Mbbs 1st year thursday exam syllabus knee joint / popliteal fossa / femoral artery / profunda femoral artery / popliteal artery / leg muscles
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Here are your complete Thursday exam notes, sourced from Gray's Anatomy for Students and the THIEME Atlas of Anatomy:
🦵 MBBS 1st Year - Anatomy Exam Notes
Thursday Exam: Lower Limb
1. KNEE JOINT
Type: Largest synovial joint in the body. Primarily a hinge joint.
Two articulations:
- Femur + Tibia (weight-bearing)
- Patella + Femur (allows quadriceps pull to be directed anteriorly without tendon wear)
Articular surfaces: Covered by hyaline cartilage
- Two femoral condyles
- Superior surfaces of tibial condyles
- Posterior patella + V-shaped trench on anterior distal femur
Menisci
- Two fibrocartilaginous C-shaped cartilages
- Medial meniscus - attached to joint capsule AND tibial collateral ligament (less mobile, more commonly injured)
- Lateral meniscus - NOT attached to capsule (more mobile)
- Connected anteriorly by the transverse ligament of the knee
- Lateral meniscus connected to tendon of popliteus muscle
- Function: improve congruency between femoral condyles and tibial plateau
Meniscal Injury (clinical): Forceful rotation/twisting. Patient gets pain, locking, clicking, giving way. MRI is gold standard.
Ligaments
Collateral Ligaments (resist valgus/varus stress):
| Ligament | Attachment |
|---|---|
| Tibial (medial) collateral | Medial femoral epicondyle → medial tibia (above pes anserinus) |
| Fibular (lateral) collateral | Lateral femoral epicondyle → head of fibula |
- Tibial collateral is attached to medial meniscus - hence medial meniscus more prone to injury
Cruciate Ligaments (inside intercondylar region):
| Ligament | Tibial attachment | Femoral attachment | Function |
|---|---|---|---|
| ACL | Anterior intercondylar area | Back of lateral wall of intercondylar fossa | Prevents anterior displacement of tibia |
| PCL | Posterior intercondylar area | Medial wall of intercondylar fossa | Prevents posterior displacement of tibia |
- ACL crosses lateral to PCL in the intercondylar region
Other ligaments:
- Patellar ligament - continuation of quadriceps tendon, from patella to tibial tuberosity
- Oblique popliteal ligament - from semimembranosus tendon, reinforces posterior capsule
- Arcuate popliteal ligament - posterolateral capsule
Locking Mechanism
- In full extension: flat areas of femoral condyles contact tibia (more stable)
- In flexion: curved/rounded posterior condyle surfaces contact tibia
- Locking = medial rotation of femur on tibia (or lateral rotation of tibia on femur)
- Unlocking = popliteus muscle (laterally rotates femur = medially rotates tibia to "unlock")
Movements & Muscles
| Movement | Muscles |
|---|---|
| Flexion | Hamstrings (biceps femoris, semitendinosus, semimembranosus), gastrocnemius, popliteus |
| Extension | Quadriceps femoris |
| Medial rotation (of flexed leg) | Popliteus, semimembranosus, semitendinosus |
| Lateral rotation (of flexed leg) | Biceps femoris |
Blood Supply to Knee
Anastomotic network from: descending genicular (from femoral) + genicular branches of popliteal artery (superior medial, superior lateral, middle, inferior medial, inferior lateral genicular arteries) + descending branch of lateral circumflex femoral + circumflex fibular.
