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