Lower Limb III Flashcards
A 20 year old lady presents with pain on the medial aspect of her thigh. Investigations show a large ovarian cyst. Compression of which of the nerves listed below is the most likely underlying cause?
A. Sciatic B. Genitofemoral C. Obturator D. Ilioinguinal E. Femoral cutaneous
Obturator
The cutaneous branch of the obturator nerve is frequently absent. However, the obturator nerve is a recognised contributor to innervation of the medial thigh and large pelvic tumours may compress this nerve with resultant pain radiating distally.
A 22 year old man suffers a compound fracture of the tibia. During attempted surgical repair the deep peroneal nerve is divided. Which of the following muscles will not be affected as a result?
A. Tibialis anterior B. Peroneus longus C. Extensor hallucis longus D. Extensor digitorum longus E. Peroneus tertius
Peroneus longus
Deep peroneal nerve
Origin From the common peroneal nerve, at the lateral aspect of the fibula, deep to peroneus longus
Nerve root values L4, L5, S1, S2
Course and relation
Pierces the anterior intermuscular septum to enter the anterior compartment of the lower leg
Passes anteriorly down to the ankle joint, midway between the two malleoli
Terminates In the dorsum of the foot
Muscles innervated
Tibialis anterior
Extensor hallucis longus
Extensor digitorum longus
Peroneus tertius
Extensor digitorum brevis
Cutaneous innervation Web space of the first and second toes
Actions
Dorsiflexion of ankle joint
Extension of all toes (extensor hallucis longus and extensor digitorum longus)
Eversion of the foot
After its bifurcation past the ankle joint, the lateral branch of the deep peroneal nerve innervates the extensor digitorum brevis and the extensor hallucis brevis
The medial branch supplies the web space between the first and second digits.
A 67 year old man is undergoing a transurethral resection of a bladder tumour using diathermy. Suddenly during the procedure the patients leg begins to twitch. Stimulation of which of the following nerves is the most likely cause?
A. Femoral B. Pudendal C. Sciatic D. Obturator E. Gluteal
The obturator nerve arises from L2, L3 and L4 by branches from the ventral divisions of each of these nerve roots. L3 forms the main contribution and the second lumbar branch is occasionally absent. These branches unite in the substance of psoas major, descending vertically in its posterior part to emerge from its medial border at the lateral margin of the sacrum. It then crosses the sacroiliac joint to enter the lesser pelvis, it descends on obturator internus to enter the obturator groove. In the lesser pelvis the nerve lies lateral to the internal iliac vessels and ureter, and is joined by the obturator vessels lateral to the ovary or ductus deferens.
Supplies
Medial compartment of thigh
Muscles supplied: external obturator, adductor longus, adductor brevis, adductor magnus (not the lower part-sciatic nerve), gracilis
The cutaneous branch is often absent. When present, it passes between gracilis and adductor longus near the middle part of the thigh, and supplies the skin and fascia of the distal two thirds of the medial aspect.
Obturator canal
Connects the pelvis and thigh: contains the obturator artery, vein, nerve which divides into anterior and posterior branches.
A 34 year old man is shot in the postero- inferior aspect of his thigh. Which of the following lies at the most lateral aspect of the popliteal fossa?
A. Popliteal artery B. Popliteal vein C. Common peroneal nerve D. Tibial nerve E. Small saphenous vein
Common peroneal nerve The contents of the popliteal fossa are (from medial to lateral): Popliteal artery Popliteal vein Tibial nerve Common peroneal nerve
The sural nerve is a branch of the tibial nerve and usually arises at the inferior aspect of the popliteal fossa. However, its anatomy is variable.
A 76 year old man complains of symptoms of claudication. The decision is made to measure his ankle brachial pressure index. The signal from the dorsalis pedis artery is auscultated with a hand held doppler device. This vessel is the continuation of which of the following?
A. Posterior tibial artery B. Anterior tibial artery C. Peroneal artery D. Popliteal artery E. None of the above
anterior tibial
The dorsalis pedis is a continuation of the anterior tibial artery.
A 67 year old man is due to undergo a revisional total hip replacement using a posterior approach. After dividing gluteus maximus in the line of its fibres there is brisk arterial bleeding. Which of the following vessels is likely to be responsible?
A. Profunda femoris artery B. External iliac artery C. Internal iliac artery D. Obturator artery E. Inferior gluteal artery
The inferior gluteal artery runs on the deep surface of the gluteus maximus muscle. It is a branch of the internal iliac artery. It is commonly divided during the posterior approach to the hip joint.
Which of the following nerves is responsible for the cremasteric reflex?
A. Lateral femoral cutaneous nerve B. Femoral nerve C. Obturator nerve D. Genitofemoral nerve E. None of the above
genitofemoral
The motor and sensory fibres of the genitofemoral nerve are tested in the cremasteric reflex. A small contribution is also played by the ilioinguinal nerve and thus the reflex may be lost following an inguinal hernia repair.
A 65 year old man with long standing atrial fibrillation develops an embolus to the lower leg. The decision is made to perform an embolectomy, utilising a trans popliteal approach. After incising the deep fascia, which of the following structures will the surgeons encounter first on exploring the central region of the popliteal fossa?
