Lower limbs
Muscles of Lower Limb
Objectives
At the end of the session, students should be able to identify:
Muscles of the gluteal region
Compartments of the thigh and muscles in each compartment along with their actions and nerve supply
Compartments of the leg and muscles in each compartment along with their actions and nerve supply
Muscles of Gluteal Region
Location: Posterolateral to the bony pelvis and proximal end of the femur
Types of Muscles: Primarily extensors, rotators, and abductors of the hip joint
Deep Group of Small Muscles: Lateral rotators of the femur, including:
Piriformis
Obturator internus
Gemellus superior
Gemellus inferior
Quadratus femoris
Superficial Group of Larger Muscles:
Gluteus minimus
Gluteus medius
Gluteus maximus
Tensor fasciae latae: Stabilizes the knee in extension
Muscles of Gluteal Region
Superficial Layer
Muscles Origin Insertion Innervation Action | ||||
Gluteus maximus | Fascia covering gluteus medius, external surface of ilium behind posterior gluteal line, fascia of erector spinae, dorsal surface of lower sacrum, lateral margin of coccyx, external surface of sacrotuberous ligament | Posterior aspect of iliotibial tract of fascia lata and gluteal tuberosity of proximal femur | Inferior gluteal nerve (L5, S1, S2) | Powerful extensor of flexed femur at hip joint; lateral stabilizer of hip and knee joints; laterally rotates and abducts thigh |
Gluteus medius | External surface of ilium between anterior and posterior gluteal lines | Elongate facet on the lateral surface of the greater trochanter | Superior gluteal nerve (L4, L5, S1) | Abducts femur at hip joint; holds pelvis stable over stance leg, preventing pelvic drop on opposite swing side during walking; medially rotates thigh |
Gluteus minimus | External surface of ilium between inferior and anterior gluteal lines | Linear facet on the anterolateral aspect of the greater trochanter | Superior gluteal nerve (L4, L5, S1) | Similar actions as gluteus medius |
Deep Layer
Muscles Origin Insertion Innervation Action | ||||
Piriformis | Anterior surface of sacrum between anterior sacral foramina | Medial side of superior border of greater trochanter of femur | Branches from S1 and S2 | Laterally rotates extended femur; abducts flexed femur |
Obturator internus | Anterolateral wall of true pelvis; deep surface of obturator membrane | Medial side of greater trochanter of femur | Nerve to obturator internus (L5, S1) | Laterally rotates the extended femur; abducts flexed femur |
Gemellus superior | External surface of ischial spine | Along the length of superior surface of the obturator internus tendon | Nerve to obturator internus (L5, S1) | Laterally rotates the extended femur; abducts flexed femur |
Gemellus inferior | Upper aspect of ischial tuberosity | Along the length of inferior surface of the obturator internus tendon | Nerve to quadratus femoris (L5, S1) | Laterally rotates the extended femur; abducts flexed femur |
Quadratus femoris | Lateral aspect of ischium just anterior to ischial tuberosity | Quadrate tubercle on the intertrochanteric crest of proximal femur | Nerve to quadratus femoris (L5, S1) | Laterally rotates femur at hip joint |
Trendelenburg’s Sign
Indicative of weak or paralyzed abductor muscles (gluteus medius and gluteus minimus)
Demonstrated by standing on one limb; if pelvis drops on the swing limb, the sign is positive
Common in pelvic fractures leading to superior gluteal nerve damage
Intramuscular Injections
Administering drugs intramuscularly in the gluteal region must avoid nerve/vessel injury
Injection site: Anterior corner of the upper lateral quadrant of the gluteal region
Important lines for position:
One vertical line from the highest point of the iliac crest
Horizontal line midway between iliac crest and ischial tuberosity
Thigh
Location: Between the hip and knee joints
Divided into three compartments by intermuscular septa:
Anterior Compartment: Primarily extends the leg at the knee joint
Posterior Compartment: Extends the thigh at the hip joint and flexes the leg at the knee joint
Medial Compartment: Primarily adducts the thigh at the hip joint
Muscles of Anterior Compartment of Thigh
