Textbook Question
Why do you think that the muscles of the erector spinae and transversospinal muscle groups remain in a state of continual contraction when we are upright?
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Ch. 9 The Muscular System
Erin C. Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822
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Table of contents
- Ch. 1 Introduction to Anatomy and Physiology26
- Ch. 2 The Chemistry of Life38
- Ch. 3 The Cell55
- Ch. 4 Histology47
- Ch. 5 The Integumentary System30
- Ch. 6 Bones and Bone Tissue36
- Ch. 7 The Skeletal System40
- Ch. 8 Articulations19
- Ch. 9 The Muscular System36
- Ch. 10 Muscle Tissue and Physiology29
- Ch. 11 Introduction to the Nervous System and Nervous Tissue28
- Ch. 12 The Central Nervous System42
- Ch. 13 The Peripheral Nervous System41
- Ch. 14 The Autonomous Nervous System and Homeostasis31
- Ch. 15 The Special Senses39
- Ch. 16 The Endocrine System42
- Ch. 17 The Cardiovascular System I: The Heart30
- Ch. 18 The Cardiovascular System II: The Blood Vessels43
- Ch. 19 Blood32
- Ch. 20 The Lymphatic System and Immunity45
- Ch. 21 The Respiratory System27
- Ch. 22 The Digestive System27
- Ch. 23 Nutrition and Metabolism7
- Ch. 24 The Urinary System39
- Ch. 25 Fluids, Electrolytes, and Acid-Base Homeostasis39
- Ch. 26 The Reproductive System10
- Ch. 27 Development and Heredity5
Erin C. Amerman2nd EditionHuman Anatomy & PhysiologyISBN: 9780136873822Not the one you use?Change textbook
Chapter 9, Problem L2.6
The rectus femoris muscle originates from the anterior superior iliac spine and inserts into the tibial tuberosity. Predict its main actions with only this information.
Verified step by step guidance1
Identify the origin and insertion points of the rectus femoris muscle. The origin is the anterior superior iliac spine (ASIS), and the insertion is the tibial tuberosity via the patellar tendon.
Understand the general principle of muscle action: muscles contract to bring the insertion point closer to the origin. In this case, contraction of the rectus femoris will pull the tibial tuberosity toward the anterior superior iliac spine.
Recognize the anatomical position of the rectus femoris. It crosses both the hip joint and the knee joint, making it a biarticular muscle. This means it can act on both joints.
Determine the actions at the hip joint. Since the muscle originates from the ASIS and crosses the hip joint anteriorly, contraction will result in flexion of the hip (bringing the thigh forward).
Determine the actions at the knee joint. Since the muscle inserts into the tibial tuberosity and crosses the knee joint anteriorly, contraction will result in extension of the knee (straightening the leg).
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Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Muscle Origin and Insertion
The origin of a muscle is the fixed attachment point, while the insertion is the movable attachment. In the case of the rectus femoris, its origin at the anterior superior iliac spine and insertion at the tibial tuberosity indicates its role in movement. Understanding these points helps predict the muscle's actions during contraction.
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Origin and Insertion
Actions of the Rectus Femoris
The rectus femoris is one of the four quadriceps muscles and primarily functions to extend the knee. Additionally, due to its origin on the pelvis, it also assists in hip flexion. Recognizing these dual actions is essential for predicting how this muscle contributes to movements like walking or running.
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Knee Extension and Hip Flexion
Knee extension is the straightening of the knee joint, while hip flexion involves lifting the thigh towards the abdomen. The rectus femoris plays a crucial role in both actions, making it vital for activities that require leg movement. Understanding these movements provides insight into the muscle's functional importance in locomotion.
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Related Practice
Textbook Question
Why do the three parts of the trapezius muscle have three different actions?
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Textbook Question
Explain why strengthening the levator ani muscle may help improve bladder and bowel continence (voluntary control over urination and defecation).
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Textbook Question
Ms. Cho presents with muscle pain in the area around her anterior neck and superior chest. She explains that she has had a respiratory infection over the past 2 weeks that made it hard for her to breathe. What is likely causing her muscle soreness? (Hint: Remember that the origin and insertion of some muscles can switch and that one likely has to breathe more deeply with a respiratory infection.)
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Textbook Question
Elise is a competitive gymnast who strained muscles in her left lower limb doing a tumbling pass. She has pain with extension of her leg and inversion of her foot. Which muscles did she potentially strain?
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Textbook Question
Chris is training for his black belt in karate and is working on developing a stronger punch. Which muscles do you recommend that he strengthen to improve his punch? Explain.
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