A. Popliteal vein B. Common peroneal nerve C. Popliteal artery D. Tibial nerve E. None of the above
Tibial nerve
The tibial nerve lies superior to the vessels in the inferior aspect of the popliteal fossa. In the upper part of the fossa the tibial nerve lies lateral to the vessels, it then passes superficial to them to lie medially. The popliteal artery is the deepest structure in the popliteal fossa.
A 43 year old lady presents with varicose veins and undergoes a saphenofemoral disconnection, long saphenous vein stripping to the ankle and isolated hook phlebectomies. Post operatively she notices an area of numbness superior to her ankle. What is the most likely cause for this?
A. Sural nerve injury B. Femoral nerve injury C. Saphenous nerve injury D. Common peroneal nerve injury E. Superficial peroneal nerve injury
Saphenous nerve injury
The sural nerve is related to the short saphenous vein. The saphenous nerve is related to the long saphenous vein below the knee and for this reason full length stripping of the vein is no longer advocated.
A 23 year old man is undergoing an inguinal hernia repair. The surgeons mobilise the spermatic cord and place it in a hernia ring. A small slender nerve is identified superior to the cord. Which nerve is it most likely to be?
A. Iliohypogastric nerve B. Pudendal nerve C. Femoral branch of the genitofemoral nerve D. Ilioinguinal nerve E. Obturator nerve
ilioinguinal nerve
The ilioinguinal nerve passes through the inguinal canal and is the nerve most commonly identified during hernia surgery. The genitofemoral nerve splits into two branches, the genital branch passes through the inguinal canal within the cord structures. The femoral branch of the genitofemoral nerve enters the thigh posterior to the inguinal ligament, lateral to the femoral artery. The iliohypogastric nerve pierces the external oblique aponeurosis above the superficial inguinal ring.
A 34 year old man undergoes excision of a sarcoma from the right buttock. During the procedure the sciatic nerve is sacrificed. Which of the following will not occur as a result of this process?
A. Loss of extension at the knee joint B. Foot drop C. Inability to extend extensor hallucis longus D. Loss of sensation to the posterior aspect of the thigh E. Loss of sensation to the posterior aspect of the lower leg
Extension of the knee joint is caused by the obturator and femoral nerves.
Where does the spinal cord terminate in neonates?
A. L1 B. L2 C. L3 D. L4 E. L5
L3
At the 3rd month the foetus’s spinal cord occupies the entire length of the vertebral canal. The vertebral column then grows longer exceeding the growth rate of the spinal cord. This results with the cord being at L3 at birth and L1-2 by adulthood.
A 24 year old lady is stabbed in the buttock. Following the injury the wound is sutured in the emergency department. Eight weeks later she attends the clinic, as she walks into the clinic room she has a waddling gait and difficulty with thigh abduction. On examination she has buttock muscle wasting. Which nerve has been injured?
A. Superior gluteal nerve B. Obturator nerve C. Sciatic nerve D. Femoral nerve E. Inferior gluteal nerve
Damage to the superior gluteal nerve will result in a Trendelenburg gait.
A 73 year old lady presents with symptoms of faecal incontinence. On examination she has weak anal sphincter muscles. What are the main nerve root values of the nerves supplying the external anal sphincter?
A. S2,3 B. L5, S1 C. S4,5 D. S5 E. S2,3,4
S2, 3, 4 Keeps the poo off the floor
Theme from September 2011 Exam
The external anal sphincter is innervated by the inferior rectal branch of the pudendal nerve, this has root values of S2, 3 and the perineal branch of S4.
A 72 year old man has a fall. He is found to have a fractured neck of femur and goes on to have a left hip hemiarthroplasty. Two months post operatively he is found to have an odd gait. When standing on his left leg his pelvis dips on the right side. There is no foot drop. What is the cause?
A. Sciatic nerve damage B. L5 radiculopathy C. Inferior gluteal nerve damage D. Previous poliomyelitis E. Superior gluteal nerve damage
Superior gluteal nerve
This patient has a trendelenburg gait caused by damage to the superior gluteal nerve causing weakness of the abductor muscles. Classically a patient is asked to stand on one leg and the pelvis dips on the opposite side. The absence of a foot drop excludes the possibility of polio or L5 radiculopathy.
Which of the following structures lies posterior to the femoral nerve in the femoral triangle?
A. Adductor longus B. Pectineus C. Psoas major D. Iliacus E. None of the above
Iliacus
The iliacus lies posterior to the femoral nerve in the femoral triangle. The femoral sheath lies anterior to the iliacus and pectineus muscles.
A 28 year old lady requires an episiotomy for a ventouse vaginal delivery. Which of the nerves listed below will usually be anaesthetised to allow the episiotomy?
A. Femoral B. Ilioinguinal C. Pudendal D. Genitofemoral E. Sacral plexus
The pudendal nerve innervates the posterior vulval area and is routinely blocked in procedures such as episiotomy.