Function: Flexors at the hip and extensors at the knee
Innervated by the Femoral Nerve
Muscles in Anterior Compartment
Muscles Origin Insertion Innervation Actions | ||||
Sartorius | Anterior superior iliac spine | Medial surface of tibia just inferomedial to tibial tuberosity | Femoral nerve (L2, L3) | Flexes thigh at hip joint; flexes leg at knee joint |
Rectus femoris | Anterior inferior iliac spine; superior to acetabulum | Quadriceps femoris tendon | Femoral nerve (L2, L3, L4) | Flexes thigh at hip joint; extends leg at knee joint |
Vastus Lateralis | Lateral part of intertrochanteric line and linea aspera | Quadriceps femoris tendon and lateral margin of patella | Femoral nerve (L2, L3, L4) | Extends the leg at the knee joint |
Vastus Intermedius | Upper two-thirds of anterior and lateral surfaces of femur | Quadriceps femoris tendon, lateral border of patella | Femoral nerve (L2, L3, L4) | Extends the leg at the knee joint |
Vastus Medialis | Medial part of intertrochanteric line and linea aspera | Quadriceps femoris tendon and medial border of patella | Femoral nerve (L2, L3, L4) | Extends the leg at the knee joint |
Muscles of Medial Compartment of Thigh
Consists of six muscles: gracilis, pectineus, adductor longus, adductor brevis, adductor magnus, and obturator externus
Functions: Mainly adduct the thigh at the hip joint; may also medially rotate the thigh
Obturator externus: Lateral rotator of thigh at hip joint
Muscles in Medial Compartment
Muscle Origin Insertion Innervation Function | ||||
Gracilis | External surfaces of the body of pubis and ischium | Medial surface of proximal tibia | Obturator nerve (L2, L3) | Adducts thigh at hip joint; flexes leg at knee joint |
Pectineus | Pectineal line of pubis | Base of lesser trochanter to linea aspera | Femoral nerve (L2, L3) | Adducts and flexes thigh at hip joint |
Adductor Longus | External surface of body of pubis | Linea aspera on middle third of shaft of femur | Obturator nerve (anterior division (L2, L3, L4) | Adducts and medially rotates thigh at hip joint |
Adductor Brevis | External surface of body of pubis | Upper one-third of linea aspera on femur | Obturator nerve (L2, L3) | Adducts and medially rotates thigh at hip joint |
Adductor Magnus | Ischiopubic ramus and ischial tuberosity | Posterior surface of proximal femur | Adductor part-Obturator Nerve (L2, L3, L4) Sciatic Nerve (tibial division) | Adducts and medially rotates thigh at hip joint |
Obturator Externus | External surface of obturator membrane and adjacent bone | Trochanteric fossa of femur | Obturator nerve (posterior division) | Laterally rotates thigh at hip joint |
Muscles in Posterior Compartment of Thigh
Comprises three long muscles: biceps femoris, semitendinosus, and semimembranosus (collectively known as hamstrings)
They flex the leg at the knee joint and extend the thigh at the hip joint
All, except the short head of biceps femoris, cross both joints
Muscles in Posterior Compartment
Muscles Origin Insertion Innervation Action | ||||
Biceps femoris | Long head from ischial tuberosity; short head from linea aspera | Head of fibula | Sciatic nerve (L5, S1, S2) | Flexes leg at knee joint; extends and laterally rotates thigh at hip joint |
Semitendinosus | Ischial tuberosity | Medial surface of proximal tibia | Sciatic nerve (L5, S1, S2) | Flexes leg at knee joint; extends thigh at hip joint; medially rotates |
Semimembranosus | Ischial tuberosity | Groove and adjacent bone on medial posterior surface of tibial condyle | Sciatic nerve (L5, S1, S2) | Flexes leg at knee joint; extends thigh at hip joint; medially rotates |
Hamstring Muscle Injury
Common source of pain, especially in athletes involved in high-power and speed sports
Susceptible to injury from excessive stretching
Leg
Extends from the knee joint to the ankle joint
Divided into anterior (extensor), posterior (flexor), and lateral (fibular) compartments by an interosseous membrane
Muscles in Posterior Compartment of Leg
Organized into two groups: superficial and deep, separated by deep fascia
Mainly plantarflex and invert the foot and flex the toes
All innervated by the tibial nerve
Muscles in Posterior Compartment
