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EVERYTHING ELMHURST > Anatomy: Skeletal Muscles (Locations & Functions) > Flashcards

Anatomy: Skeletal Muscles (Locations & Functions) Flashcards

1
Q

Sarcolemma

A

Function: Encloses the muscle fiber and conducts action potentials.
Origin: Derived from the plasma membrane of muscle cells.
Location: Surrounds each muscle fiber (cell).

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2
Q

Sarcoplasm

A

Function: Site of metabolic processes and contains organelles and myofibrils.
Origin: The cytoplasm of muscle cells.
Location: Inside the muscle fiber.

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3
Q

Mitochondrion

A

Function: Produces ATP through aerobic respiration.
Origin: Organelle found in eukaryotic cells.
Location: Scattered throughout the sarcoplasm of muscle fibers.

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4
Q

Sarcoplasmic Reticulum

A

Function: Stores and releases calcium ions (Ca²⁺) during muscle contraction.
Origin: Specialized form of endoplasmic reticulum in muscle cells.
Location: Surrounds myofibrils within the muscle fiber.

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5
Q

Myofibril

A

Function: Contains the contractile elements (sarcomeres) responsible for muscle contraction.
Origin: Composed of myofilaments (actin and myosin).
Location: Runs parallel within the muscle fiber.

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6
Q

Nucleus

A

Function: Contains genetic material and regulates cellular activities, including protein synthesis.
Origin: Found in all eukaryotic cells.
Location: Typically located at the periphery of the muscle fiber.

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7
Q

Striation

A

Function: Indicates the organized arrangement of muscle fibers and contractile proteins.
Origin: Result of alternating thick (myosin) and thin (actin) filaments.
Location: Visible across myofibrils and muscle fibers under a microscope.

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8
Q

Triad

A

Function: Facilitates rapid transmission of action potentials and calcium release.
Origin: Formed by two terminal cisternae and one transverse tubule.
Location: At the junction of the A and I bands in the myofibrils.

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9
Q

Terminal Cisternae

A

Function: Stores calcium ions and releases them during muscle contraction.
Origin: Extensions of the sarcoplasmic reticulum.
Location: Flank the T-tubules in the triad structure.

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10
Q

Transverse Tubule (T-tubule)

A

Function: Transmits action potentials deep into the muscle fiber.
Origin: Extensions of the sarcolemma.
Location: Penetrates into the muscle fiber at the junction of the A and I bands.

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11
Q

Endomysium

A

Function: Surrounds and supports individual muscle fibers.
Origin: Layer of connective tissue.
Location: Within a muscle, surrounding each muscle fiber.

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12
Q

Perimysium

A

Function: Surrounds and organizes bundles of muscle fibers (fascicles).
Origin: Connective tissue layer.
Location: Between individual fascicles within a muscle.

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13
Q

Epimysium

A

Function: Surrounds the entire muscle, providing support and protection.
Origin: Outer layer of connective tissue.
Location: Envelops the entire muscle.

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14
Q

Fascicle

A

Function: A bundle of muscle fibers that allows for organized structure and efficient force generation.
Origin: Group of muscle fibers surrounded by perimysium.
Location: Found within a muscle, grouped together to form the muscle.

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15
Q

Synergist

A

Function/Action: Assists the prime mover (agonist) by providing additional force or by reducing undesirable movements.
Definition: A muscle that works together with another muscle to enhance its effect.
Example: The brachialis acts as a synergist to the biceps brachii during elbow flexion.

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16
Q

Fixator

A

Function/Action: Stabilizes the origin of the agonist so that it can act more efficiently.
Definition: A muscle that prevents unwanted movement at a joint.
Example: The rotator cuff muscles stabilize the shoulder during arm movements.

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17
Q

Antagonist

A

Function/Action: Opposes or reverses a particular movement of the agonist.
Definition: A muscle that acts in opposition to the agonist.
Example: The triceps brachii is an antagonist to the biceps brachii during elbow flexion

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18
Q

Agonist (Prime Mover)

A

Function/Action: The main muscle responsible for a specific movement.
Definition: A muscle that is primarily responsible for movement.
Example: The biceps brachii is the agonist during elbow flexion.

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19
Q

Epicranius (Occipitofrontalis)

A

Function/Action: Raises eyebrows and wrinkles the forehead.

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20
Q

Temporalis

A

Function/Action: Elevates and retracts the mandible (closes the jaw).
Origin: Temporal fossa.
Insertion: Coronoid process of the mandible.

