MCQ

Question 1

1. The anterior triangle of the neck:
   Is bounded posteriorly by the anterior border of sternocleidomastoid [T]
   Contains the carotid sheath [T]
   Contains the external jugular vein [F]
   Is overlain by skin supplied by the transverse cervical nerve(s) [T

Question 2

2. Regarding the anterolateral abdominal wall:
   The lumbar triangle (of Petit) is bounded by the posterior border of the external oblique
   muscle, the anterior border of the latissimus dorsi muscle and the iliac crest [T]
   The floor of the lumbar triangle (of Petit) is formed by the transversus abdominis
   muscle [F]
   During a landmark technique TAP block, two ‘pops’ are felt as the needle passes
   through the thoracolumbar fascia and external oblique layer [F]
   A subcostal TAP block can be used for surgery extending above the umbilicus [T]
   The external oblique, internal oblique and transversus abdominis muscles all have the
   same innervation, which is solely from the thoracoabdominal (T7–11) and subcostal
   (T12) nerves [F]

Answer 2

The floor of the inferior lumbar triangle (of Petit) is formed by internal oblique muscle. The
two ‘pops’ felt during a TAP block are from the needle passing through the aponeuroses of
the external then internal oblique muscles. The internal oblique and transversus abdominis
muscles are also supplied by the iliohypogastric and ilioinguinal nerves (L1).

Question 3

3. At the ankle:
   All of the deep nerves supplying the foot are branches of the sciatic nerve [T]
   The deep peroneal nerve enters the dorsum of the foot between the tendons of extensor
   hallucis longus and extensor digitorum longus [T]
   The deep peroneal nerve is a hyperechoic structure on ultrasound [T]
   The superficial peroneal nerve emerges between extensor digitorum longus and
   peroneus brevis [T]
   The sural nerve lies anterior to the medial malleolus [F]

Answer 3

The saphenous nerve is a branch of the femoral nerve. The sural nerve lies posterior to
the lateral malleolus and is associated with the short saphenous vein.

Question 4

4. Regarding the larynx and trachea:
   In the adult, the narrowest part of the upper respiratory tract is at the level of the cricoid
   cartilage [F]
   In the child, the narrowest part of the upper respiratory tract is at the level of the (open)
   vocal cords [F]
   The position of the carina moves with respiration [T]
   The trachea is in contact with the left vagus nerve in the thorax [F]
   The trachea is in contact with the thoracic duct posteriorly [F]

Answer 4

The cricoid cartilage is the narrowest part of the upper respiratory tract in the child, in the
adult it is at the vocal cords. The left vagus nerve lies on the arch of the aorta (not the trachea)
and the thoracic duct lies behind and in contact with the oesophagus (not the trachea).

Question 5

5. The following is true of the ribs:
   The sympathetic trunk is an anterior relation of the neck of the first rib [T]
   Typical ribs have a head with two articular facets, for articulation with their own
   vertebra and the one below [F]
   Typical ribs have a tubercle with a smooth articular facet, which forms a synovial joint
   with the transverse process of the corresponding vertebra [T]
   Typical ribs have a tubercle with a rough non-articular facet, for attachment of the
   lateral costotransverse ligament [T]
   The costal cartilages of ribs 2–10 form primary cartilaginous joints with the sternum or
   rib/costal cartilage above [F]

Answer 5

More specifically, the stellate/cervicothoracic ganglion lies on the anterior surface of the
neck of the first rib. Typical ribs do have two articular facets, but they articulate with the
corresponding vertebra and the one above. The costal cartilages of ribs 2–10 form a
synovial joint with the sternum or costal cartilage above.

Question 6

6. Regarding autonomic dysreflexia:
   Excess sympathetic discharge occurs in response to stimuli below level of spinal cord
   lesion [T]
   Features are more pronounced with higher lesions and a stronger reaction is observed if
   a more proximal dermatome is stimulated [F]
   Patients develop tachycardia/arrhythmias, with severe hypotension and headache [F]
   Below the level of the spinal cord lesion, patients exhibit sweating, pallor and muscle
   contraction/spasticity [T]
   Central neuroaxial blockade can be used to prevent and manage autonomic dysreflexia [T]

Answer 6

After a transecting injury of the spinal cord, stimulation of spinal cord reflexes below the
level of the injury are exaggerated due to the loss of descending inhibition from higher
centres. Features are more pronounced with stimulation of more distal/lower levels.
Patients typically develop severe hypertension with reflex bradycardia.

