BLUE SKY SCHOOL OF PROFESSIONAL MASSAGE AND THERAPEUTIC BODYWORK. Musculoskeletal Anatomy & Kinesiology MUSCLES, MOVEMENTS & BIOMECHANICS

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1 BLUE SKY SCHOOL OF PROFESSIONAL MASSAGE AND THERAPEUTIC BODYWORK Musculoskeletal Anatomy & Kinesiology MUSCLES, MOVEMENTS & BIOMECHANICS MSAK101-I Session 7 Learning Objectives: 1. List the three types of muscle found in the human body. 2. Define the following terms: origin, insertion, and action. 3. Identify the general movements of the body. 4. Define fetal position. 5. Describe isotonic and isometric contractions and eccentric and concentric contractions. 6. List and describe the 5 roles of muscles. 7. Define and describe the 3 types of lever systems in the body. 1) MUSCLES: a) While there are three kinds of muscle tissue found in our body, we focus our time primarily on skeletal muscle. The anatomical and physiological differences between skeletal, cardiac, and smooth muscle is discussed in detail in CAPP I. i) Skeletal is the most abundant type of muscle tissue in the body. b) Muscle Structure and Function: Muscles attach from one bone to another bone via tendons. In doing so, they cross a joint that is located between the bones. Muscles contract and shorten When the muscle shortens, it pulls the attachment sites toward one another (and thus, the two bones toward one another), resulting in movement. Depending on which bone is fixed (not moveable) and which one is mobile (moveable), a particular type of movement occurs. Muscles can only shorten and pull in the direction of its fibers. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 1 of 9

2 2) MUSCLE TERMINOLOGY: a) Attachment points: i) Origin Generally the more proximal attachment site and more fixed point. ii) Insertion Generally the more distal attachment site and more mobile point. iii) Action This is the activity performed by a muscle. 3) TERMS OF MOVEMENT: Note the point of reference for movement is anatomical position. a) General Movements Flexion A bending movement that results in a decrease in the angle of a joint. For example, when the elbow joint bends from a straightened position (180 degrees) to a bent position (an angle less than 180 degrees). Extension A movement that increases an angle of a joint. For example, a joint goes from a bent position (less than 180) to a straight position (180 degrees). Hyperextension Describes excessive or unnatural movement in extension. Lateral flexion Side bending of head, neck or trunk. Occurs in frontal plane. Reduction Return to anatomical position from Lateral flexion OR rotation. Abduction Lateral movement away from the midline of the body in the frontal plane (except the thumb, fingers and toes). Adduction Medial movement toward the midline of the body in the frontal plane (except the thumb, fingers and toes). Protraction Movement anteriorly of the scapula or mandible Retraction Movement posteriorly of the scapula or mandible Elevation Lifting or raising a part superiorly. Depression Lowering a part inferiorly. Upward rotation Glenoid fossa of scapula upward, inferior angle moves lateral Downward rotation Glenoid fossa moves downward, inferior angle moves medial Horizontal abduction Humerus goes in horizontal plane posterior to frontal plane Horizontal adduction Humerus moves in horizontal plane anterior to frontal plane Circumduction Circular mov t combines flexion, abduction, extension, & adduction. Rotation Revolving the head, neck, trunk or pelvis about a long axis. Medial (internal) rotation Rotation of a bone on a long axis toward the midline of the body. Occurs in horizontal plane. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 2 of 9

