Lumbar puncture is needed in a 10-day-old neonate with fever, poor feeding and a bulging fontanelle. The paediatric resident, used to adults, plans to use the L2-L3 space. Her consultant asks her to use the L4-L5 space instead. What is the anatomical reason?

The conus medullaris lies at about L3 at birth

The interspinous spaces above L4 are fused

The epidural space is absent above L4

The dural sac ends at L2 at birth

In the casualty, an intercostal drain is being placed in the fifth intercostal space just anterior to the mid-axillary line for a traumatic haemothorax. The intern is told to make a blunt track with forceps passing just over the upper border of the sixth rib. Why must the track hug the upper border of the lower rib?

The neurovascular bundle runs along the lower border of each rib

The long thoracic nerve lies along each upper border

The pleura is thinnest just above each rib

The internal thoracic artery runs below each rib

Fifteen minutes after an interscalene brachial plexus block for shoulder arthroscopy, a man with COPD becomes breathless. SpO2 falls from 95% to 89% on room air, and bedside ultrasound shows paradoxical movement of the right hemidiaphragm with normal lung sliding. Which nerve has been blocked, and why is this so common with this block?

Phrenic nerve, lying on scalenus anterior

Recurrent laryngeal nerve, in the tracheo-oesophageal groove

Vagus nerve, in the carotid sheath

Long thoracic nerve, behind the plexus

On the second day after a left subclavian central venous line was placed in the ICU, which needed three passes of the needle, a patient on enteral feeds becomes increasingly breathless. He had been admitted with severe pneumonia and needed noradrenaline through that line for 24 hours. Chest X-ray shows a large left pleural effusion but no pneumothorax. Aspiration yields milky, odourless fluid with a triglyceride level of 320 mg/dL that does not clear on centrifugation, and chylomicrons are present. Which structure was most likely injured, and where does it normally end?

Thoracic duct, at the left venous angle

Left brachiocephalic vein, behind the manubrium

Cisterna chyli, at the aortic hiatus

Right lymphatic duct, at the right venous angle

Applied anatomy of procedures and nerve blocks

22 NEET-PG practice questions on Applied anatomy of procedures and nerve blocks, part of Anatomy. The first 22 are below; the first 5 with answers and explanations (tap Show answer after you have chosen), the rest in Learn with a free account.

