BLOCK 12 WEEK 4 Flashcards
The Knee
- The knee joint is a hinge joint
- Knee joint is where your femur meets your tibia
Knee Articulations
The places these bones meet are called articulations or articulating surfaces. There are two articulations in your knee:
- Patellofemoral: Where your patella meets your femur. Anterior aspect of the distal femur articulates with the patella. It allows the tendon of the quadriceps femoris (knee extensor) to be inserted directly over the knee – increasing the efficiency of the muscle.
- Tibiofemoral: Where your tibia meets your femur. Medial and lateral condyles of the femur articulate with the tibial condyles. It is the weight-bearing component of the knee joint.
Cartilage:
- hyaline/articular cartilage around the joints
- fibrocartilage is what the meniscus are made up of
Ligaments:
- collateral ligaments
- cruciate ligaments
Angular knee Joint Deformaties
Genu Valgum deformity (aka knocked knees)
- Genu valgum (knock-knees) is a common lower leg abnormality that is usually seen in the toddler, preschool and early school age child.
- In genu valgum, the lower extremities turn inward, causing the appearance of the knees to be touching while the ankles remain apart.
- Genu valgum is most severe by age 3 but then usually resolves on its own by age 7-8.
-Knock knees are slightly more common in girls than boys.
CAUSE:
- Physiological (most common cause)
- Pathological: rickets, previous fracture of tibia
Genum Varum (aka Bow legs)
- Bow legs (or genu varum) is when the legs curve outward at the knees while the feet and ankles touch.
- . Infants and toddlers often have bow legs. It’s rarely serious and usually goes away without treatment, often by the time a child is 3–4 years old.
- Bow legs don’t usually bother young children because the condition doesn’t cause pain or discomfort.
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Q angle
Q angle: This angle is created by the femur’s diagonal placement within the thigh and by the tibia’s vertical placement in the leg
- This angle is typically between 15 and 20 degrees and on average is higher in biologic females(women 17, men 14)
- a normal Q angle allows the weight supported by the knee joint to be centered through the middle of the knee, in the knee’s intercondylar region.
GENUM VALGUM:
- When the Q angle increases over the normal range
- weight bearing center to the lateral compartment of the knee
- which increases the quadriceps lateral pull
- causes the medial collateral ligament to overstretch
GENUM VARUM:
Medial Collateral Ligament
- Medial Collateral Ligament resists Valgus forces
- gives medial stability
Lateral Collateral Ligament
- Lateral Collateral Ligament resists Varus forces
- Lateral stability
Cruciate Ligaments
- gives STATIC stability
- ROTATIONAL stability
- is Intra-capsular but extra-synovial
ACL Rupture
ACL:
- Taut in EXTENSION
- Prevents posterior displacement of femur
- Axis for knee locking
- Anterior Cruciate Ligament Test is known as LACHMANS TEST
Posterior Cruiciate Ligament
- Taut in FLEXION
- Prevents Anterior Displacement of femur
- Stabilizes the flexed knee
Knee Arthroscopy
Knee arthroscopy:
- is a type of keyhole surgery used to diagnose and treat knee pain or other knee problems. It can be used for inflammation, damage, injury and infections.
- During a knee arthroscopy, your surgeon will use a camera to look inside your knee for damage to the cartilage (meniscus), joint lining and ligaments. Your surgeon may also:
- treat your knee – they may repair or remove any damaged tissue and cartilage (meniscus)
- take small tissue samples (biopsies), which may help to diagnose problems such as infections
- do some more complicated surgery, including surgery to repair torn knee ligaments or to treat an unstable kneecap
Menisci
Menisci have two main functions:
- Deepens the articular surface of the tibia – increasing the stability of the joint.
- Acts as shock absorbers– increasing surface area to further dissipate forces that are transmitted across the joint.
- They are attached at both ends to the intercondylar area of the tibia.
Medial Meniscus: In addition to this attachment, the medial meniscus is also fixed to the medial collateral ligament and the joint capsule. Damage to the medial collateral ligament is often associated with a medial meniscal tear.
Lateral Meniscus: The lateral meniscus is smaller and does not have any additional attachments, rendering it more mobile.
