Pelvis/Hip/Thigh Flashcards Preview

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Flashcards in Pelvis/Hip/Thigh Deck (101):

Between which muscles does the posterior obturator nerve run?

Adductor Brevis & Magnus


Describe the vascular tree from the Aorta

  • Aorta bifurcates at L4
  • Common Iliacs bifurcate at S1
    • Internal Illiac
      • Obturator A.
      • Vesicular A.
      • Lateral Sacral A.
      • Inf & Sup Gluteal A.
      • Internal Pudendal A.
    • External Iliac
      • Profuda Femoris
        • MFCA
        • LFCA
      • Superficial Femoral A


What is the importance of the iliac cortical density?

  • Density: on the lateral, overylying slope of the sacral ala
  • Want to be behinding it when inserting SI screws to avoid L5 nerve root

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Muscles Making up the Floor of the Femoral Triangle

Lateral to Medial:

  • Illiacus
  • Psoas
  • Pectineus
  • Adductor Longus


In the lateral approach to the hip, where does the superior gluteal nerve run?

3-5cm proximal to the tip of the GT. Be careful when splitting gluteus medius


Signs of Sacral Dimorphism.

  1. Tongue in Groove Sign
  2. Lumberalized S1
  3. Sacralized L5
  4. Mamillary Bodies
  5. Oblong/Oval Foramen


*clinical significance: SI joint screw placement


Orientation of the Acetabulum

Anteverted 15-20 degrees


Space of Retzius

Potential space posterior to the pubic symphasis, infront of the bladder. 


Which artery supplies artery of the ligmentum teres?

Obturator A. 


What kind of joint is the hip joint?

Synovial Spheroid (Ball & Socket)


What landmark is used to determine coxa profund & protrusio?

Ilioischial Line


Centre Edge Angle of Wiberg

Angle between

  1. Vertical line passing through centre of femoral head
  2. Line from centre of femoral head to lateral edge of sourcil
  • Normal 25-40 degrees
  • Sign of hip dysplasia- acetabular coverage
  • Lateral Centre Edge Angle - measured on false profile view
  • Anterior Centre Edge Angle - measured on AP

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Which Xray views do you order to assess adult hip dysplasia?

  1. AP Pelvis
    • Crossover sign
    • Anterior center edge angle - acetabular coverage
    • Ischial Spine Sign
    • Protrusio/Coxa Profunda
    • Crowe Classification
  2. False Profile
    • Assess acetabular coverage with lateral center edge angle
  3. Dunn View
    • Assess femoral-head neck offset with alpha angle
    • Assess version of femoral neck


Which nerve root lays on the Sacral Ala?



Muscles Innervated by the Femoral Nerve

  1. Illiacus
  2. Psoas
  3. Pectineus
  4. Rectus Femoris
  5. Vastus Medialis
  6. Vastus Intermedius
  7. Vastus Lateralis
  8. Sartorius


Describe the Blood Supply to the Proxmal Femur

  1. Femoral Head: retincular branches of MFCA
  2. GT: LFCN
  3. Femoral Head via Ligamentum Teres: Branches of Obturator A.


Muscles Innervated by the Obturator N. 

  1. Adductor Magnus (also innervated by tibial branch of sciatic n.)
  2. Adductor Longus
  3. Adductor Brevis
  4. Gracilis


Label the Diagram Below

Q image thumb

A image thumb

How many vertebrae are fused in the Sacrum? Coccyx?

  • Sacrum - 5
  • Coccyx - 4-5


Describe the course of the Femoral Nerve

  1. Emerges between psoas and illiacus
  2. Superficial and medial to psoas
  3. Passes under inguinal ligament into femoral triangle (deep to sartorius). Gives off Saphenous N. branch
  4. Divides to innervate the quads


Muscles of the Anterior Compartment of the Thigh (4)

  1. Rectus Femoris
  2. Vastus Lateralis
  3. Vastus Medialis
  4. Vastus Intermedius


Muscles of the Posterior Compartment of the Thigh

  1. Biceps Femoris
  2. Semimembranosus
  3. Semitendinosus


Layers of the Abdominal Wall Encountered in a Pfannensteil Approach

Superifical to Deep

  1. Skin
  2. Subcutaneous Tissue
  3. Campers Fascia
  4. Anterior Rectus Sheath
  5. Rectus Abdominus
  6. Transversalis Fascia
  7. Extraperitoneal Connective Tissue
  8. Peritoneum


Variations in the course of Lateral Femoral Cutaneous Nerve?

