 Origin: the immovable end of the muscle; attached to a relatively immovable bone  Insertion: the end of the muscle attached to a movable bone  **When a muscle contracts, its insertion is pulled toward its origin.

 Prime mover (agonist): the muscle that provides most of the movement in an action  Synergists (antagonists): the muscles around the prime mover that assist it in an action

Prime Mover Synergist

 Latin and Greek roots  Characteristics Used to Name Muscles  1) direction of their fibers  2) size  3) location  4) which bones they attach to  5) function  **The names of muscles often contain combinations of each of the above.

 Determined in relation to the midline of the body  Rectus: (Latin for “straight”)  Parallel to the midline  Ex: rectus femoris and rectus abdominis  Oblique: at an angle to the midline  Ex: internal and external obliques of the thorax

 Longus: long  Brevis: short  Maximus: largest or greatest  Major: larger  Vastus: huge  Minimus: least or smallest  Minor: smaller

 Oris: mouth Digitorum: finger or toe  Oculi: eye Pollicis: thumb  Palmaris: palm of the hand Costals: rib  Abdominus: abdomen  Brachii: arm Hallicus: great toe  Femoris: thigh Carpi: wrist  Tibialis: shin bone Spinalis: spine  Peroneus: fibula Scapularis: shoulder blade

 Spinalis thoracis  Biceps brachii  Rectus femoris  Adductor pollicis longus

 Orbicularis oculi  External intercostals  Tibialis anterior  Peroneus longus

 Many muscles are named as a result of their association with a particular bone.  The temporalis muscle is found covering the temporal bone.  The frontalis muscle is found covering the frontal bone of the skull.

 Some muscles are named for their origin and insertion.  The first part of the muscle name indicates the origin, while the second part of the name indicates the insertion.  Ex: sternocleidomastoid = sterno (breastbone) and cleido (clavicle) insertion; mastoid (breast shaped) process on the skull

 Some muscles have multiple origins.  This number will often be used in the name.  Ex: biceps brachii and triceps brachii  Bi is Latin for two  Tri is Latin for three  Ceps refers to the head  So the biceps brachii has two heads that attach to two different origins.

In addition to having the name of the bone in the muscle name, the position in relation to the bone or body part may be in the muscle name.

 Supra: above or over  Infra: below or beneath  Sub: below or under  Lateralis: the side  Medialis: the middle  Inter: between or among  External: outer  Internal: inner

 Superior: above or over  Inferior: underneath  Dorsi: the back  Anterior: in front of  Ex: supraspinatus, infraspinatus, subscapularis, vastus lateralis, vastus medialis, intercostals, external internal obliques, superior and inferior rectus of the eye

 Early anatomists often named muscles after the shapes they resembled.  Deltoid: delta = triangle; oid = like  Trapezius: trapez = table  Serratus: saw  Teres: round  Orbicularis: orbi = circle, cul = little  Latissimus: lat = broad/wide, simus = like

 Deltoid ==  Serratus ==

 Orbicularis: orbi = circle, cul = little  =

 What would the following muscles look like and where would they be found?  Latissimus dorsi  Orbicularis oculi  Orbicularis oris

 flexion : flex = bend (decreases the angle at a joint) extension : ex = out; ten = stretch (increases the angle at a joint) adduction: ad = toward; duct = lead (pulls the limb toward the midline) abduction : ab = away from; duct = lead (pulls the limb away from the midline) pronation: pron = bent forward (turning the palm downward) supination: supin = lying on the back (turning the palm upward)

EX) Flexor carpi radialis is a muscle of the human forearm that acts to flex and (radial) abduct the hand. EX) Extensor digitorum is a muscle that extends the medial four digits of the hand.