Question 1 · Hard
Lumbar puncture is needed in a 10-day-old neonate with fever, poor feeding and a bulging fontanelle. The paediatric resident, used to adults, plans to use the L2-L3 space. Her consultant asks her to use the L4-L5 space instead. What is the anatomical reason?
1. AThe interspinous spaces above L4 are fused
2. BThe conus medullaris lies at about L3 at birth
3. CThe epidural space is absent above L4
4. DThe dural sac ends at L2 at birth
Show answerHide answer
Answer: B · The conus medullaris lies at about L3 at birth
The vertebral column grows faster than the spinal cord, so the conus medullaris, at the level of the coccyx in early fetal life, lies at about L3 at birth and reaches its adult level of L1-L2 by about two years. In the newborn an L2-L3 puncture could hit the cord, so L4-L5 or L5-S1 is used. The dural sac ends lower in infants, at about S3, than in adults. Key point: In neonates the conus lies at about L3, so LP is done at L4-L5 or L5-S1.
- A: The interspinous spaces are open and wide in infants.
- C: The epidural space is present at every level.
- D: The dural sac ends lower, near S3, in infants, not at L2.
Question 2 · Easy
In the casualty, an intercostal drain is being placed in the fifth intercostal space just anterior to the mid-axillary line for a traumatic haemothorax. The intern is told to make a blunt track with forceps passing just over the upper border of the sixth rib. Why must the track hug the upper border of the lower rib?
1. AThe long thoracic nerve lies along each upper border
2. BThe pleura is thinnest just above each rib
3. CThe neurovascular bundle runs along the lower border of each rib
4. DThe internal thoracic artery runs below each rib
Show answerHide answer
Answer: C · The neurovascular bundle runs along the lower border of each rib
The intercostal vein, artery and nerve (VAN, from above down) run in the costal groove on the lower border of each rib, between the internal and innermost intercostal muscles. Passing over the upper border of the rib below avoids them. The safe triangle (pectoralis major in front, latissimus dorsi behind, the fifth space below the axilla) also avoids the long thoracic nerve and the breast. Key point: Chest drains pass over the upper border of the rib to spare the bundle in the costal groove.
- A: The long thoracic nerve runs vertically on serratus anterior, not along the ribs.
- B: Pleural thickness does not vary along the space.
- D: The internal thoracic artery runs vertically about 1 cm lateral to the sternum, far from the mid-axillary line.
Question 3 · Medium
Fifteen minutes after an interscalene brachial plexus block for shoulder arthroscopy, a man with COPD becomes breathless. SpO2 falls from 95% to 89% on room air, and bedside ultrasound shows paradoxical movement of the right hemidiaphragm with normal lung sliding. Which nerve has been blocked, and why is this so common with this block?
1. ARecurrent laryngeal nerve, in the tracheo-oesophageal groove
2. BVagus nerve, in the carotid sheath
3. CLong thoracic nerve, behind the plexus
4. DPhrenic nerve, lying on scalenus anterior
Show answerHide answer
Answer: D · Phrenic nerve, lying on scalenus anterior
The phrenic nerve (C3-C5) runs down on the front of scalenus anterior, just anterior to the interscalene groove where the local anaesthetic is injected. It is blocked in almost every interscalene block, giving ipsilateral hemidiaphragmatic paresis, which healthy people tolerate but patients with poor lung reserve may not. Lung sliding rules out pneumothorax. Key point: Interscalene block nearly always blocks the phrenic nerve on scalenus anterior.
- A: Recurrent laryngeal block causes hoarseness, not diaphragm paresis.
- B: Vagal block does not paralyse the diaphragm.
- C: The long thoracic nerve supplies serratus anterior and does not affect breathing this way.
Question 4 · Medium
A stellate ganglion block is given at the level of the C6 transverse process (Chassaignac's tubercle) for complex regional pain syndrome of the left arm. Within minutes, which sign confirms that the sympathetic chain has been blocked?
1. AWeakness of shoulder abduction
2. BIpsilateral ptosis and miosis
3. CHoarseness of voice
4. DContralateral facial flushing
Show answerHide answer
Answer: B · Ipsilateral ptosis and miosis
The stellate ganglion (fused inferior cervical and first thoracic ganglia) carries the sympathetic supply to the head, neck and upper limb. A successful block produces an ipsilateral Horner syndrome (ptosis, miosis, enophthalmos, anhidrosis) with a warm, dry, flushed arm. Hoarseness means spread to the recurrent laryngeal nerve, a side effect. Key point: A successful stellate ganglion block gives ipsilateral Horner syndrome and a warm arm.
- A: Shoulder weakness means spread to the brachial plexus roots.
- C: Hoarseness signals spread to the recurrent laryngeal nerve, not success.
- D: Flushing occurs on the same side, not the opposite side.
Question 5 · Hard