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21
Q

Masseter

A

Function/Action: Elevates the mandible (primary muscle for jaw closure).
Origin: Zygomatic arch and maxilla.
Insertion: Angle and ramus of the mandible.

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22
Q

Frontalis (Frontal Belly of the epicranius)

A

Action: Elevates eyebrows, pullls scalp forward
Origin: Top of the forehead or forehead area. (cranial aponeurosis).
Insertion: Skin of eyebrows and root of the nose.

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23
Q

Orbicularis Oculi

A

Function/Action: Closes eyelids; enables blinking and squinting.
Origin: Frontal and maxillary bones.
Insertion: Skin of the eyelid.

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24
Q

Occipitalis (Occipital Belly)

A

Function: Pulls scalp backwards (raises eyebrows)
Origin: Occipital bone
Insertion: epicranial neurosis

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25
Q

Orbicularis Oris

A

Function/Action: Closes and protrudes lips (kissing muscle).
Origin: Indirectly from maxilla and mandible.
Insertion: Encircles mouth; inserts into the muscle and skin at the angles of the mouth.

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25
Q

Zygomaticus

A

Function/Action: Raises lateral corners of the mouth (smiling).
Origin: Zygomatic bone.
Insertion: Skin and muscle at the corner of the mouth.

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26
Q

Levator Anguli Oris

A

Function/Action: Elevates the angle of the mouth (smiling).
Origin: Maxilla.
Insertion: Lips

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27
Q

Buccinator

A

Function/Action: Compresses the cheek (as in whistling or sucking).
Origin: Molar region of maxilla and mandible.
Insertion: Cheeks

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28
Q

Risorius

A

Function/Action: Draws the corner of the lip laterally.
Origin: Fascia of masseter muscle.
Insertion: Skin at the corner of the mouth.

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29
Q

Depressor Labii Inferioris

A

Function/Action: Lowers the lower lip.
Origin: Mandible.
Insertion: Skin of lower lip.

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30
Q

Depressor Anguli Oris

A

Function/Action: Draws the corners of the mouth downward (frowning).
Origin: Mandible.
Insertion: Skin and muscle at the angle of the mouth.

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31
Q

Mentalis

A

Function/Action: Protrudes the lower lip and wrinkles the chin.
Origin: Mandible.
Insertion: Skin of the chin.

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32
Q

Thyrohyoid

A

Function/Action: Swallowing
Origin: Thyroid cartilage of the larynx.
Insertion: Hyoid bone.

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32
Q

Mylohyoid

A

Function/Action: Aids in swallowing, elevates the tongue, speech
Origin: Mylohyoid line of the mandible.
Insertion: Hyoid bone.

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33
Q

Sternohyoid

A

Function/Action: Depresses the hyoid bone after it has been elevated (RESETS the hyoid bone after swallowing or speech to prepare for next action).
Origin: Manubrium of the sternum
Insertion: Hyoid bone.

34
Q

Splenius Capitis

A

Function/Action: Extends or hyperextends the head; rotates and bends the head to the same side (helps in LOOKING up)
Origin: Spinous process of cervical
vertebrae
Insertion: Mastoid process of occipital bone.

35
Q

Sternocleidomastoid

A

Function/Action: Flexes the neck
Origin: Manubrium of the sternum and medial portion of the clavicle.
Insertion: mastoid process of temporal bone

36
Q

Scalenes

A

Function/Action: Flexes and rotates the neck.
Origin: Transverse processes of cervical vertebrae (C2-C7).
Insertion: First two ribs.

37
Q

Levator Scapulae

A

Function/Action: Elevates the scapula
Origin: Transverse processes of C1-C4.
Insertion: Superior Angle of Scapula

38
Q

Pectoralis Minor

A

Function/Action: Protract the scapula, raises the ribs
Origin: Anterior surfaces of ribs 3-5.
Insertion: Coracoid process of the scapula.

39
Q

Pectoralis Major

A

Function/Action: Flexes and rotates the humerus
Origin: Clavicle, sternum
Insertion: greater tubercle

40
Q

Serratus Anterior

A

Function/Action: Protracts scapula
Origin: ribs 1-9.
Insertion: medial border of the scapula.

41
Q

Intercostalis (Intercostal Muscles)

A

Function/Action: External intercostals elevate the ribs during inspiration; internal intercostals depress the ribs during forced expiration.
Origin: Inferior/Lower border of the rib above (for both external and internal intercostals).
Insertion: Superior border of the rib below.

