Lower Limb

Question 1

Compare the stability of the shoulder joint & hip joint based on the arrangement of the following structures

1.1. Articular surfaces (30)
1.2. Capsule, ligaments & Muscles (50)
1.3. Movements & stability (20)

Answer 1

Shoulder Joint (SJ) – Articulation of Glenoid Fossa with Head of Humerus

• SJ is a multiaxial ball & socket type synovial joint.
• Head of the humerus makes 1/3rd of a sphere.
• Glenoid fossa is shallow, with the head four times larger than the fossa.
• Glenoid labrum tries to deepen the articular surface, yet congruity is less, making the articulation weak.
• Superiorly, the secondary socket formed by the coracoacromial arch provides some stability.

Hip Joint (HJ) - Articulation of Acetabular Fossa with Head of Femur

• HJ is also a multiaxial ball & socket type synovial joint.
• Head of the femur makes more than half of a sphere.
• Acetabular fossa is deep, with the acetabular labrum further deepening it.
• Congruity is high, making the articulation strong.
• Length and obliquity of the femoral neck contribute to HJ stability.

Capsule and Ligaments

• Capsule is lax but strong in both joints.
• In HJ, capsule is reinforced by the iliofemoral ligament (anteriorly), ischiofemoral ligament (posteriorly), and pubofemoral ligament (inferiorly).
• In SJ, reinforcement is mainly by the glenohumeral and coracohumeral ligaments, making it weaker inferiorly.

Muscles

• Stabilization of SJ is mainly by the rotator cuff muscle group: subscapularis, supraspinatus, infraspinatus, and teres minor. Deficient inferiorly.
• Long head of biceps prevents upward dislocation.
• Long head of triceps provides some inferior stability.
• SJ is weakest inferiorly, leading to common inferior dislocations.
• HJ is surrounded by muscles: iliopsoas (anteriorly), gluteus maximus (posteriorly), rectus femoris, gluteus medius & minimus (superiorly), and adductors (inferiorly).

Movements

• Both joints allow flexion, extension, abduction, adduction, medial and lateral rotation, and circumduction.
• SJ has a great range of movement due to laxity of the capsule, disproportionate articular surfaces, and the presence of the shoulder girdle.
• HJ has a wide range of movement due to the toughness of its capsule, deepened articulation, yet it has less movement compared to the shoulder girdle.

Question 2

Describe the blood supply of the head of the femur

Answer 2

Greater part of the head of the femur is supplied by retinacular arteries along the retinacular part of the capsule. These arteries arise from the trochanteric anastomoses, which are formed by:

• Superior gluteal artery
• Medial circumflex femoral artery (ascending branch)
• Lateral circumflex femoral artery (ascending branch)
• Inferior gluteal artery (occasionally)

Additionally:

The arteries via the ligaments capitis
- The major blood supply to the femoral head before puberty is from the acetabular branch of the obturator artery. However, this supply is negligible in adults and more prominent in children.
- The diaphysial artery is the second perforator of the profundus femoris artery.

Question 3

Explain the clinical importance of above blood supply regarding the fractures of neck of the femur

Answer 3

• Subcapital fracture, cervical fracture, and basal fracture are fractures proximal to the distal attachment of the capsule of the hip joint, thus classified as intracapsular fractures.
• Capsular attachment is anteriorly at the intertrochanteric line and posteriorly halfway down the neck of the femur.
• In adults, the femoral head primarily receives blood supply via retinacular arteries. Disruption of this blood supply occurs in the aforementioned fractures.
• The disturbance in blood supply leads to avascular necrosis of the head of the femur.
• However, a pretrochanteric fracture doesn’t disrupt this main blood supply and therefore does not lead to avascular necrosis, as it is an extracapsular fracture.
• Before puberty, the major blood supply to the head of the femur is via arteries through the ligamentum teres capitis, entering through the fovea capitis. This blood supply remains undisturbed in the above fractures.
• Avascular necrosis is relatively rare in children.

Question 4

Describe the microscopic structure of muscle fibers of the psoas muscle including its arrangement of its myofibrils (30)

Answer 4

The Psoas muscle is composed of skeletal muscle fibers (SMF) bound together by collagenous supporting tissues. Each muscle fiber is surrounded by endomysium, a loose connective tissue, and grouped together to form fasciculi, surrounded by perimysium, another connective tissue. The whole muscle mass is invested by epimysium, a dense connective tissue. Psoas muscles facilitate voluntary contractions.

Skeletal muscle fibers are elongated, unbranched, cylindrical, and multinucleated cells with nuclei located in the periphery. The organization of myofibrils within these fibers comprises two types of myofilaments: thick filaments mainly composed of the protein myosin, and thin filaments mainly composed of the protein actin. This organization results in cross-striations, alternating between broad light I bands consisting only of thin filaments, and dark A bands consisting of both types of filaments.

Within the A band, there is a lighter H band consisting only of thick filaments. Z lines bisect the I bands and extend from one Z line to another, defining the sarcomere, which is the basic unit of contraction of a skeletal muscle fiber.

Question 5

How does the microscopic structure differ from that of heart muscle fiber?

Answer 5

Skeletal Muscle Fiber:

Fibers arranged as fascicles
Elongated, cylindrical, unbranched cells
Multiple peripherally situated nuclei
Intercalated discs absent
Muscle triad located at the junction of A & I bands

Cardiac Muscle Fiber:

Arranged as interwoven bundles
Cylindrical, branched, uninucleated fibers
Single central nucleus (Some cells may be binucleated)
Intercalated discs present
Muscle triad located at Z lines

Question 6

Define the femoral triangle.

Answer 6

• It is a gutter-shaped triangular depression.
• Located in the upper third of the anterior thigh.
• Laterally bounded by the medial border of Sartorius.
• Medially bounded by the medial border of Adductor Longus.
• The base of the triangle is the inguinal ligament.
• The apex is directed downwards and continuous with the upper end of the adductor canal.
• The floor of the triangle is composed of Iliacus, Psoas major, Pectineus, and Adductor Longus from lateral to medial.
• The roof is formed by skin, superficial fascia, and fascia lata from superficial to deep.

Question 7

Describe the relations of the nerves and vessels within the femoral triangle.

