Identify the muscles of the anterior and medial compartments of the thigh including their nerve supply, attachments, and function.
From the retroperitoneal space in the abdomen
T12 , L1 through L4 = Psoas major
Originates from lumbar spine and can help move and increase lumbar lordosis
Provide hip flexion
This muscles merges with the iliacus into one muscle belly: iliopsoas
Bulk of anterior compartment: quadriceps muscles
Most anteriorly rectus femoris = just under the ASIS and spans down the length of the femur and contributes to the common extensor tendon of the quads
Inserts onto patella and ultimately onto tibial tuberosity via patellar ligament
Patella helps enhance torque for body mechanics to extend knee
Deep to rectus femoris (immediate) = vastus intermedius
All 3 vastus muscles originate from femur and Inserts onto patella and ultimately onto tibial tuberosity via patellar ligament
Rectus femoris flex hip and extends knee
Vastus muscles ONLY extend knee
Sartorius extends from pelvis to medial tibia to Pes anserinus (gooses foot)also known as the "goose's foot"), which is a common insertion point for several muscles on the medial side of the knee.
Femoral nerve serves the anterior compartment of the thigh
Femoral nerve = L2, L3, L4
--> courses underneath the inguinal ligamenet before it exapnds out quickly to several muscles (sartorius, rectus femoral, vastus lateralis, intermedias, medialaias) plus iliacus and psoas (but psoas is innervated by branches of lumbar plexus )
Obturator Nerve serves the medial compartment of the thigh (five muscles)
Obturator Nerve = L2, L3, L4
Adductor longus, magnus, gracialias, pectineus and fx to adduct the hip
Pectineus attaches onto pectineal line and is relatively short and is innervated by femoral nerve and is innervated by that branch while other people is a branch of obturator and some people have both!! Hip flexion and adduction
Lateral to gracialias is adductor longus and spans across the midthigh to insert onto posterior femur on a ride of bone called linea aspera (rough) looks like a rough ride down femur
Deep to pectineus and adductor longus is adductor brevis is on posterior femur on linea aspera
Obturator nerve courses through obturator foramen and canal and splits anterior division (brevis) and posterior (brevis)
Adductor magnus is lateral to gracialias and deep to everything else. Magnus arises from ischial tuberosity and ramus. Adductor part extends down linea aspera and hamstring part attaches to adductor tubercle. Be careful of this. Muscle has dual innervation. Adductor part innervated by obturator nerve and hamstring part in posterior thigh innervated by generally be innovated by the tibial division of the sciatic nerve
Lateral cutaneous nerve of the thigh as it distributes itself down to lateral thigh muscles
Lateral cutaneous nerve of the thigh = L2, L3
Important for dermatomes
Adductor hiatus break in muscles allows veins and arteriors to go into the popliteal fossa
Obturator externus muscles originates from obturator membrane covering obturator foramen and transmitted laterally to posterior femur
- Dual Innervation:
- Pectineus: Primarily femoral nerve, sometimes obturator nerve
- Adductor Magnus: Adductor part innervated by obturator nerve, hamstring part by tibial division of sciatic nerve
### Muscle Attachments and Functions
- Adductor Longus:
- Spans mid-thigh, inserts onto posterior femur at linea aspera
- Action: Hip adduction
- Adductor Brevis:
- Deep to Pectineus and Adductor Longus
- Originates from posterior femur at linea aspera
- Adductor Magnus:
- Lateral to Gracilis and deep to other muscles
- Arises from ischial tuberosity and ramus
- Adductor part extends down linea aspera; hamstring part attaches to adductor tubercle
### Additional Nerve and Anatomical Features
- Lateral Cutaneous Nerve of the Thigh (L2, L3):
- Distributes to lateral thigh muscles
- Important for dermatomes
- Adductor Hiatus:
- Opening in the muscles that allows passage of veins and arteries into the popliteal fossa
- Obturator Externus:
- Originates from the obturator membrane covering the obturator foramen
- Transmits laterally to the posterior femur
- Femoral Nerve:
- The femoral nerve (L2, L3, L4) supplies the anterior compartment of the thigh.
- It passes beneath the inguinal ligament and branches out to innervate muscles like sartorius, rectus femoris, vastus lateralis, vastus intermedius, and vastus medialis, as well as the iliacus and psoas muscles (though the psoas is also innervated by branches from the lumbar plexus).
- Obturator Nerve:
- The obturator nerve (L2, L3, L4) serves the medial compartment of the thigh.
- It innervates five muscles: adductor longus, adductor magnus, gracilis, pectineus, and helps with hip adduction.
- Pectineus:
- Attaches to the pectineal line of the pelvis.
- It is a short muscle, usually innervated by the femoral nerve, though it can also receive innervation from the obturator nerve (or both in some cases). It helps with hip flexion and adduction.
- Adductor Longus:
- Located laterally to the gracilis, it runs across the middle of the thigh and inserts on the posterior femur at the linea aspera (a rough ridge).
- Adductor Brevis:
- Positioned deep to the pectineus and adductor longus, it also inserts on the linea aspera of the femur.
- Adductor Magnus:
- Located lateral to the gracilis and deep to other muscles, it originates from the ischial tuberosity and ramus.
- It has a dual innervation: the adductor part is innervated by the obturator nerve, while the hamstring part (in the posterior thigh) is usually innervated by the tibial division of the sciatic nerve.
- Obturator Nerve Pathway:
- The obturator nerve passes through the obturator foramen and splits into anterior and posterior divisions, which innervate different muscles.