Musculoskeletal Anatomy & Movement Terminology

ACSM-EP ACSM Certified Exercise Physiologist

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1 Introduction & Exam Overview

The ACSM-EP Credential & Current Exam Facts Exam Blueprint, Cognitive Levels & Study Strategy

2 Foundations of Exercise Physiology

Bioenergetics & Energy Systems Cardiorespiratory Responses & Adaptations to Exercise Neuromuscular Physiology

3 Functional Anatomy & Biomechanics

Musculoskeletal Anatomy & Movement Terminology Biomechanical Principles

4 Preparticipation Health Screening & Risk Assessment

The ACSM Preparticipation Screening Algorithm & Medical Clearance Informed Consent & Health-History Questionnaire CV, Pulmonary, Metabolic & Musculoskeletal Risk Factors Clinical Reference Values

5 Health & Fitness Assessments

Selecting, Sequencing & Terminating Fitness Assessments Cardiorespiratory Fitness Testing Muscular Fitness, Flexibility & Neuromotor Assessment Anthropometric & Body Composition Assessment

6 Exercise Prescription Foundations: FITT-VP & Programming

The FITT-VP Framework & Training Principles Session Structure, Warm-Up/Cool-Down & Recovery Program Design, Overtraining & Injury Recognition

7 Cardiorespiratory Exercise Prescription

Prescribing CR Exercise & Intensity Methods ACSM Metabolic Equations & Caloric Expenditure

8 Resistance, Flexibility & Neuromotor Prescription

Resistance Training Prescription Flexibility, Neuromotor & Plyometric Prescription

9 Progression, Nutrition & Weight Management

Exercise Progression & Modification Energy Balance, Nutrition & Fuel Utilization Body-Composition Modification, Ergogenic Aids & Weight-Management Programming

10 Clients with Controlled Disease & Special Populations

Exercise for Controlled Cardiovascular, Pulmonary & Metabolic Disease Exercise for Arthritis, Osteoporosis, Obesity & Low-Back Pain Older Adults Children, Adolescents & Pregnant Clients Environmental Considerations: Heat, Cold, Altitude & Air Quality

11 Exercise Counseling & Behavior Modification

Communication Techniques & Group Exercise Leadership Behavior-Change Models & Theories Motivational Interviewing, Goal Setting & Adherence Health Literacy, Educational Resources & Stress Management Professional Standards, Mental Health & Referral (Scope of Practice)

12 Risk Management & Emergency Procedures

Risk Management, Legal & Professional Responsibilities Emergency Procedures, First Aid & Basic Life Support

Musculoskeletal Anatomy & Movement Terminology

Key Takeaways Explain This Topic AI

Tendons attach muscle to bone and transmit contractile force; ligaments attach bone to bone and stabilize joints; fascia envelops muscle groups and hyaline cartilage cushions joint surfaces.

The origin is a muscle's attachment on the more fixed, typically proximal bone, while the insertion is the attachment on the bone that moves, typically distal, and is pulled toward the origin during concentric contraction.

Flexion decreases a joint angle and extension increases it in the sagittal plane, while abduction moves a limb away from the midline and adduction moves it toward the midline in the frontal plane.

An agonist (prime mover) produces the primary force for a movement, an antagonist lengthens or contracts eccentrically to permit it, a synergist assists by neutralizing unwanted secondary actions, and a stabilizer contracts isometrically to fix a body segment in place.

Sagittal-plane movements such as flexion/extension rotate around the frontal axis, frontal-plane movements such as abduction/adduction rotate around the sagittal axis, and transverse-plane movements such as rotation occur around the vertical axis.

Last updated: July 2026

Bone, Skeletal Muscle, and Connective Tissue

Bone serves four functions central to exercise physiology: structural support , protection of vital organs, mineral storage (calcium, phosphorus), and — most relevant to prescribing exercise — a rigid lever system that skeletal muscle pulls against to produce movement. Bones are classified as long (femur, humerus), short (carpals, tarsals), flat (sternum, scapula), or irregular (vertebrae). Bone is living tissue that remodels in response to mechanical loading, which is why weight-bearing and resistance exercise are prescribed to preserve bone mineral density (covered further in Chapter 10).

Skeletal muscle is organized hierarchically: the whole muscle is wrapped in epimysium , bundles of fibers (fascicles) are wrapped in perimysium , and individual fibers are wrapped in endomysium . Each skeletal muscle attaches to bone at two points. The origin is the attachment on the more fixed, typically more proximal bone; the insertion is the attachment on the bone that moves, typically more distal. When a muscle contracts concentrically, the insertion is pulled toward the origin.

Three connective-tissue structures link the musculoskeletal system together:

Tendons connect muscle to bone and transmit contractile force to produce joint movement.

