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Questions and Answers
What are synergists?
Muscles that assist the prime mover in accomplishing a movement.
What is the role of fixators?
To stabilize insertion points during a movement.
What is an agonist?
A muscle primarily responsible for an action; also known as the prime mover.
What is an antagonist?
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Which muscle is the prime mover for flexion of the elbow?
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The ______ is the point of attachment that does not move.
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The ______ muscles assist in swallowing and speech.
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The diaphragm is part of the anterior neck muscles.
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What are the functions of the muscles of the pelvic floor?
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Which muscle group is responsible for adducting the femur?
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Study Notes
Synergists and Fixators
- Synergists assist the prime mover in accomplishing a movement.
- Example: Brachioradialis and Brachialis during flexion of the elbow.
- Fixators stabilize the insertion points during a movement.
Interactions of Skeletal Muscles in the Body
- Muscles can have multiple attachment sites.
- Tendons attach muscle to bone.
- Tendons pull on the periosteum, causing the bone to move.
- Origin is the point of attachment that does not move.
- Insertion is the point of attachment that moves.
- Prime mover is the principal muscle involved in an action.
- Example: The biceps brachii is the prime mover for flexion of the elbow.
Agonists and Antagonists
- Agonist is primarily responsible for an action (prime mover).
- Antagonist produces the opposite movement of an agonist.
- Example: Triceps brachii is the antagonist of the biceps brachii.
Connective Tissue Wrapping of Skeletal Muscle
- Endomysium surrounds a single muscle fiber.
- Perimysium surrounds a fascicle (bundle) of fibers.
Patterns of Fascicle Organization
- Fascicle is a bundled group of muscle fibers.
- Surrounded by perimysium.
- Arrangement of fascicles influences force generated and range of motion of muscle.
Muscles of the Anterior Neck
- Assist in swallowing (deglutition) and speech.
- Suprahyoid muscles originate above the hyoid bone.
- Digastric, stylohyoid, mylohyoid, geniohyoid.
- Infrahyoid muscles originate below the hyoid bone.
- Omohyoid, sternohyoid, thyrohyoid, sternothyroid
Muscles That Move the Toes
- Sole is supported by the plantar aponeurosis.
- Dorsal group: Extensor digitorum brevis.
- Plantar group: Flexor digitorum brevis, abductor hallucis, abductor digiti minimi, quadratus plantae, lumbricals, flexor digiti minimi brevis, flexor hallucis brevis.
Shoulder Movements
- Retraction
- Protraction
- Flexion
- Extension
- Abduction
- Adduction
- Internal rotation
- External rotation
Characteristics Used to Name Skeletal Muscles
- Shape: Named for their resemblance to a shape.
- Size: Muscles in a group are sometimes named for their size relative to other muscles in the group.
- Location: Named for the region where they are located.
- Orientation of fibers: Orientation of muscle fibers and fascicles is used to describe some muscles.
Muscles of the Thorax
- Diaphragm divides abdominal and thoracic cavities.
- Major muscle involved in breathing.
- Intercostal muscles:
- External, internal, innermost.
- Located between ribs.
- Assist in breathing.
Muscles That Move the Feet
-
Posterior compartment: Plantar flexion of the foot.
- Gastrocnemius, soleus, plantaris, popliteus, flexor digitorum longus, flexor hallucis longus, tibialis posterior.
- Superficial muscles insert on the calcaneal tendon.
Thigh Muscles That Move the Femur, Tibia, and Fibula
-
Medial compartment: Adduct the femur.
- Adductor longus, adductor brevis, adductor magnus, pectineus, gracilis.
-
Anterior compartment: Flex thigh, extend knee.
- Quadriceps femoris = Rectus femoris, vastus lateralis, vastus medialis, vastus intermedius.
-
Posterior compartment: Extend thigh, flex knee.
- Hamstrings = Semitendinosus, semimembranosus, biceps femoris.
Muscles of the Pelvic Floor
- Pelvic diaphragm forms the base of the pelvic cavity.
- Levator ani
- Consists of pubococcygeus and iliococcygeus.
- Forms anal and urethral sphincters.
- Ischiococcygeus.
Muscles That Move the Tongue
- Aid in speech, mastication, and swallowing.
-
Extrinsic muscles: Originate outside of the tongue.
- Genioglossus, styloglossus, palatoglossus, hyoglossus.
- Intrinsic muscles: Originate inside the tongue.
Muscles That Move the Wrist, Hand, and Fingers
-
Superficial muscles:
- Anterior muscles—most cause flexion of the hand or fingers.
- Flexor carpi radialis, palmaris longus, flexor carpi ulnaris, flexor digitorum superficialis.
- Posterior muscles—most cause extension of the hand or fingers.
- Extensor radialis longus, extensor carpi radialis brevis, extensor digitorum, extensor digiti minimi, extensor carpi ulnaris.
- Anterior muscles—most cause flexion of the hand or fingers.
Muscles of the Posterior Neck and the Back
- Lateral flexion, extension, and rotation of the head.
- Splenius capitis, splenius cervicis.
- Extension of the vertebral column.
- Erector spinae group—Iliocostalis, longissimus, spinalis.
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Description
Test your knowledge on the roles of synergists, fixators, agonists, and antagonists in skeletal muscle movement. This quiz covers muscle attachments, movements, and connective tissue types, with examples to illustrate each concept. Enhance your understanding of how muscles work together in the body.