X RAYYYYY
Terrible Triad (BLOWN KNEE)
Unhappy / TERRIBLE Triad (Blown Knee)
As the medial collateral ligament is attached to the medial meniscus, damage to either can affect both structure’s functions.
A lateral force to an extended knee, such as a rugby tackle, can rupture the medial collateral ligament, damaging the medial meniscus in the process.
The ACL is also affected, which completes the ‘unhappy triad’.
- Medial meniscus, medial (tibial) collateral ligament, Anterior cruciate ligament
Terrible Triad MRI
- Torn ACL on pic
- Torn MCL on pic 2
The wavy like appearance on the first pic indicates a tear would normally be smooth
Knee Locking Mechanism
Quadriceps femoris
Nerve Supply: femoral nerve (L2-L4)
- Myotome which extend the knee: (L3-L4)
Quads and Q-angle
Iliotibial Band
- Your iliotibial band is a strong, thick band of tissue that runs down the outside of your thigh.
- iliac crest to the lateral tibial condyle
- ACTED ON BY: tensor fascia latae and the gluteus maximus
Job: pulls the knee into hyperextension
Hamstrings
PES ANSERINUS (GOOSE FOOT)
Pes Anserinus is the conjoined tendons of three muscles which insert into the anteromedial surface of tibia above the ACL:
- SARTORIUS
- GRACILLIS
- SEMITENDINIOUS
Popliteal Fossa
The popliteal fossa is a diamond shaped area located on the posterior aspect of the knee. It is the main path by which vessels and nerves pass between the thigh and the leg.
Diamond shaped 4 borders:
- Superomedial – semimembranosus.
- Superolateral – biceps femoris.
- Inferomedial – medial head of the gastrocnemius.
- Inferolateral – lateral head of the gastrocnemius and plantaris.
Floor: posterior surface of the knee joint capsule, popliteus muscle and posterior femur.
Roof: popliteal fascia and skin
CONTENTS:
- Popliteal artery
- Popliteal vein
- Tibial nerve
- Common fibular nerve (common peroneal nerve)
The tibial and common fibular nerves are the most superficial of the contents of the popliteal fossa. They are both branches of the sciatic nerve. The common fibular nerve follows the biceps femoris tendon, travelling along the lateral margin of the popliteal fossa.
The small saphenous vein pierces the popliteal fascia and passes between the two heads of gastrocnemius to empty into the popliteal vein.
In the popliteal fossa, the deepest structure is the popliteal artery. It is a continuation of the femoral artery, and travels into the leg to supply it with blood.
BAKERS CYST
The appearance of mass in the popliteal fossa usually is because of a bakers cyst or aneurysm of the popliteal artery.
BAKERS CYST (popliteal cyst):
- A Baker’s cyst (popliteal cyst) refers to the inflammation and swelling of the semimembranosus bursa – a sac-like structure containing a small amount of synovial fluid. It usually arises in conjunction with osteoarthritis of the knee.
- Whilst it usually self-resolves, the cyst can rupture and produce symptoms similar to deep vein thrombosis.
POPLITEAL ANEURYSM
Popliteal Aneurysm:
- An aneurysm is a dilation of an artery, which is greater than 50% of the normal diameter. The popliteal fascia (the roof of the popliteal fossa) is tough and non-extensible, and so an aneurysm of the popliteal artery has consequences for the other contents of the popliteal fossa.
- The tibial nerve is particularly susceptible to compression from the popliteal artery. The major features of tibial nerve compression are:
- Weakened or absent plantar flexion
- Paraesthesia of the foot and posterolateral leg
An aneurysm of the popliteal artery can be detected by an obvious palpable pulsation in the popliteal fossa. An arterial bruit may be heard on auscultation.
Knee - BURSAE
A bursa is a sac-like structure containing a small amount of synovial fluid. It functions to decrease friction between tendons, bone, and skin during movement
Knee bursae (4):
- SUPRAPATELLAR BURSAE: located between the quadriceps femoris and the femur.
- PREPATELLAR BURSAE: located between the apex of the patella and the skin.
- INFRAPATELLAR BURSAE: split into deep and superficial. The deep bursa lies between the tibia and the patella ligament. The superficial lies between the patella ligament and the skin.
- SEMIMEMBRANEOUS BURSAE: located posterior to the knee joint, between the semimembranosus muscle and the medial head of the gastrocnemius.