Answer 7

The relations of the nerves and vessels within the femoral triangle are as follows:

• The external iliac artery continues as the femoral artery below the inguinal ligament and is initially contained within the femoral sheath. The femoral vein lies medial to it.
• The femoral sheath, an elongation of the Transversalis and Iliacus fascia, has three compartments:
  
  1. The lateral compartment contains the femoral artery and the femoral branch of the genitofemoral nerve.
  2. The middle compartment contains the femoral vein.
  3. The medialmost compartment is the femoral canal, which contains the node of Cloquet, a deep inguinal lymph node.
• The femoral nerve lies lateral to the femoral artery outside the femoral sheath, on the Psoas muscle. It gives terminal branches one inch below the inguinal ligament. The nerve to Vastus Medialis continues into the adductor canal. The Saphenous nerve is initially superficial and then medial to the femoral artery.
• The three superficial arteries of the femoral artery reach the superficial fascia through the saphenous opening or by piercing the fascia lata. They are the superficial circumflex iliac, superficial external pudendal, and superficial epigastric arteries.
• The femoral artery also gives three deep branches:
  
  1. The profunda femoris artery originates from the lateral side of the femoral artery and runs between pectineus and adductor longus to descend over adductor brevis and magnus.
  2. The profunda femoris gives the lateral circumflex femoral artery, which goes between the anterior and posterior divisions of the femoral nerve.
  3. It also gives the medial circumflex femoral artery, which runs between Psoas major and pectineus to leave the femoral triangle.
• The lateral cutaneous nerve of the thigh enters the triangle laterally below the inguinal ligament and leaves the triangle into the superficial fascia.
• The femoral vein drains the greater saphenous vein just below the femoral sheath. The three superficial arteries are accompanied by veins that drain into the greater saphenous vein.

Question 8

Describe the origin, course and distribution of the femoral nerve.

Answer 8

• The femoral nerve is the chief nerve of the anterior compartment of the thigh.
• It is formed by the posterior division of the anterior rami of lumbar nerves 2, 3, and 4.
• After emerging at the lateral border of the psoas major, it runs in the iliac fossa.
• It travels in the groove between the iliacus and psoas major.
• The femoral nerve supplies the iliacus muscle in the abdomen via the nerve to iliacus.
• Upon entering the femoral triangle by passing deep to the inguinal ligament, it lies on the lateral side of the femoral sheath, which separates the nerve from the femoral artery (the artery is medial to the nerve).
• Upon entering the femoral triangle, the femoral nerve gives a branch to pectineus, which runs deep to the femoral sheath and enters the anterior surface of the pectineus muscle, supplying it just distal (4cm) to the inguinal ligament.
• The nerve divides into its terminal anterior and posterior branches, which are separated from each other by the lateral circumflex femoral artery.
• The anterior branch supplies the Sartorius muscle via the nerve to Sartorius, which is continuous as the intermediate cutaneous nerve of the thigh.
• The medial side of the thigh is supplied by the medial cutaneous nerve of the thigh.
• The posterior division supplies the quadriceps femoris via the nerve to rectus femoris, which continues to supply the hip joint and via the nerve to vasti (medial, lateral, and intermediate), which continues to supply the knee joint.
• The saphenous nerve also arises from the posterior division. It runs in the adductor canal with the femoral vessels and leaves it by piercing the fascial roof of the canal and runs downwards (crosses the femoral artery lateral to medial, superficially in the adductor canal) to supply the medial part of the leg up to the base of the big toe.

Question 9

Give an account on femoral canal (30)

Answer 9

The femoral canal can be described as follows:

• It is the medial compartment of the femoral sheath.
• Conically shaped, being wide above and narrow below.
• The upper end or base is referred to as the femoral ring.
• It is bounded:
  
  • Anteriorly by the inguinal ligament.
  • Posteriorly by pectineus muscle and its covering fascia.
  • Medially by the crescentic edge of the lacunar ligament.
  • Laterally by a septum separating it from the femoral vein.
• Contains a lymph node of Cloquet/Rosenmuller, lymphatics, and a small amount of areolar tissue.
• The lymph node drains the glans penis of males and the clitoris of females.
• Femoral hernia enters the femoral canal through the femoral ring.
• Incising the lacunar ligament may be necessary to release such strangulated hernias (extra).
• Abnormal obturator artery may be at risk within this region.

Question 10

Give a brief account of the adductor canal (50 marks)

Answer 10

The adductor canal can be described as follows:

• It is an intermuscular space.
• Situated on the medial side of the middle 1/3 of the thigh.
• Extends above from the apex of the femoral triangle and below to the tendinous opening in the adductor magnus (adductor hiatus).
• Triangular in cross-section.
• Boundaries include:
  
  • Anterolateral wall: vastus medialis.
  • Posteromedial wall/floor: adductor longus (above) and adductor magnus (below).
  • Medial wall/roof: fibrous membrane joining anterolateral and posteromedial walls.
• The roof is overlapped by the Sartorius muscle.
• Subsartorial plexus of nerves lies on the fibrous roof under the cover of Sartorius, formed by branches of the medial cutaneous nerve of the thigh, saphenous nerve, and the anterior division of the obturator nerve. It supplies the overlying fascia lata and neighboring skin.
• Contents include:
  
  • Femoral artery, which enters at the apex of the femoral triangle and leaves through the adductor hiatus. In the canal, it gives muscular branches and the descending genicular branch.
  • Femoral vein, which begins as an upward continuation of the popliteal vein, lies posterior to the artery in the upper part and lateral to the artery in the lower part of the canal.
  • Saphenous nerve, which crosses the femoral artery anteriorly from lateral to medial and leaves the adductor canal by piercing the roof.
  • Anterior division of the obturator nerve emerges at the lower border of the adductor longus and ends by supplying the femoral artery. The posterior division runs on the anterior surface of the adductor magnus and accompanies the femoral artery in the canal.

