7.2 Joints of the Limbs Flashcards
What is flexion?
Movement that decreases the angle between two body parts
What is extension?
Movement that increases the angle between two body parts
What is dorsiflexion?
The action of moving the foot/toes upwards/towards the shin (remember this through the idea of creating a dorsal fin)
What is plantarflexion?
The action of moving the foot/toes downwards/towards the ground if the foot was suspended (remember this through the idea of ‘planting’ your foot on the ground)
To what body part are dorsi- and plantarflexion specific?
The ankle joint/foot
What is abduction?
The action of moving a body part away from the midline/laterally (remember this through the idea of abduction as stealing a human)
What is adduction?
The action of moving a body part towards the midline/medially (remember this through a-d-duction, ‘adding’)
What is eversion?
Movement of the foot so that the sole is facing outwards/has been moved away from the midline
What is inversion?
Movement of the foot so that the sole is facing inwards/has been moved inwards - this is what happens when you twist your ankle
Why are inversion and eversion useful?
Important for walking across uneven ground
What is lateral flexion?
This is the bending of the neck or body away from the midline, i.e. to the left or right
What is medial rotation?
The rotating of a joint so that it faces more internally
What is lateral rotation?
The rotating of a joint so that it faces more externally
What is rotation?
Movements made about the longitudinal axis and in the transverse plane
What is pronation?
The act of rotating the forearm so that the palm is facing down (remember: the whip sequence)
What is supination?
The act of rotating the forearm so that the palm is facing upwards (remember: lying down as if supine)
What is circumduction?
The movement of a limb or extremity so that the distal end completes a circle whereas the proximal end remains in one place (performed best at ball and socket joint)
What are the different movements of the scapula?
- Elevation (moving upwards)
- Depression (moving downwards)
- Retraction (moving inwards)
- Protraction (moving outwards)
- Medial rotation
- Lateral rotation
What are the movements of the pollux/thumb?
- Abduction (movement away from the hand along sagittal plane)
- Adduction (movement towards the hand along sagittal plane)
- Extension (movement away from the hand along the coronal plane)
- Flexion (movement towards and across the hand along the coronal plane)
- Opposition (UNIQUE, ability to touch little finger with thumb)
- Reposition (UNIQUE, ability to return hand to normal shape after opposition)
What are the movements of the fingers?
Abduction - splaying the fingers
Adduction - closing the fingers
Middle finger acts as midline
What are the three types of joint?
- Fibrous
- Cartilaginous
- Synovial
What are the different types of fibrous joint and with what type of bone are they associated?
- Suture (join together flat bones)
- Syndesmosis (between long bones, e.g. interosseous membranes)
What is the function of a fibrous joint?
Restrict movement, add stability
What type of connective tissue makes up fibrous joints?
Dense connective tissue (similar to tendons and ligaments)
What are the different types of cartilaginous joint and with what type of bone are they associated?
- Primary/synchondroses (developing bone, seen in epiphyseal plates)
- Secondary/symphyses (midline joints/intervertebral discs (annulus fibrosus), make up fibrocartilage)
What type of connective tissue makes up synchondroses?
Hyaline cartilage
What sort of connective tissue makes up symphyses?
Fibrous cartilage
What are the different classifications of joint that are lined with hyaline cartilage?
Any highly mobile joint:
- Plane joint (small gliding movement e.g. between cuneiform bones of foot)
- Saddle joint (e.g. interphalangeal)
- Hinge joint (e.g. knee)
- Pivot joint (e.g. wrist)
- Ball and socket joint (e.g. shoulder, hip)
- Ellipsoid/condylar joint (e.g. where the radius and ulna meet the wrist)
What defines a synovial joint?
The presence of synovial fluid within the joint capsule (secreted by the hyaline cartilage)
What are the features of a synovial joint?
- Fibrous joint capsule that is continuous with the periosteum
- Joint cavity containing synovial fluid
- Articulating surfaces are lined with hyaline cartilage
- Synovial membrane lines the cavity
- Ligaments are present within joint capsule
- Where does osteoarthritis usually occur?
What are the risk factors?
In weight bearing joints
Risk factors:
- Age
- Bodyweight
- What causes osteoarthritis?
Destruction of articular cartilage (and/or bone) at a joint, presents as a severely reduced joint space in imaging and pain/reduced mobility of the joint
- Where does rheumatoid arthritis usually occur?
In smaller joints, is also usually symmetrical
- What causes rheumatoid arthritis?
Autoimmune of synovial membrane, articular cartilage and bone
What are the joints involved in the pectoral girdle?
- Coracoacromial joint
- Acromioclavicular joint (AC)
- Coracoclavicular joint
- Glenohumeral joint
(- Sternoclavicular joint - not in the shoulder)
What is the purpose of the coracoacromial joint/ligament?
