Muscle Anatomy and Function

What is a tendon?

Rope-like structure connecting muscle to bone

What is an aponeurosis?

Sheet-like connective tissue

What type of connective tissue are tendons?

Dense regular connective tissue

Why are tendons strong?

Parallel collagen fibers resist tension

What surrounds a muscle fiber?

Endomysium

What surrounds a fascicle?

Perimysium

What surrounds the entire muscle?

Epimysium

What is the origin in muscle anatomy?

Stationary attachment

What is the insertion in muscle anatomy?

Movable attachment

What happens during contraction?

Insertion moves toward origin

On limbs, where is the origin usually located?

Proximal

On limbs, where is the insertion usually located?

Distal

What is the prime mover (agonist)?

Main muscle responsible for movement

What is an antagonist?

Muscle that opposes movement

What is a synergist?

Assists prime mover

What is a fixator?

Stabilizes a bone

What is coactivation?

Agonist and antagonist contract together for stability

What is the action of the biceps brachii?

Flexes forearm

What is the action of the triceps brachii?

Extends forearm

What is unique about facial muscles?

Insert into skin

Which cranial nerve innervates facial muscles?

Cranial nerve VII

What is the action of the orbicularis oris?

Puckers lips

What is the action of the orbicularis oculi?

Closes eye

What is the action of the zygomaticus?

Smiling (elevates mouth corners)

What is the action of the mentalis?

Pouting

What is the action of the platysma?

Tenses neck

What is the primary muscle of inspiration?

Diaphragm

What is the action of the diaphragm?

Flattens and increases thoracic volume

What happens to pressure during inspiration?

Decreases

What happens to pressure during expiration?

Increases

What is the action of the external intercostals?

Elevate ribs (inspiration)

What is the action of the internal intercostals?

Depress ribs (forced expiration)

What type of process is quiet inspiration?

Active process

What type of process is quiet expiration?

Passive process

What muscles are involved in forced inspiration?

Scalenes and sternocleidomastoid

What muscles are involved in forced expiration?

Internal intercostals and abdominals

What do abdominal muscles do in breathing?

Push viscera up to aid expiration

What is the order of inspiration?

Muscle contraction → volume increases → pressure decreases → air enters

What is the order of expiration?

Muscles relax → volume decreases → pressure increases → air leaves

What is the action of the latissimus dorsi?

Extends and adducts arm

What is the action of the deltoid?

Elevates arm

What is the action of the brachialis?

Flexes forearm

What is the action of the brachioradialis?

Flexes forearm

What is the action of the quadriceps?

Extends leg

What is the action of the gastrocnemius?

Plantar flex foot

What is the action of the tibialis anterior?

Dorsiflex foot

What is carpal tunnel syndrome?

Compression of median nerve

What is the flexor retinaculum?

Structure forming carpal tunnel

What is the best site for IM injection?

Deltoid or gluteus medius

Why should you avoid the gluteus maximus for IM injection?

Risk of sciatic nerve injury