Question 11

With the help of a labelled diagram explain the anatomy of the Popliteal fossa. (2009 repeat)

Answer 11

• Popliteal Artery: Direct continuation of the femoral artery beyond the opening of the adductor magnus or hiatus, at the junction of the middle and lower 1/3rd of the thigh. It runs downwards, reaching the lower end of the popliteus muscle, where it terminates by dividing into its terminal anterior tibial and posterior tibial arteries. The popliteal artery is the deepest structure in the popliteal fossa.
• Popliteal Surface of Femur: Forms the posterior wall of the knee joint, along with its capsules.
• Popliteus Muscle: Related to the artery deeply/anteriorly from above downwards in the popliteal fossa.
• Popliteal Vein: Posteriorly related to the artery.
• Tibial Nerve: Further posteriorly related to the artery, separated from it by the vein in the fossa.
• Biceps Femoris: Laterally related to the artery in the upper part of the fossa.
• Semitendinosus & Semimembranosus: Medially related to the artery in the upper part of the fossa.
• Gastrocnemius Muscle: In the lower part of the fossa, the artery becomes the most lateral structure, related laterally to the lateral head of gastrocnemius and medially to the medial head of gastrocnemius, popliteal vein, and tibial nerve.
• Genicular Arterial Branches: Arise from the popliteal artery and form an anastomotic chain to supply the knee joint. They include the superior medial genicular, superior lateral genicular, inferior medial genicular, inferior lateral genicular, and middle genicular branches.
• Muscular Branches: Large muscular branches are given off from the popliteal artery, terminating by anastomosing with the 4th perforating artery.
• Cutaneous Branches: Arise directly from the popliteal artery or from the muscular arteries.

Question 12

What is the clinical importance of the adductor canal? (10)

Answer 12

In treatment for the popliteal artery aneurysm femoral artery can only be ligated in the adductor canal.

Question 13

State the clinical relevance of the medial boundaries of femoral ring. (30)

Answer 13

• It’s bounded medially by the concave margin of the lacunar ligament.
  
  • Laterally by the femoral vein.
  • Anteriorly by the inguinal ligament.
  • Posteriorly by the pectineal ligament.
• In cases of strangulation of a femoral hernia, the femoral ring has to be enlarged.
  
  • This is possible only by cutting the lacunar ligament.
  • Normally, this can be done without danger.
  • Occasionally, however, an abnormal obturator artery may lie along the edge of the lacunar ligament, and cutting it may cause alarming hemorrhage.

Question 14

Describe the course, distribution and relations of the popliteal artery (100)

Answer 14

• Popliteal artery is a direct continuation of the femoral artery beyond the opening of the adductor magnus/hiatus at the junction of middle & lower 1/3rds of the thigh.
  
  • Artery runs downwards, reaching the lower end of the popliteus muscle, and terminates by dividing into its terminal anterior tibial and posterior tibial arteries.
  • Popliteal artery is the deepest structure in the popliteal fossa.
• Popliteal surface of femur:
  
  • Forms the knee joint & its capsules.
  • Popliteus muscle:
    
    • Related to the artery deeply/anteriorly, above downwards in the popliteal fossa.
    • Posteriorly, artery is related to the popliteal vein and further posteriorly to the tibial nerve/nerve is separated from artery by vein in the fossa.
    • In the upper part of the popliteal fossa, artery is the most medial structure and relates to biceps femoris laterally and to semitendinosus, semimembranosus medially.
    • Inside the fossa, artery deviates laterally and becomes the most lateral structure in its lower part.
      
      • Related laterally to lateral head of gastrocnemius and medially to medial head of gastrocnemius, popliteal vein, and tibial nerve.
• Branches:
  
  • Superior medial genicular.
  • Superior lateral genicular.
  • Inferior medial genicular.
  • Inferior lateral genicular.
  • Middle genicular branch arises from the artery and winds around the knee joint to form an anastomotic chain to supply the joint.
• Large muscular branches are given off that terminate by anastomosing with the 4th perforating artery.
• Cutaneous branches also arise directly from the popliteal artery or by the muscular arteries.

Question 15

Which meniscus is the most likely to damage? Give reasons for your answer.

(2009-main)

Answer 15

The medial meniscus is more likely to be damaged. This is primarily because it is more fixed and less mobile compared to the lateral meniscus. The reasons for this are:

• Attachment: The medial meniscus is firmly attached to the capsule and the medial collateral ligament, providing less freedom of movement.
• Stability: Its attachment to the capsule and ligament provides stability but limits its ability to accommodate stress and movement.
• Limited Mobility: Due to its fixed attachment, the medial meniscus has less mobility, making it more susceptible to damage when subjected to forces or sudden movements.
• Contrast: In contrast, the lateral meniscus is separated from the capsule by the tendon of the popliteus muscle and the lateral collateral ligament, allowing it more freedom of movement and thereby reducing its vulnerability to damage.

Therefore, due to its anatomical and functional characteristics, the medial meniscus is at a higher risk of damage compared to the lateral meniscus.

Question 16

Describe the intra-articular ligaments of the knee joint and their function.

Answer 16

The intra-articular ligaments of the knee joint and their functions are described as follows:

Menisci:
- Intracapsular and intrasynovial fibrocartilaginous discs.
- Crescent-shaped structures that deepen the articular surface of the tibia, dividing the knee joint cavity into upper (for flexion and extension) and lower (for rotation) compartments.
- The medial meniscus is nearly semicircular, while the lateral meniscus is nearly circular.
- Medial meniscus: Attached to the tibial collateral ligament at its peripheral margin.
- Lateral meniscus: Attached to the femur through the meniscofemoral ligament at its posterior end.
- Function:
- Increase congruity of the knee joint.
- Serve as shock absorbers.
- Lubricate the joint cavity.
- Provide sensory function (proprioception).
- The medial meniscus is more prone to damage due to its greater fixity compared to the lateral meniscus.

Cruciate Ligaments:
- Thick, strong, fibrous bands located within the knee joint.
- Intracapsular and extrasynovial.
- Function:
- Maintain anteroposterior stability of the knee joint.
- Anterior Cruciate Ligament (ACL):
- Begins from the anterior intercondylar area of the tibia, running upwards, backwards, and laterally.
- Attached to the posterior part of the medial surface of the lateral condyle of the femur.
- Becomes taut during extension of the knee.
- More commonly damaged in violent hyperextension or anterior dislocation of the tibia on the femur.
- Posterior Cruciate Ligament (PCL):
- Begins from the posterior intercondylar area of the tibia, running upwards, forwards, and medially.
- Attached to the anterior part of the lateral surface of the medial condyle of the femur.
- Becomes taut during flexion of the knee.
- Injured in posterior dislocation of the tibia on the femur.
- Both ligaments are supplied by the middle genicular nerve and arteries.

