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Questions and Answers
Which type of muscle tissue is under voluntary control?
Which type of muscle tissue is under voluntary control?
What is one function of the muscles?
What is one function of the muscles?
What surrounds individual muscle fibers in skeletal muscle?
What surrounds individual muscle fibers in skeletal muscle?
Which muscle assists in raising the eyelid?
Which muscle assists in raising the eyelid?
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What is the primary role of myoglobin in skeletal muscle fibers?
What is the primary role of myoglobin in skeletal muscle fibers?
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What is the main function of the trapezius muscle?
What is the main function of the trapezius muscle?
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Which of the following is NOT a function of muscles?
Which of the following is NOT a function of muscles?
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Which muscle is responsible for closing the eye?
Which muscle is responsible for closing the eye?
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What is the primary function of the external intercostal muscles?
What is the primary function of the external intercostal muscles?
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Which muscle contributes to both urinary and fecal continence?
Which muscle contributes to both urinary and fecal continence?
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Which part of the deltoid muscle is responsible for arm abduction?
Which part of the deltoid muscle is responsible for arm abduction?
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What is the main role of the internal intercostal muscles during respiration?
What is the main role of the internal intercostal muscles during respiration?
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Which muscle lies on the anterior aspect of the upper arm and assists with flexion?
Which muscle lies on the anterior aspect of the upper arm and assists with flexion?
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Which pelvic floor muscle helps facilitate the passage of the baby during childbirth?
Which pelvic floor muscle helps facilitate the passage of the baby during childbirth?
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Which muscle helps extend the elbow joint?
Which muscle helps extend the elbow joint?
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What does the coccygeus muscle help to form in the pelvic floor?
What does the coccygeus muscle help to form in the pelvic floor?
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What is the primary function of the quadratus lumborum muscle?
What is the primary function of the quadratus lumborum muscle?
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Which muscle is referred to as the ‘six-pack’ muscle?
Which muscle is referred to as the ‘six-pack’ muscle?
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Where does the latissimus dorsi muscle originate?
Where does the latissimus dorsi muscle originate?
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Which of the following muscles helps to provide a stable base for lifting and twisting?
Which of the following muscles helps to provide a stable base for lifting and twisting?
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What action do the oblique muscles perform when only one side contracts?
What action do the oblique muscles perform when only one side contracts?
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What distinguishes the internal oblique muscle from the external oblique?
What distinguishes the internal oblique muscle from the external oblique?
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What muscle lies between the spinous and transverse processes of the vertebrae?
What muscle lies between the spinous and transverse processes of the vertebrae?
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Which function is NOT associated with the muscles of the anterior abdominal wall?
Which function is NOT associated with the muscles of the anterior abdominal wall?
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Study Notes
Muscular System Overview
- The muscular system is composed of specialized contractile cells called muscle fibers.
- There are three types of muscle tissue: smooth, cardiac, and skeletal.
- Skeletal muscles are attached to bones via tendons and are responsible for moving the skeleton.
- Skeletal muscles fatigue more quickly than other muscle types.
- Skeletal muscles play a crucial role in voluntary movement.
Skeletal Muscle Structure
- Epimysium: Surrounds the entire muscle.
- Perimysium: Surrounds bundles of muscle fibers (fascicles).
- Endomysium: Surrounds individual muscle fibers.
- Muscle fibers: Are cylindrical in shape and lie parallel to each other.
- Mitochondria: Abundant in skeletal muscle fibers, essential for producing ATP from glucose, powering the contractile mechanism.
- Myoglobin: A specialized oxygen-binding protein that stores oxygen within the muscle.
- T-tubules: Extensions of the sarcolemma that transmit action potentials into the muscle fiber.
- Sarcoplasmic reticulum: Stores calcium ions, releasing them when an action potential arrives.
- Myofibrils: Long cylindrical structures within muscle fibers, composed of repeating units called sarcomeres.
Functions of Muscles
- Producing movement: Muscles generate force to move the body.
- Maintaining posture: Muscles support the body against gravity.
- Stabilizing joints: Maintaining joint alignment and preventing excessive movement.