To prevent superior dislocation of the humerus, connects the acromion process of the scapula to the coracoid process of the scapula
How is the scapula held in place?
By muscles - its only attachment to the axial skeleton is through the clavicle, it has no real attachment to the thorax
What are the two components of the coracoclavicular ligament?
From medial to lateral:
- Conoid
- Trapezoid
(Remember, diagnose using a CT scan)
- How can the coracoclavicular ligaments be disrupted?
Through dislocation of the acromioclavicular joint
What is the purpose of the coracoclavicular joint?
- Helps to suspend a lot of the weight of the limb from the clavicle
- Stabilises the acromioclavicular (AC) joint
What is present within the joint capsule of the acromioclavicular (AC) joint?
A fibrocartilage articular disc, joint capsule is strengthened by the AC ligaments
What is the general function of the pectoral girdle?
- To give the upper limb a greater range of movement, allowing it to carry out roles of grasping and manipulating objects now that it has been freed from locomotion
- Alters the position of the glenoid fossa of the scapula and suspends it away from the thorax to allow greater movement
What deepens the glenoid fossa?
The glenoid labrum - fibrocartilaginous ring that is around the fossa, adding stability to the joint
- How can you tell that a clavicle has been broken rather than dislocated?
Both will show deformities, but length of clavicle should be equal on both sides - if lengths are unequal, then there is likely to have been a break. Ligaments attached to a clavicle can draw it upwards if it is broken
What are the glenohumeral ligaments?
Superior, medial and inferior glenohumeral ligaments
- Pass from the margins of the glenoid cavity to the humerus and support the joint anteriorly
What is the should joint at great risk of?
Dislocation - joint is relatively lax which makes it prone to this
How is the lower part of the glenohumeral joint capsule adapted to improve movement?
Lower part is lax and folded
What is the most common direction for a shoulder dislocation and why?
Anteriorly, due to lack of joint support in this region
How can a shoulder dislocation be identified?
- Acromion will be prominent
- Shoulder flattened
- Bulge of humeral head seen
What type of joint is the glenohumeral joint and what does this allow?
Multiaxial synovial ball and socket joint, allows a huge range of mobility
What downside does the hypermobility of the shoulder joint have?
Causes the joint to be inherently weak and prone to dislocation (especially in comparison to the hip joint)
What are bursae?
Sacs filled with synovial fluid that act as cushions to reduce friction where tendons and muscles lie close to the bone
What is the most important bursa near the glenohumeral joint?
The subacromial (subdeltoid) bursa that separates the coracoacromial arch from the tendon of supraspinatus and the glenohumeral joint
What are the four rotator cuff muscles?
Supraspinatus
Infraspinatus
Teres minor
Subscapularis
Where do the four rotator cuff muscles attach?
Supraspinatus, infraspinatus and teres minor: Greater tuberosity of the humerus
Subscapularis: Lesser tuberosity of the humerus
What are the main stabilising factors of the shoulder joint?
The rotator cuff muscles, they form a musculotendinous cuff that extends around the glenohumeral joint, stabilising it
What movement does supraspinatus aid?
Assists with initial arm abduction
What movement do infraspinatus and teres minor aid?
Lateral shoulder rotation
What movement does subscapularis aid?
Medial shoulder rotation
What type of capsule surrounds the elbow joint and where is it weakest?
Fibrous capsule, weakest anteriorly and posteriorly
What are the proper names for the elbow joint?
Humeroulnar joint and humeroradial joint make up the elbow
What are the ligaments in the elbow joint?
- Lateral (radial) collateral ligament
- Medial (ulnar) collateral ligament
- Anular/annular ligament
What other joint is also in the proximity of the elbow?
The proximal radioulnar joint
What movement does the anular/annular ligament allow?
Allows the pivoting/rotation of pronation and supination - joint capsule is attached to this rather than directly to the radius, allowing the freedom of movement between the radius and ulna. Is also circular, wraps around the radial head to form a pivot joint.
What type of joint is the elbow and what movements does it allow?
Synovial hinge joint, allows flexion and extension
What ligaments stablise the elbow and in what way?
The collateral ligaments (medial/ulnar and lateral/radial), permit flexion/extension but prevent abduction, adduction and axial rotation
Where does the medial/ulnar collateral ligament run from and to?
From the medial epicondyle of the humerus to the ulna
Where does the lateral/radial collateral ligament run from and to?
From the lateral epicondyle of the humerus to the radial notch of the ulna and the anular ligament, NOT the radius itself
How is the elbow joint stabilised?
- Stable shape of articulating surfaces
- Strong collateral ligaments
- Surrounding cuff of muscles (including triceps brachii, brachialis and biceps brachii)
- In what position is the elbow joint at its most stable?
90 degrees flexion, in a position of mid pronation-supination
What movement do the radioulnar joints permit?
Pronation and supination
What type of joint is the interosseous membrane?