Question 17

Describe the factors contributing to the stability of the knee joint (50 marks)

Answer 17

Factors contributing to the stability of the knee joint include:

• Cruciate Ligaments: These ligaments maintain anteroposterior stability. They are strong fibrous connections between the femur and tibia, located intra-capsularly but extra-synovially. The anterior cruciate ligament prevents forward displacement of the tibia on the femur, while the posterior cruciate ligament prevents backward displacement of the femur on the tibia.
• Menisci: These structures provide a stable articulation between the tibia and fibula. They are crescent-shaped, intra-capsular, and intra-synovial fibrocartilaginous discs. Menisci are thick peripherally and thin centrally, enhancing stability.
• Collateral Ligaments: These ligaments maintain side-to-side stability, restricting rocking movement. The tibial collateral ligament blends with the capsule and medial meniscus, while the fibular collateral ligament is separated from the capsule and lateral menisci by the popliteal tendon and embraced by the biceps tendon.
• Capsule Strength: Factors strengthening the capsule also contribute to knee joint stability. The capsule attaches slightly beyond the margin of the articular surface of the tibia and femur and is attached to the sides of the patella. It is anteriorly deficient and replaced by the patella, quadriceps femoris, and ligament of patella.
• Iliotibial Tract: This structure plays an important role in knee joint stability.
• Muscle Support: The knee joint can work efficiently with ligamentous damage due to the presence of the powerful quadriceps femoris muscle, which provides additional stability.

These factors work together to ensure the stability and proper functioning of the knee joint, allowing for efficient movement and weight-bearing activities.

Question 18

Explain the locking mechanism of the knee joint (20 marks)

Answer 18

• Locking of the knee joint is a result of the medial rotation of the femur against a fixed tibia at the last stage of extension.
• Due to locking, the knee remains in full extension and the ligaments are taut.
• Not much muscular effort is needed against gravity.
• Unlocking of the knee joint is due to lateral rotation of the femur against a fixed tibia (when sitting down from a standing position) produced by the popliteus muscle.

Question 19

State the locations of the pulse points found in the lower limb (20 marks)

Answer 19

• The femoral pulse is felt in the femoral triangle.
  
  • The femoral artery is palpated inferior to the inguinal ligament and midway between the anterior superior iliac spine and pubic symphysis.
• The popliteal pulse is felt in the popliteal fossa.
  
  • The popliteal artery is palpated deep in the popliteal fossa near the midline.
• The posterior tibial pulse is felt in the tarsal tunnel.
  
  • The posterior tibial artery is palpated posteroinferior to the medial malleolus in the groove between the medial malleolus and the calcaneal tuberosity.
• The dorsalis pedis pulse is felt on the dorsal aspect of the foot.
  
  • The dorsalis pedis artery is palpated as it passes over the tarsal bones between the tendon of extensor halluces longus and the tendon of extensor digitorum longus to the second toe.

Question 20

List the structures that contribute to the stability of the patella.

Answer 20

• Patellar ligament
• Quadriceps femoris tendon
• Horizontal fibers of Vastus Medialis
• Forward prominence of the lateral femoral condyle
• Medial patellar retinaculum

Question 21

Describe the origin, course and distribution of nerve of the common perineal nerve (50)

Answer 21

• Origin: Nerve roots arise from the dorsal division of anterior primary rami L4, L5, S1, and S2.
• Course:
  
  • It constitutes the smaller terminal branch of the sciatic nerve.
  • Terminates at the superior angle of the popliteal fossa.
  • Crosses the popliteal fossa from the medial to the lateral side along the medial border of the biceps femoris.
  • It then winds around the neck of the fibula.
  • Enters the substance of the peroneus longus muscle.
• Distribution:
  
  • Terminates by dividing into superficial and deep peroneal nerves.
  • Gives off the lateral cutaneous nerve of the calf and the sural communicating nerve, supplying cutaneous sensation of the lateral half of the leg.
  • Provides superior and inferior lateral genicular branches, which supply the knee joint.

Question 22

Explain the anatomical basis of above clinical feature of foot drop.

Answer 22

• The common peroneal nerve is frequently damaged due to its vulnerable anatomical position.
• Its branch, the deep peroneal nerve, innervates all the dorsiflexors of the foot, including the tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius muscles.
• When the common peroneal nerve is compressed, such as by a plaster on the leg where it winds around the neck of the fibula, it leads to paralysis of all the dorsiflexors of the foot.
• This paralysis results in the unopposed action of plantarflexors and the effect of gravity, causing the foot to be in a plantarflexed position, clinically termed as footdrop.
• Additionally, the superficial peroneal nerve, another branch of the common peroneal nerve, supplies cutaneous sensation to the lower 1/3rd of the lateral half of the leg and the dorsum of the foot (except for areas supplied by the sural, saphenous, and deep peroneal nerves).
• Compression of the common peroneal nerve leads to loss of cutaneous sensation on the dorsum of the foot, resulting in numbness.
• However, the cutaneous sensation of the upper lateral half of the leg remains unaffected as compression occurs beyond the origin of the lateral cutaneous nerve of the calf, which supplies those areas of the leg.

Question 23

Describe the origin, course and relations of the sciatic nerve. (2012-main,2013main)

Answer 23

• The sciatic nerve arises from both dorsal and ventral divisions of the sacral (ventral) rami, originating from nerve roots L4, L5, S1, S2, and S3.
• The tibial part of the sciatic nerve is formed by the ventral divisions of nerve roots L4-S3.
• The common peroneal part is formed by the dorsal divisions of nerve roots L4-S2, making it the thickest nerve in the body.
• It enters the gluteal region through the greater sciatic foramen from a midpoint between the posterior superior iliac spine and the ischial tuberosity, below the piriformis muscle.
• Running downward from the midpoint between the greater trochanter and the ischial tuberosity, it enters the posterior compartment of the thigh.
• Deep or anterior to the nerve are the body of the ischium, the tendon of the obturator internus with the gemelli, quadratus femoris, obturator externus, and the capsule of the hip joint.
• It runs deep to the gluteus maximus, leaving its inferior border to enter into the thigh.
• Continuing downward in the posterior compartment of the thigh, it passes between the hamstring muscles, with the long head of the biceps femoris crossing the nerve superficially and the adductor magnus lying deep to the nerve medially.
• Semitendinosus and semimembranosus muscles are situated medially, with the biceps femoris placed laterally.
• It ends by dividing into its terminal branches on the superior angle of the popliteal fossa, which is the junction between the upper 2/3rd and lower 1/3rd of the thigh, into the tibial and common peroneal nerves.
• The division may occur at a variable position, possibly even high up in the thigh.

