Podcast
Questions and Answers
What is the primary action of the pectineus muscle?
What is the primary action of the pectineus muscle?
Which nerve innervates both the iliacus and pectineus muscles?
Which nerve innervates both the iliacus and pectineus muscles?
What makes the sartorius muscle unique compared to other hip flexors?
What makes the sartorius muscle unique compared to other hip flexors?
Which of the following muscles does NOT share the same innervation as the quadriceps?
Which of the following muscles does NOT share the same innervation as the quadriceps?
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Which muscle's actions can be symbolized by sitting cross-legged?
Which muscle's actions can be symbolized by sitting cross-legged?
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What is the normal angle of inclination between the shaft of the femur and the neck of the femur in the frontal plane?
What is the normal angle of inclination between the shaft of the femur and the neck of the femur in the frontal plane?
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Which condition is indicated when the angle of inclination of the femur is closer to a right angle?
Which condition is indicated when the angle of inclination of the femur is closer to a right angle?
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What is the primary action of the muscles in the anterior compartment of the thigh?
What is the primary action of the muscles in the anterior compartment of the thigh?
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Which structure serves as a lateral thickening in the fascia lata?
Which structure serves as a lateral thickening in the fascia lata?
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Which nerve innervates all of the muscles in the anterior compartment of the thigh?
Which nerve innervates all of the muscles in the anterior compartment of the thigh?
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What is the location of the greater trochanter on the femur?
What is the location of the greater trochanter on the femur?
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Which structure is a large ridge extending down from the greater and lesser trochanters?
Which structure is a large ridge extending down from the greater and lesser trochanters?
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What does the adductor tubercle articulate with?
What does the adductor tubercle articulate with?
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Which of the following describes the epicondyles of the femur?
Which of the following describes the epicondyles of the femur?
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Where is the Linea Aspera located on the femur?
Where is the Linea Aspera located on the femur?
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Study Notes
Anterior Thigh Compartment Muscles
- The anterior compartment of the thigh has six key muscles that perform two actions: hip flexion and knee extension
- All anterior compartment muscles are innervated by the femoral nerve
- The femoral artery supplies blood to this compartment
Proximal Anterior Thigh Muscles
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Pectineus
- Small, oblique muscle running from the superior pubic ramus to the pectineal line on the femur
- Contributes to hip flexion and adduction
- Innervated by the femoral nerve (L2, L3)
-
Iliacus
- Primarily acts to flex the hip
- Attaches to iliac crest and fossa, joins with psoas major to insert on lesser trochanter
- Innervated by the femoral nerve (L2, L3)
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Psoas Major
- Major function is hip flexion
- Muscle attaches to the vertebral bodies and discs, and transverse processes of the lower thoracic and lumbar regions
- Joins with iliacus to insert on lesser trochanter
- Innervated by L2-L3 nerve roots
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Sartorius
- One of the longest muscles, running from the ASIS on the ilium to the medial surface of the superior tibia (pes anserine)
- Action: flexion and external rotation of the hip, flexion of the knee.
- Innervated by the femoral nerve (L2, L3)
Quadriceps Muscles
-
Rectus Femoris
- Most superficial quad, only one that crosses the hip joint
- Attaches to the AIIS on the ilium and inserts on the patella, via the patellar ligament
- Function: knee extension, assists with hip flexion
- Innervated by the femoral nerve (L3, L4)
-
Vastus Lateralis
- A large muscle on the lateral side of the thigh, wrapping around to the posterior.
- Attaches to the greater trochanter and linea aspera on the femur
- Inserts on the patella, via the patellar ligament
- Function: knee extension
- Innervated by the femoral nerve (L3, L4)
-
Vastus Medialis
- Large muscle on the medial side of the thigh, wrapping around to the posterior.
- Attaches to the intertrochanteric line and the medial aspect of the linea aspera
- Inserts on the patella, via the patellar ligament
- Function: knee extension
- Innervated by the femoral nerve (L3, L4)
-
Vastus Intermedius
- Smallest quad muscle, deep and centrally located
- Attaches to the anterolateral surface of the femur
- Inserts on the patella, via the patellar ligament
- Function: knee extension
- Innervated by the femoral nerve (L3, L4)
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Articulares Genu
- Tiny muscle, connects to the posterior aspect of Vastus Intermedius and distal femur, inserts at the synovium of the knee joint
- Function: pulls the synovial capsule out of the way when the quads contract to extend the knee.
Important Note:
- Although the video does not provide a detailed explanation of the neurovascular structures of the anterior compartment, it does mention that the femoral nerve and femoral artery are involved. This is important to remember but more detailed information is needed from additional sources.
