Introduction to the limbs Flashcards
What are the 3 functions of the upper limbs?
- They have almost no locomotor function, however they can be used as a locomotor prop (e.g Crutches to walk)
- Highly mobile joints
- Leavers/allows hand to be brought to any point in space and kept steady
What are the 2 key features of the upper limbs?
They are less stable but highly mobile
What are the 3 functions of the lower limbs?
- Support body weight
- Involved mainly in locomotion
What are the key 3 features of the lower limbs?
The bone of the lower limb are more robust and stable than the bones and joints of the upper arm but less moveable
Where do limbs develop from in a foetus and when?
The upper and lower limb buds
32-35 days
What develops after the limb buds grow?
The digital rays develop which will later become digits (fingers)
42-49 days
When and where do limbs develop?
Around week 4 of development, specialised cells migrate from somites and the lateral plate of the mesoderm and limb buds form where the arms and legs will develop
How does the upper limb develop?
The upper limb develops with the thumb pointing superiorly
What are the 3 different types of muscles?
Skeletal muscle, Cardiac muscle and Smooth muscle
What is the Origin?
The origin is usually the proximal end of the muscle which remains fixed during muscular contraction, making it more stable
What is the Insertion?
The insertion is usually the distal end of the muscle which is moveable, making it less stable
What happens to a muscle when stimulated?
The muscle contracts and shortens, trying to bring its two ends closer (Insertion and Origin)
What muscle moves closer to the other during a muscle being stimulated?
The muscles usually shorten in the Insertion -> Origin direction, so insertion becomes closer to the Origin
What is Isometric muscle contraction?
Increase in muscle tone but muscles don’t change in length or shorten
What is an Isotonic muscle contraction?
Muscle length changes so the muscle wither elongates or shortens but the muscle tone is not changed
Give an example of Isometric muscle contraction?
Carrying an object in front of you
Give an example of Isotonic muscle contraction?
Walking and running
What are the 2 varieties of Isotonic contractions and their differences?
Concentric contraction - Muscle contracts according to the sliding filament mechanism and shortens
Eccentric contraction - The muscle elongates while under tension due to an opposing force greater than the muscle generates - Works as a breaking force in opposition to a concentric contraction to protect from injury (E.g - Bicep Eccentric contraction prevents dropping of weight)
What is a prime mover?
A muscle/muscles that play the primary role in moving a body part
What is an Agonist muscle?
A muscle/ muscles that act directly to produce a desired movement - Aids the prime mover
What are Synergist muscles?
Muscles which prevent unwanted movements associated with the action of prime movers
What are Antagonistic muscles?
Muscles which directly oppose a movement (E.g - flexing elbow, the muscles on back resist to prevent hyperextension
What are Fixating muscles?
Muscles that provide the necessary support to assist in holding the rest of the body in place while movement occurs (Stabilises Origin or Insertion)
What is Fascia and its 2 subdivisions and their properties?
Fascia is a connective tissue (1 continuous sheet with 2 layers)
- Superficial Fascia; Just beneath the skin and contains Adipose tissue (Fat)
- Deep (investing) Fascia;
- Ensheath muscles but are continuous
- Help/facilitate contractions
- Barrier between muscles
- Compartment muscles and neurovascular bundles
- Passages for nerves and vessels
- Point of attachment for muscles (e.g by forming Interosseous membranes - fascia running from bone to bone in arm)
- Becomes thicker in structures (e.g wrist joint) to hold tendons in place (by forming Rentinaculae