Question 7

7. The following are true of the internal auditory meatus/auditory canal:
   It transmits the vestibulocochlear nerve and the facial nerve [T]
   It is directed laterally in the petrous bone [T]
   It connects the middle cranial fossa to the inner ear [F]
   It contains only the motor component of CN 7 [F]
   The vestibular ganglion lies within the internal auditory meatus [T]

Answer 7

The internal auditory meatus/auditory canal connects the posterior cranial fossa and
inner ear. The vestibular ganglion (equivalent to the DRG of a spinal nerve) lies within
the IAM

Question 8

8. Regarding the rectus abdominis:
   The rectus abdominis muscle lies superficial to the external oblique aponeurosis [F]
   The superior epigastric artery is a branch of the internal thoracic artery [T]
   The arcuate line of the rectus sheath lies approximately halfway between the pubic
   symphysis and umbilicus [T]
   Motor supply of the rectus abdominis is partly by the iliohypogastric nerve [F]
   Perforation of the inferior epigastric artery is a common complication of rectus sheath
   block [F]

Answer 8

The external oblique aponeurosis contributes to the anterior layer of the rectus sheath,
hence the rectus abdominis muscle lies deep to it. Motor supply to rectus abdominis is
from the thoracoabdominal (T7–11) and subcostal (T12) nerves. Perforation of the
inferior epigastric artery is a minor risk of rectus sheath block, especially when per-
formed at or below the level of the umbilicus.

Question 9

9. The following is true of the lower limb vasculature:
   The femoral artery lies in the adductor (subsartorial/Hunter’s) canal [T]
   The inferior epigastric artery is a branch of the femoral artery [F]
   The femoral vein lies medial to the femoral artery initially, but lies posteriorly to it at
   the apex of the femoral triangle [T]
   The popliteal vein is the deepest structure in the popliteal fossa [F]
   The peroneal artery provides little or no arterial supply to the foot [T]

Answer 9

The inferior epigastric artery arises from the external iliac artery, just before the latter
passes beneath the inguinal ligament to become the femoral artery. The popliteal artery
is the deepest structure in the popliteal fossa, making it difficult to palpate. The peroneal
(fibular) artery arises from the tibioperoneal trunk, along with the posterior tibial
artery, and supplies the lateral compartment of the leg. The foot is supplied by the
anterior and posterior tibial arteries, the former becoming the dorsalis pedis artery as it
crosses the ankle joint into the foot.

Question 10

10. Regarding the scalp block:
    The infraorbital nerve is targeted [F]
    The transverse cervical nerves are targeted [F]
    The third occipital nerve is targeted [F]
    A scalp block can be the sole technique used for awake craniotomy, without
    sedation or general anaesthesia, as the brain itself is not sensitive to painful
    stimuli [T]
    Intra-arterial injection into the superficial temporal artery is possible when targeting
    the auriculotemporal nerve [T]

Answer 10

The supraorbital (not infraorbital) nerve is targeted (although the infratrochlear nerve
may be affected due to its proximity). The greater and lesser occipital nerves are
targeted, whilst the third occipital usually supplies posterior skin further down the neck.
However, since the greater and third occipital nerves often communicate (being derived
from the dorsal rami of C2 and C3, respectively), the spread of local anaesthetic mayinadvertently block the third occipital nerve. The auriculotemporal nerve travels with
the superficial temporal artery, which can be damaged (or injected) when performing a
scalp block.

