Lecture 8: Neuromuscular Fundamentals

What are two advantages that Biarticular muscles have over Uniarticular muscles?

- Can cause and/or control motion at more than one joint - Maintain a relatively constant length due to "shortening" at one joint and "lengthening" at another joint

What is neutralizers muscle?

- Counteract or neutralize the action of another muscle to prevent undesirable movements. - Contract to resist specific actions of other muscles

When do force couples occur?

- Force couples occur when two or more forces are pulling in different directions on an object, causing the object to rotate about its axis.

What are examples of ACTIVE AND PASSIVE INSUFFICIENCY? (Quadriceps)

#1 (Quadriceps): Quadriceps contracts concentrically to both flex the hip and extend the knee while hamstrings lengthens for these actions

What are examples of ACTIVE AND PASSIVE INSUFFICIENCY? (Rectus Femoris)

#2 (Active insufficency): Active insufficiency of rectus femoris in performing both hip flexion and knee extension simultaneously

What are examples of ACTIVE AND PASSIVE INSUFFICIENCY? (Hamstrings)

#3 Passive insufficiency of hamstrings stretching at hip and knee joint simultaneously.

When is Active insufficiency reached?

- Active insufficiency is reached when the muscle becomes shortened to the point that it cannot generate or maintain active tension - The muscle cannot shorten any farther

What are examples of neutralizers muscles? PT1 (Bicep Brachii)

when only the supination action of the biceps brachii is desired, the triceps brachii contracts to neutralize the flexion action of the biceps brachii.

What are examples of neutralizer muscles? PT2 (Bicep curl)

- In a biceps curl, when only flexion force of the biceps brachii is desired, the pronator teres contracts to neutralize the supination component of the biceps.

What is an example of force couples?

- Middle trapezius, lower trapezius, and serratus anterior each pull on the scapula from a different direction to produce the combined result of upward rotation.

What are Multiarticular muscles?

- Multiarticular muscles act on three or more joints between their origin and insertion crossing multiple joints - Principles relative to Biarticular muscles apply similarly to Multiarticular muscles

What produces concentric or eccentric contraction?

Agonists muscles EX: Bicep curl, bicep brachii - Works concentrically during elbow flexion - Works eccentrically during elbow flexion

What is the role of muscle?

Movement is the result of multiple muscles working together in one or the other role.

What are Biarticular Muscles?

Muscles cross and act on two different points. EX: Quadriceps muscle

How is active and passive insufficiency observed?

Observed in either biarticular or multiarticular muscles when full range of motion is attempted in all joints crossed by the muscle.

What are Antagonist muscles?

- These muscles are located on opposite side of the joint from the Agonist. -Produces opposite joint movement to Agonist -Contralateral muscles

What are Agonists muscles?

- These muscles cause joint motion -These are the prime movers of muscles - Movement here could have multiple agonists

What is the muscle synergist?

- They assist agonist muscles (Guiding them) EX: brachioradialis is synergist to biceps brachii and brachialis

What happens when squating up?

-Hip and knee joints extend simultaneously.

What are stabilizers muscle?

-Surrounds the joint or body part -Establishes a firm base for the distal joints to carry out movements -Contract to fixate or stabilize the area to enable the body segment to move.

What are the different types of muscle roles?

1. Agonists 2. Antagonists 3. Stabilizers 4. Synergists 5. Neutralizers

What is the main function of the synergist muscle?

Assists in refined movement

What is an example of stabilizers muscle?

EX: Bicep curl - Muscles of the scapula and glenohumeral joint maintain the shoulder complex in a relatively static position for the biceps brachii to perform curls more effectively.

What are examples of Uniarticular Muscles?

EX: Brachialis: can only pull the humerus and ulna closer together

What are examples of Multiarticular muscles?

Finger Flexors

What is the function of force couples?

Helps to have more efficient movements.

What happens in hamstrings?

Hip extension and knee flexion.

What happens in Quadriceps?

Hip flexion and knee extension.

What are examples of Biarticular?

Hips and knee are Biarticular when doing squats

What happens when you squat down?

Hips and knee joints flex simultaneously. - Quadriceps shortens at hip joint and lengthens at the knee joint - Hamstrings lengthens at hip joint and shortens at knee joint

When is Passively insufficiency reached?

Passively insufficiency is reached when the opposite muscle becomes stretched to the point where it can no longer lengthen and allow movement.

What is the main function of Antagonist muscles?

The main function is to relax and allow agonist muscles to produce movement.

What are Uniarticular Muscles?

These are muscles that cross and act directly only on the joint that they cross.