Muscle Origin Insertion Innervation Function | ||||
Gastrocnemius | Medial head from posterior surface of distal femur; lateral head from lateral femoral condyle | Posterior surface of calcaneus via calcaneal tendon | Tibial nerve (S1, S2) | Plantarflexes foot, flexes knee joint |
Plantaris | Inferior part of lateral supracondylar line of femur | Posterior surface of calcaneus via calcaneal tendon | Tibial nerve (S1, S2) | Plantarflexes foot, flexes knee joint |
Soleus | Soleal line and medial border of tibia; posterior aspect of fibular head | Posterior surface of calcaneus via calcaneal tendon | Tibial nerve (S1, S2) | Plantarflexes the foot |
Popliteus | Lateral femoral condyle | Posterior surface of proximal tibia | Tibial nerve (L4 to S1) | Stabilizes knee joint, unlocks knee joint |
Flexor hallucis longus | Posterior surface of fibula and adjacent interosseous membrane | Plantar surface of distal phalanx of great toe | Tibial nerve (S2, S3) | Flexes great toe |
Flexor digitorum longus | Medial side of posterior surface of tibia | Plantar surfaces of bases of distal phalanges of lateral four toes | Tibial nerve (S2, S3) | Flexes lateral four toes |
Tibialis posterior | Posterior surfaces of interosseous membrane and adjacent regions | Tuberosity of navicular and medial cuneiform | Tibial nerve (L4, L5) | Inversion and plantarflexion of foot; supports medial arch of foot |
Calcaneal or Achilles Tendon
Formed by converging muscle fibers of gastrocnemius and soleus, attaching to the calcaneus (heel) of the foot
Muscles in Lateral Compartment of Leg
Comprises two muscles: fibularis longus and fibularis brevis (Peroneus Longus & Brevis)
Functions: Evert the foot and innervated by superficial fibular nerve, a branch of the common fibular nerve
Muscles in Lateral Compartment
Muscle Origin Insertion Innervation Function | ||||
Fibularis longus | Upper lateral surface of fibula | Distal end of medial cuneiform and base of metatarsal I | Superficial fibular nerve (L5, S1, S2) | Eversion and plantarflexion of foot; supports arches |
Fibularis brevis | Lower two-thirds of lateral surface of fibula | Lateral surface at base of metatarsal V | Superficial fibular nerve (L5, S1, S2) | Eversion of foot |
Muscles in Anterior Compartment of Leg
Comprises four muscles: tibialis anterior, extensor hallucis longus, extensor digitorum longus, and fibularis tertius
Function: Dorsiflex the foot at the ankle joint, extend the toes, and invert the foot
Innervated by deep fibular nerve
Muscles in Anterior Compartment
Muscle Origin Insertion Innervation Function | ||||
Tibialis anterior | Lateral surface of tibia and adjacent interosseous membrane | Medial cuneiform and base of metatarsal I | Deep fibular nerve (L4, L5) | Dorsiflexion of foot at ankle joint; inversion of foot |
Extensor hallucis longus | Middle part of medial surface of fibula and interosseous membrane | Dorsal surface of base of distal phalanx of great toe | Deep fibular nerve (L5, S1) | Extension of great toe and dorsiflexion of foot |
Extensor digitorum longus | Proximal half of medial surface of fibula | Dorsal digital expansions to lateral four toes | Deep fibular nerve (L5, S1) | Extension of lateral four toes and dorsiflexion of foot |
Fibularis tertius | Distal part of medial surface of fibula | Dorsomedial surface of base of metatarsal V | Deep fibular nerve (L5, S1) | Dorsiflexion of foot and eversion |
Footdrop
Condition characterized by an inability to dorsiflex the foot
Common cause: Damage to the common fibular nerve, potentially from fibular neck fractures
Muscles of Foot
Relevant Structures
Muscles and tendons involved in movement such as:
Anterior tibial artery
Tendon of extensor hallucis longus
Tendon of extensor digitorum longus
Fibularis tertius
Important Muscles to Learn
Focus on origin, insertion, innervation, and actions for:
Gluteus Maximus, Minimus, and Medius
Sartorius
Adductor Magnus
Soleus
Learn innervations and actions for:
Hamstring muscles
Short lateral rotators of the hip: piriformis, obturator internus, gemellus superior, gemellus inferior, quadratus femoris
Identification of muscles involved in plantar flexion, dorsiflexion, eversion, and inversion of the foot.