On the second day after a left subclavian central venous line was placed in the ICU, which needed three passes of the needle, a patient on enteral feeds becomes increasingly breathless. He had been admitted with severe pneumonia and needed noradrenaline through that line for 24 hours. Chest X-ray shows a large left pleural effusion but no pneumothorax. Aspiration yields milky, odourless fluid with a triglyceride level of 320 mg/dL that does not clear on centrifugation, and chylomicrons are present. Which structure was most likely injured, and where does it normally end?
1. ALeft brachiocephalic vein, behind the manubrium
2. BCisterna chyli, at the aortic hiatus
3. CRight lymphatic duct, at the right venous angle
4. DThoracic duct, at the left venous angle
Show answerHide answer
Answer: D · Thoracic duct, at the left venous angle
Milky fluid with triglycerides above 110 mg/dL and chylomicrons is chyle. The thoracic duct ascends through the posterior mediastinum, crosses to the left at about T5, arches over the left pleural dome and ends at the junction of the left subclavian and left internal jugular veins (the left venous angle). Repeated left subclavian or internal jugular punctures can tear it, causing a left chylothorax. Key point: Chylothorax after a left subclavian or jugular line means thoracic duct injury at the left venous angle.
- A: Injury to the brachiocephalic vein causes haemothorax, not chyle.
- B: The cisterna chyli lies in the abdomen at L1-L2, far from the needle.
- C: The right lymphatic duct ends on the right and would not cause a left chylothorax.
Question 6 · Easy
Lumbar puncture in the midline at L3-L4: which structures does the needle pass through before reaching CSF? 1. Supraspinous ligament. 2. Posterior longitudinal ligament. 3. Ligamentum flavum. 4. Dura and arachnoid mater.
1. A2, 3 and 4 only
2. B1, 3 and 4 only
3. C1, 2, 3 and 4
4. D1 and 3 only
Answer and explanation in LearnFree account
Question 7 · Easy
In a 'cannot intubate, cannot oxygenate' emergency, the scalpel for front-of-neck access is passed through which membrane?
1. AThyrohyoid membrane
2. BQuadrangular membrane
3. CCricothyroid membrane
4. DCricotracheal ligament
Answer and explanation in LearnFree account
Question 8 · Medium
Echocardiography in a man with tuberculous pericarditis, three weeks into anti-tubercular treatment and admitted with breathlessness and muffled heart sounds, shows a large effusion with diastolic collapse of the right atrium and right ventricle. BP is 80/60 mmHg with a pulsus paradoxus of 22 mmHg and raised JVP. Pericardiocentesis is done from the angle between the xiphoid process and the left costal margin, with the needle aimed towards the left shoulder at 30 degrees to the skin. If the needle is pushed too far, which structure is most likely to be punctured?
1. ALeft lobe of the liver
2. BRight atrium
3. CLeft ventricle
4. DRight ventricle
Answer and explanation in LearnFree account
Question 9 · Easy
At a routine immunisation session, into which muscle should a 6-week-old infant receive the intramuscular pentavalent vaccine?
1. AVastus lateralis
2. BDeltoid
3. CRectus femoris
4. DGluteus maximus
Answer and explanation in LearnFree account
Question 10 · Medium
In a shocked patient with collapsed neck veins after a road accident, the casualty doctor decides to place a femoral venous line. He feels the femoral pulse 2 cm below the mid-inguinal point, midway between the anterior superior iliac spine and the pubic symphysis. Where should he insert the needle?
1. AAbout 1 cm medial to the pulse
2. BAbout 1 cm lateral to the pulse
3. CAbove the inguinal ligament, over the pulse
4. DDirectly over the pulse
Answer and explanation in LearnFree account
Question 11 · Medium
Ultrasound is not available, so an ICU resident cannulates the right internal jugular vein by landmarks, inserting the needle at the apex of the triangle formed by the two heads of sternocleidomastoid and aiming towards the ipsilateral nipple. Bright red, pulsatile blood fills the syringe and the patient's neck begins to swell. Which vessel has most likely been punctured, and where does it lie relative to the vein?
1. AVertebral artery, posterior to the vein
2. BExternal carotid artery, anterior to the vein
3. CCommon carotid artery, medial to the vein
4. DSubclavian artery, lateral to the vein
Answer and explanation in LearnFree account
Question 12 · Medium
Before a hernia repair in a 3-year-old boy, the anaesthetist palpates two bony prominences at the upper end of the natal cleft and inserts a short needle between them, through a membrane, into the sacral canal for a caudal block. Which opening is she using, and why is it present?
1. ASacral hiatus; the S5 laminae fail to fuse
2. BCoccygeal cornua; the coccyx fails to fuse
3. CSacral promontory; the S1 body projects forward
4. DPosterior sacral foramina; the S2 rami exit there
Answer and explanation in LearnFree account
Question 13 · Easy
A health worker at a PHC is taught to give intramuscular injections into the deltoid no lower than about two to three finger-breadths below the acromion. Which nerve, winding round the surgical neck of the humerus beneath the muscle, is she protecting?
1. ARadial nerve
2. BAxillary nerve
3. CSuprascapular nerve
4. DMedial cutaneous nerve of arm
Answer and explanation in LearnFree account
Question 14 · Hard
