Week 2: Joints & Ligaments Flashcards
What bones form the lower limb?
- Sacrum and coccyx (gluteal region)
- Pelvic/hip/innominate bone (gluteal region)
- Femur (Thigh)
- Patella
- Tibia (leg, medial)
- Fibula (leg, lateral)
- Bones of the foot: Tarsal bones (7); Metatarsals (5); Phalanges (14)
What are the 3 types of joints?
- Fibrous
- Cartilaginous
- Hyaline cartilage (synchondrosis)
- Fibrocartilage (symphysis) - Synovial
What 4 aspects affect the stability around a joint?
- Shape of the articular surfaces
- Capsule and ligaments
- Intra-articular structures in some joints (e.g. menisci, labrum)
- Muscles
Describe the motion and location of a fibrous joint:
- Dense fibrous connective tissue binds the bones together allowing virtually no motion
1. Suture: between bones of the skull
2. Gomphosis: between teeth and their sockets
3. Syndesmosis: Interosseous membrane
Describe the motion and location of hyaline cartliage:
- Allows virtually no motion (but is present to allow bone growth)
- Epiphyseal plate
Describe the motion and location of fibrocartilage:
- Cartilaginous allow some motion
- Intervertebral disc & pubic symphysis
Describe the motion and location of a synovial joint:
- Joint space enveloped in the joint capsule and reinforced by ligaments allows free motion
- In many places of the body
What are the 6 features of a synovial joint?
- Articular surfaces (cartilage)
- Joint cavity
- Synovial fluid from synovial membrane
- Joint capsule
- Ligaments (DFCT): Capsular - part of capsule; Accessory - intracapsular (within joint) & extracapsular (outside capsule/joint)
- Other features: Intra-articular inclusions - labrum & menisci; Bursae
Describe the gross morphology of a fibrous capsule:
- It completely enclose a joint and attaches around the articular ends of bones
- It’s perforated by vessels & nerves
- May have openings to allow the synovial membrane to protrude as bursae
- Usually has capsular ligaments - localised thickenings of parallel interlacing collagen fibres within the joint which provide strength but little elasticity
Describe the gross morphology of a synovial membrane:
- It lines the fibrous joint capsule and attaches around the edges of articular surfaces
- It covers the non-articular surfaces in the joint cavity and may be found lining bursae and tendon sheaths
What are the 2 main functions of the synovial membrane?
- Secretes and absorbs synovial fluid
- Removes debris from joint cavity
What is the function of synovial fluid? And where is it found?
- Moistens and lubricates the articular surfaces, synovial membrane, articular discs and the other intra-articular inclusions
- Normally found in low volumes in synovial joints, in bursae and in tendon sheaths
What are bursae?
Fluid-filled sac which sits between ligament & bone or muscle & bone or muscle & ligament to prevent friction
What is the overall function of ligaments?
They are designed to prevent excessive or abnormal motion, but do not resist normal motion
How would you expect the collagen fibres to be arranged within ligaments, and why?
Predominantly arranged in parallel (in one direction) to withstand loading
What are accessory ligaments? Give examples of each.
Not part of the joint capsule
Intracapsular:
* Anterior cruciate ligament (ACL)
* Posterior cruciate ligament (PCL)
Extracapsular:
* Lateral collateral ligament (LCL)
* Medial collateral ligament (MCL)
Name 6 places in the body you would expect to find collateral ligaments:
- Elbow
- Wrist
- Metacarpophalangeal
- Interphalangeal
- Knee
- Ankle
What types of movement do collateral ligaments restrict?
Movement that does not occur in the sagittal plane (e.g. abduction and adduction forces)
What is the implication of poor vascular supply for healing of ligaments?
Healing is prolonged, normally takes at least 6 weeks
What is the structural classification of the hip joint and what movements are available?
- Synovial ball and socket (multiaxial - allows movements in > 3 planes)
- Flexion/extension (frontal plane)
- Abduction/adduction (coronal plane)
- Internal/external rotation (transverse plane)
Which region’s muscles and tendons cause flexion at the hip joint?
Anterior region
What type of movement & rotation would a posterior muscle around the hip produce?
Extension in the sagittal plane
Lateral rotation in the transverse plane
What type of movement & rotation would an anterior muscle around the hip produce?
Flexion in the sagittal plane
Medial rotation in the transverse plane
What type of movement would a lateral muscle around the hip produce?
Abduction in the coronal plane
What type of movement would a medial muscle around the hip produce?
Adduction in the coronal plane
Describe the morphology of the articular surfaces of femoral condyles and tibial plateau:
Curved femoral condyles
Fairly flat tibial surfaces
What is the structural classification of the knee (tibiofemoral) joint and what movements are available?
*Condylar (allows movement in two planes)
- Flexion/extension
- External/internal rotation
What type of movement would a posterior muscle around the knee produce?
Flexion in the sagittal plane
What type of movement would an anterior muscle around the hip produce?
Flexion in the sagittal plane
What type of rotation would a lateral muscle around the hip produce?
External (lateral) rotation in the transverse plane
What type of rotation would a medial muscle around the hip produce?
Internal (medial) rotation in the transverse plane
Describe the form of the articular surfaces of the talus and distal tibia and fibula:
- Distal tibia and fibula form a socket (mortise) for the talus to articulate
- Talus: Trochlea is basically convex
What is the structural classification of the ankle (talocrural) joint?
Hinge
What type of movement would an anterior muscle around the ankle produce?
Dorsiflexion in the sagittal plane
What type of movement would a posterior muscle around the ankle produce?
Plantarflexion in the sagittal plane
At what point during development do limbs start to rotate?
7th week of gestation
- Upper limb rotate externally
- Lower limb rotate internally
