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Flashcards in Muscles of the Thigh Deck (73):

Muscle compartments of the thigh

- Anterior compartment
- Medial compartment
- Posterior compartment


Anterior compartment muscles

- Sartorius
- Quadriceps femoris (rectus femoris, vastus lateralis, vastus medialis, vastus intermidus)
- Articularis genu


Medial compartment of the thigh

o Gracilis
o Pectineus
o Adductor longus
o Adductor brevis
o Adductor magnus


Posterior compartment of the thigh

Hamstring muscles:
- Biceps femoris
- Semitendinosus
- Semimembranosus



Anterior compartment
- Longest muscle in the body
- Descends across the thigh (lateral to its medial position)
- Forms the roof of the adductor (subsartorial) canal


Sartorius origin

ASIS and notch below it


Sartorius insertion

Proximal part of medial surface of body of tibia (same as gracilis and semitendinosus) – It extends obliquely from lateral to medial across the upper thigh, then descends nearly vertically to its insertion


Sartorius nerve supply

Femoral nerve


Sartorius function

Flexes, abducts and laterally rotates at the hip
Also, flexes the knee and medially rotates the leg from flexed position


Variation in sartorius muscle

May be absent or may be split into two parts
- May have accessory sites of origin on the inguinal ligament, notch of the ilium, iliopectineal line or pubis


Quadriceps femoris group

- Four muscles of the thigh are collectively called the quadriceps femoris
- Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius
- Each muscle converges at a common insertion


Quadriceps femoris origin

Unique to each individual muscle


Quadriceps femoris insertion

Entire group  Tibial tuberosity via patellar ligament
- Depends on how you view the patella
- If patella is regarded as a sesamoid bone in the quadriceps tendon, then the proper tendon of insertion is the so-called patellar ligament, which continues to the tibial tuberosity
- If patella is not considered a sesamoid, the muscle can properly be thought of as inserting into the patella
- Regardless of how you see it, the primary function of the quadriceps femoris is extension of the knee, so the ultimate insertion must be the tibial tuberosity


Quadriceps femoris nerve supply

Femoral nerve


Quadriceps femoris function

- Extension of the knee
- Rectus femoris also assists in flexion of the hip


Rectus femoris origin

Two tendons
- Straight (anterior) tendon --> from AIIS
- Reflected (posterior) tendon --> from groove above acetabulum

The tendons merge to form a broad aponeurosis on the ventral surface of the muscle, so fibers of the muscle actually arise from this aponeurosis


Rectus femoris insertion

The base (superior border) of the patella, via a thick aponeurotic tendon then via the patellar ligament to the tibial tuberosity


Vastus lateralis origin

Four origins:
- Lateral lip of linea aspera
- Lateral lip of gluteal tuberosity
- Anterior and inferior borders of greater trochanter
- Proximal intertrochanteric line


Vastus lateralis insertion

Lateral border of patella and tendon of quadriceps femoris then via the patellar ligament to the tibial tuberosity


Vastus medialis origin

Five origins:
- Distal intertrochanteric line
- Medial intermuscular septum
- Tendons of adductor longus and magnus
- Proximal medial supracondylar line
- Medial lip of linea aspera


Vastus medialis insertion

Medial border of patella and tendon of quadriceps femoris then via the patellar ligament to the tibial tuberosity


Vastus intermedius origin

Proximal two thirds of the anterior and lateral surfaces of the femur


Vastus intermedius insertion

The quadriceps tendon then via the patellar ligament to the tibial tuberosity


Articularis genu origin

Anterior surface of distal femur


Articularis genu insertion

Into the synovial membrane of the knee joint


Articularis genu innervation

Femoral nerve


Articularis genu fnction

To draw the synovium proximally


Articularis genu notes

Small muscle located deep to the vastus intermedius


Articularis genu variation

May be blended with the vastus intermedius


Medial compartment of the thigh

- Gracilis
- Pectineus
- Adductor longus
- Adductor brevis
- Adductor magnus


Gracilis notes

Thin muscle located superficially on the medial thigh


Gracilis origin

Three origins:
- Inferior ½ of the pubic symphysis
- Pubic body
- Superior ½ of the pubic arch (inferior pubic ramus)


Gracilis insertion

Passes distally posterior to the medial condyle of the tibia to insert on the proximal part of the medial surface of the tibia (same as sartorius and semitendinosus)


Gracilis nerve supply

Anterior division of the obturator nerve


Gracilis function

- Adductor and medial rotator at the hip
- Flexor at the knee


Pectineus origin

Three origins:
- Pecten pubis
- Bone anterior to pecten pubis between the pubic tubercle
- Iliopectineal eminence


Pectineus insertion

Pectineal line (line between lesser trochanter and linea aspera)


Pectineus nerve supply

Femoral nerve
- If accessory obturator nerve is present, it gives a branch to pectineus
- The obturator nerve may also provide a branch