In the casualty, a child of 6 years with a severe facial burn and rapidly worsening stridor cannot be intubated, and bag-mask ventilation is failing (SpO2 78% and falling). The resident picks up a scalpel to perform a surgical cricothyrotomy, as he has seen done in adults. The consultant stops him and asks for a different technique. There is no time to move the child to the operation theatre, and the ENT surgeon is 40 minutes away. What is the recommended emergency airway for this child, and what is the anatomical reason?
1. ANasotracheal intubation; the cords lie higher in children
2. BSurgical cricothyrotomy; the membrane is relatively larger in children
3. CNeedle cricothyrotomy; the cricoid is the key support of a small airway
4. DEmergency tracheostomy through the thyroid isthmus
Answer and explanation in LearnFree account
Question 15 · Medium
In the dental OPD, an inferior alveolar nerve block is given for a lower molar extraction. A few minutes later the patient cannot close his eye on that side, the corner of his mouth droops and he cannot wrinkle that half of his forehead. The dentist reassures him that it will wear off in a few hours. Where did the anaesthetic most likely go?
1. AInto the submandibular gland
2. BInto the parotid gland behind the ramus
3. CInto the medial pterygoid muscle
4. DInto the pterygomandibular space
Answer and explanation in LearnFree account
Question 16 · Medium
For excision of a sebaceous cyst in the skin of the first web space on the dorsum of the foot, an ankle block is planned. Which nerve must be included, found beside the dorsalis pedis artery?
1. ASaphenous nerve
2. BSuperficial peroneal nerve
3. CMedial plantar nerve
4. DDeep peroneal nerve
Answer and explanation in LearnFree account
Question 17 · Medium
During an elective tracheostomy in the ICU for prolonged ventilation, the surgeon divides the pretracheal fascia and retracts the isthmus of the thyroid upwards before opening the trachea. Over which tracheal rings does the isthmus usually lie, and which structure must be watched for in the midline below it?
1. A1st ring only; superior thyroid artery
2. B2nd to 4th rings; inferior thyroid veins
3. C5th to 7th rings; brachiocephalic artery
4. DCricoid cartilage; cricothyroid artery
Answer and explanation in LearnFree account
Question 18 · Hard
During transurethral resection of a tumour on the left lateral wall of the bladder under spinal anaesthesia with a sensory block to T10, the patient's left thigh suddenly jerks inwards each time the diathermy loop is activated, and the urologist worries about perforating the bladder wall. The anaesthetist notes that the spinal block itself is working well. Which nerve is being stimulated, and what is the remedy?
1. AObturator nerve; add an obturator nerve block
2. BPudendal nerve; give a pudendal block
3. CGenitofemoral nerve; general anaesthesia without relaxant
4. DFemoral nerve; deepen the spinal block
Answer and explanation in LearnFree account
Question 19 · Hard
Ten minutes after a fall from scaffolding at a construction site, a heavily built mason is brought to the district hospital with severe right-sided chest pain and air hunger. His respiratory rate is 38/min and SpO2 82% on 15 L/min oxygen by a non-rebreather mask. The right chest is hyper-resonant with no breath sounds, the trachea is pushed to the left, the neck veins are distended and BP is 72/40 mmHg. A chest drain tray is being opened, but the team decides to relieve the pressure at once with a large-bore cannula. According to ATLS (10th edition), where should needle decompression be done in this adult?
1. ASubxiphoid, aiming at the left shoulder
2. B2nd intercostal space, mid-clavicular line
3. C4th or 5th space, just anterior to mid-axillary line
4. D6th intercostal space, posterior axillary line
Answer and explanation in LearnFree account
Question 20 · Medium
For an elderly woman with a fractured neck of femur in the casualty, a femoral nerve block is planned before X-ray to ease her pain. Under ultrasound at the inguinal crease, the femoral artery and vein are seen in their sheath. Where will the femoral nerve be found?
1. ABetween the artery and vein, in the sheath
2. BLateral to the artery, superficial to fascia lata
3. CMedial to the vein, inside the femoral canal
4. DLateral to the artery, deep to the fascia iliaca
Answer and explanation in LearnFree account
Question 21 · Medium
In the labour room, a lumbar epidural catheter is being threaded for labour analgesia when blood flows back freely along it, though no CSF is aspirated. The catheter is withdrawn and resited one space higher. Which structure in the epidural space was most likely entered?
1. ABasivertebral vein in the vertebral body
2. BInternal vertebral venous plexus
3. CRadicular artery
4. DAnterior spinal artery
Answer and explanation in LearnFree account
Question 22 · Medium
After an axillary brachial plexus block for surgery on the forearm, the patient feels the incision along the lateral side of the forearm, while the rest of the forearm and the hand are numb. Which nerve has escaped the block, and why?
1. AAxillary nerve, leaving through the quadrangular space
2. BMedial cutaneous nerve of forearm, outside the sheath
3. CMusculocutaneous nerve, leaving the sheath high in coracobrachialis
4. DRadial nerve, lying behind the axillary artery
Answer and explanation in LearnFree account

