Ch. 10 Muscular Anatomy PT1

agonist

muscle that causes an action when it contracts

antagonist

muscle working in opposition to agonist

synergists

muscles that work together to cause movement

prime mover

plays major role in movement

fixators

stabilize joints crossed by the prime mover; prevent movement of the origin of the prime mover

origin

muscle end attached to the more stationary of the two bones

insertion

muscle end attached to the bone with the greatest movement of the two

belly

largest space between the two muscle points

tendons

attach muscles to bones

aponeurosis

very broad tendon

concentric phase

muscle is shortening and producing force

eccentric phase

muscle is lengthening and producing force

How are muscles named?

• location: pectoralis, gluteus, brachial

• size: maximus, minimus, longus, brevis

• shape: deltoid, quadratus, teres

• fascicle orientation: rectus

• origin/insertion: sternocleidomastoid, brachioradialis

• number of heads: biceps, triceps

• function: abductor, adductor, masseter

head and neck - flexion

happens in muscles deep within the neck along the anterior margins of vertebral bodies

head and neck - extension

happens in posterior neck muscles attached to occipital bone

head and neck - rotation and abduction

happens in lateral and posterior groups

semispinalis capitis

neck - extension, rotation

splenius capitis

neck - extension, rotation, lateral flexion

scalenes

neck - flexion, lateral flexion, rotation

sternocleidomastoid

neck

• singular: lateral flexion to same side, rotation to opposite side

• both: flexion

trapezius

neck - lateral flexion and extension

buccinator

• draws corners of mouth posteriorly

• compresses cheek to hold food between teeth

masseter

elevates and protracts mandible (chewing)