Muscles of the Thigh - Anterior Compartment

Muscles of the Thigh - Anterior Compartment

• Primarily responsible for hip flexion and/or knee extension.
• Blend into the quadricep tendon which houses the patella.
• The patellar ligament (tendon) attaches to the tibial tuberosity.
• Most are innervated by the Femoral Nerve (L2-L4).
• Key muscles:
• Pectineus: Hip flexor, ADD
• Sartorius: Hip flexor and ER, Knee Flexor and IR
• Distal ends of Iliopsoas: Hip flexor
• Tensor Fascia Lata (TFL): Hip flexor, ABD, IR
• Quadriceps Femoris: Knee extensors

Pectineus

• Proximal Attachment: Superior pubic ramus.
• Distal Attachment: Pectineal Line of the femur, just inferior to the lesser trochanter.
• Innervation: Femoral Nerve; sometimes also innervated by Obturator Nerve.
• Action: Hip ADD, Hip Flexion.

Sartorius

• Proximal Attachment: (not mentioned)
• Distal Attachment: Medial surface of the proximal tibia at the pes anserine.
• Innervation: Femoral Nerve.
• Action: Hip Flexion, Hip ER, and Knee Flexion; it can also assist with Hip ABD.

Psoas Major

• Distal portions are in anterior compartment as Iliopsoas
• Proximal Attachment: Bodies and Transverse Processes of T12-L5 and discs between them.
• Distal Attachment: Lesser Trochanter.
• Innervation: Anterior Rami of Lumbar Nerves.
• Action: Hip Flexion, Trunk Flexion, Anterior Pelvic Tilt.

Iliacus

• Distal portions are in anterior compartment as Iliopsoas
• Proximal Attachment: Iliacus fossa.
• Distal Attachment: Lesser Trochanter.
• Innervation: Femoral Nerve.
• Action: Hip Flexion, anterior pelvic tilt.

Tensor Fascia Lata (TFL)

• Proximal Attachment: ASIS, Anterior part of iliac crest.
• Distal Attachment: Iliotibial tract which attaches to the lateral condyle of tibia (Gerdy's Tubercle).
• Innervation: Superior Gluteal Nerve.
• Action: Hip IR, Hip ABD, and Hip Flexion.
• Lateral support of the knee.

Quadriceps Femoris

• Four-headed muscle of the femur.

Rectus Femoris

• Proximal Attachment: AIIS
• Distal Attachment: Tibial tuberosity.
• Innervation: Femoral Nerve.
• Action: Knee extension, Hip Flexion.

Vastus Medialis

• Proximal Attachment: Intertrochanteric Line and Medial linea aspera.
• Distal Attachment: Tibial tuberosity.
• Innervation: Femoral Nerve.
• Action: Knee extension

Vastus Lateralis

• Proximal Attachment: Lateral linea aspera and greater trochanter.
• Distal Attachment: Tibial tuberosity.
• Innervation: Femoral Nerve.
• Action: Knee extension.

Vastus Intermedius

• Proximal Attachment: Anterior and lateral femoral shaft.
• Distal Attachment: Tibial tuberosity.
• Innervation: Femoral Nerve.
• Action: Knee extension.

Anterior & Medial Thigh Compartments

• Anterior Compartment:
• Hip Flexors, Knee extensors
• Femoral Nerve
• Medial Compartment:
• Hip Adductors
• Obturator Nerve

Muscles of the Thigh - Medial Compartment

• Primarily hip adductors.
• Innervated by the Obturator Nerve (L2-L4).
• The hamstring portion of the Adductor Magnus is innervated by the Sciatic Nerve.
• Key muscles:
• Gracilis: Hip ADD, Knee Flexor and IR
• Adductor Longus: Hip ADD
• Adductor Brevis: Hip ADD
• Adductor Magnus: Hip ADD and Extensor
• Obturator Externus: Hip ER
• Honorable mention to Pectineus to Hip ADD, Hip Flexion since it crosses to both sections

Gracilis

• Proximal Attachment: Body of pubis & Inferior pubic ramus
• Distal Attachment: Superior portion of medial surface of tibia via Pes Anserine
• Innervation: Obturator N
• Action: Hip ADD, Hip Flex, Knee Flex, IR of leg

Adductor Longus

• Proximal Attachment: Body of pubis.
• Distal Attachment: Middle 1/3rd of linea aspera.
• Innervation: Obturator Nerve.
• Action: Hip ADD: assists with Hip Flexion.

