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ACE’s Essentials of Exercise Science for Fitness Professionals Chapter 1: Human Anatomy Lesson 1.2 LEARNING OBJECTIVES • After completing this session, you will be able to: Describe the structures and functions of the central nervous system (CNS) and the peripheral nervous system (PNS) List the different types of muscle tissue and musclefiber types Identify muscles that act at the following joints: shoulder, scapulothoracic articulation, wrist, elbow, trunk, hip, knee, and ankle List the principal endocrine glands © 2014 ACE NERVOUS SYSTEM • The nervous system connects the muscles to the brain and spinal cord through a network of nerve circuits. © 2014 ACE PROPRIOCEPTION • Proprioception is the sense of knowing where the body is in relation to its various segments and the external environment. © 2014 ACE MUSCULOTENDINOUS RECEPTORS • Muscle spindle: Located in the muscle belly lying parallel to the fibers Causes a reflexive contraction (stretch reflex) in the muscle when the muscle senses a stretch force. Simultaneously causes the antagonist to relax (reciprocal inhibition) when it senses tension • Golgi tendon organ (GTO): Located between the muscle belly and its tendon Causes muscle inhibition (autogenic inhibition) when it senses tension © 2014 ACE MUSCULAR SYSTEM • There are three types of muscles in the human body. © 2014 ACE SKELETAL MUSCLE FIBER TYPES • Skeletal fibers can be divided into two general categories based on how quickly they contract. © 2014 ACE MUSCLE-FIBER MICROANATOMY • Skeletal muscles are made up of many muscle fibers held in place by connective tissue (fascia). • Muscle fibers are made up of myofibrils (protein filaments) composed of a series of repeating segments called sarcomeres. • Sarcomeres, made up of thick (myosin) and thin (actin) myofilaments, are the functional contracting unit of skeletal muscle. © 2014 ACE MUSCLE CONTRACTION • Sliding filament model When acetylcholine is released from the CNS and detected, calcium is released. Calcium exposes binding sites along the actin for the myosin to attach. If sufficient ATP is present, cross-bridges are formed and the myosin pulls the actin toward the center, shortening the sarcomere. © 2014 ACE SHOULDER GIRDLE • The muscles of the shoulder girdle act on the scapula, primarily to stabilize it. © 2014 ACE MAJOR MUSCLES THAT ACT AT THE SHOULDER GIRDLE © 2014 ACE MAJOR MUSCLES THAT ACT AT THE SHOULDER © 2014 ACE MOVEMENTS AT THE ELBOW AND WRIST © 2014 ACE TRUNK • The major muscles of the trunk support, stabilize, and move the spine. The abdominal wall, made up of the rectus abdominis, obliques, and transverse abdominis, has no skeletal support. Its strength comes from the multidirectional layers of muscle. © 2014 ACE MAJOR MUSCLES THAT ACT AT THE TRUNK © 2014 ACE HIP FLEXORS • There are 21 major muscles involved in the actions of the hip joint. Actions of the hip joint include flexion, extension, internal rotation, external rotation, adduction, and abduction. More than half of these muscles are involved in multiple actions. © 2014 ACE HIP EXTENSORS © 2014 ACE HIP INTERNAL AND EXTERNAL ROTATORS • The hip internal rotators include the tensor fasciae latae, semitendinosus (slight), and semimembranosus (slight). • The hip external rotators include the iliopsoas, gluteus maximus, biceps femoris (slight), gluteus medius and minimus (posterior fibers), sartorius, pectineus, and the six deep external rotators. © 2014 ACE HIP ADDUCTORS © 2014 ACE HIP ABDUCTORS © 2014 ACE KNEE • The muscles of the thigh are responsible for movement at the knee. © 2014 ACE ANTERIOR COMPARTMENT OF THE LEG • The lower leg is divided into three primary compartments: anterior, posterior, and lateral. © 2014 ACE POSTERIOR COMPARTMENT OF THE LEG • The posterior compartment is made up of muscles that plantarflex the foot and/or flex the toes and is divided further into the superficial posterior and deep posterior compartments: Superficial posterior compartment: gastrocnemius, soleus, and plantaris Deep posterior compartment: flexor hallucis longus, flexor digitorum longus, posterior tibialis, and popliteus © 2014 ACE POSTERIOR COMPARTMENT OF THE LEG © 2014 ACE LATERAL COMPARTMENT OF THE LEG • © 2014 ACE The lateral compartment is made up of muscles that plantarflex and evert the foot, including the peroneus longus and peroneus brevis. MAJOR ENDOCRINE GLANDS AND THEIR HORMONES © 2014 ACE SUMMARY • Being able to identify the structures and functions of the CNS and PNS allows a fitness professional to understand the contributions of the nervous system to effective movement. • Understanding the different types of muscle tissue and muscle-fiber types helps a personal trainer design exercise programs that target the appropriate energy systems based on a client’s needs and goals. • Understanding how the muscles of the upper and lower extremities and trunk act at the various joints helps a personal trainer design workouts appropriate for a client’s needs and goals. • Having a general understanding of the principal endocrine glands is important for conceptualizing how the endocrine system plays a part in general health and function. © 2014 ACE