Applied anatomy of procedures and nerve blocks

Lumbar puncture is needed in a 10-day-old neonate with fever, poor feeding and a bulging fontanelle. The paediatric resident, used to adults, plans to use the L2-L3 space. Her consultant asks her to use the L4-L5 space instead. What is the anatomical reason?

A stellate ganglion block is given at the level of the C6 transverse process (Chassaignac's tubercle) for complex regional pain syndrome of the left arm. Within minutes, which sign confirms that the sympathetic chain has been blocked?

Lumbar puncture in the midline at L3-L4: which structures does the needle pass through before reaching CSF? 1. Supraspinous ligament. 2. Posterior longitudinal ligament. 3. Ligamentum flavum. 4. Dura and arachnoid mater.

In a 'cannot intubate, cannot oxygenate' emergency, the scalpel for front-of-neck access is passed through which membrane?

At a routine immunisation session, into which muscle should a 6-week-old infant receive the intramuscular pentavalent vaccine?

Before a hernia repair in a 3-year-old boy, the anaesthetist palpates two bony prominences at the upper end of the natal cleft and inserts a short needle between them, through a membrane, into the sacral canal for a caudal block. Which opening is she using, and why is it present?

A health worker at a PHC is taught to give intramuscular injections into the deltoid no lower than about two to three finger-breadths below the acromion. Which nerve, winding round the surgical neck of the humerus beneath the muscle, is she protecting?

For excision of a sebaceous cyst in the skin of the first web space on the dorsum of the foot, an ankle block is planned. Which nerve must be included, found beside the dorsalis pedis artery?

For an elderly woman with a fractured neck of femur in the casualty, a femoral nerve block is planned before X-ray to ease her pain. Under ultrasound at the inguinal crease, the femoral artery and vein are seen in their sheath. Where will the femoral nerve be found?

In the labour room, a lumbar epidural catheter is being threaded for labour analgesia when blood flows back freely along it, though no CSF is aspirated. The catheter is withdrawn and resited one space higher. Which structure in the epidural space was most likely entered?

After an axillary brachial plexus block for surgery on the forearm, the patient feels the incision along the lateral side of the forearm, while the rest of the forearm and the hand are numb. Which nerve has escaped the block, and why?