Question 24

State the locations of the pulse points found in the lower limb (20 marks)

Answer 24

• The femoral pulse is felt in the femoral triangle.
• The femoral artery is palpated inferior to the inguinal ligament and midway between the anterior superior iliac spine and pubic symphysis.
• The popliteal pulse is felt in the popliteal fossa.
• The popliteal artery is palpated deep in the popliteal fossa near the midline.
• The posterior tibial pulse is felt in the tarsal tunnel.
• The posterior tibial artery is palpated posteroinferior to the medial malleolus in the groove between the medial malleolus and the calcaneal tuberosity.
• The dorsalis pedis pulse is felt on the dorsal aspect of the foot.
• The dorsalis pedis artery is palpated as it passes over the tarsal bones between the tendon of extensor hallucis longus and the tendon of extensor digitorum longus to the second toe.

Question 25

Describe the venous drainage of lower limb.

Answer 25

• Venous drainage of the lower limb can be classified into:
  
  • Superficial veins
  • Deep veins
  • Perforating veins

Deep veins:
- Include anterior tibial, peroneal, popliteal, femoral vein
- Accompany deep arteries
- Have more valves than superficial veins
- Supported by the surrounding muscles
- Drain more blood than superficial veins

Superficial veins:
- Located in superficial fascia
- Examples include great and small saphenous vein
- Great saphenous vein & its tributaries:
- Starts by union of medial marginal vein & the medial end of the dorsal venous arch
- Ascends in front of the medial malleolus
- Crosses the lower 1/3rd of the tibia obliquely
- Then ascends along the medial border of the tibia accompanied by the saphenous nerve
- Goes a hand’s breadth behind the knee joint
- Then curves around the anterior convexity of thigh to drain into femoral vein through the saphenous opening by piercing cribriform fascia
- A constant valve present near the opening
- Opening is situated 4cm below & lateral to pubic tubercle
- Before piercing cribriform fascia it receives:
- Superficial external pudendal
- Superficial circumflex iliac
- Superficial epigastric vein
- After piercing, it receives deep external pudendal vein
- Have 10-15 valves

Small saphenous vein:
- Starts by union of lateral end of dorsal venous arch with lateral marginal vein
- Ascends posterior to the lateral malleolus
- Ascends in the midline of the calf
- Accompanies the sural nerve
- Drains into the popliteal vein within the popliteal fossa piercing the deep fascia

Perforating veins:
- Drain blood from superficial veins to deep veins
- Indirect perforators – through the muscular veins
- Direct perforators – direct venous channels connecting superficial vein to deep veins
- Position of direct perforators:
- Hand’s breadth above the knee joint
- Hand’s breadth below the knee joint
- Hand’s breadth above the ankle joint on both medial and lateral side

Factors helping venous drainage of the lower limb:
- High venous tone - veins are more muscular
- More valves present
- Muscular pump tight fascial sleeve – make the muscular compression more efficient
- Negative thoracic pressure
- Because deep veins accompany arteries, arterial pulsation helps the venous drainage
- Incompetence of valve leads to varicose vein

Question 26

Describe the anatomical basis of varicose veins.

Answer 26

Varicose veins are due to incompetence of valves in perforating veins or at the termination of the superficial veins. When the muscles of the lower limb contract, blood in deep veins leak into superficial veins causing them to dilate. Due to this high pressure, superficial veins start to degenerate forming varicose ulcers.

Question 27

Explain the arrangement of the structures that pass through the greater sciatic foramen. (Consider the order of the structures) (25)

Answer 27

The greater sciatic foramen serves as a crucial passage for various structures in the pelvic region. Here’s an explanation of the arrangement of these structures, considering their order:

1. Piriformis Muscle: This muscle emerges from the pelvis and occupies most of the space within the greater sciatic foramen. It plays a significant role in the region, acting as a key muscle.
2. Structures Passing Above the Piriformis:
   
   • Superior Gluteal Nerve: This nerve travels above the piriformis muscle.
   • Superior Gluteal Vessels: These blood vessels also pass above the piriformis.
3. Structures Passing Below the Piriformis (from Medial to Lateral):
   
   • Pudendal Nerve: This nerve passes below the piriformis muscle.
   • Internal Pudendal Vessels: These blood vessels follow the course below the piriformis.
   • Nerve to Obturator Internus: Another nerve in this region, passing below the piriformis muscle.
   • Inferior Gluteal Nerve: This nerve travels below the piriformis.
   • Inferior Gluteal Vessels: These blood vessels also pass below the piriformis.
4. Sciatic Nerve: This significant nerve traverses through the greater sciatic foramen, though it’s not specifically mentioned whether it passes above or below the piriformis muscle.
5. Nerve to Quadratus Femoris: Another nerve in the region, likely passing in proximity to the sciatic nerve.

This arrangement showcases the layered organization of structures passing through the greater sciatic foramen, with the piriformis muscle acting as a central landmark.

Question 28

State the appropriate site for the intramuscular injections in gluteal region. Give the reason. (10)

Answer 28

• Intramuscular injections are administered in the anterosuperior quadrant of the gluteal region, specifically targeting the glutei medius and minimus muscles.
• This choice of injection site is made to prevent injury to large vessels and nerves that pass through the lower part of this region.

Question 29

Action and innervation of three gluteal muscles.(30)

Answer 29

• Gluteus Maximus:
  
  • Action:
    
    • Chief extensor of the hip joint.
    • Active when standing from a sitting position.
    • Acts as the primary antigravity muscle when standing.
    • Performs lateral rotation of the thigh.
    • Assists in abduction of the thigh.
    • A significant portion of the muscle inserts into the iliotibial tract, contributing to stabilization of the knee joint.
  • Innervation:
    
    • Supplied by the inferior gluteal nerve.
• Gluteus Medius and Gluteus Minimus:
  
  • Action:
    
    • Both muscles are supplied by the superior gluteal nerve.
    • Function as powerful abductors of the thigh.
    • Play a crucial role in maintaining balance when the opposite foot is off the ground.
    • Contraction of these muscles on the same side prevents tilting of the pelvis on the opposite side under the influence of gravity.
    • Additionally, they contribute to medial rotation of the thigh.

These gluteal muscles collectively play essential roles in various movements and stability of the hip and pelvis.

