This document summarizes the origin, insertion, action, synergists, and antagonists of several muscles in the pelvis, thigh, and lower leg regions. Key muscles discussed include the iliopsoas, gluteus maximus, medius and minimus, sartorius, quadriceps femoris group (rectus femoris, vastus lateralis, medialis and intermedius), and hamstrings. These muscles act to flex, extend, abduct, rotate and stabilize the hip, knee and ankle joints during movements like walking, running, sitting and climbing stairs. Understanding muscle origins and insertions is important for comprehending their functional actions.

1. Lab 9: Muscles of Lower Extremity, Abdomen, and Skull
Muscle Origin Insertion Action Synergists Antagonists
Pelvic Region Move femur
Iliopsoas: Iliacus/psoas 1. Transverse process Lesser trochanter of Flexion at Hip -Adductor longus -Gluteus maximus
major and bodies of lumbar femur -Sartorius -Biceps femoris
-Can be seen on anterior vertebrae (psoas major) -Rectus femoris -Semitendinosus
surface medial to sartorius 2. Iliac Fossa (iliacus) -Semimembranosus
-Iliacus- fan-shaped, more -Adductor magnus
lateral Torso Flexion
-Psoas major- longer,
thicker and more medial
Gluteal Muscles (posterior Common origin on pelvis or sacrum Abduction of Thigh
hip)
Gluteus maximus 1. Ilium Gluteal tuberosity of Extension at Hip -Biceps femoris -Adductor longus
-Largest and most 2. Sacrum femur -Semitendinosus -Sartorius
superficial of glutes 3. Coccyx -Semimembranosus -Rectus femoris
-Meant for powerful -Adductor magnus -Iliopsoas
movements Lateral rotation at Hip -Sartorius -Gluteus medius
-Gluteus minimus
-Adductor magnus
-Adductor longus
-Gracilis
Abduction at Hip -Gluteus medius -Adductor magnus
-Gluteus minimus -Adductor longus
-Sartorius -Gracilis
Gluteus medius Ilium Greater trochanter of Medial Rotation at Hip -Adductor magnus -Sartorius
-Deep to gluteus max. femur -Adductor longus -Gluteus maximus
Walking” Muscles -Gracilis
Abduction at Hip -Gluteus maximus Adductor magnus
-Sartorius -Adductor longus
-Gracilis
Gluteus minimus Ilium Greater trochanter of Medial Rotation at Hip -Adductor magnus -Sartorius
-Smallest and deepest of femur -Adductor longus -Gluteus maximus
glutes -Gracilis
-Walking” Muscles Abduction at Hip -Gluteus maximus Adductor magnus
-Sartorius -Adductor longus
-Gracilis

2. Piriformis- landmark Anterolateral surface of Greater trochanter of Only need to ID: Follow sciatic nerve up leg, ends in triangular shaped muscle,
-Posterior part of hip joint sacrum femur inferior to the gluteus minimus, pyramidal shaped
Muscle Origin Insertion Action Synergists Antagonists
Thigh (Anterior) Tibial tuberosity of Extension of knee (
tibia
Sartorius (exception) Anterior superior iliac spine Medial proximal tibia Flexion of Knee Biceps femoris -Hamstrings
-Longest muscle, runs -Semimembranosus -Short head biceps
obliquely across anterior -Semitendinosus femoris
surface of thigh -Gracilis -Adductor magnus
-“Indian style” sitting -Gluteus maximus
Abduction at Hip -Gluteal Muscles -Adductor magnus
-Adductor longus
-Gracilis
Lateral rotation at Hip -Gluteus Maximus -Adductors
-Gracilis
Flexion at Hip --Adductor longus --Hamstrings
-Rectus femoris -Adductor magnus
-Iliopsoas
Quadriceps Femoris Tibial tuberosity via Extension of knee - -Biceps femoris
-Rectus femoris patellar tendon -Semimembranosus
-Vastus muscles (3) -Semitendinosus
-Sartorius
-Gracilis
-Gastrocnemius
Rectus Femoris Anterior inferior iliac spine Tibial tuberosity via Extension at Knee Rectus femoris See Quad Antagonists
-Superficial, runs straight patellar tendon Vastus medialis
down anterior surface of Vastus intermedius
thigh Vastus lateralis
Flexion at Hip Semimembranosus -Hamstrings
-Semitendinosus -Adductor magnus
-Sartorius -Gluteus maximus
Vastus lateralis Linea aspera of posterior Tibial tuberosity via Extension at Knee Rectus femoris See Quad Antagonists
-Lateral part of thigh femur patellar tendon Vastus medialis
-Largest head of quads Vastus intermedius
Vastus medialis Linea aspera of posterior Tibial tuberosity via Extension at Knee Rectus femoris See Quad Antagonists
-Inferomedial part of thigh femur patellar tendon Vastus lateralis

