Body movements

5 Golden Rules of Skeletal Muscle Activity All muscles cross at least one point. Typically, the bulk of muscle lies proximal to the joint crossed. All muscles have at least two attachments: the origin and the insertion Muscles can only pull, they never push During contraction, the muscle insertion moves toward the origin.

Types of Body Movements Every one of our 600 muscles is attached to bone or another connective tissue structure at no less than 2 points Origin Attached to the immovable or less movable bone Insertion Attached to the movable bone When the muscle contracts, the insertion moves toward the origin Muscles of the face are attached to skin.

Body movement occurs when muscles contract across joints, The type of movement depends on The mobility of the joint Where the muscle is located in relation to the joint

Movements Produced by Muscle Contractions Flexion – movement reduces the angle between two bones at their joint. Bending the knee or elbow Extension – opposite of flexion – increases the angle at a joint. Straitening the knee or elbow Abduction – moving a body part away from the midline of the body. Adduction – moving a body part toward the midline of the body. Rotation – movement of a body part around an axis. Shaking your head

Movements Produced by Muscle Contractions Supination – refers to hand position – movement turns palm up to the anterior position (anatomical position). Pronation – palm of hand turned posteriorly. Dorsiflexion – top of foot is elevated with toes pointing upward. Plantar flexion – foot directed downward (standing on your toes).

Types of Muscles Prime movers (agonist) – provide the major force for producing a specific movement Antagonists – oppose or reverse a particular movement (will be on opposite side of the joint and inactive while agonist is active)) Synergists Add force to a movement and reduce undesirable or unnecessary movement. Will stabilize one joint if a muscle crosses two joints. Synergists that immobilize a bone or muscle’s origin are called fixators. (ex. scapula is held to axial skeleton by fixators that can immobilize it)

Naming Skeletal Muscles Direction of Fibers Location Size Number Of Origins Shape Origin & Insertion Action

Naming of the muscle Location of muscle – bone or body region associated with the muscle Shape of muscle – e.g., the deltoid muscle (deltoid = triangle) Relative size – e.g., maximus (largest), minimus (smallest), longus (long) Direction of fibers – e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis)

Direction of Muscle Fibers Relative to the Midline RECTUS = parallel to the midline Rectus Abdominus TRANSVERSE = perpendicular to midline Transverse Abdominus OBLIQUE = diagonal to midline External Oblique

Location Structure near which muscle is found FRONTALIS = near FRONTAL bone OCCIPITALIS = near OCCIPITAL bone

Size Relative Size of Muscle MAXIMUS = largest MEDIUS = middle Gluteus Maximus MEDIUS = middle Gluteus Medius MINIMUS = smallest Gluteus Minimus LONGUS = longest Fibularis Longus BREVIS = short Fibularis Brevis TERTIUS = shortest Fibularis Tertius

Number of Origins Number of tendons of origin BICEPS = Two Biceps Brachii Biceps Femoris TRICEPS = Three Triceps Brachii QUADRICEPS = Four Quadriceps Femoris

Shape Relative Shape of the Muscle DELTOID = triangular shape Δ TRAPEZIUS = trapezoid shape  SERRATUS = saw- toothed ♒ RHOMBOIDEUS = rhomboid shape  TERES = round ○

Origin & Insertion Origin – attachment to an immoveable bone Insertion – attachment to a movable bone ILIO COSTALIS= attaches to the ilium & ribs (costal = ribs)

Action NAME ACTION EXAMPLE FLEXOR EXTENSOR ABDUCTOR ADDUCTOR LEVATOR Decrease angle at a joint Flexor Carpi Radialis EXTENSOR Increase angle at a joint Extensor Carpi Ulnaris ABDUCTOR Move bone away from midline Abductor Pollicis Longus ADDUCTOR Move bone toward midline Adductor Longus LEVATOR Produce upward movement Levator Scapulae DEPRESSOR Produce downward movement Depressor Labii Inferioris SUPINATOR Turn palm upward/anterior Supinator PRONATOR Turn palm downward/posterior Pronator Teres