42
Q

Rectus Abdominis

A

Function/Action: Flexes the vertebrae.
Origin: Pubic bones
Insertion: Costal Cartilage of inferior ribs

43
Q

Internal Oblique

A

Function/Action: Compresses abdominal contents, flexes and rotates the trunk.
Origin: Iliac Crest
Insertion: pubic bone, Inferior/last 3 ribs

44
Q

Transversus Abdominis

A

Function/Action: stabilizes the vertebrae and abdomin
Origin: Illiac crest
Insertion: Pubic Bone

45
Q

External Oblique

A

Function/Action: Compresses abdominal cavity, aids in trunk rotation and lateral flexion.
Origin: Inferior 8 ribs
Insertion: Illiac crest, pubic bone

46
Q

Infraspinatus

A

Function/Action: Rotates the humerus laterally; stabilizes the shoulder joint.
Origin: Infraspinous fossa
Insertion: Greater tubercle of the humerus.

46
Q

Trapezius

A

Function/Action: Elevates, retracts, rotates, and stabilizes the scapula; extends the neck.
Origin: Cervical Vertebrae
Insertion: Spine of the scapula

47
Q

Supraspinatus

A

Function/Action: Abducts the arm; stabilizes the shoulder joint.
Origin: Supraspinous fossa of the scapula.
Insertion: Greater tubercle of the humerus.

48
Q

Subscapularis

A

Function/Action: Medially rotates the humerus.
Origin: Subscapular fossa of the scapula.
Insertion: Lesser tubercle of the humerus.

49
Q

Teres Major

A

Function/Action: Extends, adducts, and medially rotates the humerus.
Origin: Posterior inferior scapula
Insertion: Intertubercular sulcus of the humerus.

50
Q

Rhomboid Major

A

Function/Action: Retracts the scapula
Origin: Spinous processes of T2-T5.
Insertion: Medial border of the scapula.

51
Q

Latissimus Dorsi

A

Function/Action: Extends, adducts, and medially rotates the humerus.
Origin: Inferior Thoracic vertabrae & Lumbar Vertabrae
Insertion: Bicipital groove of the humerus.

52
Q

Deltoid

A

Function/Action: Abducts, flexes, and extends the arm.
Origin: Lateral clavicle, and scapula
Insertion: Deltoid tuberosity of the humerus.

53
Q

Triceps Brachii

A

Function/Action: Extends the forearm; the long head also aids in adducting the shoulder.
Origin: Posterior shaft of humerus
Insertion: Olecranon process

54
Q

Biceps Brachii

A

Function/Action: Flexes the forearm and supinates the forearm.
Origin: Short head - coracoid process of the scapula; long head - supraglenoid tubercle of the scapula.
Insertion: Radial tuberosity

55
Q

Pronator Teres

A

Function/Action: Pronates the forearm and assists in flexion of the elbow.
Origin: Medial epicondyle of the humerus and coronoid process of the ulna.
Insertion: Lateral radius

55
Q

Brachialis

A

Function/Action: Primary flexor of the forearm.
Origin: Diaphysis of humerus
Insertion: Coronoid process of the ulna.

56
Q

Supinator

A

Function/Action: Supinates the forearm.
Origin: Lateral epicondyle of the humerus and proximal ulna.
Insertion: Proximal end of the radius.

57
Q

Brachioradialis

A

Function/Action: Flexes the forearm, especially in a mid-pronated position.
Origin: distal humerus
Insertion: Distal radius.

58
Q

Flexor Carpi Radialis

A

Function/Action: Flexes wrist and hand
Origin: Medial epicondyle of the humerus.
Insertion: Metacarpals 2 & 3

59
Q

Flexor Carpi Ulnaris

A

Function/Action: Flexes and ADDUCTS the wrist/hand.
Origin: Medial epicondyle of the humerus
Insertion: 5th metacarpal

60
Q

Palmaris Longus

A

Function/Action: Flexes the wrist and tenses the palm.
Origin: Medial epicondyle of the humerus.
Insertion: Connective tissue in palm of hand

61
Q

Extensor Carpi Radialis Longus

A

Function/Action: Extends and abducts the wrist/hand.
Origin: lateral lower diaphysis of humerus
Insertion: Base of the second metacarpal.