3. Vastus intermedius
Vastus intermedius Anterior Femur Tibial tuberosity via Extension at Knee Rectus femoris See Quad Antagonists
-Deep to rectus femoris patellar tendon Vastus medialis
-Between other vastus Vastus lateralis
muscles
Tensor fasciae latae Anterior Iliac crest and IT band ID ONLY- TFL pulls on IT band, which is a thickened fascia that runs down
ASIS lateral side of thigh. TFL overlies rectus femoris and vastus lateralis.
Iliotibial (IT) Band Iliac crest Knee
Muscle Origin Insertion Action Synergists Antagonists
Thigh (Medial) Adductors at Hip
Gracilis Inferior ramus of pubis Medial proximal tibia Flexion of Knee -Biceps femoris -Rectus femoris
-Long, thin superficial -Semimembranosus -Vastus lateralis
muscle of medial thigh -Semitendinosus -Vastus medialis
-Sartorius -Vastus intermedius
-Gastrocnemius
Adduction at Hip -Adductor magnus -Gluteal Muscles
-Adductor longus -Sartorius
Adductor longus Pubis Linea aspera of Flexion at hip -Sartorius -Hamstrings
-Most anterior of adductor posterior femur -Rectus femoris -Adductor magnus
muscles, overlies middle -Iliopsoas -Gluteus maximus
aspect of adductor magnus Adduction at Hip -Adductor Magnus -Gluteal Muscles
-Gracilis -Sartorius
Medial Rotation at Hip -Adductor magnus -Gluteus Maximus
-Gracilis -Sartorius
-Gluteus medius
-Gluteus minimus
Adductor magnus 1. Ischial ramus 1. Linea aspera of Flexion at Hip (ant) -Sartorius -Hamstrings
-Triangular muscle, medial to 2. Inferior pubic ramus posterior femur -Rectus femoris -Adductor magnus
Semimembranosus, lateral to 3. Ischial tuberosity 2. Medial -Iliopsoas -Gluteus maximus
Gracilis supracondylar line of Adduction at Hip (ant) -Adductor longus -Gluteal Muscles
-Anterior part acts like femur -Gracilis -Sartorius

4. adductor 3. Adductor tubercle Medial Rotation (ant) -Adductor longus -Gluteus Maximus
-Posterior part acts like of femur -Gracilis -Sartorius
hamstring -Gluteus medius
-Gluteus minimus
Extension of hip (post) -Hamstrings --Sartorius
-Gluteus maximus -Rectus femoris
-Iliopsoas
-Adductor Longus
Muscle Origin Insertion Action Synergists Antagonists
Thigh (Posterior) Flexion of knee
Hamstrings Ischial tuberosity Extend hip, flex knee
Biceps Femoris 1. Long head- Ischial 1. Head of fibula Flexion at Knee -Gracilis -Rectus femoris
-Long head is medial to short tuberosity 2. Proximal lateral -Semimembranosus -Vastus lateralis
head 2. Short head- Linea aspera tibia -Semitendinosus -Vastus medialis
-Only long head is hamstring of posterior femur -Sartorius -Vastus intermedius
-Most lateral of hamstrings -Gastrocnemius
Extension at Hip (only -Gluteus maximus -Adductor Longus
long head) -Semitendinosus -Iliopsoas
-Semimembranosus -Sartorius
-Adductor magnus -Rectus Femoris
Semitendinosus Ischial tuberosity Proximal medial tibia Flexion at Knee -Gracilis -Rectus femoris
-Medial to biceps femoris (with Gracilis and -Semimembranosus -Vastus lateralis
Sartorius) -Biceps Femoris -Vastus medialis
-Sartorius -Vastus intermedius
-Gastrocnemius