Question 30

Trochanteric anastomosis (30)

Answer 30

Trochanteric Anastomosis:

• Main source of blood supply to the head of femur.
• Lies near the trochanteric fossa.
• Formed by:
  
  • Superior gluteal artery.
  • Ascending branch of medial circumflex femoral artery.
  • Ascending branch of lateral circumflex femoral artery.
  • Inferior gluteal artery usually joins the anastomosis.
• Branches from the anastomosis pass along the femoral neck and combine with the retinacular fibers of the capsule to supply the head of femur.
• In fractures of the neck of the femur, except pertrochanteric fractures or fractures outside the capsule, the blood supply via retinacular arteries is compromised.
• This compromised blood supply can lead to avascular necrosis of the head of the femur.

Question 31

Sciatic nerve in gluteal region (40)

Answer 31

Sciatic Nerve in Gluteal Region:

• Root values are L4, L5, S1, S2, S3, arising from the sacral plexus.
• Enters the gluteal region through the greater sciatic foramen.
• Travels below the piriformis muscle and under the cover of the gluteus maximus.
• Crosses the posterior surface of the ischium along with its gemelli and quadratus femoris muscles.
• Runs downward between the greater trochanter and ischial tuberosity.
• Enters the back of the thigh at the lower border of the gluteus maximus.
• Does not give any branches in the gluteal region.
• Terminates by dividing into the tibial and common peroneal nerves, although the level of this division is variable.
• At this level of division, the nerve is an immediate posterior relation of the hip joint. In cases of posterior dislocation of the hip joint, the nerve may be damaged, leading to paralysis of muscles supplied by it.
• This damage can result in foot drop.

Question 32

A young man presented with a penetrating injury to the back of the midthigh. On examination of the leg and foot, features consistent with a sciatic nerve lesion are present. List the deformities and disabilities found in his leg and foot, explaining the neuroanatomical basis for each. (60 marks)

Answer 32

Disabilities:
1. Loss of all movements below the knee:
- Absence of flexion of the knee due to paralysis of hamstrings:
- Hamstring muscles, including the long head of biceps femoris, semimembranosus, semitendinosus, and ischial part of the adductor magnus, are supplied by the tibial part of the sciatic nerve.
- Absence of dorsiflexion of foot due to paralysis of muscles of the anterior compartment of the leg and extensor digitorum brevis on the dorsum of the foot:
- Muscles of the anterior compartment of the leg, including tibialis anterior, extensor digitorum longus, extensor hallucis longus, and peroneus tertius, along with extensor digitorum brevis, are supplied by the deep peroneal nerve, a terminal branch of the common peroneal nerve.
- Absence of plantar flexion of the foot due to paralysis of muscles of the posterior compartment of the leg:
- Muscles of the posterior compartment of the leg, such as gastrocnemius, soleus, tibialis posterior, flexor digitorum longus, flexor hallucis longus, and plantaris, are supplied by the tibial nerve, a terminal branch of the sciatic nerve.
- Absence of inversion and eversion of the foot:
- Inversion of the foot is primarily done by tibialis anterior and tibialis posterior, supplied by deep peroneal and tibial nerves respectively, both branches of the sciatic nerve.
- Eversion of the foot is mainly done by peroneus longus and peroneus brevis, supplied by the superficial peroneal nerve, a terminal branch of the common peroneal nerve.
- Absence of intrinsic movements of the foot due to paralysis of the intrinsic muscles of the foot:
- Intrinsic muscles of the sole are supplied by the medial and lateral plantar nerves, terminal branches of the tibial nerve. Additionally, extensor digitorum brevis on the dorsum of the foot is supplied by a terminal branch of the deep peroneal nerve.

Deformities:
- Foot drop:
- Due to the paralysis of plantar flexors and dorsiflexors of the foot, which are supplied by branches of the sciatic nerve, the foot cannot be voluntarily dorsiflexed or plantar flexed. Due to gravity, the foot remains plantar flexed, resulting in foot drop.

Question 33

50 yrs old somapala met with a road traffic accident &was admitted to the hospital. The clinician found that his left lower limb shortened and laterally rotated.

a.Explain the anatomical basis of above condition. (30)

Answer 33

The left lower limb of Somapala appears shortened and laterally rotated due to the following anatomical mechanisms:

1. Shortening:
   
   • Fracture at the proximal half of the femur causes the proximal segment to be flexed by the illiacus and psoas muscles.
   • The gluteus medius and minimus muscles, attaching proximally to the femur, contribute to the abduction of the proximal segment.
   • Simultaneously, the distal segment is pulled medially by the adductor muscles, which are attached distal to the fracture site.
   • This results in shortening due to the flexion of the proximal segment by the illiacus and psoas muscles and the medial pull on the distal segment by the adductor muscles.
2. Lateral Rotation:
   
   • The abduction of the proximal segment by the gluteus medius and minimus muscles contributes to lateral rotation.

Question 34

Describe the boundaries and contents of the adductor canal. (60)

Answer 34

The intermuscular space situated on the medial side of the middle 1/3 of the thigh is known as the adductor canal or subsartorial canal. Here are its key features:

• Location and Extent:
  
  • Situated on the medial side of the middle 1/3 of the thigh.
  • Extends:
    
    • Above: from the apex of the femoral triangle.
    • Below: to the tendinous opening in the adductor magnus (adductor hiatus).
• Structure:
  
  • Triangular in cross-section.
• Boundaries:
  
  • Anterolateral wall: vastus medialis.
  • Posteromedial wall/floor: adductor longus (above) and adductor magnus (below).
  • Medial wall/roof: fibrous membrane joining anterolateral and posteromedial walls.
    
    • Roof is overlapped by the Sartorius muscle.
    • Subsartorial plexus of nerves lies on fibrous roof undercover of Sartorius.
• Contents:
  
  • Femoral Artery:
    
    • Enters the canal at the apex of the femoral triangle.
    • Gives off muscular branches and a descending genicular branch within the canal.
    • Leaves the adductor canal through the opening in the adductor magnus muscle to continue as the popliteal artery in the popliteal fossa.
  • Femoral Vein:
    
    • Begins as the upward continuation of the popliteal vein from the popliteal fossa.
    • Lies posterior to the femoral artery in the upper part and lateral to the artery in the lower part of the canal.
  • Saphenous Nerve:
    
    • Crosses the femoral artery anteriorly from lateral to medial side.
    • Leaves the canal with the saphenous artery by piercing the fibrous roof.
  • Branches of Obturator Nerve:
    
    • The anterior division emerges at the lower border of the adductor longus, gives branches to the subsartorial plexus, and ends by supplying the femoral artery.
    • The posterior division of the obturator nerve runs on the anterior surface of the adductor magnus, accompanies the femoral and popliteal arteries, and ends by supplying the knee joint.