Articularis Genu
- Small muscle in the anterior compartment of the thigh
- Connects to the posterior aspect of vastus intermedius, distal femur, and inserts into the synovium of the knee joint
- Action: pulls the knee joint capsule out of the way when the quadriceps contract to straighten the knee, preventing it from getting pinched
Anterior Compartment Neurovascular
- Femoral nerve: innervates all muscles in the anterior compartment and continues as the saphenous nerve down the leg
- Femoral artery: continuation of the external iliac artery, runs under the inguinal ligament and enters the femoral triangle
Femoral Triangle
- Superior border: inguinal ligament
- Lateral border: sartorius muscle
- Medial border: adductor longus muscle
- Apex: where sartorius crosses adductor longus
- Floor: iliopsoas and pectineus muscles
- Covered by fascia lata
- Contents: femoral nerve, femoral artery, femoral vein, and lymphatic structures within the femoral canal
Femoral Sheath
- Connective tissue that encircles the femoral artery, femoral vein, and femoral canal
Adductor Canal
- Passageway through the anterior to medial thigh just deep to the sartorius muscle
- Created by the sartorius muscle running between adductor longus and vastus medialis
- Contents: femoral artery, femoral vein, nerve to vastus medialis, and saphenous nerve
Adductor Hiatus
- Opening in adductor magnus through which the femoral artery and vein pass to enter the posterior thigh and popliteal fossa
- The nerve to vastus medialis and saphenous nerve do not pass through the adductor hiatus
- Saphenous nerve emerges superficially at the medial knee and continues in the skin of the medial leg
Medial Compartment Overview
- Muscles run obliquely towards the femur, allowing for adduction of the thigh
- Most muscles attach to the pubis (rami, body, or ischial rami)
- Innervated by the obturator nerve (except for the hamstring fibers of adductor magnus)
- Blood supply from the profunda or deep femoral artery
Medial Compartment Muscles
- Pectineus: unique muscle with dual function, both hip flexion (anterior compartment) and adduction (medial compartment)
- Adductor Longus and Adductor Brevis: superficial muscles, innervated by the obturator nerve, primarily responsible for adduction of the thigh
-
Adductor Magnus: large muscle with two parts:
- Oblique fibers: adduction function, innervated by the obturator nerve
- Vertical or hamstring fibers: hip extension function, innervated by the tibial nerve
- Gracilis: long, thin muscle, adduction of the thigh and knee flexion, inserts at the pes anserine (with sartorius)
Medial Compartment Blood Supply
- Femoral artery: continuation of external iliac artery
- Profunda femoral artery: deep branch of the femoral artery, supplies the medial compartment and sends perforating arteries to the posterior compartment (hamstrings)
Medial Compartment Innervation
- Obturator nerve: innervates most medial compartment muscles
- Tibial nerve: innervates the hamstring fibers of adductor magnus
Blood Supply to the Thigh
- Femoral Artery: Runs through the adductor canal, becomes the popliteal artery after passing through the adductor hiatus.
- Deep Femoral Artery (Profunda Femoris): Supplies the medial compartment and gives off perforating branches to the posterior compartment.
- Lateral and Medial Circumflex Femoral Arteries: Branch off the femoral artery and wrap the proximal femur.
- Obturator Artery: Branches from the internal iliac artery, passes through the obturator foramen, and provides minor blood supply to the medial compartment.
Innervation of The Thigh
- Femoral Nerve (L2, 3, 4): Innervates the anterior thigh muscles (quadriceps) and provides sensory innervation.
- Obturator Nerve (L2, 3, 4): Innervates the medial thigh muscles (except adductor magnus) and provides sensory innervation.
- Tibial Nerve: Innervates the posterior thigh muscles (hamstrings), except the short head of biceps femoris.
Posterior Thigh Muscles:
- Hamstring Muscles: Consist of biceps femoris, semitendinosus, and semimembranosus.
- Action: Extension of the hip (thigh), flexion of the knee.
-
Attachments:
- All three have an attachment to the ischial tuberosity.
- Biceps femoris has a short head that attaches to the posterior femur, and a long head that attaches to the ischial tuberosity.
- Semitendinosus and semimembranosus attach to the medial aspect of the superior tibia.
- Semitendinosus inserts at the pes anserinus.
- Semimembranosus inserts on the posterior aspect of the medial condyle.
- Biceps femoris attaches to the head of the fibula.
- Innervation: Innervated by the tibial nerve, except the short head of biceps femoris which is innervated by the common fibular nerve.
Cross-Section of the Thigh:
- Divisible into three compartments: anterior, medial, and posterior.
- Anterior compartment: Contains the quadriceps muscle group and sartorius.
- Medial compartment: Contains the adductor muscles, adductor magnus being the largest muscle.
- Posterior compartment: Contains the hamstring muscles.
- Sartorius is easily identifiable due to its thinness and proximity to neurovascular structures in the adductor canal.
Pes Anserinus:
- A common attachment site for sartorius, gracilis, and semitendinosus.
- Located at the proximal medial tibia.
Sensory Innervation of the Thigh:
- Lateral cutaneous nerve of thigh: Provides sensory innervation to the lateral thigh.
- Femoral nerve: Provides sensory innervation to the anterior thigh.
- Obturator nerve: Provides sensory innervation to a portion of the medial thigh.
- Posterior femoral cutaneous nerve: Provides sensory innervation to the posterior thigh.
Dermatomes of The Thigh:
- L1: Inguinal ligament
- L2: Superior and slightly lateral thigh
- L3: Inferior thigh, slightly medial, and over the knee
- S2: Posterior thigh
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