3 Lateral (external) rotation Rotation of a bone on a long axis away from the midline of the body. Occurs in horizontal plane. Opposition Thumb pad brought to finger pad Dorsiflexion Movement of the dorsal surface of foot towards the anterior leg as seen in standing on your heels Plantar flexion Movement of the dorsal surface of foot away from anterior leg as seen in standing on your toes Eversion of foot Plantar surface faces laterally Inversion of foot Plantar surface faces medially Supination Rotation of forearm so palm faces anteriorly Pronation Rotation of forearm so palm faces posteriorly b) Fetal Position This is considered to be a position of total flexion for all the joints of the spine and extremities. When in doubt about flexion or extension, imagine how the joint would appear in fetal position. 4) TYPES OF CONTRACTIONS: a) Isotonic Contraction: Tension is developed in the muscle. Muscle either shortens or lengthens. There are two forms: i) Concentric Contraction: o Tension develops in muscle. o Muscle SHORTENS. o Causes movement against gravity. ii) Eccentric Contraction: o Tension develops in muscle. o Muscle LENGTHENS. o Controls movement with gravity. b) Isometric Contraction: Tension develops in muscle. NO CHANGE is seen in muscle length. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 3 of 9

4 5) ROLES OF MUSCLES: a) Agonist Main muscle(s) that produces the movement. b) Antagonist Muscles that are opposite to the agonist. c) Synergist Muscle(s) that assists the agonist. d) Stabilizers Muscle(s) that surround the joint or body part and contract to fixate or stabilize the area to enable another limb or body segment to move. e) Neutralizer Counteract or neutralize action of another muscle to prevent undesired mov t. Note: When a muscle contracts, it attempts to perform all of the actions above. Many muscles are capable of performing more than one action. However, different factors play into what they can actually do. 6) GRAVITY How does this play a role? a) Gravity is very important to consider when looking at contractions, movements, and roles of muscles. Gravity usually determines what type of contraction is happening and what muscle is the prime mover. i) Example 1: Raising a book and lowering it back down If a movement occurs against gravity, the muscle(s) that produces that movement (biceps brachii) is the agonist and is concentrically contracting. The triceps brachii is along for the ride. It is lengthening, but without tension. If a controlled movement occurs with gravity, (e.g. lowering the book back down), the muscle(s) that is producing that movement is the same one as above (it remains the agonist), however it is eccentrically contracting. Again, triceps is along for the ride. It is shortening, but without tension. ii) Example 2: Raising a weight above your head with a bent elbow. iii) Breakdown: The first movement is raising the weight above your head while your elbow is bent. While extending your elbow, the movement with the agonist (triceps brachii) occurs against gravity (concentric contraction). The second movement is lowering weight back down. The movement with agonist (triceps) occurs with gravity and is controlled (eccentric contraction). If you noticed, both movements involved the same action flexing and extending the elbow joint. However, the difference in what type of way one was moving against or with gravity determined which muscles were being used and when they were concentrically and eccentrically contracting. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 4 of 9

5 7) RANGE OF MOTION (ROM): a) Range of motion measures the angle at a joint from the neutral (anatomical) position to a position that is the maximum for the particular action (i.e. flexion, extension, internal rotation, abduction, etc.). b) We will be measuring this later in MSAK as it is important for bodyworkers to be able to assess ROM. 8) RULES OF MUSCLES: If you understand the following concepts and know your bony landmarks really well, remembering muscular origins, insertions, and actions becomes very easy. a) Direction of Muscle Fibers: The direction of the muscle fibers is the direction in which the muscle will contract and pull. The surface of the body on which the muscle origin lies and the direction of its muscle fibers gives an indication of direction in which its insertion moves; i.e.: If a muscle lies or originates on the anterior surface of the body, it moves its insertion at least in the anterior direction If a muscle s fibers run in a medial to lateral direction, the insertions moves from lateral to medial i.e. insertion always moves towards origin. b) Relationship to the Joint: If a muscle crosses a joint, it has an action at that joint. c) Position of Tendon: If a muscle crosses a joint posteriorly, it moves the body part posteriorly. If a muscle crosses a joint anteriorly, it moves the body part anteriorly. If a muscle crosses a joint medially, it moves the body part medially. If a muscle crosses a joint laterally, it moves the body part laterally. d) How Muscles are Named i) Take advantage of the free information that the name of the muscle offers. Direction of Fibers: o Rectus = straight o Transverse = perpendicular to midline of body o Oblique = at an angle to midline of body Location: o Named for a nearby structure o Example: Brachialis = brachium or humerus Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 5 of 9

