NAMING MUSCLES: TipsNAMING MUSCLES: Tips

• Most skeletal muscles have names that describe some feature of the muscle.

• Often several criteria are combined into one name. • Associating the muscle's characteristics with its name

will help you learn and remember them. • The following are some terms relating to muscle

features that are used in naming muscles.

Naming Skeletal Muscles

1 – LocationLocation of the muscle2 – ShapeShape of the muscle3 – SizeSize of the muscle4 – Direction/OrientationDirection/Orientation of the muscle fibers/cells5 – Number of OriginsNumber of Origins 6 – LocationLocation of the Attachments7 – ActionAction of the muscle

Location:

• ____________________ (chest)• ____________________ (buttock)• ____________________ (arm) • ______________________(above)• ______________________ (below)• _____________________(under or beneath)• _______________________ (lateral).

Shape:

• deltoid (_______________)• rhomboid (like a rhombus with equal and parallel sides)• latissimus (____________)• teres (__________)• trapezius (like a trapezoid, a four-sided figure

with two sides parallel).

Size:

• ____________ (huge)• _______________ (large)• __________________(long)• ____________ (small)• __________________(short)

Direction of fibers:

• ____________ (straight)• _____________ (across)• ___________(diagonally)• ______________(circular)

Number of origins:

• biceps (two heads)• triceps (three heads)• quadriceps (four heads)

                                     

Triceps Brachii

Origin long head: infraglenoid tubercle of scapulalateral head: upper half of the posterior surface of humerusmedial head: distal two thirds of the posterior surface of humerus

Origin and insertion:

• sternocleidomastoid (origin on the sternum and clavicle, insertion on the mastoid process)

• brachioradialis (origin on the brachium or arm, insertion on the distal end of radius at the styloid process)

Action:

• ____________(to abduct a structure)• _____________(to adduct a structure)• ______________(to flex a structure)• _____________ (to extend a structure)• _____________ (to lift or elevate a structure)

How Muscles Attach to Bone

• Indirect Attachment – ___________________• the _______________________ (sheath of

connective tissue that surrounds the exterior of the muscle fibre) extends past the muscle as a ____________________ and then attaches to ____________________________.

How Muscles Attach to Bone

• Direct Attachment – the epimysium adheres to and fuses with the periosteum

Review:

• What is origin?• What is Insertion?

Try to Remember…

• The origin usually stays fixed and the insertion moves closer to it

Origin

Insertion

3 Basic Types of Muscle Contractions Concentric

– ________________________________– Ex. biceps shorten when lifting an object

Eccentric– ___________________________________– Ex. biceps lengthen as the same weight is

placed back on the ground

Isometric (static)– _________________________________________– Ex. trying to lift an immovable object.

Push or Pull???

• Muscles _____________ by contracting and relaxing, muscles _________________

• They work in pairs to create smooth movement, they are called _________________________(opposing pairs).

Agonist vs Antagonist?

• Agonist–

• Antagonist -

Example:

• In elbow flexion, the biceps brachii will concentrically contract while the triceps brachii will eccentrically contract.

Fixators/Stabilizer

• Muscles that are active isometrically (muscle does not shorten or lengthen) in order to fixate an area when the agonist contracts

• Fixators/ Stabilizers -

Fixators/Stablizer

• Example: When performing a push-up, the serratus anterior stabilizes the shoulder girdle during the downward stage in order to prevent adduction

Examples of opposing muscles and muscle groups

AGONIST (Prime Mover)

ANTAGONIST

Elbow flexion Biceps brachiiBiceps brachii Triceps brachiiTriceps brachiiShoulder abduction

Medial shoulder rotation

Knee extension

Wrist flexion

Dorsi flexion

Trunk flexion

Hip flexion