Question 11

11. Regarding the lungs and pleura:
    The pulmonary ligament consists of pleura [T]
    The visceral pleura has no sensory innervation [F]
    At the midpoint between full inspiration and expiration, the inferior border of the lung
    lies at the level of the sixth rib in the midclavicular line [T]
    The horizontal fissure of the right lung lies at the level of the fourth costal cartilage
    and runs horizontally backwards to meet the oblique fissure in the midaxillary
    line [T]
    The blunt posterior border of the lung lies in the paravertebral gutter, either side of the
    midline [T]

Answer 11

The pulmonary ligament is a fold/cuff of pleura at the lung root, formed by the
reflection/continuity of the parietal and visceral layers, which provides dead space for
lung root to descend during inspiration and permits expansion of the pulmonary vessels.
The visceral pleura receives nociceptive innervation via sympathetic nerves of the
pulmonary plexus (which enter/leave the lung via the root). The inferior border of the
lung lies behind the 6th rib in the midclavicular line, 8th rib in midaxillary line, 10th rib
in midscapular line (lateral border of erector spinae) and from there passes horizontally
to the lower border of the T10 vertebra. The oblique fissure of both lungs starts
posteriorly at the level of the spinous process of T3, then runs downwards and forwards
to lie behind the 6th rib in the midclavicular line (roughly in line with the 5th rib). The
sharp anterior and inferior borders lie in the costomediastinal and costodiaphragmatic
recesses respectively.

Question 12

12. Regarding Brown–Séquard syndrome:
    It typically results after complete transection of the spinal cord [F]
    It results in an ipsilateral upper motor neurone lesion (spastic paralysis) below the level
    of the injury [T]
    It results in an ipsilateral lower motor neurone lesion (flaccid paralysis) below the level
    of the injury [F]
    It results in ipsilateral loss of vibration sensation and proprioception (dorsal column)
    below the level of the injury [T]
    It results in contralateral loss of pain and temperature sensation (spinothalamic tract)
    below the level of the injury [T]

Answer 12

Brown–Séquard syndrome follows hemisection of the spinal cord, resulting in a lower
motor neurone lesion at the level of the injury (damage to the anterior grey horn).
However, the injury also transects the white matter columns:
Descending fibres of the corticospinal tract (upper motor neurones, which have already
decussated proximally)
Ascending fibres of the spinothalamic tract (second order sensory neurones, which
decussated at the level of entry of the first order sensory neurone in the peripheral
spinal nerve)Ascending fibres of the dorsal column–medial lemniscal pathway (first order neurones,
which are destined to synapse and then decussate more proximally)
This leads to paralysis and loss of vibration/proprioception below the level of the injury on
the same side of the body, but loss of pain/temperature sensation on the opposite side

Question 13

13. The following bones contribute to the pterion:
    Sphenoid (greater wing) [T]
    Frontal [T]
    Temporal (squamous part) [T]
    Parietal [T]
    Occipital [F]

Question 14

14. Regarding the bronchial circulation:
    The bronchial arteries supply the lung parenchyma with oxygenated blood [T]
    The bronchial arteries arise from the corresponding pulmonary artery [F]
    There are two bronchial arteries supplying the right lung [F]
    The bronchial veins return deoxygenated blood directly to the inferior vena cava [F]
    The bronchial and pulmonary circulations allow mixing of oxygenated and
    deoxygenated blood [T]

Answer 14

Two bronchial arteries arise from the descending thoracic aorta to supply the left lung,
the single bronchial artery to the right lung arises from the third right posterior
intercostal artery. The superficial bronchial veins drain the surface of the lung to the
azygos system of veins; the deep bronchial veins drain the deeper tissue to either the
pulmonary veins or directly into the left atrium (and this contributes to the mixing of
oxygenated and deoxygenated blood; known as shunt*).
*N.B. The venae cordis minimae of the heart also contribute to shunt, as some of the venules
also drain directly into the left atrium

Question 15

15. Regarding the blood supply of the upper limb:
    The axillary artery is a continuation of the subclavian artery at the lateral border of
    scalenus anterior [F]
    The cords of the brachial plexus are named according to their relationship to the second
    part of the axillary artery [T]
    The axillary artery gives rise to medial and lateral circumflex humeral arteries [F]
    The ulnar artery gives rise to the common interosseous artery [T]
    The superficial (palmar) branch of the radial artery travels into the hand deep to the
    flexor retinaculum [F]

Answer 15

The subclavian artery becomes the axillary artery at the outer border of first rib. The
second part of the axillary artery lies behind pectoralis minor, surrounded by the cords
of the brachial plexus. The axillary artery gives rise to the anterior/posterior circumflex
humeral arteries (the femoral artery gives rise to medial/lateral circumflex femoral
arteries). The common interosseous artery divides into anterior and posterior interosse-
ous arteries, which travel with anterior (from the median) and posterior (from theradial) nerves respectively. The superficial (palmar) branch of the radial artery lies
superficial to the flexor retinaculum.

