ESS 205 Anatomy and Physiology Lecture 13Outline of Last Lecture I. 3 Hormones related to vital homeostasisII. Other factors affecting boneIII. Bone fracture and repairIV. Overview of muscle systemOutline of Current LectureV. Parts of Skeletal MusclesVI. Skeletal Muscle ShapesVII. Muscle ActionsVIII. Muscle InnervationIX. Athletic InjuriesCurrent Lecture1. There are three main sections of skeletal muscles. The first is the origin. This is the most stationary end of muscle NOTE: not fully stationary, just less movable. The second section is called insertion. It is the more mobile end of muscle. Last is the belly. It is the thicker, middle region of the muscle. 2. There are five main skeletal muscle shapes. a. Fusiform= tapered ends but more thick in the middle. An example would be the biceps brachii. b. Convergent= broad at origin and tapers to a narrower insertion. An example would be the pectoralis major.c. Parallel= parallel fascicles (muscle cells). Rectus abdominis would be an example. d. Circular= act as sphincters or a ring around a body opening. Anus, muscles around mouth, eye, etc. These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.e. Pennate= fascicles insert obliquely on a tendon. There are unipennate, bipennate, and multipennate. All the fascicles run into a narrow insertion. They are highly efficient. Example would be deltoid.3. There are four main muscle actions. The prime mover out of all four is the Agonist. It produces the most force. Synergist aids the prime mover. It stabilizes and modifies direction of movement. This muscle action is EXTREMELY important. Antagonist moves opposite of Agonist. It prevents excessive movement. Last is the Fixator. It prevents a movement of bone that the prime mover (Agonist) is attached to. Think of them as the stage crew. An example of all movements in action would be elbow flexion. The Agonist is the biceps brachii; the Synergist is the brachialis; the Antagonist is the triceps brachii; and the fixators are the muscles that hold the scapula in place. 4. Skeletal innervation involves cranial and spinal nerves. The cranial nerves arise from the brain. They exit the skull through foramina and are numbered one through twelve. The second is spinal nerves. They exit the vertebral column through intervertebral foramina. **If nerves do not touch muscle than muscle WILL NOT contract**5. Athletic injuries are common. Know RICE (rest, ice, compression, elevation). Muscle cells do not regenerate like bone does. Instead injured muscle fills with scar tissue making it less