2. POPLITEAL FOSSA
Shape: Diamond-shaped space posterior to knee joint
Boundaries
| Boundary | Structure |
|---|---|
| Upper medial | Semimembranosus + semitendinosus |
| Upper lateral | Biceps femoris |
| Lower medial | Medial head of gastrocnemius |
| Lower lateral | Plantaris + lateral head of gastrocnemius |
| Floor | Posterior femur, posterior knee joint capsule, popliteus muscle |
| Roof | Deep fascia (continuous with fascia lata above and deep fascia of leg below) |
Contents (superficial to deep - medial to lateral)
From posterior to anterior:
- Tibial nerve (most superficial, most medial)
- Popliteal vein (middle)
- Popliteal artery (deepest, most medial - direct continuation of femoral)
- Common fibular nerve - most lateral, runs along medial border of biceps femoris tendon
Mnemonic: TAN (Tibial, Artery, Nerve) - from lateral to medial: Common fibular N → Tibial N → Popliteal V → Popliteal A
Nerves in Popliteal Fossa
Tibial nerve:
- Descends vertically through fossa
- Exits deep to plantaris, enters posterior compartment of leg
- Supplies gastrocnemius, soleus, plantaris, popliteus in the fossa
Common fibular nerve:
- Follows biceps femoris tendon along lateral margin
- Winds around neck of fibula
- Divides into deep fibular and superficial fibular nerves
- Most commonly injured nerve at the knee (vulnerable at fibular neck)
3. FEMORAL ARTERY
Origin: Continuation of external iliac artery, begins as it passes under the inguinal ligament
Palpation: Femoral triangle, just below inguinal ligament, midway between ASIS and pubic symphysis (midinguinal point)
Course:
- Femoral triangle (under inguinal ligament)
- Adductor canal (subsartorial canal) - between vastus medialis and adductor muscles, under sartorius
- Passes through adductor hiatus in adductor magnus → becomes popliteal artery
Branches of Femoral Artery
- Superficial epigastric artery - supplies anterior abdominal wall
- Superficial circumflex iliac artery - supplies lateral thigh/iliac region
- Superficial external pudendal artery - perineum
- Deep external pudendal artery - perineum
- Profunda femoris (Deep artery of thigh) - LARGEST branch
- Descending genicular artery - contributes to anastomosis around knee
4. PROFUNDA FEMORIS ARTERY (Deep Artery of Thigh)
Origin: From lateral side of femoral artery in the femoral triangle
Course:
- Passes posteriorly between pectineus and adductor longus
- Then between adductor longus and adductor brevis
- Then between adductor longus and adductor magnus
- Terminates by perforating adductor magnus to connect with branches of popliteal artery
It is the MAJOR blood supply to the thigh
Branches of Profunda Femoris
1. Lateral Circumflex Femoral Artery
Originates from lateral side of profunda (or directly from femoral)
- Ascending branch - ascends deep to TFL, connects with medial circumflex around femoral neck
- Descending branch - descends deep to rectus femoris into vastus lateralis, anastomoses near knee
- Transverse branch - circles proximal femur shaft, forms cruciate anastomosis with medial circumflex, inferior gluteal, and 1st perforating artery
2. Medial Circumflex Femoral Artery
Originates from posteromedial profunda (or directly from femoral)
- Passes medially between pectineus + iliopsoas, then between obturator externus + adductor brevis
- Gives acetabular branch (enters hip joint, supplies femoral head)
- Main trunk passes over adductor magnus, participates in trochanteric and cruciate anastomoses
- Key clinical point: Main blood supply to femoral head - damaged in femoral neck fractures → avascular necrosis
3. Perforating Arteries (3 in number)
- All three penetrate adductor magnus near linea aspera attachment
- Supply posterior compartment of thigh
- Anastomose longitudinally + contribute to anastomoses around hip and knee
5. POPLITEAL ARTERY
Origin: Continuation of femoral artery after it passes through adductor hiatus
Course:
- Enters popliteal fossa → runs between gastrocnemius and popliteus muscles
- Passes deep under tendinous arch of soleus
- Terminates at lower border of popliteus by dividing into:
- Anterior tibial artery
- Posterior tibial artery
It is the DEEPEST structure in the popliteal fossa (closest to bone)
Branches of Popliteal Artery
- Sural arteries (2) - one each side, supply gastrocnemius, soleus, and plantaris
- Superior medial genicular
- Superior lateral genicular
- Middle genicular - supplies cruciate ligaments and synovium
- Inferior medial genicular
- Inferior lateral genicular (Last 5 form the anastomotic network around the knee)
Terminal Branches:
Anterior tibial artery:
- Passes forward through aperture in upper part of interosseous membrane
- Supplies anterior compartment of leg
- Continues as dorsalis pedis artery on dorsum of foot
Posterior tibial artery:
- Supplies posterior and lateral compartments
- Descends through deep posterior compartment
- Passes through tarsal tunnel behind medial malleolus into sole
- Branches: circumflex fibular artery + fibular (peroneal) artery
- Fibular artery - runs lateral to tibialis posterior along medial crest of fibula; supplies posterior + lateral compartments; has perforating branch through inferior interosseous membrane
6. MUSCLES OF THE LEG (Three Compartments)
Anterior Compartment
Nerve: Deep fibular nerve | Action (general): Dorsiflexion, extension of toes, inversion
| Muscle | Origin | Insertion | Nerve | Action |
|---|---|---|---|---|
| Tibialis anterior | Lateral surface of tibia + interosseous membrane | Medial cuneiform + base of metatarsal I | Deep fibular (L4, L5) | Dorsiflexion + inversion of foot |
| Extensor hallucis longus | Middle ½ of medial fibula + interosseous membrane | Base of distal phalanx of great toe | Deep fibular (L5, S1) | Extension of great toe + dorsiflexion |
| Extensor digitorum longus | Proximal ½ of medial fibula + lateral tibial condyle | Dorsal digital expansions of lateral 4 toes | Deep fibular (L5, S1) | Extension of lateral 4 toes + dorsiflexion |
| Fibularis tertius | Distal medial fibula | Dorsomedial base of metatarsal V | Deep fibular (L5, S1) | Dorsiflexion + eversion |
Lateral Compartment
Nerve: Superficial fibular nerve | Action: Eversion of foot, plantarflexion
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| Fibularis longus | Upper 2/3 lateral fibula | Plantar surface of medial cuneiform + base of metatarsal I (crosses sole obliquely) | Eversion + plantarflexion; supports transverse arch |
| Fibularis brevis | Lower 2/3 lateral fibula | Tuberosity at base of metatarsal V | Eversion + plantarflexion |
Posterior Compartment
Superficial group (Triceps surae + plantaris):
Nerve: Tibial nerve | Action: Plantarflexion
| Muscle | Details |
|---|---|
| Gastrocnemius | Two heads from femoral condyles; powerful plantarflexor + assists knee flexion; inserts via calcaneal (Achilles) tendon |
| Soleus | From fibular head + soleal line of tibia; deep to gastrocnemius; inserts via Achilles tendon; postural muscle |
| Plantaris | Small, from lateral supracondylar line; thin tendon runs between gastrocnemius and soleus; inserts medially into calcaneus |
| Triceps surae = gastrocnemius + soleus (share Achilles tendon) |
Deep group:
Nerve: Tibial nerve | Action: Plantarflexion + toe flexion + inversion
| Muscle | Origin | Insertion | Action |
|---|---|---|---|
| Popliteus | Lateral femoral condyle | Posterior tibia above soleal line | Unlocks knee (medially rotates tibia / laterally rotates femur) |
| Tibialis posterior | Posterior tibia + fibula + interosseous membrane | Navicular + all tarsals except talus | Plantarflexion + inversion; supports medial arch |
| Flexor digitorum longus | Posterior tibia | Bases of distal phalanges lateral 4 toes | Flexion of lateral 4 toes + plantarflexion |
| Flexor hallucis longus | Posterior fibula | Base of distal phalanx great toe | Flexion of great toe + plantarflexion |
FHL - grooves around medial malleolus and sustentaculum tali ("the dancer's muscle", most powerful toe flexor)
Quick Nerve Summary for Leg
| Compartment | Nerve | From |
|---|---|---|
| Anterior | Deep fibular nerve | Common fibular nerve |
| Lateral | Superficial fibular nerve | Common fibular nerve |
| Posterior (all) | Tibial nerve | Sciatic nerve |
Key Clinical Points for Exam
- Common fibular nerve injury at fibular neck → foot drop (loss of dorsiflexion + eversion)
- Tibial nerve injury at tarsal tunnel → tarsal tunnel syndrome (plantar foot numbness)
- Popliteal artery is the most vulnerable vessel in posterior knee dislocations
- Medial meniscus more commonly torn than lateral (because attached to capsule + TCL - "unhappy triad" = ACL + MCL + medial meniscus)
- ACL tear → positive anterior drawer test / Lachman test
- PCL tear → positive posterior drawer test
- Medial circumflex femoral = main supply to femoral head → femoral neck fractures = avascular necrosis risk
- Achilles tendon = longest and strongest tendon in body; rupture common in athletes (Thompson test)
Sources: Gray's Anatomy for Students; THIEME Atlas - General Anatomy & Musculoskeletal System
Good luck tomorrow! 🎯
All clinicals of knee
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I now have everything needed. Let me compile the complete clinical notes.