Pectineus function

Flexion, adduction and medial rotation of the hip


Pectineus variation

May have two strata, either completely or incompletely separated
- When present, the dorsal stratum is innervated by the femoral nerve or accessory obturator (when present)
- Obturator nerve supplies ventral stratum when present


Adductor longus notes

Most anterior of the adductor muscles


Adductor longus origin

Front of the body of the pubis


Adductor longus insertion

Medial lip of linea aspera (btw attach. of vastus medialis & adductor magnus)


Adductor longus nerve supply

Anterior branch of obturator nerve


Adductor longus function

Flexor and adduction of the hip


Adductor longus variation

May be doubled, fused with pectineus, or descend as far down as the knee


Adductor brevis notes

- Just posterior to the adductor longus is the adductor brevis
- Divisions (ant./post.) of obturator nerve divide to surround muscle


Adductor brevis origin

Pubic body and inferior pubic ramus between gracilis and obturator externus


Adductor brevis insertion

Proximal part of linea aspera


Adductor brevis nerve supply

Obturator nerve (anterior division, usually)


Adductor brevis function

Adductor and flexor of the hip


Adductor brevis variation

May have two or three parts, or may be fused with adductor magnus


Adductor magnus notes

The largest of the adductors
- Lies deep to the adductor brevis
- Upper fibers run nearly horizontally while its lower fibers are nearly vertical in orientation
- There are usually five openings in the muscle, four for the passage of perforating branches of the deep femoral artery
- The most distal opening is the adductor hiatus (hiatus tendineus) which allows passage of the femoral vessels to the popliteal fossa


Adductor magnus origin

Three origins:
- Inferior pubic ramus
- Ramus of the ischium
- Ischial tuberosity (triangular region)


Adductor magnus insertion

Four insertions:
- Gluteal tuberosity (line)
- Linea aspera
- Medial supracondylar line
- Adductor tubercle of the femur


Adductor magnus nerve supply

Posterior division of obturator nerve and tibial portion of sciatic nerve


Adductor magnus function

Adductor, flexor and extensor of the hip
- All of these functions are possible because of the different fiber orientations in the muscle


Adductor magnus variation

May be fused with quadratus femoris or with either the adductor longus or brevis


Posterior compartment of the thigh - Hamstring muscles

- Three components
o Biceps femoris (found laterally in the posterior compartment and has 2 heads)
o Semitendinosus (found medially in the posterior compartment)
o Semimembranosus (found medially in the posterior compartment)


Biceps femoris origin

Long head
- Posterior part of ischial tuberosity below oblique line (by a common tendon with the semitendinosus)
- Sacrotuberous ligament

Short head
- Lateral lip of linea aspera (between the adductor magnus and vastus lateralis muscles)
- Lateral supracondylar line of femur
- Lateral intermuscular septum


Biceps femoris insertion

Long head
- Pass laterally in an oblique course across sciatic nerve
- Ends in an aponeurosis which overlies the muscles and is also the insertion of the short head

Combined aponeurosis
- Aponeurosis narrows to a tendon, which is inserted into…
o Lateral side of the styloid process of the head of the fibula
o Lateral condyle of the tibia
- Tendon surrounds the fibular collateral ligament and the common fibular nerve runs along its medial border


Biceps femoris nerve supply

Long head
- Tibial portion of the sciatic nerve

Short head
- Common fibular portion of the sciatic nerve


Biceps femoris function

Both heads
- Flex the knee
- Laterally rotate the knee from the flexed position

Long head
- Extends and laterally rotates the hip


Biceps femoris variation

Short head
- May be absent or there may be accessory heads arising from the ischial tuberosity, linea aspera or the medial supracondylar ridge of the femur

An extension of the biceps femoris may attach to the gastrocnemius muscle


Semitendinosus origin

Originates with the long head of the biceps femoris from the…
- Posterior ischial tuberosity below the oblique line
- Aponeurosis which connects the two muscles for about 8 cm from their origin


Semitendinosus insertion

Semitendinosus ends in a tendon at the middle of the thigh
- Long tendon lies along medial border of popliteal fossa then curves around medial condyle of tibia and over tibial collateral ligament (there is usually an intervening bursa)
- Then inserts into the proximal part of the medial surface of the tibia


Semitendinosus nerve supply

Tibial portion of sciatic nerve


Semitendinosus function

- Flexes at the knee and medially rotates from full extension
- Also extends the hip


Semimembranosus origin

Two origins:
- Upper outer (lateral) position of the oblique line of the ischial tuberosity above the semitendinosus and biceps femoris
- Aponeurotic expansion of the tendon of origin


Semimembranosus insertion

Three insertions:
- Groove on the medial surface of the medial condyle of the tibia
- Posterior surface of the lateral condyle of the femur

Gives rise to fibers that proceed superolaterally to form a popliteal ligament
- This forms the 3rd insertion into the fascia which covers the popliteus muscle


Semimembranosus nerve supply

Tibial portion of sciatic nerve


Semimembranosus function

- Flexor at the knee and a medial rotator from full extension
- Also extends the thigh


Semimembranosus variation

May be absent or doubled