Form And Actoins At Joints Flashcards
What are the anatomical levers, fulcrums, applied force, and load
Bones = levers
Joint = fulcrum
Muscle contraction = applied force
External/internal (weight/body weight) = load
Outline a class one lever
The fulcrum is in between the applied force and the load (Neck extension at the atlanto occipital joint)
Outline a class 2 lever
the load is in between the fulcrum and the applied force (plantar flex action at the ankle joint)
Outline a class 3 lever
The applied force is in between the load and the fulcrum (flexion at the elbow joint)
What 3 factors does muscle form depend on
Length, number, and arrangement of muscle fibres
What effect does the length of muscle fibre have on muscle form
Fibres shorten up to 50% of resting length hence longer fibres allow large range of movement
What effect does the number of muscle fibres have on muscle form
Tension is proportional to cross sectional area, hence greater number of fibres increase cross sectional area and results in greater tension
What affect does the arrangement of muscle fibres have on muscle form
Parallel arrangement allows greater fibre length thus greater range of movement
Pennate arrangement allows more fibres into the same space thus increasing muscle tension - however range of movement is decreased as maximum contraction is 50% of shortest fibres resting length
What are the 3 types of muscle action
Concentric
Eccentric
Isometric
What is concentric action
Muscle is active, develops tension, tension greater than load, muscle shortens, joint angle decreases
What is eccentric action
Muscle is active, develops tension, load is greater than tension, muscles elongate, joint angle increases
What is isometric action
Muscle is active, develops tension, tension is equal to load, no change in muscle length, no change in joint angle
What are the 4 difference roles a muscle can have at a joint
Agonist
Antagonist
Stabiliser
Neutraliser
What are agonistic and antagonistic roles
Agonistic - prime joint mover acting concentrically to decrease joint angle
Antagonistic - acts eccentrically to oppose and control the movement
What is a stabiliser role
Stabiliser - Isomeric action of a muscle(s) to hold a joint still
What is a neutraliser role
Neutraliser - muscle eliminates an unwanted movement caused by another muscle
E.g. pronation muscles neutralise supinating effect of flexion biceps brachii
What are the concentric actions of muscles, and for which joint do they not apply
Anterior - flexion
Posterior - extension
Medial - adduction
Lateral - abduction
Does not apply for knee joint
What is the biceps brachii
Origin is the scapular, insertion at radial tuberosity
Provides flexion at both shoulder and elbow
Provides supination at radioulnar joints
What is the triceps brachii
Connected to humerus and scapula, as well as ulna
Provides extension at both the elbow and the shoulder
What is the deltoid
Attached to the pectoral girdle (clavicle and scapula)
Attached to the diaphysis of the humerus
Enables flexion (anterior fibres), abduction (lateral fibres), and extension (posterior fibres)
What is the lliopsoas
Connected to vertebrae, ilium, and anterior of femur
Enables hip flexion
What is gluteus maximus
Connected to hip, sacrum, coccyx, and posterior of the femur
Enables extension of the hip
Quadriceps femoris
Group of 4 muscles of the quads
Most superficial is rectus femoris (connects to anterior inferior iliac spine of ilium, and tibial tuberosity via patella and patellar ligament )
Deep component are vasti muscles
Allows knee extension, hip flexion
Hamstrings
Grouped muscles (biceps femoris, semi membranosus, semi tendinosus)
Allows hip extension
Allows knee flexion, and rotation when knee flexed