🦵 ALL CLINICALS OF THE KNEE JOINT
(MBBS 1st Year - Anatomy Exam Prep)
1. UNHAPPY TRIAD (O'Donoghue's Triad)
Structures injured: ACL + Tibial Collateral Ligament (MCL) + Medial Meniscus
Mechanism: Valgus + external rotation force on a flexed knee (e.g., football tackle from the side, skiing injury)
What happens step by step:
- Knee forced into valgus + external rotation
- ACL becomes taut (acts as fulcrum)
- MCL gets stressed and tears
- Medial meniscus tears (attached to MCL - so pulled along)
- ACL finally ruptures
Why swelling is delayed (hemarthrosis)?
- ACL is extra-synovial but intracapsular - rich blood supply
- When torn, blood enters joint cavity and irritates synovium
- Swelling develops gradually over hours (not immediate)
Medial meniscus is more commonly torn than lateral because:
- Medial meniscus is firmly attached to joint capsule AND MCL
- Less mobile - cannot "escape" the damaging force
- Lateral meniscus is free from capsule - more mobile, moves out of the way
2. MENISCAL INJURIES
Mechanism: Forceful rotation/twisting of the knee. Can occur even without significant trauma (degenerate tears in older patients).
Symptoms:
- Pain at medial or lateral joint line
- Knee locking or clicking (bucket-handle tear)
- Sensation of knee "giving way"
- Swelling (intermittent, delayed - unlike ligament tears)
Types of tears:
| Type | Description |
|---|---|
| Bucket-handle tear | Longitudinal tear; displaced fragment into intercondylar notch → causes locking |
| Vertical tear | Perpendicular to tibial plateau |
| Horizontal tear | Parallel to long axis of meniscus |
| Radial tear | Perpendicular to circumferential fibers; disrupts hoop stresses |
| Flap tear | |
| Degenerate tear | Older patients, no specific injury |
Investigation: MRI is gold standard (identifies tear type + associated injuries)
Clinical tests:
- McMurray's test - flex knee fully, then extend with internal/external rotation; click/pain at joint line = positive
- Apley's grind test - prone patient, knee 90°, compress + rotate tibia on femur; pain = positive
- Thessaly test - standing on affected leg, knee 20° flexion, rotate body; joint-line pain = positive
Treatment:
- Tears with mechanical symptoms (locking, giving way) → arthroscopic repair or debridement
- Factors favoring repair: young patient, early presentation, simple tear, vascular outer 1/3 of meniscus, stable knee
- Degenerate tears without mechanical symptoms → conservative first
Why meniscal loss is dangerous: Loss of meniscus removes shock absorption and hoop stress protection → accelerates cartilage degeneration → osteoarthritis
3. ANTERIOR CRUCIATE LIGAMENT (ACL) INJURY
Most common serious knee ligament injury
Mechanism: Twisting/landing injury in pivoting sports (football, basketball, skiing). Audible "pop," immediate swelling, inability to continue activity ("carried off field").
Why females are at higher risk:
- Smaller ligaments
- Smaller femoral notch
- Different landing biomechanics
Clinical Tests:
| Test | How | Positive = |
|---|---|---|
| Lachman test | Knee at 30° flexion, pull tibia anteriorly | Excessive anterior translation (most sensitive test) |
| Anterior drawer test | Knee at 90° flexion, pull tibia anteriorly | Anterior translation of tibia |
| Pivot shift test | Extend knee with valgus force + internal rotation | Clunk as tibia relocates (specific for ACL) |
Note: Anterior drawer can be falsely negative if hamstrings are in spasm (tense) or if the knee cannot be bent to 90° due to pain. Lachman test is therefore preferred.
