Anatomy of Knee Flashcards
what nerve innervates the posterior compartment of the thigh?
The sciatic nerve and its two branches provide all motor innervation to the posterior thigh.
the posterior thigh is
* hamstring group
* acts to extend the hip + flex the knee
* all tendons attach to ischial tuberosity
what muscles is the posterior compartment of thigh composed of
The posterior thigh is composed of three muscles: biceps femoris long and short head, semitendinosus, and semimembranosus. These three muscles are collectively referred to as the hamstring muscles.
what nerve innervates the anterior compartment of the thigh? +note its blood supply
the femoral nerve
The function of the anterior compartment muscles is to extend the lower limb at the knee joint. The innervation of the anterior compartment of the thigh is from the femoral nerve, which originates from spinal roots L2-L4, and blood supply is from the femoral artery and its first branches.
what nerve innervates the medial compartment of the thigh?
The obturator nerve
The obturator nerve : Provides motor innervation to the medial compartment of the thigh.
what muscles is the anterior compartment of thigh composed of
Three major muscles (better described as two muscles and one muscle group) comprise the anterior compartment of the thigh — the pectineus, sartorius, and quadriceps femoris. Additionally, the end of the iliopsoas muscle passes through the anterior compartment
what muscles is the medial compartment of thigh composed of
The muscles in the medial compartment of the thigh are collectively known as the hip adductors. There are five muscles in this group; gracilis, obturator externus, adductor brevis, adductor longus and adductor magnus.
what is pes anserinus (colloquially termed goose’s foot); what condition is commonly associated w this region
The term “pes anserinus” translates to “goose’s foot” in Latin and refers to the conjoined tendons of the sartorius, gracilis, and semitendinosus as they insert on the anteromedial proximal tibia
Pes anserine bursitis is an inflammation of the bursa located between the shinbone (tibia) and three tendons of the hamstring muscle at the inside of the knee. It occurs when the bursa becomes irritated and produces too much fluid, which causes it to swell and put pressure on the adjacent parts of the knee
Popliteus is a very small muscle deep in the popliteal fossa. What is its role?
- mechanically a ‘weak’ flexor of the knee
- unlocks the knee by laterally rotating the femur (closed-chain movement)
- unlocks the knee by medially rotating the tibia (open-chain movement)
- popliteus initiates the subsequent actions of the hamstrings to flex the knee
describe knee joint complex
- Knee joint complex - overall a hinge joint
- Made of 2 articulations, 3 bones
- Saddle joint and condyloid joints
Patellofemoral joint (saddle) + tibiofemoral joint (2x condyloid) - All articulations share same joint capsule
- Allow knee to flex/extend
Stability determined by ligaments/tendons - act to restrain excessive motion (e.g. hyperflexion) - allows to fine tune movement
is the fibula weight bearing?
no the fibula is not weight bearing
Unlike the tibia, the fibula is not a weight-bearing bone. Its main function is to combine with the tibia and provide stability to the ankle joint. The distal end of the fibula has several grooves for ligament attachments which then stabilize and provide leverage during the ankle movements
what do we mean by the following anatomical deformities:
* genu varum
* genu valgum
- genu varum= aka bow legs. ‘Rum makes knees open’ , distal tibia points medially ; smaller Q angle
*genu valgum= aka knocked knees. ‘Gum makes knees stick together’; distal tibia points laterally; larger Q angle
what produces the synovial fluid in the knee joint
BURSAE PRODUCE THIS SYNOVIAL FLUID. PARTICULARLY; Synovial fluid production is from fibroblast like type B synovial cells.
what are bursae
Bursa, and bursas or bursae for the plural form, is an important lubricated fluid-filled thin sac located between bone and surrounding soft tissue, bones and tendons, and/or muscles around joints, and are useful to the human body by reducing tension and negative effects of wear-and-tear at points of friction
- Almost all bursa are extensions of knee synovial cavity, filled with synovial fluid
Act as cushions against friction/rubbing of tendons, ligaments and bones around knee joint
clinical note: Prepatellar bursitis - lots of fluid in patella become inflamed
which collateral ligament of the knee is thicker; medial collateral ligament or lateral collateral ligament
the medial collateral ligament is thicker than the lateral!
what are the menisci of the knee + their functions
Menisci are plates of fibrocartilage
* Helps deepen joint - similar in function to glenoid labrum or acetabular labrum
* Borders are thicker than central parts to hold bones in place
* Act as shock absorbers where 2 condyles articulate with tibia
* Sits on tibial plateau
Functions to:
* Bear weight
* Support articulating surfaces of tibia and femur
* Guide rotation between 2 bones
* Stabilise translation of the joint - movement between articular surfaces that isn’t flexion/extension
n.b. Medial meniscus is bigger