Question 16

16. The following is true regarding relations of the orbit:
    The anterior cranial fossa is a superior relation of the orbit [T]
    The ethmoid air sinuses are a medial relation of the orbit [T]
    The sphenoid air sinus is a posterior relation of the orbit [F]
    The maxillary air sinus is a medial relation of the orbit [F]
    The infratemporal fossa and middle cranial fossa are posterolateral relations of the
    orbit [T]

Answer 16

The anterior cranial fossa and frontal lobe lie above the orbit. The ethmoid sinuses and
upper part of the nasal cavity lie between the orbits. The maxillary air sinus lies below
the orbit. The sphenoidal sinus lies between the posterior extent of the orbits.

Question 17

17. Which of the following are boundaries of the paravertebral space?
    The superior costotransverse ligament is a superior boundary [F]
    The visceral pleura of the thorax is an anterolateral boundary [F]
    The psoas muscle is an anterolateral boundary at the lumbar level [T]
    The endothoracic fascia is a medial boundary [F]
    The vertebral body is a medial boundary [T]

Answer 17

The superior costotransverse ligament is a posterior boundary and the parietal pleura is
an anterolateral boundary. The endothoracic fascia is found between the parietal pleura
and the ribs/innermost layer of intercostal muscles.

Question 18

18. Regarding central cord syndrome:
    It is commonly due to a crush injury (without transection) of the spinal cord [T]
    Hyperextension of the cervical spine is a common feature [T]
    The upper limbs are affected more than the lower limbs [T]
    The cervical fibres of the spinothalamic tract are more superficial than the sacral fibres [F]
    The anterior horn of grey matter is not affected [F]

Answer 18

Since the cell bodies of the lower motor neurones to the upper limb muscles are located
more centrally in the anterior grey horn, the upper limbs are preferentially affected in
central cord syndrome.

Question 19

19. Regarding sutures of the cranium:
    They are secondary cartilaginous joints [F]
    They fuse at around 20–40 years of age [T]
    The lambda represents the closed/ossified posterior fontanelle [T]
    The anterior fontanelle closes/ossifies after the posterior fontanelle [T]
    An extradural haematoma crosses lines of sutural intersection [T]

Answer 19

The sutures of the cranium are fibrous joints. The sutures fuse between ages 20 and
40 years, from the inside to out. Initially, the sutural joints provide mobility required
during parturition and then growth of the brain. The lambda represents the closed/
ossified posterior fontanelle – the point of intersection between the sagittal (between
parietal bones) and lambdoid (between parietal and occipital bones) sutures. Closure
occurs in the first year and can be as early as 6–8 weeks. The larger anterior
fontanelle closes at around 12–18 months to form the bregma – the point ofintersection between the coronal and sagittal sutures. An extradural haematoma can
cross lines of sutural intersection since it develops between the dura mater and the
endocranium* (periosteum of bone on the inner surface of the cranium). In com-
parison, a fracture-haematoma is limited by periosteal boundaries as the periosteum
of bone on inner and outer surfaces of the cranium is fused with the sutural joint.
This type of haematoma is therefore limited by sutural joints to the margins of the
involved bone.

Question 20

20. The following is true in relation to the right lung root:
    The right upper lobe bronchus and accompanying artery are found above the main
    bronchus [T]
    The pulmonary arteries lie anterior to their respective bronchi [T]
    Four pulmonary veins drain the lung [F]
    Branches of the phrenic nerve supply the lung parenchyma [F]
    Pulmonary lymphatics drain the lung via this route [T]

Answer 20

The eparterial bronchus (to the right upper lobe) branches off before the right main
bronchus reaches the hilum of the lung. Each lung drains by two pulmonary veins to the
left atrium. The lung parenchyma receives an autonomic supply; the parietal pleura
receives a somatic innervation from the intercostal (T1–6), thoracoabdominal (T7–11),
subcostal and phrenic nerves. Branches of the pulmonary plexus (autonomic) pass
through the hilum of the lung to innervate the lung parenchyma.