Fibrous joint
What type of joint is the distal radioulnar joint?
Synovial pivot joint (allows pronation and supination)
What type of joint is the radiocarpal/wrist joint?
Synovial ellipsoid joint
What type of joint are the midcarpal joints?
Synovial plane joints, but are important for wrist flexion and extension
- What is ‘nursemaid’s’ or ‘pulled elbow’?
Radial subluxation or dislocation, especially common in children due to ossification not being completely finished. Once fracture is excluded, can be easily reduced
What happens to the radius during supination and pronation?
The radius rotates around the ulna - during supination they lie parallel, during pronation the radius crosses over the ulna
How is the distal radioulnar joint separated from the radiocarpal (wrist) joint?
By a fibrocartilage articular disc
What articulations occur in the proximal radiohumeral joint?
The radius articulates with the radial notch on the ulna, and is able to rotate within a fibrosseous ring formed by this notch and the anular ligament
What articulations occur in the distal radiohumeral joint?
The head of the ulna articulates with the ulnar notch of the radius
What is the interosseous membrane?
- Extremely strong fibrous sheet between the two bones
- Transmits forces from the hand onto the elbow joint/humerus
- Site of attachment for deep muscles of forearm compartments
What articulation in the radiocarpal/wrist joint?
- Concave distal radius
- Articular disc of ulna
- Convexities of the scaphoid, lunate and triquetrum
What movements are allowed by the radiocarpal/wrist joint?
- Flexion
- Extension
- Radial deviation
- Ulnar deviation
(Last two are abduction and adduction, but different depending on which way the arm is facing so it is clearer to use these terms)
Where are the midcarpal joints found?
Between the distal and proximal rows of carpal bones
What type of joint is the first carpometacarpal joint (base of thumb) and what movement does this allow?
Synovial saddle joint, allows opposition and reposition
What are the major differences between the hand and the foot?
- Orientation of hallux (big toe) and pollux (thumb) differs greatly
- Different shapes of joints (carpometacarpal joint is a completely different shape compared to the tarsometatarsal joint)
These differences relate to function - big toe cannot carry out opposition and has no need to
What movements does opposition include?
- Flexion
- Abduction
- Rotation
- Adduction
What type of joint are the second, third, fourth and fifth carpometacarpal joints (between the wrist and the four fingers)?
Plane synovial joints
What movement does the metacarpophalangeal joint of the thumb not allow?
Abduction/adduction - this is instead allowed by the first hypermobile carpometacarpal joint
What limits movements in the second to fifth carpometacarpal joints?
The action of the palmar and dorsal ligaments
What type of joint are the second to fifth metacarpophalangeal joints and what movements does this allow?
Synovial ellipsoid joints, allow:
- Flexion/extension
- Abduction/adduction
What stabilises the second to fifth metacarpophalangeal joints?
Collateral ligaments, muscles and tendons
What joints exist between the phalanges of the fingers?
- Distal interphalangeal joint (DIP)
- Proximal interphalangeal joint (PIP)
What type of joints are the distal and proximal interphalangeal joints and what stabilises them?
Synovial hinge joints, stabilised by collateral ligaments
How many interphalangeal joints does the thumb have?
Only one
- What is a way to remember the name ‘acetabulum’?
Acetic acid = vinegar, acetabulum = vinegar cup, the romans used to drink vinegar from the acetabulum of a hip bone
What is the hip joint?
The articulation between the acetabulum of the hip bone and the head of the femur
What type of joint is the hip joint?
Synovial ball and socket
What movements are permitted by the hip joint?
- Flexion/extension
- Abduction/adduction
- Circumduction
- Medial/lateral rotation
What is the function of the hip joint?
- Locomotion
- Transmission of weight whilst standing and moving (therefore must be strong/stable and still allow movement)
What bones form the acetabulum?
The three bones of the hip, the pubis, ilium and ischium
What is the acetabular labrum?
A ring of fibrocartilage that deepens the acetabulum socket, attaches to the transverse acetabular ligament
Compare the shoulder and the hip joint.
- Features are shared, both synovial ball and socket joints with labrums deepening the socket
- Both are supported by muscles, ligaments and (to only some extent in the shoulder) bone shape
- Wider range of movement in shoulder is sacrificed for stability (shoulder is less stable than hip)
- Hip combines motility and transmission of weight, arm only has to manage its own weight/is freely suspended
What is the femoral head lined with?
Hyaline cartilage, except for a section which attaches to the femoral head ligament
What ligament bridges the acetabular notch?
The transverse acetabular ligament (supports and stabilises joint)
What is the lunate surface?
The articular surface of the acetabulum, lined with hyaline cartilage
What are the three main ligaments that stabilise the hip?
- Iliofemoral ligament
- Pubofemoral ligament
- Ischiofemoral ligament
Where does the iliofemoral ligament lie?