The adductor canal serves as a crucial pathway for vessels and nerves traversing between the thigh and the popliteal fossa.

Question 35

Medial meniscus of the knee joint is more liable to get injured than the lateral meniscus (25 Marks) [22nd Repeat]

Answer 35

• Menisci are intracapsular and extra-synovial fibrocartilaginous crescentic rings that are attached to the condylar surfaces of the tibia.
• They are triangular in cross-section and deepen the articular surfaces while aiding in shock absorbance.
• There are two menisci: the medial and lateral.

Factors making the medial meniscus more vulnerable to injury:
1. The medial meniscus is firmly attached to the knee joint capsule and tibial collateral ligament, making it less mobile. Forces on the capsule or collateral ligament directly transmit to the meniscus.
2. Unlike the lateral meniscus, the lateral meniscus is not attached to the capsule or collateral ligament due to the intervention of the popliteus tendon. Some fibers from the popliteus muscle are attached to the posterior convexity of the lateral meniscus, making it more mobile during sudden movements.
3. There is greater anteroposterior movement in the medial condyle of the femur, increasing the likelihood of the medial meniscus getting trapped between the moving surfaces of the tibia and femur.
- The medial meniscus may be damaged during forcible abduction and external rotation of the leg, such as kicking a football.
- Sometimes, the torn meniscus may get lodged within the joint, resulting in a bucket handle lesion and a locked knee.

Question 36

Describe the medial longitudinal arch of the foot (30 marks)
[24th Proper, 23rd Proper, 25th CA 4]

Answer 36

• The bones of the foot (tarsal and metatarsal) are arranged into two longitudinal and one transverse arch, crucial for locomotion and weight-bearing.

Medial Longitudinal Arch:
- The highest arch, located longitudinally on the medial side of the foot.
- Comprised of:
- Calcaneus
- Talus
- Navicular
- Three cuneiforms
- Medial three metatarsals.
- Structure resembles a bridge with two pillars and an apex:
- Anterior pillar: Medial three metatarsals.
- Posterior pillar: Calcaneal tuberosity.
- Apex: Talus.

Factors Contributing to Stability:

Muscles:
- Muscular tone primarily stabilizes the medial arch.
- Flexor hallucis longus tendon, flexor digitorum longus tendon to the second and third toes act as bowstrings.
- Short muscles of the first layer of the sole (e.g., adductor hallucis, medial part of flexor hallucis brevis) aid in stabilizing the joint.
- Tibialis anterior attaches to the medial cuneiform and first metatarsal, suspending the arch from above.
- Tibialis posterior has a fan-like insertion on the plantar surface, supporting the arch from below. Among these, the flexor hallucis longus tendon is the main stabilizing factor.

Ligaments:
- Plantar aponeurosis acts as the primary ligamentous support, resembling a bowstring between the two pillars.
- The spring ligament extends from the calcaneus to the navicular bone, supporting the talus head (apex) from below.
- Interosseous ligaments also contribute to maintaining the arch.

Bony:
- The sustentaculum tali acts as a shelf, supporting the head of the talus from below, providing minor stability.

Clinical Point:
- The medial arch may present abnormally high (Pes cavus) or collapsed (Pes planus/valgus) in clinical conditions.

Question 37

Discuss the important structures around the knee joint which are involved in maintaining the erect position. [40 marks] [24th Proper]

Answer 37

The knee joint, being a modified hinge joint, plays a crucial role in maintaining the erect position. Several important structures around the knee joint contribute to its stability and functionality:

• Knee joint has the line of gravity passing anteriorly, making it crucial for weight-bearing and stability in the erect posture.
• In the erect posture, the knee joint is extended, providing a more stable position with maximum contact of articular surfaces for weight transfer, while supporting ligaments remain taut.
• Muscular and bony support also aid in stabilizing the joint.
• The joint is located between the condyles of the femur and tibia, with a saddle joint between the femur and patella.
• The intercondylar eminence of the tibia prevents the sideways slipping of the femur on the tibia.
• The lateral femoral condyle is more prominent than the medial condyle, preventing lateral displacement of the patella.
• Fibrous capsular attachments to the femur, tibia, and patella ligament stabilize the joint, with the capsule also attached to the menisci through coronary ligaments.
• The quadriceps femoris tendon attaches to the patella and continues through the patella ligament to the tibial tuberosity, providing anterior stability to the joint.
• Patella retinacula connect the patella with the tibia, and medial patella retinacula fibers, along with vastus medialis fibers, prevent lateral dislocation of the patella by stabilizing it medially.
• Tibial collateral ligament provides medial stability to the knee joint, while the fibular collateral ligament provides lateral stability.
• The oblique popliteal ligament provides stability posteriorly.
• Anterior and posterior cruciate ligaments prevent forward and backward displacement of the tibia on the femur, respectively, contributing to anteroposterior stability.
• Arcuate popliteal ligament and anterior and posterior meniscofemoral ligaments also provide stability to the joint.
• Menisci increase the depth of articular surfaces of the tibial condyles, acting as shock absorbers and stabilizers.
• The locking mechanism in the knee joint medially rotates the femur on the tibia to lock the knee joint in extension, aided by the long anteroposterior length of the medial femoral condyle.

Question 38

Describe the arterial anastomoses in gluteal region and back of thigh. (35 marks) [25th Proper]

Answer 38

Arterial anastomoses in the gluteal region and back of the thigh establish communication between the internal iliac and external iliac arteries. Various arteries contribute to these anastomoses, including the femoral artery, profunda femoris artery, lateral and medial circumflex femoral arteries, superior and inferior gluteal arteries, and obturator artery.

In the gluteal region, two main anastomotic connections exist: the trochanteric and cruciate anastomoses.

Trochanteric Anastomosis:
- Located at the trochanteric fossa.
- Formed by:
- Descending branch of the superior gluteal artery.
- Ascending branch of the medial circumflex femoral artery.
- Ascending branch of the lateral circumflex femoral artery.
- Inferior gluteal artery.
- These branches pass along the femoral neck with retinacular fibers to supply the femoral head.

Cruciate Anastomosis:
- Located at the lesser trochanter.
- Formed by:
- Transverse branch of the medial circumflex femoral artery.
- Transverse branch of the lateral circumflex femoral artery.
- Ascending branch of the 1st perforating artery.
- Descending branch of the inferior gluteal artery.