Question 21

21. Regarding the brachial plexus:
    It comprises five roots, three trunks, five divisions and three cords [F]
    The branching pattern of the brachial plexus often varies between the right and left
    sides in the same individual [T]
    The sheath surrounding the brachial plexus is at its smallest volume in the
    supraclavicular fossa [T]
    The roots lie anterior to the anterior scalene muscle [F]
    It provides motor innervation to the serratus anterior muscle [T]

Answer 21

Each trunk of the brachial plexus gives anterior and posterior divisions (i.e. six in total).
The roots emerge between scalenus anterior (in front) and medius (behind). (N.B. The
posterior scalene muscle is part of the middle scalene, which continues down to attach to
the second rib.) The long thoracic nerve (C5/6/7), arising from the roots of the brachial
plexus, provides the motor innervation to serratus anterior (and therefore brachial
plexus injury can lead to winging of the scapula).

Question 22

22. The following bones contribute to the orbital margin/rim:
    Frontal [T]
    Zygomatic [T]
    Maxilla [T]
    Nasal [F]
    Ethmoid [F]

Answer 22

The frontal, zygomatic bone and maxilla contribute approximately one-third each to the
orbital rim. The ethmoid contributes to the medial wall of the orbit, the nasal bone to
the bridge of the nose

Question 23

23. Concerning the oesophageal sphincters:
    Atropine reduces lower oesophageal sphincter pressure [T]
    The lower oesophageal sphincter is in a state of tonic contraction [T]
    The upper oesophagus consists of skeletal muscle, but is not under voluntary
    control [T]
    Upper oesophageal sphincter tone is reduced by all intravenous anaesthetic induction
    agents [F]
    Upper oesophageal sphincter tone is reduced by both non-depolarising and
    depolarising neuromuscular blocking drugs [T]

Answer 23

Upper oesophageal sphincter tone is not reduced by ketamine

Question 24

24. Regarding anterior spinal artery syndrome:
    Proprioception is preserved below the level of the lesion [T]
    Voluntary motor function is lost below the level of the lesion [T]
    An upper motor neurone lesion (spastic paralysis) will develop below the level of the
    lesion [T]
    Pain and temperature sensation is preserved below the level of the lesion [F]
    The lateral spinothalamic tract is typically affected [T]

Answer 24

Anterior spinal artery syndrome causes ischaemia/infarction of the anterior two-thirds
of the cord (and medulla), affecting the spinothalamic (pain/temperature) corticospinal
(motor) tracts. A lower motor neurone lesion is seen at the level of the lesion and an
upper motor neurone lesion below. Vibration sense and proprioception is conveyed in
the dorsal column-medial lemniscal pathway, which is preserved.

Question 25

25. The carotid sheath:
    Contains the external carotid artery [F]
    Contains the internal jugular vein [T]
    Contains the recurrent laryngeal nerve [F]
    Contains the ansa cervicalis within its anterior wall [T]
    Lies anterior to the phrenic nerve [T]

Answer 25

The carotid sheath contains the common carotid artery inferiorly and the internal
carotid artery superiorly (after it bifurcates at the level of C4/upper border of the thyroid
cartilage). The external carotid artery leaves the sheath to supply structures of the face
and facial skeleton. The sheath also contains CN 10 (but not its recurrent laryngeal
branch, which runs in the tracheo-oesophageal groove).
N.B. A note on the carotid sheath – unlike the investing fascia of the neck, the carotid sheath is
not a separate entity/distinct fascial layer per se:
Anterior wall is a thickening of posterior layer of deep investing fascia of the neck
Medial wall is a thickening of the lateral wall of the pretracheal fascia
Posterior wall is a thickening of the anterior wall of the prevertebral fascia