Ligaments connect bone to bone and provide passive stability at a joint.

Fascia envelops and organizes muscles and muscle groups, while hyaline cartilage cushions the articulating surfaces of synovial joints and reduces friction.

An EP-C who can name these structures accurately can explain assessment findings, describe injury mechanisms (e.g., a "strain" injures muscle or tendon; a "sprain" injures ligament), and communicate technique cues using correct anatomical vocabulary.

Major Muscles: Location and Primary Action

The exam expects an EP-C to identify major muscles by location and know their primary joint action(s), because interpreting strength and flexibility assessments (Chapter 5) and building targeted FITT prescriptions (Chapters 6–8) both depend on this knowledge.

Muscle Location Primary Action(s)
Pectoralis major Anterior chest Shoulder horizontal adduction, flexion, internal rotation
Trapezius Upper back/neck Scapular elevation, depression, retraction, upward rotation
Latissimus dorsi Mid-to-lower back Shoulder extension, adduction, internal rotation
Deltoid (anterior/middle/posterior) Cap of the shoulder Shoulder flexion, abduction, extension
Rectus abdominis Anterior abdomen Trunk (spinal) flexion
External/internal obliques Lateral abdomen Trunk rotation, lateral flexion
Quadriceps femoris Anterior thigh Knee extension (rectus femoris also flexes the hip)
Hamstrings (biceps femoris, semitendinosus, semimembranosus) Posterior thigh Knee flexion, hip extension
Gastrocnemius Posterior lower leg (calf) Ankle plantarflexion; assists knee flexion
Soleus Deep to gastrocnemius Ankle plantarflexion
Gluteus maximus Buttock Hip extension, external rotation
Biceps brachii Anterior upper arm Elbow flexion, forearm supination
Triceps brachii Posterior upper arm Elbow extension
Joints and Their Movements

Most exercise-relevant joints are synovial — freely movable joints enclosed in a fluid-filled capsule. Synovial joints are further classified by the movement pattern they permit:

Hinge (elbow, knee) — uniplanar flexion/extension only

Ball-and-socket (shoulder, hip) — multiplanar flexion/extension, abduction/adduction, rotation, and circumduction

Pivot (proximal radioulnar, atlantoaxial) — rotation only
Condyloid (wrist) — flexion/extension and abduction/adduction, but no independent rotation
Saddle (thumb carpometacarpal) — flexion/extension, abduction/adduction, and opposition

Knowing a joint's structural classification predicts which movements — and therefore which assessments and exercises — are anatomically appropriate at that joint.

Directional and Movement Terminology

Precise anatomical language lets an EP-C describe assessment findings and cue exercise technique without ambiguity. Directional terms are always defined relative to the anatomical position (standing upright, palms facing forward):

Anterior/posterior — toward the front of the body/toward the back
Proximal/distal — closer to the trunk or point of attachment/farther away
Medial/lateral — closer to the midline of the body/farther from the midline
Superior/inferior — above a reference point/below it

Movement terms describe the specific joint action produced:

Flexion/extension — decreasing a joint angle/increasing it (predominantly sagittal-plane)
Abduction/adduction — moving a limb away from the midline/toward it (predominantly frontal-plane)

Internal (medial) rotation/external (lateral) rotation — rotating a limb toward/away from the midline around its long axis

Supination/pronation — rotating the forearm so the palm faces up/down
Dorsiflexion/plantarflexion and inversion/eversion — ankle-specific sagittal- and frontal-plane movements

Functionally, muscles are also classified by the role they play during a given movement:

Agonist (prime mover) — generates the primary force that produces the movement
Antagonist — opposes the agonist and lengthens, or contracts eccentrically, to permit controlled movement
Synergist — assists the agonist, often by neutralizing an unwanted secondary action of another muscle

Stabilizer (fixator) — contracts isometrically to hold a body segment steady so the agonist can act efficiently

Planes and Axes of Movement

Human movement is described relative to three cardinal planes, each paired with a perpendicular axis of rotation:

Plane Example Movements Axis of Rotation
Sagittal Flexion, extension (biceps curl, squat) Frontal (mediolateral) axis
Frontal (coronal) Abduction, adduction (lateral raise, jumping jack) Sagittal (anteroposterior) axis
Transverse Internal/external rotation, trunk rotation Vertical (longitudinal) axis

An EP-C uses plane-of-motion language to select assessment protocols and to design programs that train movement in all three planes rather than the sagittal plane alone, which is the plane most commonly over-trained in traditional resistance programs. Recognizing which plane and axis a given exercise or assessment movement occurs in is directly testable and underlies safe, well-rounded program design.