Muscles of Posterior Thigh Flashcards
What are the muscles of the posterior thigh collectively called?
Hamstrings/hip extensors
Name the muscles in the posterior compartment of the thigh
Biceps femoris, semitendinosus, semimembranosus
What is the action of the hamstrings?
Extension at hip, flexion at knee
What is the innervation of the hamstrings?
Sciatic nerve (L4-S3)
Where is the biceps femoris positioned?
Most lateral muscle in posterior compartment of thigh
What are the attachments of the biceps femoris?
. Long head originates from ischial tuberosity and short head originates from linea aspera
. Heads joint to form tendon, which inserts into lateral surface of fibular head
What is the innervation of the biceps femoris?
. Long head innervated by tibial branch of sciatic nerve
. Short head innervated by common fibular part of sciatic nerve
(Long head more superficial than short head)
Where is the semitendinosus?
Lies medial to biceps femoris, superficial to semimembranosus
What are the attachments of the semitendinosus?
Originates from ischial tuberosity of pelvis, attaches to medial surface of tibia
What are the actions of the semitendinosus?
Extension at hip, flexion and medial rotation at knee (only medial rotation at knee when knee flexed)
What is the innervation of the semitendinosus?
Tibial part of sciatic nerve
What are the actions of the biceps femoris?
Extension at hip, flexion and lateral rotation at knee (only lateral rotation at knee when knee flexed)
Where is the semimembranosus located?
Deep to semitendinosus
Describe the semimembranosus and semitendinosus.
Semimembranosus is flattened and broad, semitendinosus is largely tendinous
What are the attachments of the semimembranosus?
Originates from ischial tuberosity (superior to semitendinosus and biceps femoris), attaches to medial tibial condyle
What are the actions of the semimembranosus?
Extension at hip, flexion and medial rotation at hip (only medial rotation at knee when knee flexed)
What is the innervation of the semimembranosus?
Tibial part of sciatic nerve
What is an avulsion fracture?
When a bit of bone breaks off the main body of bone
What happens in an avulsion fracture of the ischial tuberosity?
Hamstring tendons tear off part of the ischial tuberosity (usually due to rapid contraction and relaxation of hamstring muscles)
What are the nerve roots of the sciatic nerve?
L4-S3