  • Sartorius Type (36%): between sartorius and ITB
  • Posterior Type (32%): two main branches, one between sartorius and ITB, second crosses over ITB and runs posteriorly
  • Fan Type (32%): fans out between sartorius and ITB

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At what age to do the SI joints fuse?

50 years old


Blocks To Reduction in Dislocated Pediatric Hip

  1. Psoas Tendon
  2. Redundant Capsule
  3. Inverted Labrum
  4. Inverted Limbus
  5. Pulvinar
  6. Hypertrophied Ligamentum Teres
  7. Transverse Acetabular Ligament


Morel- Lavalee Lesion

  • Internal degloving of subcuatneous tissue off of underlying fascia
  • Usually reserved for lesions overlying the GT but can happen anywhere

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Branches of the Lumbosacral Plexus (hint, also the nerves of the posterior abdominal wall)

  1. Subcostal N. (T12)
  2. Iliohypogastric N.
  3. Ilioinguinal N.
  4. Genitofemoral N.
  5. Lateral Femoral Cutaneous N.
  6. Femoral N.
  7. Obturator N.
  8. Lumbosacral Trunk


When does the triradiate cartilage fuse?

14-16 years old


Ligamentes of the Pubic Symphasis

  1. Superior Pubic Ligament (stronger)
  2. Inferior (Arcuate) Public Ligament


What denotes an adequate AP Pelvis?

  1. Coccyx in line with symphasis
  2. Symmetric teardrops
  3. Symmetric obturator foramen
  4. Sacrococcygeal junction to superior symphasis
    1. 32mm in men
    2. 47mm in women
  5. Tip of coccyx to superior symphsis 1-3 cm


What two tendons make up the conjoint tendon of the thigh?

Long Head of Biceps Femoris & Semitendonosis


What fascia separates the middle and lateral window in the ilioinguinal approach?

Iliopectineal Fascia


Which nerve roots contribute to the Lumbar Plexus? Sacral Plexus?

  • Lumbar: L1-L4
  • Sacral L5-S4

*all except S4 divides into anterior and posterior branch


In patients undergoing S1 SI joint screw fixation. What is the most common deficit in this screw trajectory?

Great toe extension (L5 nerve root)


What is a reliable landmark for positioning of the acetabular cup in THA?

Transverse Acetabular Ligament


Nerves of the Posterior Abdominal Wall

  • Emerging Lateral to Psoas
    • Ilioinguinal N.
    • Illiohypogastric N.
    • LFCN
  • Emerging Medial to Psoas
    • Obturator N.
    • Lumbosacral Trunk
  • Emerging Between Psoas and Iliacus: Femoral N.
  • Peircing then running anterior to Psoas: Genitofemoral N.

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Acetabular Zones & Dangers

​Made by two intersecting perpendicular lines:

  1. ASIS to centre of acetabulum
  2. Line perpendicular to first
  • Posterior Superior (SAFE ZONE)
    • Risks: Sciatic N., Superior Gluteal N & vessels
  • Posterior Inferior
    • Next saftest zone. Keep screws <20mm
    • Risks: Sciatic N, inferior gluteal N and vessels, internal pudendal N and vessels
  • Anterior Superior (Avoid)
    • Risks: External Illiac A & V
  • Anterior Inferior (Avoid)
    • Risks: Obturator N & vessels


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Structures at risk with posteior illiac crest bone graft harvest?

  1. Superior gluteal A.-  runs in scaitic notch, stay superior to notch
  2. Cluneal N - runs 8cm lateral to SI joint stay medial and use vertical incision

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Peripheral Nerves of the Lumbosacral Plexus


Superior Gluteal N., N to Quadratus Femoris

Inferior Gluteal N, N. to Obturator Internus

Posterior Femoral Cutaneous N.

Pudendal N.

Sciatic N.

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Labrum of the Hip (Shape, Attachement & Function)

  • Shape: triangular cross section
  • Attachement
    • Anterior: marginal attachment
    • Posterior: continuous with cartilage
  • Function:
    • Deepens socket by 30%
    • Seals fluid flow


Ligaments of the SI Joint

  1. Posterior SI Ligaments
  2. Anterior SI Ligaments
  3. Interosseus Ligaments
  4. Sacrotuberous (sacrum to ischial tuberosity)
  5. Sacrospinal (sacrum to ischial spine)
  6. Illiolumbar (Illiac crest to 5th lumbar TP)


What is the interval for the posterior approach to the SI joint?