Investigation: MRI - confirms tear, identifies associated meniscal/cartilage injury
Treatment:
- Initial: RICE, brace, physiotherapy, reduce swelling
- Surgical reconstruction: indicated in multiligament injuries, persistent instability, young/high-demand athletes
- Reconstruction uses: patellar ligament graft OR hamstring tendons (semitendinosus/gracilis) - hamstring grafts have less donor site morbidity
- Surgery best when: acute swelling has settled and knee has full range of motion
4. POSTERIOR CRUCIATE LIGAMENT (PCL) INJURY
Much less common than ACL (1:10 ratio)
Mechanism: Dashboard injury (knee hits dashboard in forced flexion - tibia pushed posteriorly); direct fall on flexed knee
Clinical Test:
- Posterior drawer test - knee at 90°, push tibia posteriorly → excessive posterior translation
- Sag sign - with knee at 90°, tibia sags posteriorly compared to other side
Treatment: Often conservative (PCL has better healing capacity than ACL)
5. COLLATERAL LIGAMENT INJURIES
Medial Collateral Ligament (MCL) Injury
Mechanism: Valgus stress (force from lateral side pushing knee medially)
- MCL has superficial and deep layers; deep layer attached to medial meniscus
- Most common collateral ligament injury
- Usually heals with conservative management (brace + physiotherapy)
Test: Valgus stress test at 0° and 30° flexion
Lateral Collateral Ligament (LCL) Injury
Mechanism: Varus stress
- LCL works with popliteus, biceps femoris, popliteofibular ligament, and iliotibial band = posterolateral corner (PLC)
- Less likely to heal conservatively
- Often requires surgical reconstruction
Test: Varus stress test at 0° and 30° flexion
6. BURSITIS AROUND THE KNEE
| Bursa | Location | Condition |
|---|---|---|
| Prepatellar bursa | Subcutaneous, anterior to patella | "Housemaid's knee" - repeated kneeling; swelling over patella |
| Superficial infrapatellar bursa | Subcutaneous, over patellar ligament | "Clergyman's knee" - kneeling more upright |
| Deep infrapatellar bursa | Deep to patellar ligament | Overuse/irritation |
| Suprapatellar bursa | Above patella, communicates with joint cavity | Fills with fluid in knee effusion |
| Semimembranosus bursa | Posterior medial | Baker's cyst |
Baker's Cyst (Popliteal Cyst)
- Distension of semimembranosus bursa (or posterior joint capsule herniation)
- Located in popliteal fossa, medial side
- Associated with intraarticular pathology (meniscal tear, OA, RA)
- Presents as posterior knee swelling
- Can rupture → pain/swelling in calf (mimics DVT)
- Treatment: address underlying cause; aspiration/excision if symptomatic
7. PATELLAR DISLOCATION
Direction: Almost always lateral dislocation
Mechanism: Twisting injury; more common in females, knock-kneed (genu valgum), shallow trochlear groove
Predisposing factors:
- Shallow femoral trochlear groove
- Genu valgum (knock knee)
- High-riding patella (patella alta)
- Weak VMO (vastus medialis oblique)
- Abnormal Q-angle (angle between quadriceps force and patellar tendon)
Clinical: Obvious deformity, medial retinaculum tear, medial patellar tenderness, associated osteochondral fracture (cartilage chip)
Apprehension test: Gently push patella laterally - patient becomes anxious/resists = positive
8. EXTENSOR MECHANISM RUPTURE
Structures: Quadriceps tendon OR patellar tendon rupture
Risk factors: Steroid use, steroid injections, chronic kidney disease, previous knee surgery
Presentation: Sudden pain, swelling, inability to actively extend knee, palpable gap in tendon
Treatment: Urgent surgical repair (delay leads to permanent loss of extension)
9. OSTEOCHONDRAL / ARTICULAR CARTILAGE INJURY
Important features:
- Hyaline cartilage = no blood vessels, no lymphatics, no nerves → very limited healing capacity
- Partial-thickness defects: do NOT heal
- Full-thickness defects in young: may form fibrocartilage repair tissue