61
Q

Flexor Digitorum Superficialis

A

Function/Action: flexes digits and hand
Origin: Medial epicondyle of the humerus
Insertion: Middle phalanges of fingers 2-5.

61
Q

Extensor Carpi Ulnaris

A

Function/Action: Extends and adducts the wrist.
Origin: Lateral epicondyle of the humerus
Insertion: Base of the fifth metacarpal.

62
Q

Extensor Digitorum

A

Function/Action: extends digits and hand
Origin: Lateral epicondyle of the humerus.
Insertion: phalanges 2-5

63
Q

Piriformis

A

Function/Action: Laterally rotates and abducts the thigh.
Origin: Anterior surface of the sacrum.
Insertion: Greater trochanter of the femur.

64
Q

Tensor Fascia Lata

A

Function/Action: Abducts, flexes, and medially rotates the thigh; tenses the iliotibial band, stabilizing the knee.
Origin: Iliac crest
Insertion: (IT band).

65
Q

Gluteus Maximus

A

Function/Action: Extends and laterally rotates the thigh; assists in thigh abduction.
Origin: Dorsal ilium, sacrum, and coccyx.
Insertion: Gluteal tuberosity of the femur and iliotibial tract.

66
Q

Biceps Femoris (Hamstrings)

A

Function/Action: Extends the thigh, flexes the knee, and laterally rotates the leg when the knee is flexed.
Origin: distal half of femur
Insertion: Head of the fibula

67
Q

Semitendinosus

A

Function/Action: Extends the thigh, flexes the knee, and medially rotates the leg when the knee is flexed.
Origin: Ischial tuberosity.
Insertion: Medial surface of the proximal tibia.

68
Q

Adductor Longus

A

Function/Action: Adducts, flexes, and medially rotates the thigh.
Origin: body of pubis
Insertion: Linea aspera of the femur.

68
Q

Semimembranosus

A

Function/Action: Extends the thigh, flexes the knee, and medially rotates the leg when the knee is flexed.
Origin: Ischial tuberosity.
Insertion: Medial condyle of the tibia.

68
Q

Pectineus

A

Function/Action: Adducts and flexes the thigh; assists in medial rotation.
Origin: Superior ramus of the pubis.
Insertion: posterior femur

69
Q

Gracilis

A

Function/Action: Adducts the thigh, flexes, and medially rotates the leg.
Origin: Inferior ramus and body of the pubis.
Insertion: Medial surface of the tibia just below the condyle.

69
Q

Sartorius

A

Function/Action: Flexes, abducts, and laterally rotates the thigh; flexes the knee.
Origin: Anterior superior iliac spine.
Insertion: Medial aspect of the proximal tibia.

70
Q

Rectus Femoris

A

Function/Action: Extends the knee and flexes the thigh at the hip.
Origin: Anterior inferior iliac spine and superior margin of the acetabulum.
Insertion: Patella and tibial tuberosity via the patellar ligament.

71
Q

Vastus Intermedius

A

Function/Action: Extends the knee.
Origin: Anterior and lateral surfaces of the proximal femur shaft.
Insertion: Patella and tibial tuberosity via the patellar ligament.

71
Q

Fibularis Longus (Peroneus Longus)

A

Function/Action: Everts and plantarflexes the foot.
Origin: Head and upper lateral fibula.
Insertion: Base of the first metatarsal and medial cuneiform.

71
Q

Vastus Medialis

A

Function/Action: Extends the knee.
Origin: Linea aspera, intertrochanteric line, and medial supracondylar line of the femur.
Insertion: Patella and tibial tuberosity via the patellar ligament.

71
Q

Vastus Lateralis

A

Function/Action: Extends the knee.
Origin: Greater trochanter, intertrochanteric line, and linea aspera of the femur.
Insertion: Patella and tibial tuberosity via the patellar ligament.

72
Q

Tibialis Anterior

A

Function/Action: Dorsiflexes and inverts the foot.
Origin: Lateral condyle and upper shaft of the tibia.
Insertion: First metatarsal and medial cuneiform.

72
Q

Extensor Digitorum Longus

A

Function/Action: Extends toes 2-5 and dorsiflexes the foot.
Origin: Lateral condyle of the tibia
Insertion: Phalanges 2-5

73
Q

Gastrocnemius

A

Function/Action: Plantarflexes the foot and flexes the knee.
Origin: Lateral and medial condyles of the femur.
Insertion: calcaneous

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