THIGH - ANTERIOR - three main groups of muscles: adductors, flexors, extensors; on the leg the extensors are on the back; flexors on the front; adductors on the inside and front

ADDUCTORS - a complex group - seven separate muscles which form a large mass — they are seldom seen separately

adductors LONGUS and MAGNUS affect surface form

origin: above and along the superior and inferior rami of the pubis and the ischium

insertion: six main adductors — into the linea aspera of the femur

action: LONGUS adducts and flexes thigh; MAGNUS adducts and extends thigh

origin: ramus of the ischium

insertion: tuberosity of the tibia after wrapping around medial condyle of the femur and tibia

form: long line so characteristic of inside of upper leg and knee

action: adducts and flexes thigh, flexes leg, rotates it inward

QUADRICEPS (extensor group) - single muscle - four parts: only three are subcutaneous, one is very deep

VASTUS MEDIALIS

origin: linea aspera of femur

VASTUS LATERALIS

origin: great trochanter and linea aspera of the femur; joins common tendon slightly higher than MEDIALIS

RECTUS FEMORIS - from L. femoris, of the thigh

origin: on pelvis at two points: right above the acetabulum and the anterior inferior iliac spine; fullest width is higher than MEDIALIS or LATERALIS; has a pronounced bulge forward — in spite of its name it has no attachment on the femur

insertion: common tendon to patella (quadriceps tendon) continues over patella into fibers of the patellar ligament which inserts at the tuberosity of the tibia

action: all extend leg; RECTUS FEMORIS also flexes and abducts the thigh

form: VASTUS MEDIALIS creates characteristic bulge on the inner side of the knee — "tear drop" muscle;

FEMORIS creates fullness at the front of the thigh;

LATERALIS creates the shape of the outer thigh

these are large, powerful muscles as they must lift the entire weight of the body

 

SARTORIUS - longest muscle on the body (named the tailor’s muscle since at one time tailors sat cross-legged on the ground and this muscle became prominent

origin: anterior superior iliac spine of the pelvis - winds down the groove between the extensors and the adductors over the vastus medialis to the back and forward again over the gracilis

insertion: behind the medial epicondyle of femur to the tuberosity of the tibia

form: ties upper and lower leg together physically and visually

action: flexor — two types of flexion: flexes and abducts thigh, rotates it outward; flexes the lower leg, rotates it inward

 

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BACK OF THIGH - three flexors:

The semimembranosis and the semitendinosus muscles are commonly referred to as the "hamstrings." Students should remember the form and function of these two muscles.

SEMIMEMBRANOSIS - deepest

origin: posterior of ischium

insertion: medial condyle of tibia

action: extends thigh backwards, adducts it, rotates it outward; flexes leg, rotates it outward

SEMITENDINOSUS

origin: ischial tuberosity of the pelvis

insertion: tuberosity of the tibia (in common with the gracilis, behind the sartorius tendon

action: extends thigh backward, adducts it, rotates it inward; flexes leg, rotates it inward

BICEPS FEMORIS - two heads (located on outer back side of thigh, usually the muscles that provides the back line of the thigh from a side view.

long head:

origin: just outside semimembranosus and semitendinosus on posterior of ischium

insertion: head of fibula

short head:

origin: deeper muscles - linea aspera of the femur

insertion: head of fibula

action: extends thigh backward, adducts it, rotates it outward; flexes leg, rotates it outward

 

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posterior muscles have greatest effect on form; all muscles contained by stocking of fascia with muscle groups separated by partition to the bone

ANTERIOR:

TIBIALIS ANTICUS - tibialis anterior

origin: lateral condyle and surface of tibia; interosseous membrane

insertion: inner tarsal and metatarsal of the big toe

form: softens form of the tibia

action: extensor of the foot (raises front of foot), inverts foot

EXTENSOR LONGUS DIGITORUM (counterpart to extensor digitorum (communis)

origin: lateral condyle of the tibia; head and crest of the fibula; interosseous membrane

insertion: below front of the ankle, by 4 tendons to the phalanges of toes II - V

form: fills space between tibialis anticus and peroneus longus

action: raises the foot; everts and abducts foot; raises toes II - V

 

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LATERAL - one muscles on the top of the other — main effect is to smooth out the form between the tibialis anticus and the soleus

PERONEUS BREVIS

origin: lateral surface of the fibula, one third of the way down from the head of fibula

insertion: tendon passes behind outer malleolus and attaches to the tuberosity of metatarsal V

action: points foot; everts and abducts foot

PERONEUS LONGUS

insertion: tendon passes behind outer malleolus and forward to sole of the foot

action: points foot; inverts and adducts foot; flexes big toe

 

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the soleus and gastrocnemius share a common tendon — the Achilles — the thickest, strongest, biggest tendon in the body

SOLEUS

origin: head of fibula and posterior surface of fibula and tibia

insertion: underside of Achilles tendon which attaches to the calcaneous

form: on outside creates curve just below knee; on the inside creates fullness below gastrocnemius

action: points foot; inverts and adducts foot

GASTROCNEMIUS (overlies soleus)

origin: lateral head (high) above lateral condyle of femur

medial head (low) above medial condyle of femur

insertion: by Achilles tendon to calcaneous

form: creates fullness high on back of leg; creates complete interlocking of thigh and leg

action: flexes leg; points foot; inverts and adducts foot

The Achilles tendon gets wider as the muscle develops; the length of the Achilles tendon affect the form of the leg; long tendon — thinner ankle; if it inserts far back on the calcaneous have a wider profile at the ankle when both the SOLEUS and the GASTROCNEMIUS are in action the whole weight of the body can be raised on the toes

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