5. Extension at Hip -Gluteus maximus -Adductor Longus
-Long head of biceps -Iliopsoas
femoris -Sartorius
-Semimembranosus -Rectus Femoris
-Adductor magnus
Semimembranosus Ischial tuberosity Proximal medial tibia Flexion at Knee -Gracilis -Rectus femoris
-Deep and medial to (not with Gracilis -Biceps Femoris -Vastus lateralis
Semitendinosus, lateral to and Sartorius) -Semitendinosus -Vastus medialis
adductor magnus -Sartorius -Vastus intermedius
-Gastrocnemius
Extension at Hip -Gluteus maximus -Adductor Longus
-Long head of biceps -Iliopsoas
femoris -Sartorius
-Semitendinosus -Rectus Femoris
-Adductor magnus
Muscle Origin Insertion Action Synergists Antagonists
Leg (Posterior Comp.)
Gastrocnemius 1. Medial condyle of femur Calcaneal tuberosity Flexion of Knee -Gracilis Triceps Brachii
-Part of triceps surae, on 2. Lateral condyle of femur via calcaneal tendon -Semimembranosus
posterior calf -Semitendinosus
-Superficial muscle -Sartorius
-2 heads (lateral and medial) -Biceps femoris
-Forms proximal curve of calf Plantar Flexion at -Tibialis posterior Tibialis anterior
Ankle -Soleus
-Fibularis

6. Soleus 1. Superior tibia Calcaneal tuberosity Plantar Flexion at -Tibialis posterior - Tibialis anterior
-Part of triceps surae, flat / 2. Fibula via calcaneal tendon Ankle -Gastrocnemius
broad 3. Interosseous membrane -Fibularis
-Deep to Gastrocnemius on
posterior surface
Tibialis posterior To locate: originates on superior tibia and fibula and Plantar Flexion at -Soleus -Tibialis anterior
-Thick, flat muscles deep to interosseous membrane, inserts into tarsals and Ankle -Gastrocnemius
soleus metatarsals -Fibularis
-Crossed over by flexor -tendon is directly posterior to tibia, crosses under Inversion at Ankle -Tibialis anterior --Fibularis
digitorum longus on distal flexor digitorum longus
end
-Placed lateral to flexor
digitorum longus
Flexor Digitorum Longus Only Need to ID: long narrow, runs medial to Tibialis posterior and partially overlies it, originates on posterior tibia, inserts into
phalanges
Leg (Anterior Comp.)
Tibialis Anterior To locate: originates on lateral condyle, interosseous Dorsiflexion at Ankle -Extensor digitorum -Gastrocnemius
-Superficial muscles of membrane and inserts into inferior surface of medial longus -Soleus
anterior leg cuneiform and 1st metacarpal -Tibialis posterior
-Laterally parallels anterior -Tendon anterior to tibia -Fibularis
tibia Inversion at Ankle -Tibialis Posterior -Fibularis
Extensor Digitorum Longus Only Need to ID: anterolateral surface of leg, lateral to Tibialis anterior, inserts on phalanges of digits 2-5,
Leg (Lateral Comp.)
Fibularis (longus and brevis) To locate: longus originates on head and upper portion Plantar Flexion at -Tibialis posterior -Tibialis anterior
-Longus: superficial, overlies of lateral side of fibula, same insertion as Tibialis Ankle -Gastrocnemius
fibula anterior-first metatarsal and medial cuneiform -Soleus
-Brevis is deep to longus, Brevis originates on distal fibula shaft and inserts on Eversion at Ankle -Tibialis anterior
smaller and wider proximal end of fifth metatarsal -Tibialis posterior
Muscle Origin Insertion Action Synergist Antagonists
Muscles of Mastication Elevate mandible

7. Temporalis- fan shaped Temporal fossa (lateral Coronoid process of Elevation of Mandible Masseter Digastric
muscles that covers temple of cranium) mandible Pterygoids
skull
Masseter Zygomatic arch (bone + 1. Angle of mandible Elevation of Mandible Temporalis Digastric
-Covers lateral aspect of process of temporal bone) 2. Ramus of mandible Pterygoids
mandibular ramus Lateral Motion of Pterygoids
mandible
Pterygoids Lateral sphenoid Medial ramus of Elevation of Mandible Masseter, Temporalis Digastric
mandible Lateral Motion of Masseter
Mandible
Muscles of Abdominal Wall Direction of Fibers Action Location
External oblique Superolaterally to inferomedially Flex trunk, Most superficial of lateral abs
Rotation of trunk
Lateral flexion of trunk
Internal Oblique Inferolaterally to superomedially Flex trunk Deep to internal oblique
Rotation of trunk
Lateral flexion of trunk
Transversus Abdominis Horizontal Compress viscera Deepest of lateral muscles
Rectus Abdominis (6 pack) Vertical Flexion of trunk Medial muscle group, aponeuroses of
lateral muscles surround, separated
by 3 tendinous intersections
horizontally
Linea alba ID only: tendinous raphe that runs vertically to separate left from right rectus abdominis