AnteroLateral Ligament
ALL: resists lateral rotation of the femur on the tibia
- Commonly damaged with the ACL which causes long term rotational instability
Total Artoplasty
TIBIAL NERVE
-The tibial nerve is a major peripheral nerve of the lower limb.
-It has several cutaneous and motor functions in the leg and foot.
- Tibial Nerve Roots: L4-S3
SENSORY : Innervates the skin of the posterolateral leg, lateral foot and the sole of the foot.
MOTOR: Innervates the posterior compartment of the leg and the majority of the intrinsic foot muscles.
TIBIAL NERVE JOURNEY
The tibial nerve is a branch of the sciatic nerve, and arises at the apex of the popliteal fossa.
It travels through the popliteal fossa, giving off branches to muscles in the superficial posterior compartment of the leg.
Here, the tibial nerve also gives rise to branches that contribute towards the sural nerve, which innervates the posterolateral aspect of the leg.
The tibial nerve continues its course down the leg, posterior to the tibia. During its descent, it supplies the deep muscles of the posterior leg.
At the foot, the nerve passes posteriorly and inferiorly to the medial malleolus, through a structure known as the tarsal tunnel.
Within this tunnel, branches arise from the tibial nerve to supply cutaneous innervation to the heel
Immediately distal to the tarsal tunnel, the tibial nerve terminates by dividing into sensory branches, which innervate the sole of the foot.
MOTOR FUNCTIONS OF THE TIBIAL NERVE
-The tibial nerve innervates the muscles of the posterior leg
- the majority of the intrinsic foot muscles.#
ALL of the muscles in the back of the leg are innervated by the tibial nerve deep and superficial.
INTRINSIC MUSCLES:
- The medial and lateral plantar branches of the tibial nerve provide innervation to all the intrinsic muscles of the foot (exept the extensor digitorum brevis, which is innervated by the deep fibular nerve).
CUTANEOUS BRANCHES OF THE TIBIAL NERVE
In the popliteal fossa, the tibial nerve gives off cutaneous branches. These combine with branches from the common fibular nerve to form the sural nerve. This sensory nerve innervates the skin of the posterolateral side of the leg and the lateral side of the foot.
The tibial nerve also supplies all the sole of the foot via three branches:
-Medial calcaneal branches: These arise within the tarsal tunnel, and innervate the skin over the heel.
-Medial plantar nerve: Innervates the plantar surface of the medial three and a half digits, and the associated sole area.
-Lateral plantar nerve: Innervates the plantar surface of the lateral one and a half digits, and the associated sole area.
TARSAL TUNNEL SYNDROME
CUTANEOUS INNERVATION
SURAL NERVE
FEMORAL NERVE
Nerve roots: L2-L4
Motor functions: Innervates the anterior thigh muscles that flex the hip joint (pectineus, iliacus, sartorius) and extend the knee (quadriceps femoris: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius),
Sensory functions: Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous branches of the femoral nerve) and the medial side of the leg and foot (saphenous nerve).
FEMORAL NERVE JOURNEY
- Arising from the lumbar plexus, the femoral nerve travels inferiorly through the psoas major muscle of the posterior abdominal wall. It supplies branches to the iliacus and pectineus muscles prior to entering the thigh
- The femoral nerve then passes underneath the inguinal ligament to enter the femoral triangle
- Approximately 4cm below the inguinal ligament, the femoral nerve divides into anterior and posterior divisions
- The terminal cutaneous branch of the femoral nerve is the saphenous nerve. Saphenous nerve exits via the exits prior to the adductor hiatus.
- The saphenous nerve innervates the medial aspect of the leg and the foot.
FEMORAL NERVE MOTOR INNERVATION
- The hip flexors and knee extensors are supplied by the femoral nerve
FEMORAL NERVE SENSORY FUNCTIONS
There are two main sensory branches that arise from the femoral nerve:
- Anterior cutaneous branches – derived from the anterior division of the femoral nerve. They supply the skin of the anteromedial thigh.
- Saphenous nerve – a continuation of the posterior division of the femoral nerve. It supplies the skin of the medial leg and foot.
