Lecture 10-Levers and Muscle names Flashcards
Biceps Brachii
2 headed- Anterior
Origin( proximal attachment)= scapula
Insertion( distal)= Radial Tuberosity
Movement= flexion of the shoulder
supination( palm facing) of the radioulnar joints
Triceps Brachii
2 headed- posterior
Origin- Scapula and Humerous
Insertion- olecranon process of Ulna(a proximal bit of ana)
Movement- Extension of shoulder and elbow
Deltoid
Triangle shaped
Origin: scapula and clavicle=pectoral girdles
Insertion= Deltoid tuberosity(middle of humorous)
Movement= Anterior fibres: flexion
Posterior fibres: extension
Lateral fibres: Abduction
Iliaposas
made of 2 muscles- ANTERIORLY
Ilium and psoas
Origin: Iliac fossa( inner part of Ilium) and Lumber vertebrae( the lower bit, remember dinner at 5)
Insertion: both are inserted at the proximal end of the femur
Movement:
Flexion of hip because anterior
Gluteus maximus
biggest of the glute muscles
Posterior- butt
Origin: Ilium and sacrum
Insertion: femur
Movement: posterior so extension of the hip( opposite to iliopsoas)
Quadriceps femoris
Anteriorly. muscle group has 4 muscles
-Rector femoris
-vastus lateralis
-vastus medialis
-vastus intermedius
Orgin: Rectus femoris= Ilium
the other 3: femur
Insertion:
Tibial Tuberosity( where tibia and kneecap meet)
Movement:
Flexion of hip( R.F only)
Extension of the knee( cuz the rule is the opposite for the knee)
Hamstrings
Posterior of thigh
has 3 Muscles
- semimembranosus
-semitendinous
- Biceps femoris
Orgin: Isschium BUT FEMUR for Biceps Femoris
Insertion: Tibia but FIBULA for Biceps Femoris
Movement: Hip- extension
knee- Flexion, also rotation when the knee is flexed.
Tibilia Anterior
Anteriorly
Origin: Tibia
Insertion: Tarsals
Movement: Dorsiflexion of ankle( its located anteriorly so ankle will be flexed( decreasing angle)
Triceps surae
Posterior
2 muscles: Gastrocnemius and soleus
Origin: Gastro… = condyles of femur(distal)
soleus= Tibia(medial) and Fibula(lateral)
Insertion: Calcaneuous( heel bone) via calcaneal tendon( strongest tendon connect heel bone and calf muscles)
Movement:
Flexion of knee( gastrocnemius)
Plantarflexion of ankle( ankle will be extended( increasing angle) because it’s located posteriorly.
Anatomical levers
Bone=lever
Joint-pivot or fulcrum
Muscle contraction= applied force/pull
Weight of what is being moved( external or internal) = load
Lever arrangement determines function
Describe the 3 classes of levers with examples
Class 1 lever:
The fulcrum in the middle, applied force and load downwards.
stabilises joint position
eg neck extension and seesaw
Class 2 lever:
load between the fulcrum and force, effective at overcoming heavy loads. eg plantarflexion of ankle and wheelbarrow
Class 3 lever- large range of movement happening quickly. fulcrum stays at the same end as class 2 but now force is between fulcrum and load.
eg tweezers, and flexion of the elbow joint
Muscle form( what muscle looks like) depends on the function, describe and explain the 3 form factors that determine muscle function
- Length of muscle fibres
* Fibres can shorten up to 50% of resting length
* If large ROM required = long muscle fibres - Number of muscle fibres
(CSA)
* Tension is directly
proportional to the
cross-sectional area
–>Greater number of
fibres
* greater CSA
* greater tension
The bigger the muscle, the more tension it can produce, more tension meaning more fibres and thus more strength. - Arrangement of fibres
- parallel fibres are fibres that move vertically between tendons. fewer fibres can fit due to small CSA, but greater ability to shorten the muscle.
-Pennate fibres are fibres that run at an angle to the tendon, meaning more fibres can fit in the same area so more force generated. GREATER CSA BUT LESS SHORTENING.
unipenate(1 angle)
bipenate(2 angle)
Multipenate( multiple angle)
Muscle can contract in 3 ways, state and explain them
- Concentric shortening of the muscle
Muscle is active, develops tension, tension is greater than load so it shortens, change in joint position
eg, elbow flexion( ANGLE DECREASES), biceps brachii contracts concentrically - Eccentric
- lengthening of the muscle
Muscle is active, tension develops but tension is lesser than load so muscle elongates( pulls in opp direction by gravity or another muscle)
Change in joint position
eg elbow extension( ANGLE INCREASES), biceps brachii contracts eccentrically. - Isometric-joint stays the same
Muscle is active, develops tension
but the load doesn’t outweigh the tension and the tension doesn’t outweigh the load.
NO CHANGE in the length of muscle or JOINT.
eg biceps brachii contracts isometrically to keep the elbow joint still
EXPLAIN the rule for concentric actions of muscles.
ANTERIOR= FLEXION
POSTERIOR= EXTENSION
MEDIAL= ADDUCTION
LATERAL= ABDUCTION
FOR KNEE JOINTS ITS OPPOSITE
explain muscle role-Agonists and Antagonist
Agonist :
* Act concentrically
to create a
movement at a
joint
* E.g. biceps
brachii shortens
Antagonist :
* Act eccentrically
to oppose and
control the
movement
* E.g. triceps
brachii lengthens
SOME EXPLANATION:
the triceps brachii acts eccentrically when controlling elbow flexion (lowering a dumbbell from a bicep curl). However, during elbow extension (pushing up in a push-up), the triceps brachii is actually the agonist, acting concentrically.
Explain muscle role- stabilisers and neutralisers
Stabilisers
* Holds a joint still
* Prevents movement of joint
* E.g. holding a heavy book
* Biceps brachii role = stabilizer
* Biceps brachii action = isometric
* No change in length of biceps brachii
* No movement at the elbow joint
Nuetralisers:
Eliminates unwanted movement caused by another muscle.
eg pronator muscles in the forearm prevent supination but still allow flexion.
EXPLANATION: The biceps brachii causes both elbow flexion and forearm supination (turning the palm up).
If you only want elbow flexion (e.g., in a bicep curl), another muscle (like the pronator teres) acts as a neutraliser to stop supination