Pudendal nerve
The pudendal nerve arises from nerve roots S2, S3 and S4 and exits the pelvis through the greater sciatic foramen. It re-enters the pelvis through the lesser sciatic foramen. It travels inferior to give innervation to the anal sphincters and external urethral sphincter. It also provides cutaneous innervation to the region of perineum surrounding the anus and posterior vulva.
Traction and compression of the pudendal nerve by the foetus in late pregnancy may result in late onset pudendal neuropathy which may be part of the process involved in the development of faecal incontinence.
A 68 year old man with critical limb ischaemia is undergoing a femoro-distal bypass graft. During mobilisation of the proximal part of the posterior tibial artery which of the following is at greatest risk of injury?
A. Tibial nerve B. Sciatic nerve C. Saphenous nerve D. Common peroneal nerve E. Medial superior genicular artery
Tibial nerve
The tibial nerve is closely related to the posterior tibial artery. The tibial nerve crosses the vessel posteriorly approximately 2.5cm distal to its origin. At its origin the nerve lies medial and then lateral after it crosses the vessel as described.
Posterior tibial artery
Larger terminal branch of the popliteal artery
Terminates by dividing into the medial and lateral plantar arteries
Accompanied by two veins throughout its length
Position of the artery corresponds to a line drawn from the lower angle of the popliteal fossa, at the level of the neck of the fibula, to a point midway between the medial malleolus and the most prominent part of the heel
Relations of the posterior tibial artery
Proximal to distal
Anteriorly Tibialis posterior
Flexor digitorum longus
Posterior surface of tibia and ankle joint
Posterior Tibial nerve 2.5 cm distal to its origin
Fascia overlying the deep muscular layer
Proximal part covered by gastrocnemius and soleus
Distal part covered by skin and fascia
Which of the following muscles does not insert to the medial surface of the greater trochanter?
A. Gemelli B. Obturator internus C. Piriformis D. Quadratus femoris E. Obturator externus
The quadratus femoris fibres pass laterally to be inserted into the quadrate tubercle on the intertrochanteric crest of the femur. The other muscles all insert on the trochanteric fossa lying medial to the greater trochanter.
Which of the following structures lies deepest in the popliteal fossa?
A. Popliteal artery B. Popliteal vein C. Tibial nerve D. Common peroneal nerve E. Popliteal lymph nodes
Popliteal artery
From superficial to deep:
The common peroneal nerve exits the popliteal fossa along the medial border of the biceps tendon. Then the tibial nerve lies lateral to the popliteal vessels to pass posteriorly and then medially to them. The popliteal vein lies superficial to the popliteal artery, which is the deepest structure in the fossa.
An intravenous drug user develops a false aneurysm and requires emergency surgery. The procedure is difficult and the femoral nerve is inadvertently transected. Which of the following muscles is least likely to be affected as a result?
A. Sartorius B. Vastus medialis C. Pectineus D. Quadriceps femoris E. Adductor magnus
Adductor magnus
Next question
Mnemonic for femoral nerve supply
(don’t) M I S V Q Scan for PE
M edial cutaneous nerve of the thigh
I ntermediate cutaneous nerve of the thigh
S aphenous nerve
V astus
Q uadriceps femoris
S artorius
PE ectineus
Adductor magnus is innervated by the obturator and sciatic nerve. The pectineus muscle is sometimes supplied by the obturator nerve but this is variable. Since the question states least likely, the correct answer is adductor magnus
What is the nerve root value of the external urethral sphincter?
A. S4 B. S1, S2, S3 C. S2, S3, S4 D. L3, L4, L5 E. L5, S1, S2
The external urethral sphincter is innervated by branches of the pudendal nerve, therefore the root values are S2, S3, S4.
Which of the following structures does not pass posteriorly to the medial malleolus?
A. Posterior tibial artery B. Tibial nerve C. Tibialis anterior tendon D. Tendon of flexor digitorum longus E. Tendon of flexor hallucis longus
Tibialis anterior tendon
Mnemonic for structures posterior to the medial malleolus:
Tom Dick And Nervous Harry
T ibialis posterior tendon flexor Digitorum longus A rtery N erve H allucis longus
Medial malleolus
The following structures pass posterior to medial malleolus (in order):
Tibialis posterior tendon Flexor digitorum longus tendon Posterior tibial artery Tibial nerve Tendon of flexor hallucis longus
A 44 year old man has a malignant melanoma and is undergoing a block dissection of the groin. The femoral triangle is being explored for intra operative bleeding. Which of the following forms the medial border of the femoral triangle?
A. Femoral artery B. Biceps femoris C. Adductor longus D. Sartorius E. Adductor magnus
Adductor longus
Vastus medialis forms the lateral border of the adductor canal. The sartorius muscles forms the roof of the adductor canal.
Adductor longus forms the medial boundary of the femoral triangle (see below).
Femoral triangle anatomy
Boundaries Superiorly Inguinal ligament Laterally Sartorius Medially Adductor longus Floor Iliopsoas, adductor longus and pectineus Roof Fascia lata and Superficial fascia Superficial inguinal lymph nodes (palpable below the inguinal ligament) Great saphenous vein