Gluteus Maximus (inferior gluteal n.) & Multifidus (posteior spinal n. branches)


Corona Mortis

Anastomosis between the Obturator A and:

  • External Iliac A, or
  • Inferior Epigastric A


  • Runs 4-9cm lateral to symphasis pubis at the intenal aspect of the pelvis brim
  • Ligate on approaches to the pelvis. If cut, will retract into the pelvis and bleed like crazy. Difficult to control if retracted. 


Describe the course of the Superficial Femoral Artery

Supplies Medial Thigh

  1. Branches at Femoral Triangle
  2. Runs between vastus medialis and adductor longus
  3. Runs deep to sartorius
  4. Runs into the Adductor Hiatus (Hunter's Canal)


What passess through the Obturator Canal

Obturator N, A & V

*obturator internus and externus attached to obturator membrane on either side of the foramen


What structures are near the posterior sacral foramina? Anterior foramina?

  • Posterior: Dorsal primary rami
  • Anterior: Ventral primary rami


What is the only muscle innervated by the Common Peroneal N. proximal to the Fibula?

Biceps Femoris (Short Head)


Bones of the Pelvis Girdle

  1. Inominate (2)
  2. Coccyx
  3. Sacrum


What direction does the Coccyx point in Males? Females?

  • Males: Anteriorly directed towareds the pubis
  • Females: Vertically oriented


Judet Views

45 degrees oblique from AP

  • Obturator Oblique
    • Anterior Column, Posterior Wall
  • Illiac Oblique
    • Posteior Column, Anterior Wall


Label the Diagram Below

Q image thumb

  1. Vastus Lateralis
  2. Tensor Fascia Lata
  3. Rectus Femoris
  4. Sartorius
  5. Adductor Longus
  6. Adductor Brevis
  7. Pectineus
  8. Illiopsoas
  9. Adductor Magnus
  10. Gluteus Maximus

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Which Xray views do you order to assess acetabular fractures?

AP Pelvis & Judet Views


Vessles of the Trochanteric Anastamosis

  1. Ascending branch MFCA
  2. Ascending branch LFCA
  3. Descending branch inferior gluteal a.
  4. Descending branch superior gluteal a.

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Branches of the Internal Iliac Artery

  1. Vesicular A.
  2. Pudendal A.
  3. Lateral Sacral A. 
  4. Superior & Inferior Gluteal A.
  5. Obturator A.


Superior and Inferior Glurteal N. are named based on relationship to which structure?



Young Burgess Classification of Pelvic Ring Injuries

  • Lateral Compression
    • I - Posterior compression of the SI joint without ligament disruption (stable). Ipsilateral sacral ala compression fracture, and pubic ramus fracture
    • II-  Posterior SI ligament rupture, sacral crush injury or iliac wing fracture. Rami fracture and ipsilateral ilium fracture dislocation (crescent fracture)
    • III-  LCII with AP injury to contralateral pelvis. Windswept pelvis.
  • Anteroposterior
    • I- Symphasis diastasis <2.5cm
    • II- Symphasis diastasis >2.5cm, sacrospinous and anterior SI ligamet disruption
    • III- Symphsis diastasis >2.5cm with complete disruption of anterior and posterior SI ligaments
  • Vertical Sheer: vertical displacement of symphasis and SI joints

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Dangers of the Stoppa Approach (4)

  1. Corona Mortis
  2. Bladder
  3. Obturator N & vessels
  4. External Iliac Vessels


Radiographic signs of acetabular retroversion.

  1. Crossover sign
  2. Posterior wall sign - posteior wall is medial to the centre of the femoral head
  3. Ischial spine sign - ischial spines protrude into the true pelvis
  4. Laterally protruding illiac wing
  5. Narrow ischium


How can you adduct after an obturator neurectomy?

Pectineus (Femoral N.)


Which artery to you need to watch out for in the Kocher Langenbeck approach?

Branches of the MFCA (runs along superior boarder of Quadratus Femoris)


Describe the course of the Obturator N.