6 Size: o Magnus = Large o Maximus = Largest o Medius = Middle-sized o Minimus = Smallest Number of Heads: o Biceps (bi = 2) o Triceps (tri = 3) Shape: o Deltoid (triangular) o Trapezius (trapezoidal) Attachment Points: o Coracobrachialis = Coracoid process + brachium (humerus) Action: o Flexor, Extensor, Adductor Length and Width: o Longus = Long o Brevis = Short Depth: o Superficialis = Superficial o Profundus = Deep 9) LEVERS: a) Definitions i) Lever: defined as a rigid bar or rod that moves about an axis of rotation or a fixed point called a fulcrum. In the body, the skeletal bones are levers. ii) Axis (A) or fulcrum: the fixed point about which a lever pivots. In the body, this is a joint. iii) Force (F): the lever rotates about the axis as a result of force or effort. Effort or force in the body is muscle contraction and results in movement. iv) Resistance (R): the weight or load that opposes the force. In the body, this may be the weight of a bone, an object being lifted, or the weight of the whole body such as in walking. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 6 of 9

7 b) Types of levers i) First class levers: Axis is between the effort (or force) and the resistance. (1) Produce balanced movements when axis is midway between force & resistance (e.g., seesaw) (2) Produce speed & range of motion when axis is close to force, (triceps in elbow extension) (3) Produce force motion when axis is close to resistance (crowbar) (4) Very few first class levers in the body (5) Example: (a) Capital extension at occipitoaxial joint (i) Head balanced on neck in flexing/extending (ii) Agonist & antagonist muscle groups are contracting simultaneously on either side of a joint axis 1. agonist produces force while 2. antagonist supplies resistance (b) Elbow extension with shoulder fully flexed & arm beside the ear (i) Elbow extension in triceps applying force to olecranon (F) in extending the nonsupported forearm (R) at the elbow (A) (ii) Force is applied where muscle inserts in bone, not in belly of muscle (iii)the triceps applies force to the olecranon of ulna behind the axis of elbow joint. As the applied force exceeds the amount of forearm resistance, the elbow extends. Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 7 of 9

8 ii) Second class levers: Resistance is between axis and effort (1) Produces force or strength movements, since a large resistance can be moved by (2) a relatively small force (a) Wheelbarrow (b) Nutcracker (c) Loosening a lug nut (3) Few second class levers in the body (4) Example (a) Gastrocnemius and soleus, planar flexion of foot to stand on toes (i) Plantar flexion of foot to raise the body up on the toes where ball (A) of the foot serves as the axis as ankle plantar flexors apply force to the calcaneus (F) to lift the resistance of the body at the tibial articulation (R) with the foot (b) Brachioradialis as an elbow flexor iii) Third class levers: effort is between the resistance and axis (1) Produce speed & range-of-motion movements Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 8 of 9

9 (2) Requires a great deal of force to move even a small resistance (a) Paddling a boat (b) Shoveling - application of lifting force to a shovel handle with lower hand while upper hand on shovel handle serves as axis of rotation (c) Similar to a screen door that closes by means of a spring or door closer (3) Most common lever type in body; allows for speed & ROM w/ little muscle shortening (4) Example: (a) Biceps brachii flexing the elbow to lift a weight (i) Using the elbow joint (A) as the axis, the biceps brachii applies force at its insertion on radial tuberosity (F) to rotate forearm up, with its center of gravity (R) serving as the point of resistance application. (b) Quadriceps group knee extensors (c) Brachialis - true 3rd class leverage - pulls on ulna just below elbow; pull is direct & true since ulna cannot rotate (d) Biceps brachii supinates forearm as it flexes so its 3rd class leverage applies to flexion only (e) Hamstrings contracting to flex leg at knee while in a standing position (f) Using iliopsoas to flex thigh at hip Updated: 2/11 Blue Sky School of Professional Massage and Therapeutic Bodywork Page 9 of 9