composed of?
6. What are its attachments?
7. What is its nerve supply?
8. What is a Bochdalek hernia?

Answer 17

3. IVC hiatus transmits:
   inferior vena cava and
   right phrenic nerve.

Oesophageal hiatus
transmits: 
oesophagus, 
left gastric vessels and
 vagus nerve. 

Aortic hiatus transmits:
aorta,
azygos vein and thoracic duct.
4. The diaphragm separates the abdominal cavity from the thorax and is the principle
muscle of respiration.
5. The diaphragm is a sheet of skeletal muscle composed of a central tendinous part and a
peripheral muscular part.
6. The central tendon is in contact with the pericardium superiorly. T
he muscular part is
attached posteriorly to the psoas muscle and quadratus lumborum via the arcuate
ligaments, medially to the xiphisternum and anteriorly to the costal cartilages of the
lower six ribs.

7. The diaphragm is supplied by the phrenic nerve (C3, C4 and C5).
8. A Bochdalek hernia is a type of congenital diaphragmatic hernia. Disruption of the
   diaphragm during fetal development allows the abdominal viscera to push into the
   thoracic cavity. It can cause pulmonary hypertension and hypoplastic lungs, resulting in
   respiratory distress of the newborn.
   Congenital diaphragmatic hernia carries a mortality rate of 35%–60%

Question 18

1. Label structures 1–6.

page 25

Answer 18

1. 1. Lateral corticospinal tract
2. Vestibulospinal tract
3. Fasciculus cuneatus
4. Posterior spinocerebellar tract
5. Lateral spinothalamic tract
6. Anterior spinothalamic tract

Question 19

2. What are the functions of the spinothalamic tracts?
3. What is the blood supply to the spinal cord?
4. What is the artery of Adamkiewicz?
5. What is its venous drainage?
6. What is anterior spinal artery syndrome?
7. How many pairs of spinal nerves are there?
8. What are the anterior primary rami?
9. What are the features of spinal shock

Answer 19

2. The spinothalamic tracts can be divided into anterior and lateral.
   Anterior spinothalamic – ascending pathway that transmits contralateral sensations of
   touch and pressure.
   Lateral spinothalamic – ascending pathway that transmits contralateral sensations of pain
   and temperature.
3. The spinal cord receives its arterial blood supply from three main sources:
   Anterior spinal artery
   This lies on the anterior median fissure and receives it supply from the vertebral
   arteries at the foramen magnum. It supplies the anterior part of the cord
   Posterior spinal artery
   Formed from the posterior cerebellar arteries. It supplies the posterior cord and tends
   to be smaller than its anterior counterpart
   Other spinal arteries
   These are branches of vertebral, intercostal, lumbar or sacral arteries, depending on
   the cord level. They are collectively called radicular arteries
   There are few/no anastomoses between the blood supply to the anterior and posterior
   cord. This leaves those areas vulnerable to ischaemia from disruption to the anterior or
   posterior spinal arteries (e.g. thrombosis, spasm and hypotension).
4. The artery of Adamkiewicz (so called after a Polish pathologist), also known as the arteria
   radicularis magna is one of the radicular arteries arising from the lower thoracic region. It
   is of importance because it has a major role in the blood supply to the lower half of the
   spinal cord.
5. Venous drainage of the spinal cord is via lateral, anterior and posterior venous plexuses.
   They unite to drain into larger regional vessels such as the azygos vein, vertebral, lumbar
   and sacral veins.
6. Anterior spinal artery syndrome results from infarction or ischaemia of the anterior
   spinal artery. It presents with paralysis and loss of pain and temperature sensation below
   the level of the insult. Proprioception is usually preserved.
7. There are 31 pairs of spinal nerves – 8 cervical, 12 thoracic, 5 lumbar, 5 sacral and 1 coccygeal.
8. The anterior primary rami give cutaneous and motor supply to the limbs and the anterior
   and lateral parts of the neck, thorax and abdomen.
   The posterior primary rami give sensory and motor supply to the muscles and skin of the
   back.
9. Spinal shock occurs following injury to the spinal cord. It initially presents with loss of
   sensory and motor function below the level of the lesion; it may be accompanied by
   hypotension and bradycardia, depending on the level of the injury, due to disruption of
   Section 1: Anatomy – Spinal cord
   26
   sympathetic tone. Following the initial period of hyporeflexia, some reflexes will return
   over the next week or so with a period of hyperreflexia appearing within the following four
   to six weeks. Roughly six weeks following injury, there may be evidence of hyperreflexia
   and spasticity as well as autonomic dysfunction.
   Autonomic dysreflexia is a condition associated with spinal cord injury that usually
   results from cord injury above the level of T6. It can result in extreme hypertension,
   compensatory bradycardia, flushing, sweating and headaches. It is often triggered by
   painful stimuli below the level of the cord lesion

Question 20

Page 29

Answer 20

1. 1. Radial artery
2. Flexor carpi radialis
3. Median nerve
4. Ulnar artery
5. Ulnar nerve

Question 21

page 31

Answer 21

1. 1. Epiglottis
2. Cuneiform cartilage
3. Superior horn (cornu) of the thyroid cartilage
4. Oblique arytenoid muscle (part of the interarytenoid muscles)
5. Corniculate cartilage
6. Transverse arytenoid muscle (other part of the interarytenoid muscles)
7. Posterior cricoarytenoid muscle