Adductor Brevis

• Proximal Attachment: Body and inferior ramus of pubis.
• Distal Attachment: Pectineal line & proximal linea aspera.
• Innervation: Obturator Nerve.
• Action: Hip ADD and assists with hip flexion.

Adductor Magnus

• Proximal (ADD portion): Ischiopubic ramus, Innervation: Obturator N
• Proximal (HAM portion): Ischial tuberosity, Innervation: Tibial N. (div. of Sciatic N.)
• Distal (HAM portion): Adductor tubercle
• Distal (ADD portion): Gluteal tuberosity, linea aspera, medial supracondylar line
• Action: ADD: Hip ADD and Hip Flexion, HAM: Hip extension

Obturator Externus

• Proximal Attachment: Margins of obturator foramen and obturator membrane.
• Distal Attachment: Trochanteric Fossa.
• Innervation: Obturator Nerve.
• Action: Hip ER, stabilizes femur in acetabulum.

Pes Anserine

• Goose's Foot, Adds stability to the knee
• Common insertion for the following muscles: Satorius, Gracilis, Semitendinosus

Femoral Triangle

• Triangular depression in anterior thigh.
• Located in the inguinal region, inferior to the inguinal ligament.
• Contains NAVL (lateral to medial): Femoral N., Femoral A., Femoral V., and Lymphatics.

Adductor Canal & Hiatus

• Passage for the Femoral Artery and Femoral Vein.
• Adductor Canal: Space between Vastus Medialis, Sartorius, and Adductor longus.
• Adductor Hiatus: Opening between Adductor and Hamstring portions of Adductor Magnus.

Anterior Compartment Leg

• Anterior compartment: deep fibular nerve territory; dorsiflexors of ankle and extensors of toes
• Lateral compartment: superficial fibular nerve territory; evertors of foot
• Posterior compartment: tibial nerve; plantarflexors of ankle and flexors of toes

Anterior Compartment

• Dorsiflexor/Extensor Compartment
• Primarily dorsiflexes the ankle and extends the digits.
• Innervated by the Deep Fibular Nerve.
• Muscles:
• Tibialis Anterior: Ankle DF, Inversion of the foot
• Extensor Hallucis Longus: Great toe extension, Ankle DF
• Extensor Digitorum Longus: Extends digits 2-5, Ankle DF
• Fibularis Tertius: Ankle DF, Eversion of foot

Tibialis Anterior

• Proximal Attachment: Lateral Condyle of tibia; Superior 1/2 of lateral surface of tibia.
• Distal Attachment: Inferior surface of Medial cuneiform & base of 1st metatarsal
• Innervation: Deep fibular Nerve
• Action: Ankle Dorsiflexion, supports medial longitudinal arch of foot, inversion of foot

Extensor Hallucis Longus

• Proximal Attachment: Middle, anterior surface of fibula; interosseous membrane.
• Distal Attachment: Dorsal base of distal phalanx of great too (digit 1).
• Innervation: Deep fibular Nerve.
• Action: Extends Digits 1, Ankle Dorsiflexion.

Extensor Digitorum Longus

• Proximal, Lateral condyle of tibia; Superior 3/4ths of anterior fibula; interosseous membrane
• Distal: Extensor expansions to distal phalanges of of 2-5 digits
• Innervation: Deep fibular Nerve.
• Action: Extends digits 2-5, Ankle Dorsiflexion.

Fibularis Tertius

• Proximal Attachment: Inferior 1/3rd of anterior surface of fibula and interosseous membrane.
• Distal: Dorsal base of 5th metatarsal.
• Innervation: Deep fibular Nerve. Action: Ankle Dorsiflexion, eversion of foot.