Sem 2 - I - Posterior thigh & Popliteal fossa - Hamstrings, Sciatic nerve, Popliteal fossa, Popliteal artery & branches Flashcards
What are the three true hamstring muscles? What is the main function of the hamstring muscles and what compartment of the thigh are they located in?
Three true hamstring muscles Biceps femoris (long head) Semitendinosus Semimembranosus Located in the posterior compartment of the thigh They extend the hip joint and flex the knee joint
The most medial hamstring muscle is the semimembranosus What is the attachments and nerve supply?
Semimembranosus arises at the ischial tuberosity and inserts into the posterior surface of the medial condyle of the tibia It is supplied by the tibial division of the sciatic nerve (L5, S1, S2 roots)
Why does the semimembranosus muscle get its name? Which hamstring muscle runs over the lateral aspect of the semimembranosus?
Semimembranosus gets its name due to its shiny membranous appearance The semitendinosus runs slightly over the lateral aspect of the semimebranosus muscle
What are the attachment of the semitendinosus muscle and what is its nerve supply?
Attachments - ischial tuberosity to the superior aspect of the medial surface of the tibia Innervated by tibial division of the sciatic nerve (L5,S1,2 roots)
What are the attachments of the biceps femoris and what is its nerve supply?
Long head arises from ischial tuberosity (tibial divsion of sciatic nerve (L5,S1,2 roots)
Short head arises from the linea aspera and lateral supracondylar line (common fibular division sciatic nerve (L5,S1,2 roots)
The two heads join to insert at head of the fibula
When is extension at the hip joint due to the hamstring muscles greatest and why?
Because the hamstring muscles cross two joints, they can therefore act on both these joints using up the muscles finite contractility
Therefore if the knee is fully extended, the hip joint can be extended to a greater extent as the hamstring muscles will only be acting on the hip joint
Three muscles insert onto the superior aspect of the medial surface of the tibia What are these muscles? What is this known as?
Pes anserinus (goose foot) refers to the conjoined tendon of three muscles that insert onto the superior aspect of the medial surface of the tibia
Say Grace before Tea
- * Sartorius
- * Gracilis
- * Semitendanosus
When can rotation of the knee occur and which muscles bring about this action?
Rotation of the knee can occur when the knee is flexed
- Lateral rotation of the knee - due to biceps femoris
- Medial rotation of the knee -
- * Semimebranosus
- * Semitendanosus
- * Gracilis
- * Sartorius
What is the course of the sciatic nerve from origin to its division?
Sciatic nerve arises from lumbosacral trunk (L4,5) and S1,2,3 nerve roots
It passes through the greater sciatic foramen inferior to the piriformis and then travels inferiorly
Once in the posterior thigh it is deep to the long head of the biceps femoris where it will divide into the tibial nerve and common fibular nerve which will enter the popliteal fossa
The popliteal fossa is a diamond shaped area found on the posterior side of the knee. It is the main path in which structures move from the thigh to the leg. What forms the roof of the popliteal fossa and what pierces the roof?
The roof of the popliteal fossa is formed by deep fascia (on top of this is fat and skin)
Passing through the roof (deep fascia) is the short saphenous vein (draining into popliteal vein) and the sural nerve (made up of branches from tibial and common fibular nerve)
What forms the boundaries of the popliteal fossa?
- Superiorly - the diverging tendons of the hamstring muscles
- * Biceps femoris laterally
- * Semitendanosus and semimembranosus medially
- Inferiorly - medial and lateral heads of the gastrocnemius
What are the contents of the popliteal fossa from medial and deep to lateral and superficial?
- Most medial and deep we have the popliteal artery
- The popliteal vein runs directly on top of the popliteal artery
- Travelling close to the midline we have the tibial nerve
- Most lateral and superficial we have the common fibular nerve which moves around the neck of fibula to the lateral leg
Which structures pierce the roof of the popliteal fossa?
What are the boundaries? What are the contents?
Small saphenous vein and sural nerve pierce the deep fascia roof
Superior boundary -
- Biceps femoris laterally
- Semitendinosus and semimembranosus medially
Inferior boundary - medial & lateral heads of gastrocenumius
Contents - Popliteal artery, vein, tibial & common fibular nerve
What structures form the floor of the popliteal fossa?
Popliteal surface of femur
The capsule of the knee joint
The popliteus muscle - which lies on a small area of the superior tibia
Oblique popliteal ligament
How is the oblique popliteal ligament arise formed? What does this ligament reinforce?
As some of the semimembranosus fibres come laterally, they fuse with the posterior aspect of the knee joint capsule to form the the oblique popliteal ligament The oblique popliteal ligament is an expansion of the semimembranosus muscle which reinforces the knee joint capsule posteriorly
Which vessels pierce the knee joint capsule to supply the cruciate ligaments of the knee?
The middle genicular vessels pierce the knee joint capsule to supply the cruciate ligaments of the knee
What is the continuation of the femoral artery known as? When does it get its name and where does it run to? What are its terminal branches?
Continuation of the femoral artery after it passes through the adductor hiatus is the popliteal artery
Popliteal artery runs from adductor hiatus to inferior border of the popliteus Terminal branches of popliteal artery - anterior & posterior tibial arteries
The popliteal artery gives rise to 5 genicular branches that help supply the knee joint What are the 5 genicular branches?
The 5 genicular branches from the popliteal artery
- * Superior lateral genicular artery
- * Superior medial genicular artery
- * Middle genicular artery
- * Inferior lateral genicular artery
- * Inferior medial genicular artery
The 5 genicular arteries travel anteriorly to form an important anastamosis with other arteries to supply the knee joint What is the anastamosis known as and what arteries contribute?
The Periarticular Genicular Anastamosis
- 5 genicular branches from popliteal artery
- Descending genicular artery from femoral artery
- Descending branch of lateral circumflex femoral artery
- Recurrent branches from anterior and posterior tibial arteries
Why is the PERIARTICULAR GENICULAR ANASTAMOSIS important?
Important because as the popliteal artery runs posterior to the knee joint, when the knee is flexed, this anastamsois will allow for adequate perfusion of the knee joint and leg