Question 26

26. Regarding the coronary circulation:
    There are no anastomoses between the regions of arterial supply in the heart [F]
    80–90% of coronary venous circulation is returned to the right atrium via the coronary
    sinus [T]
    Blood supply to the right ventricle ceases during systole [F]
    The myocardium typically extracts approximately 50% of oxygen from arterial blood [T]
    The right ventricle is mainly supplied by the right coronary artery, originating from the
    proximal pulmonary trunk [F]

Answer 26

Anastomoses exist at the arteriolar level, ‘potential anastomoses’, which can develop a
collateral circulation in chronic ischaemic heart disease (but are unable to prevent
ischaemia in the event of an acute atheromatous plaque rupture during myocardial
infarction). Arterial blood to the left ventricle ceases during systole, but the right
(lower pressure) ventricle is supplied by arterial blood (at higher/systemic pressure)
throughout the cardiac cycle. The right coronary artery arises from the proximal
ascending aorta

Question 27

27. Regarding the brachial plexus:
    The divisions lie in the infraclavicular fossa [F]
    The trunks lie anterior to the subclavian artery [F]
    The three cords are described in relation to the subclavian artery [F]
    Pectoralis major lies anterior to the cords [T]
    The supraclavicular nerve typically branches from the upper trunk [T]

Answer 27

The divisions lie behind (or slightly above) the clavicle and the trunks lie posterior to the
subclavian artery*. The three cords are described/named in relation to the second part of
the axillary artery (the continuation of the subclavian artery at the outer border of the
first rib).
*Remember the heart lies anterior to the spinal cord, hence the nerves originate from a more
posterior position than the vessels

Question 28

27. Regarding the brachial plexus:
    The divisions lie in the infraclavicular fossa [F]
    The trunks lie anterior to the subclavian artery [F]
    The three cords are described in relation to the subclavian artery [F]
    Pectoralis major lies anterior to the cords [T]
    The supraclavicular nerve typically branches from the upper trunk [T]

Answer 28

The divisions lie behind (or slightly above) the clavicle and the trunks lie posterior to the
subclavian artery*. The three cords are described/named in relation to the second part of
the axillary artery (the continuation of the subclavian artery at the outer border of the
first rib).
*Remember the heart lies anterior to the spinal cord, hence the nerves originate from a more
posterior position than the vessels

Question 29

28. CN 3 (the oculomotor nerve) supplies the following muscles of the orbit/eye:
    Lateral rectus [F]
    Superior oblique [F]
    Levator palpebrae superioris [T]
    Medial rectus [T]
    Dilator muscle of the iris [F]

Answer 29

A helpful aide-memoire for the nerve supply of muscles in the orbit is the ‘formula’
LR6SO4*. The lateral rectus is supplied by CN 6, superior oblique by CN 4, and all others
by CN 3. The superior division of CN 3 supplies superior rectus and levator palpebrae
superioris (which also has sympathetic innervation). The inferior division of CN 3 sup-
plies medial rectus, inferior rectus and inferior oblique. The constrictor muscle of the
iris is innervated by parasympathetic fibres of CN 3; the dilator muscle is supplied by
the long ciliary nerves, carrying sympathetic fibres that have hitch-hiked along the
nasociliary nerve (CN 5.1).

Question 30

29. Regarding oesophageal pathology:
    Boerhaave’s syndrome refers to oesophageal rupture secondary to iatrogenic injury [F]
    Nasogastric tube placement is contraindicated in the presence of oesophageal
    varices [F]
    Achalasia refers to failure of the lower oesophageal sphincter to relax [T]
    Adenocarcinoma of the oesophagus occurs mainly in the distal

Answer 30

Boerhaave’s syndrome refers to oesophageal rupture associated with vomiting. Concern
over variceal bleeding provoked by blind nasogastric tube placement in patients with
known varices originated from expert opinion, but this has not been substantiated by
published evidence to date. Equally, rebleeding frequency and transfusion rate has not
been shown to be different with or without nasogastric tube insertion following rup-
tured oesophageal varices. There are clear benefits to the use of nasogastric tubes in
critically unwell patients, and these must be weighed against the perceived risk of
precipitating bleeding by insertion