OBTURATOR NERVE
The cutaneous branch of the obturator nerve supplies the skin of the middle part of the medial thigh.
-Nerve roots: L2-L4
-Motor functions: Innervates the muscles of the medial compartment of the thigh (obturator externus, adductor longus, adductor brevis, adductor magnus and gracilis).
-Sensory functions: Cutaneous branches of the obturator nerve innervate the skin of the medial thigh.
SCIATIC NERVE
-Nerve roots: L4-S3.
-Motor functions:
Innervates the muscles of the posterior thigh (biceps femoris, semimembranosus and semitendinosus) and the hamstring portion of the adductor magnus (remaining portion of which is supplied by the obturator nerve).
Indirectly innervates (via its terminal branches) all the muscles of the leg and foot.
-Sensory functions: No direct sensory functions. Indirectly innervates (via its terminal branches) the skin of the lateral leg, heel, and both the dorsal and plantar surfaces of the foot.
COMMON FIBULAR NERVE
-Nerve roots: L4 – S2
-Motor: Innervates the short head of the biceps femoris directly. Also supplies (via branches) the muscles in the lateral and anterior compartments of the leg.
-Sensory: Innervates the skin of the lateral leg and the dorsum of the foot.
COMMON FIBULAR NERVE MOTOR
The common fibular nerve innervates the short head of the biceps femoris muscle
Superficial fibular nerve: Innervates the muscles of the lateral compartment of the leg; fibularis longus and brevis. These muscles act to evert the foot.
Deep fibular nerve: Innervates the muscles of the anterior compartment of the leg; tibialis anterior, extensor digitorum longus and extensor hallucis longus. These muscles act to dorsiflex the foot and extend the digits. It also innervates some intrinsic muscles of the foot.
JOURNEY OF COMMON FIBULAR NERVE
- The nerve begins at the apex of the popliteal fossa, where the sciatic nerve bifurcates into the tibial and common fibular nerves.
- CFN supplies the short head of the biceps femoris
- Goes down in a lateral and inferior direction, over the lateral head of the gastrocnemius. At this point, the nerve gives rise to two cutaneous branches, which contribute to the innervation of the skin of the leg.
- To enter the lateral compartment of the leg, the nerve wraps around the neck of the fibula, passing between the attachments of the fibularis longus muscle. Here, the common fibular nerve terminates by dividing into the SUPERFICIAL FIBULAR and DEEP FIBULAR nerves.
CUTANEOUS INNERVATION OF COMMON FIBULAR NERVE
There are two cutaneous branches that arise directly from the common fibular nerve as it moves over the lateral head of the gastrocnemius:
Sural communicating nerve – combines with a branch of the tibial nerve to form the sural nerve, which innervates the skin over the lower posterolateral leg.
Lateral sural cutaneous nerve – innervates the skin over the upper lateral leg.
In addition to these nerves
The terminal branches of the common fibular nerve also have a cutaneous function:
Superficial fibular nerve: Innervates the skin of the anterolateral leg, and dorsum of the foot (except the skin between the first and second toes).
Deep fibular nerve: Innervates the skin between the first and second toes.
DAMGE TO COMMON FIBULAR NERVE
The common fibular nerve is most commonly damaged by a fracture of the fibula, or the use of a tight plaster cast. The anatomical course of the common fibular nerve causes it to wrap round the neck of the fibular, and so any fractures of the fibular neck can cause nerve palsy.
Patients with common fibular nerve damage will lose the ability to dorsiflex the foot at the ankle joint. Hence the foot will appear permanently plantarflexed – known as footdrop. They may also present with a characteristic gait, as a result of the footdrop (for more information, see Walking and Gaits).
There will also be a loss of sensation over the dorsum of the foot, and lateral side of the leg. Innervation is preserved on the medial side of the leg (supplied by the saphenous nerve, a branch of the femoral), and the heel and sole (supplied by the tibial nerve, a branch of the sciatic).
SUPERFICIAL FIBUALAR (PERIONEAL) nerve
Nerve roots: L4-S1
Motor: Innervates the muscles in the lateral compartment of the leg (FIBULARIS LONGUS AND BREVIS)
Sensory: Supplies the anterolateral aspect of the distal leg and the majority of the dorsum of the foot (apart from the webbing between the hallux and the second digit).