Additionally, in the proximal part of the thigh, other anastomotic connections include:
1. Between the medial circumflex femoral artery and obturator artery.
2. Between the superior gluteal artery and superficial circumflex iliac artery.

At the back of the thigh, the profunda femoris artery gives off four perforating arteries, passing backward through the adductor magnus. The first passes above, the second through, and the third and fourth below the adductor brevis. These arteries form a series of anastomoses with each other, with the cruciate anastomosis above, and with the popliteal artery below. The second and third perforating arteries supply nutrient arteries to the femur, and a nutrient artery may arise from the fourth.

These anastomotic connections provide an alternate route of blood supply to the limbs, ensuring adequate circulation even if one pathway is compromised.

Question 39

A. Briefly describe the ligaments stabilizing the knee joint. (40 marks) [25th repeat]

Answer 39

The knee joint, being the largest and most complex joint in the body, relies on several ligaments to maintain stability:

• Tibial Collateral Ligament: Originating from the medial epicondyle, this ligament attaches to the medial surface of the upper tibia and the medial meniscus, providing substantial medial stability.
• Fibular Collateral Ligament: Attached to the lateral femoral condyle and the head of the fibula, this strong cord-like ligament offers lateral stability to the knee joint.
• Oblique Popliteal Ligament: Formed as an expansion of the tendon of the semimembranosus muscle, this ligament blends with the knee joint capsule at the back, contributing to posterior stability.
• Arcuate Popliteal Ligament: Shaped like a “Y” and thickening the posterior capsule, this ligament aids in providing stability to the knee joint.
• Anterior Cruciate Ligament (ACL): Extending from the tibial intercondylar area to the lateral femoral condyle, the ACL prevents forward displacement of the tibia on the femur.
• Posterior Cruciate Ligament (PCL): Running from the intercondylar area of the tibia to the medial femoral condyle, the PCL prevents backward displacement of the tibia on the femur, crucial for activities like walking downstairs.
• Cruciate Ligaments: Together, the ACL and PCL offer anteroposterior stability to the knee joint.
• Coronary Ligaments: Vital for the stability of the menisci, these ligaments anchor them securely to the joint capsule.
• Anterior and Posterior Meniscofemoral Ligaments: These ligaments connect the lateral meniscus with the medial femoral condyle, contributing to stability.
• Transverse Ligament: Connecting the lateral and medial menisci anteriorly, this ligament adds further stability to the joint.

Overall, these ligaments work together to ensure the stability and proper functioning of the knee joint during various activities.

Question 40

Briefly describe the femoral triangle and its contents. (35 marks) [26th Repeat]

Answer 40

• Femoral triangle is a gutter-shaped inverted triangle located in the upper anterior thigh.
  Boundaries:
  
  • Medial: Medial border of adductor longus
  • Lateral: Medial border of sartorius
  • Superior: Inguinal ligament
  • Floor: Comprised of iliacus, psoas, pectineus, adductor longus (from lateral to medial)
  • Roof: Consists of skin, superficial fascia, and fascia lata
  • Apex: Continuous with the adductor canal below.

Contents:
- Femoral triangle contains the femoral nerve, artery, vein, and inguinal lymph nodes from lateral to medial.
- Nerve to pectineus branches off from the femoral nerve within the triangle.
- Femoral branch of genitofemoral nerve lies between the femoral nerve and artery.
- Transversalis fascia in front and psoas fascia behind fuse with the adventitia of femoral vessels to form the femoral sheath.
- Femoral nerve lies outside the sheath, while femoral vessels are inside.
- Lateral cutaneous nerve of the thigh is located in the upper lateral corner of the triangle.
- Femoral canal, adjacent to the medial side of the femoral vein, contains Cloquet’s lymph nodes.
- Widest abdominal end of the canal is called the femoral ring, with boundaries: anterior - inguinal ligament, medial - lacunar ligament, posterior - pectineal ligament, lateral - femoral vein.
- Femoral nerve passes in the gutter between iliacus and psoas, supplying all muscles in the thigh’s extensor compartment.
- Femoral artery enters the triangle at the mid-inguinal point, lying on the tendon of psoas major.
- It gives off the profunda femoris artery from the lateral side, along with the lateral and medial circumflex femoral arteries.
- Femoral vein enters the triangle at its apex, posterior to the artery, and moves upward, lying on the medial side of the artery.
- It receives the profunda femoris vein posteriorly and saphenous vein anteriorly.

Clinical:
- Femoral hernia enters the femoral canal through the femoral ring. In hernia repair, the accessory obturator artery on the lacunar ligament may be at risk.
- Incompetence of valves at the saphenofemoral junction can lead to varicosities in the great saphenous vein.
- Femoral artery is commonly used for assessing pulsations, arterial cannulations, and creating arteriovenous fistulas.

Question 41

Outline the blood supply of the femoral head and its clinical significance (30 marks)

Answer 41

The head of the femur benefits from a robust vascular network, which forms functional anastomoses crucial for preventing avascular necrosis. The blood supply originates from three main sources:

1. Retinacular Arteries:
   
   • These arteries are the primary suppliers of blood to the femoral head.
   • Named for being anchored by retinacular fibers of the capsule as they ascend around the femoral neck.
   • Originates from the Trochanteric anastomosis, located in the trochanteric fossa, mainly contributed by the circumflex femoral artery.
   • The trochanteric anastomosis comprises ascending branches of the medial and lateral circumflex femoral arteries, along with branches of the superior and inferior gluteal arteries.
2. Nutrient Artery:
   
   • An intramedullary vessel that ascends through the femoral diaphysis.
   • Arises from the 2nd or 3rd perforating branch of the Profunda Femoris artery.
3. Artery of Ligamentum Teres Femoris:
   
   • Originates from the posterior branch of the obturator artery.
   • Particularly significant in children, where it helps maintain femoral head viability until around age seven when it typically atrophies, though it may persist in some cases.
   • Unable to sustain viability independently.

Clinical Significance:
- Femoral neck fractures pose risks to the arterial supply, with two primary types:
1. Extracapsular:
- Disrupts the intraosseous blood supply while leaving the retinacular arteries intact, preventing avascular necrosis.
2. Intracapsular:
- Involves disruption of both retinacular and nutrient arteries, leading to avascular necrosis as the artery of the ligamentum teres femoris cannot maintain viability independently.