- Can be associated with ACL tears or patellar dislocations
Treatment options for full-thickness defects:
- Microfracture - drill holes through subchondral bone to release marrow cells
- Microfracture + collagen membrane (enhanced)
- Mosaicplasty - osteochondral plugs transplanted from non-weight-bearing area
- ACI/MACI - autologous chondrocyte implantation (harvest, culture, re-implant)
- Osteochondral allograft
10. OSTEOARTHRITIS (OA) OF KNEE
Most common joint disease - degenerative loss of articular cartilage
Risk factors: Age, obesity, previous injury/meniscectomy, malalignment
Compartments: Medial > lateral > patellofemoral
X-ray findings (4 key signs):
- Loss of joint space (especially medial)
- Subchondral sclerosis (bone density increases under damaged cartilage)
- Osteophytes (bony spurs at joint margins)
- Subchondral cysts
Deformity: Medial OA → varus deformity (bow-legged)
Treatment ladder:
- Conservative: weight loss, physiotherapy, analgesia, bracing
- Injections: corticosteroid, hyaluronic acid
- Surgical: unicompartmental knee replacement (UKR) or total knee replacement (TKR)
TKR details (exam favourite):
- Femoral surface = metal; tibial surface = polyethylene in metal baseplate
- Cemented with PMMA (polymethylmethacrylate)
- CR (cruciate retaining) or PS (PCL sacrificing) designs
- Revision rate < 5% at 15 years
- Goal: correct mechanical axis, balance ligaments
11. GENU VALGUM & GENU VARUM
| Genu Valgum | Genu Varum | |
|---|---|---|
| Common name | Knock knee | Bow leg |
| Deformity | Knees touch, ankles apart | Ankles touch, knees apart |
| Mechanical axis | Lateral to knee | Medial to knee |
| Compartment OA | Lateral compartment | Medial compartment |
| Normal in children | Up to age 7 years | Up to age 2 years |
12. COMMON FIBULAR NERVE INJURY AT THE KNEE
Most commonly injured nerve at the knee - winds around neck of fibula (very superficial)
Causes: Fracture of fibular neck, tight plaster cast, pressure (crossing legs), knee dislocation
Result: Foot drop
- Loss of dorsiflexion (deep fibular nerve)
- Loss of eversion (superficial fibular nerve)
- High-stepping gait
- Sensory loss over dorsum of foot and lateral leg
13. POPLITEAL ARTERY INJURY
Most vulnerable in posterior knee dislocations (high-energy trauma)
Why dangerous: Popliteal artery is the deepest structure in the popliteal fossa, tightly bound to posterior joint capsule → torn in severe dislocations
Must check: Distal pulses (dorsalis pedis, posterior tibial), capillary refill, ABI (ankle-brachial index)
Complications: Limb ischemia → compartment syndrome → amputation if not urgently revascularized
14. ARTHROSCOPY OF THE KNEE
Entry portals: Anterolateral and anteromedial aspects of the knee
Uses: Diagnosis + treatment of meniscal tears, ACL reconstruction, cartilage procedures, synovial biopsy, removal of loose bodies
Advantage over open surgery: Less trauma, faster recovery, lower infection risk
Quick Clinical Test Summary Table
| Test | Structure tested | Positive finding |
|---|---|---|
| Lachman test (30° flex) | ACL | Anterior tibial translation |
| Anterior drawer (90° flex) | ACL | Anterior tibial translation |
| Posterior drawer (90° flex) | PCL | Posterior tibial translation |
| Pivot shift | ACL | Clunk on extension |
| Valgus stress test | MCL | Medial joint opening |
| Varus stress test | LCL | Lateral joint opening |
| McMurray's | Meniscus | Click + joint line pain |
| Apley's grind | Meniscus | Pain on compression + rotation |
| Patellar apprehension | Patella stability | Anxiety + resistance to lateral push |
| Sag sign | PCL | Tibia sags posteriorly at 90° |
| Thompson test | Achilles tendon | No plantarflexion on calf squeeze |
Sources: Gray's Anatomy for Students; Bailey & Love's Short Practice of Surgery 28th Ed; THIEME Atlas of Anatomy - General Anatomy & Musculoskeletal System
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