  1. Comes from lumbosacral plexus
  2. Exit pelvis via obturator foramen
    1. Anterior Division: anterior to obturator externus, posterior to pectineus. Innervates adductor longus, brevis, gracilis and skin of medial thigh
    2. Posterior Division: runs between adductor brevis and magnus. Innervates obturator externus, adductor brevis and superior adductor magnus


Describe the course of the Sciatic Nerve

  1. From lumbosacral trunk
  2. Passes beneath piriformis
  3. Through greater sciatic notch
  4. Travels down posterior thigh to popliteal fossa (superior to biceps femoris and deep to adductor magnus)
  5. Travels into posterior compartment, superficial to adductor magnus (crosses posteriorly to be deep to biceps femoris)
  6. Divides into two branches at popliteal fossa (Tibial N and Common Peroneal N.)


What do the "Dimples of Venus" correlate to?

SI joints


Contents & Boundaries of the Greater Sciatic Notch

  • Contents
    • Superior to Piriformis
      • Superior Gluteal N & vessles
    • Piriformis
    • Inferior to Piriformis (POPSIQ)
      • Pudendal N & vessels
      • Obturator, nerve to
      • Posterior Femoral Cutaneous N.
      • Sciatic N.
      • Inferior Gluteal N. & vessels
      • Quadratus Femoris, nerve to


  • Boundaries
    • Ilium & Sacrospinous Ligament


Alpha Angle (FAI)

Angle between:

  1. Line bisecting femroal neck through centre of femoral head
  2. Line from center of femoral neck to head-neck junction


  • >40 degrees abnormal, indicative of CAM deformity and head-neck offset deformity
  • Measured on frog-leg lateral or Dunn View

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Denis Zones of the Sacrum

  1. Zone 1- lateral to the sacral foramen
  2. Zone 2- through the sacral foramen
  3. Zone 3 - medial to the sacrl foramen

*risk of nerve root injury increases as the zones increase


Hip Internal Rotators (6)

  1. Gluteus Medius (Anterior Fibres)
  2. GLuteus Minimus (Anterior Fibres)
  3. TFL
  4. Semimembranosus
  5. Semitendinosus
  6. Adductor Magnus (Posterior Fibres)


Label the diagram below


Q image thumb

  1. Vastus Lateralis
  2. Vastus Medialis & Intermedius
  3. Rectus Femoris
  4. Sartorius
  5. Adductor Longus
  6. Adductor Brevis
  7. Gracilis
  8. Semitendinosus 
  9. Gluteus Maximus

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Adductor/Hunter's Canal (Boundaries & Contents)

  • Boudaries
    • Anterior and Lateral: vastus medialis
    • Posterior:
      • adductor longus (sup)
      • adductor magnus (inf)
    • covered by strong aponeurosis from vastus medialis to adductor magnus/longus. Sartorius lies on this aponeurosis
  • Contents:
  1. Femoral A & V
  2. Branches of Femoral N
    1. Saphenous N.
    2. N. to Vastus Medialis


Hip Abductors (3)

  1. Gluteus Medius
  2. Gluteus Minimus
  3. TFL


Muscles Attached to the Sacrum

  1. Latissimus Dorsi
  2. Piriformis
  3. Iliacus
  4. Gluteus Maximus
  5. Coccygeus
  6. Erector Spinae
  7. Sacrospinalis
  8. Mutifidus
  9. Extensor Coccygeus (sometimes)


Describe the course of the Lateral Femoral Cutaneous Nerve

  1. Emerges lateral to the psoas
  2. Runs anteriorly on illiacus
  3. Exits pelvis under inguinal ligament ~2cm medial to ASIS
  4. Runs between sartorius and TFL
  5. Innervates anterolateral thigh


Hip External Rotators (6)

  1. Piriformis
  2. Superior & Inferior Gemellus
  3. Obturator Internus
  4. Obturator Externus
  5. Quadratus Femoris
  6. Gluteus Maximus


What nerve is at risk with retractor under the the transverse acetabular ligament?

Obturator N.


Orientation of the Femoral Neck

  • Anteversion 15 degrees (30-40 degrees at birth)
  • Neck Shaft Angle ~127 degrees (150 degrees at birth)


Boundaries & Contents of Lesser Sciatic Notch

  • Boundaries
    • Ischial Spine & Tuberosity
    • Superior Boarder: Sacrospinous Ligament
    • Inferior Boarder: Sacrotuberous Ligament


  • Contents
    1. Obturator Internus
    2. N. to Obturator Internus
    3. Pudendal N.
    4. Internal Pudendal Vessels


Where does the External Illiac Artery become the Femoral Artery?

When it crosses the inguinal ligament.