Question 31

30. The following is true with regard to adult and paediatric neuroaxial blockade:
    The spinal cord ends at L1/2 in adults, but lower in children [T]
    The dura ends at S2 in adults, but higher in children [F]
    The subarachnoid space extends into the sacral canal [T]
    The male sacrum displays a greater curvature than the female sacrum [T]
    The sacrum articulates with four bones [T]

Answer 31

In children, the spinal cord ends at L3 and the dura at S4 (but reaches the adult level of
S2 by the age of 2 years). Since the dural sac extends to S2, the subarachnoid space also
extends to S2 and can therefore be entered via the sacral canal. Sex differences of the
sacrum are pronounced, with the shape of the female sacrum adapted for parturition
(shorter, wider and less curved). The sacrum articulates with the L5 vertebra, the coccyx
and the ilium on either side.

Question 32

31. The following is true of the muscular branches of the cervical plexus (aka deep
    cervical plexus):
    The phrenic nerve (C3/4/5) is not a branch of the cervical plexus [F]
    The parietal pleura receives sensory innervation from a muscular branch of the cervical
    plexus [T]
    The ansa cervicalis (C1–3) forms part of this plexus [T]
    Branches from C2/3 and C3/4 transmit proprioceptive sensation from
    sternocleidomastoid and trapezius [T]
    The cervical plexus does not innervate any structures inside the cranial cavity [F]

Answer 32

The phrenic nerve is a branch of the deep cervical plexus and provides the sole motor
supply of the diaphragm. It also provides sensory innervation to the central diaphragm,
mediastinal and (central part of the) diaphragmatic parietal pleura, fibrous/parietal
pericardium and (central part of the) diaphragmatic parietal peritoneum. Meningealbranches (C1–3) provide sensory supply to the dura and arachnoid mater in posterior
cranial fossa.
N.B. Ansa cervicalis
Superior root (C1): formed from hitch-hiking fibres of C1 that peel off from CN 12 (distal to
the branches to geniohyoid and thyrohyoid); after leaving CN 12, the superior root travels
down in the anterior wall of the carotid sheath to meet the inferior root
Inferior root (C2/3): forms behind the IJV, travels down in the carotid sheath and courses
around the lateral side of the IJV to meet the superior root
Supplies three of the four strap muscles: sternothyroid, sternohyoid and omohyoid
(thyrohyoid is supplied from the hitch-hiking fibres of C1 travelling with CN 12)

Question 33

32. Regarding the diaphragm:
    The central part is derived from the pleuroperitoneal membranes [F]
    The central tendon is derived from the septum transversum [T]
    It arises in part from the lateral arcuate ligament [T]
    The sympathetic chain enters the abdomen behind the medial arcuate ligament [T]
    The median arcuate ligament forms the aortic hiatus [T]

Answer 33

The peripheral part of the diaphragm is largely derived from the pleuroperitoneal
membranes (with a contribution from the body wall); the central part is largely from
the septum transversum, a fibrous division that lies between the heart and abdominal
structures during development (with a contribution from the dorsal oesophageal
mesentery).
See OSCE Station 8 (Diaphragm) figure for information on other structures passing through/
behind the diaphragm
N.B. The arcuate ligaments:
Median: formed by fibres from the medial parts of the right and left crura of the diaphragm
Medial: a thickening of psoas fascia over the psoas muscle, running from the body of T2
(left) or T3 (right) to the transverse process of T1
Lateral: a thickening of psoas fascia over the

Question 34

33. Regarding the axillary brachial plexus block:
    It reliably blocks the intercostobrachial nerve [F]
    Motor innervation to biceps brachii is via the musculocutaneous nerve [T]
    The axillary artery typically lies posterior to the conjoint tendon of teres major and
    latissimus dorsi [F]
    The musculocutaneous nerve appears as a hypoechoic structure, due to the lack of
    connective tissue [F]
    The axillary nerve is normally blocked [F]

Answer 34

The intercostobrachial nerve is the lateral cutaneous branch of the second intercostal
nerve (T2). Although it innervates a variable area of skin of the axilla and proximal
(medial) arm, it is not part of the brachial plexus and is not covered by a brachial plexusblock. The axillary artery lies anterior to the conjoint tendon (which forms the posterior
wall of the axilla)