- Generating heat: Heat is a byproduct of muscle metabolic activity.
Muscles of the Face
- Orbicularis oculi: Surrounds the eye, closes the eye, and can "screw up" the eyes when strongly contracted.
- Levator palpebrae superioris: Extends from the posterior part of the orbital cavity to the upper eyelid, raises the eyelid.
- Masseter: Draws the mandible up to the maxilla, closes the jaw, and exerts considerable pressure on food during chewing.
- Temporalis: Passes behind the zygomatic arch, inserting into the coronoid process of the mandible; closes the mouth and aids in chewing.
Muscles of the Neck
- Sternocleidomastoid: Assists in turning the head from side to side. When one side contracts, it draws the head towards the shoulder.
- Trapezius: Covers the shoulder and back of the neck, pulls the head backwards, squares the shoulders, and controls scapula movements when the shoulder joint is utilized.
Muscles of the Back
- Arrangement of back muscles: The muscles are arranged in the same way on both sides of the vertebral column.
- Latissimus dorsi: Originates from the lower thoracic and lumbar vertebrae and the iliac crest; adducts, medially rotates, and extends the arm.
- Teres major: Originates from the inferior angle of the scapula and connects to the humerus; extends, adducts, and medially rotates the arm.
- Quadratus lumborum: Starts from the hip bone, goes up beside the spine, and connects to the 12th rib; works with another muscle to help breathe and bend backward.
- Sacrospinalis (Erector spinae): Lie between spinous and transverse processes of vertebrae; extend the vertebral column.
Muscles of the Anterior Abdominal Wall
- Rectus abdominis: The most superficial muscle, curls the trunk, and supports the abdominal wall during straining, forced expiration, or defecation.
- External oblique: When contracted, helps twist the body, bend sideways, and support the abdomen.
- Internal oblique: Lies deep to the external oblique; when contracted, helps twist the body, bend sideways, and support the abdomen.
- Transversus abdominis: The deepest muscle of the abdominal wall; allows bending, twisting, and lifting, providing a stable base for the body; protects organs in place during activities like lifting, coughing, and breathing.
Muscles of the Thorax
- Intercostal muscles: Are deep muscles between ribs; external intercostals help raise the rib cage during inhalation, while internal intercostals depress the rib cage during forced exhalation.
Muscles of the Pelvic Floor
- Functions of pelvic floor muscles: Support pelvic organs and maintain continence (resistance to intra-pelvic pressure during urination and defecation).
- Organization of pelvic floor muscles: Divided into two identical halves that unite along the midline.
- Levator ani: A group of broad, flat muscles forming the anterior portion of the pelvic floor.
- Coccygeus: Completes pelvic floor formation; perforated in males by the urethra and anus, and in females by the urethra, vagina, and anus.
- Pelvic floor functions: Maintain continence; assist in childbirth.
Muscles of the Shoulder and Upper Limb
- Deltoid: Forms the fleshy contour of the shoulder; responsible for arm movement.
- Biceps brachii: Located on the anterior aspect of the upper arm; stabilizes and flexes the shoulder joint, aids in elbow flexion and supination.
- Triceps: Located on the posterior aspect of the humerus; stabilizes the shoulder joint, aids in adduction of the arm, and extends the elbow joint.
- Brachialis: Located on the anterior aspect of the upper arm, deep to the biceps; the main flexor of the elbow joint.
Muscles of the Hip and Lower Limb
- Quadriceps femoris: A group of four muscles on the front and sides of the thigh; rectus femoris flexes the hip joint; all four muscles extend the knee joint.
- Gluteal muscles: Gluteus maximus, medius, and minimus form the buttock; cause extension, abduction, and medial rotation of the hip joint.
- Hamstrings: Located on the posterior aspect of the thigh; include biceps femoris, semitendinosus, and semimembranosus muscles; flex the knee joint.
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Description
Explore the intricacies of the muscular system, its types, and the structural details of skeletal muscles. This quiz covers muscle fibers, their functions, and the connective tissues surrounding them. Test your knowledge on this essential body system.
