Muscuoloskelton System: Form And Action At Joints Flashcards
How does skeletal muscles cause movement at synovial joints
attaches to bone ( lever )
Muscle structure ( length! Mumble of fibres, arrangement of fibres)
Type of contraction ( roles/action )
Where it crosses a joint ( location )
What are skeletal muscles
They’re the muscles that connect to your bones to allow you to preform a wide range of movements and functions
How are bones levers
They provide a rigid structure nessarcy to transmit forces generated by muscles. Depending on the shape and arrangement, bones can act as direct types of levers in the body
Joint as a pivot or fulcrum
Joints are the points where bones meet and allow movement, they serve as a pivot of fulcrum around which the lever ( bone ) moves when a force ( muscle contraction ) is applied.
What are joints as atomically levers
Pivot or fulcuim
WHat are bones as atomically levers
Levers
Muscle contraction as applied force/ pull
Muscles contract to generate force, this is applied to the bone, causing it to move around the joint. And this is going to pull on the lever
Weight of what is being moved as the load ( external or internal )
External ( the little weights )
Internal ( weight that’s part of the body )
What are classes of levers
There are 3 classes of levers based on three relative position of the fulcrum ( pivot point ), the applied force ( effort ) and the load ( resistance )
What is the first class lever and give examples
- fulcrum is between the effort ( force applied ) and the load ( resistance )
- this lever type is good for stabilising joint position and alternating the direction of the force, eg: seesaw, or scissors
- in the body the neck is an example of the first class lever, where the skull (load ) is balanced on the vertebral column ( fulcrum) and the muscles at the back of the neck stabilised the head ( effort )
What is the second class lever and give examples
- load is between the fulcrum and effort
- lever type is effective for overcoming heavy loads with relatively little effort eg: wheel barrow or can opener
- in the body : the calf muscles can be an example, when you stand on your toes, the ball of the foot acts as the fulcrum and the weight of the body is the load and the contraction of the calf muscles ( efforts ) lifts the body
What is the third class lever and give examp,e
- the effort ( applied forced ) is poisoned between the fulcrum and the load
- allowing for large range of movement and speed but requires greater effort to move through load
- tweezer or fishing rod
- in the body many of the limbs are third class levers, eg when flexing forearm, elbow joint acts as a fulcrum, the hand ( load ) is lifers, and the biceps muscles ( effort )
What does the muscle forms determines on
Length of muscle fibres
Number of muscle fibres
Arrangement of muscle fibre
Explain length of muscle fibres
-Fibres can shorten up to 50% of resting length, this is critical for generating force and producing movement in the body
- if larger ROM ( range of movement ) is required at the joint such as gymnastics or dance. Long muscle fibres will be more suited for movements that require extensive stretching and contracting.
Explain number of muscle fibres (CSA) cross sectional area
- tension is directly proportional to the CSA, CSA refers to the total number of muscle fibres it contains , and muscle tension is the force generated when the muscle contracts. So the larger the CSA of a muscle, the greater its capacity to produce tension
- greater number of fibres = greater CSA: an increase in CSA means that there is greater potential for the muscle to generate force or tension when it contracts so allowing a stronger contraction.
Arrangement of muscle fibres
Parallel muscle arrangement :
- this is when muscle fibres run parallel to the long axis of the muscle
- smaller CSA, so greater shortening
Pennants muscle arrangement
- muscle fibres orientated obliquely to the tendon
- greater CSA, less shortening
Types of muscle action
- concentric
- eccentric
- isometric
Concentric
This is when muscle actively shortens while generating tension greater than the external load, resulting in movement at the associated joint.
Eccentric
This is when the muscle actively elongates while under tension, generating less force than the external load and controlling movement in the opposite direction
Isometric
When muscle generates tension without changing length or joint position, effectively stabilising the body or resisting external forces
What are the types of muscle roles
Agonist: creates movement
Antagonist: opposes/controls movement
Stabiliser: holds joints still
Neutraliser: stops unwanted movement
Agonist
Acts concentrically to create movement at a joint
Antagonist
Acts eccentrically to oppose and control the movement
Stabilisers
Holds the joint still and prevents movement of joints
For example: holding a heavy rock, bicep brachii role = stabiliser, bicep brachii action = isometric, no change in length of bicep brachii, no movement in elbow joint
Neutraliers
Eliminates unwanted movement caused by another muscle
Biceps brachii
Origin:
- scapula
Insertion:
- radial tuberosity
Movement:
- shoulder = flexion
- elbow = flexion
- radioulnar joints = supination
Triceps brachii
Origin
- scapula and humorous
Insertion
- olecranon process of ulna
Movement
- shoulder = extension
- elbow = extension
Deltoid
Origin
- scapula and clavicle
Insertion
- deltoid tuberosity
Movement
- shoulder
flextion ( anterior fibres )
Abduction ( lateral fibres )
Extension ( posterior fibres )
Lliopsoas ( lower limb )
Muscle that moves the hip joint
Origin
- iliac fossa and lumbar vertebrae
Insertion
- femur
Movement
- hip: flexsion
Gluteus maximus
Origin
- llium and sacrum
Insertion
- femur
Movement
- hip: extension
Quadriceps femuris
Origin
- rectus femoris = ilium
- vastus medialis, intermedius and lateralis = femur
Insertion
- tibial tuberosity
Movement
- hip= flexion
-knee = extension
Hamstring
Origin
- Ischium ( + femur for biceps femoris )
Insertion
- tibia ( semimembranosus and semitendinosus )
- fibula ( bicep femoris )
movement
- hip = extension
- knee = flexion and rotation ( when knee is flexed )
Tibialis anterior
Origin
-tibia
Insertion
-tarsals
Movement
-ankle = dorsiflexion
Triceps surae
Origin
- condyles of femur ( gastrocnemius )
- tibia and fibula ( soleus )
Insertion
- calcaneus via calcaneal/ Achilles tendon
Movement
- knee = flexion
- ankle = planterflexsion
Hip joints
Lliopsoas - anterior and flextion
Gluteus maximus - posterior extension
Rectus femoris - anterior flextion
Hamstring - posterior and extension
Knee joint
Quadriceps femoris - anterior extension
Hamstring - posterior, rotation and flexsion
Gastrocnemius - posterior flextion