Lies interiorly between the ilium and the region between the greater and lesser trochanters of the femur (intertrochanteric line), this is allowed by the ligament’s Y or V shape
Where does the pubofemoral ligament lie?
Between the pubis and the intertrochanteric line (between the greater and lesser trochanters of the femur)
Where does the ischiofemoral ligament lie?
Between the ischium and the greater trochanter
How do the ilio-, ischio- and pubofemoral ligaments responds to flexion and extension?
- Flexion: relax/loosen
- Extension: tighten
In this way they limit the movement/extension of the hip joint
Why is dislocation of the hip rare?
- Deep acetabulum
- Acetabular labrum
- Three stabilising hip ligaments
- Thick fibrous capsule (strengthened anteriorly by fused tendons of quadriceps and laterally by the iliotibial tract, a thick fibrous band)
- Which direction of dislocation in the hip is most common and why?
Posteriorly, most likely to occur when hip is flexed/ligaments are lax, e.g. when passengers are seated in a high speed car accident
What are and what is the function of the menisci?
Crescent-shaped pieces of fibrocartilage on the tibial condyles (in the knee joint), reduce friction, increase congruency and disperse weight
Both medial and lateral menisci are present
What is the patella?
- A sesamoid bone (in the quadriceps femoris tendon) that articulates with the femoral condyles at the patellofemoral joint.
- Smooth oval facet on posterior is covered in hyaline cartilage for articulation
What are the two ligaments that originate from the epicondyles of the femur?
- Medial (tibial) collateral ligament, from medial epicondyle to the shaft of the tibia
- Lateral (fibular) collateral ligament, from the lateral epicondyle to the head of the fibula, shaped like a rounded cord
What ligament is the medial meniscus attached to?
Medial collateral ligament (this means that damage to the ligament can also damage the meniscus)
Is the lateral meniscus attached to a ligament?
No, it is separate from the fibrous joint capsule by the tendon of the popliteus muscle
What locks the knee during extension?
The medial femoral condyle
What is ‘close packed’ position of the knee?
This is where the knee joint is fully extended, the ligaments of the knee are tightened and the knee is stabilised
What muscle ‘unlocks’ the knee?
The popliteus muscle, laterally rotates the femur on the tibia when initiating flexion
What are the two cruciate ligaments?
- Anterior cruciate ligament (ACL)
- Posterior cruciate ligament (PCL)
Cruciate means ‘crossing’
What ligaments primarily maintain the stability of the knee?
Collateral and cruciate ligaments, reinforced by muscles and tendons which also cross the joint
What is the function of the anterior cruciate ligament (ACL)?
Prevents excessive anterior movement of the tibia relative to the femur above
Where does the anterior cruciate ligament (ACL) lie?
From the anterior part of the intercondylar area of the tibia and attaches to the inner surface of the lateral condyle of the femur (lateral wall of the intercondylar fossa)
Remember through putting ‘hands in pockets’ - lateral to medial, posterior to anterior, proximal to distal
What is the function of the posterior cruciate ligament (PCL)?
Prevents excessive posterior movement of the tibia relative to the femur above
Where does the posterior cruciate ligament (PCL) lie?
Attaches to the posterior part of the intercondylar region of the tibia to the lateral surface of the medial medial condyle of the femur
Are the cruciate ligaments prone to tears?
Yes, an ACL tear in particular is a common injury. They can tear in both contact and non-contact sports
What is the talocrural joint?
Aka the ankle joint, between:
- The distal ends of the tibia/fibula
- The talus bone of the ankle
What type of joint is the talocrural (ankle) joint and what movement does this allow?
Synovial hinge joint that allows:
- Dorsiflexion
- Plantarflexion
How is the joint capsule of the talocrural (ankle) joint adapted to allow dorsi- and plantarflexion?
- Thin and weak capsule posteriorly and anteriorly
- Lined by a loose synovial membrane
What are the joints between tarsal bones called and what movements are they important for?
Intertarsal joints, important for:
- Inversion
- Eversion
What is the subtalar joint?
The joint between the talus and the calcaneus
What is the midtarsal joint?
Complex articulations between the:
- Talus, calcaneus and navicular bones
- Calcaneus and cuboid
How is the ankle joint strengthened medially and laterally?
By collateral ligaments
What is the medial deltoid ligament?
- A ligament formed from four bands
- Radiates/reaches from the medial malleolus of the tibia to the talus, calcaneus and navicular bones
What is the lateral collateral ligament of the ankle?
- Made from three bands
- Passes from the lateral malleolus of the fibula to the talus (x2 connections) and the calcaneus
Why are ankle sprains more likely to occur medially?
Because the medial deltoid ligament is stronger than the lateral collateral ligament
Ankle sprains will usually involve the anterior talofibular part of the lateral collateral ligament