Hip Adductors (4)

  1. Adductor Magnus
  2. Adductor Brevis
  3. Adductor Longus
  4. Gracilis


Femoral Triangle (Boarders & Contents)

  • Boarders:
    • Lateral: Sartorius
    • Superior: Inguinal Ligament
    • Medial: Adductor Longus
  • Contents lateral to medial (NAVEL)
    • N - Femoral NERVE
    • A - Femoral ARTERY
    • V- Femoral VEIN
    • Empty Spae
    • Lymphatics


Branches of the External Iliac Artery

  • Profunda Femoral A
    • MCFA
    • LFCA
    • Branches to vastus lateralis through intramuscular septum
  • Superfical Femoral A. 
    • carries down leg, along the lateral aspect between vastus medialis and adductor longus
    • into adductor canal


Hip Flexors (4)

  1. Illiopsoas
  2. Rectus Femoris
  3. Sartorius
  4. Pectineus


What is the most common nerve injury during a THA?

Peroneal Branch of the Sciatic (more lateral)


Describe the course of the Saphenous N.

  1. Branches at apex of femoral triangle from Femoral N.
  2. Travels deep to Sartorius. Gives off supply to
    1. Subsartorial Plexus
    2. Infrapatellar branch at knee
    3. Medial Cural cutaneous 
  3. Travels through Hunter's Canal to the knee


What kind of joint is the Pubic Symphasis?

Non-synovial, amphiarthroidal joint


What muscle do you have to take down to see the quadrilateral plate in the Stoppa Approach?

Obturator Internus


What kind of Joint is the SI Joint?

  • Diarhtrodial Gliding Joint
    • Sacral surface - hyaline cartilage
    • Illial surface- fibrocartilage


Tonnis Angle

Made Between:

  1. Line starting at inferior sorucisl, paralell to the horizontal line connecting two teardrops.
  2. Line from inferior sourcil to lateral most point of sourcil


  • >10 degrees is abnormal
  • Measures inclination of weightbearing zone- sign of dysplasia if abnormal.
  • Measured on AP


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Ligaments of the Hip Capsule

  • Anterior
    1. Illiofemoral Ligament (Y-Ligament of Bigalow)
    • Strongest ligament in the body
    • AIIS to intertrochanteric line
    1. Pubofemoral Ligamen t
  • Posterior
  1. Ischiofemoral - attaches to femoral neck



  • Iliofemoral 12:45-3:00
  • Pubofemoral 3:30-5:30
  • Ischiofemoral 7:45-10:30


Lines of Letournel (6)

  1. Iliopectineal - anterior column
  2. Ilioischial - posterior column
  3. Dome - roof of acetabulum
  4. Teardrop - medial wall
  5. Anterior Wall
  6. Posterior Wall


What is the most common nerve injury in the Smith Peterson Approach?

Lateral Femoral Cutneous Nerve


What is the difference between coxa profunda and acetabular protrusio?

  • Coxa Profunda: deep acetabular socket.
    • Acetabular fossa medial to ilioischal line
  • Protrusio: femoral head is medial to ilioischial line


Which muscle originates from the ventral aspect of the sacrum?



What is the main blood supply to the femoral head?

Retinacular Branches of the MFCA


Components of the Cruciate Anastamosis

  • Components:
    • Internal Illiac 
    • Inferior Gluteal A.
    • MFCA
    • LFCA
    • 1st perforator, ascending branch

Allows distal flow in case of blockage between illiac and femoral arteries.


Parts of the Inominate Bone

  1. Ilium
  2. Ischium
  3. Pubis


Muscles of the Medial Compartment of the Thigh

  1. Adductor Brevis
  2. Adductor Longus
  3. Adductor Magnus
  4. Gracilis


Which Xrays do you order to assess pelvic ring injuries?

AP Pelvis & Inlet/Outlet Views


Variations in the Sciatic Nerve in relation to the Piriformis.

  • 88% - Anterior to Piriformis
  • 11% - 2 Branches, 1 anterior to piriformis, one through
  • 0.86% - 2 Branches, 1 anterior to piriforimis, one posteior to piriformis
  • 0.13% - 1 branch through piriformis

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Expansions/Insertions of the Semimembranosus (5)

  1. Posteriomedial tibial condyle (deep to MCL)
  2. Oblique Popliteal Ligament
  3. Posterior Capsule and Posterior Horn Medial Meniscus
  4. Posterior Oblique Ligament
  5. Expansion to aponeurosis of the Popliteus


What is the Zona Orbicularis?

Circulatr fibres forming collar at femoral neck. "Annular Ligament" of the femoral neck.