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326 > Muscles of the Thorax > Flashcards

Muscles of the Thorax Flashcards

1
Q

List the layers of the back muscles and the muscles that belong to each layer

A

Superficial (most superficial to deep): trapezius, latissimus dorsi, serratus posterior
- act largely on upper limb and ribs (serratus posterior only)

Intermediate (lateral to medial): iliocostalis, longissimus, spinalis

Deep: transversospinalis which encompasses the 3 deep muscles. Superficial to deep: semispinalis, multifidus, rotatores

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2
Q

What comprises the shoulder complex?

A

3 bony articulations and one physiological coupling

Bony articulations (synovial joints):
- Sternoclavicular joint
- Acromioclavicular joint
- Glenohumeral joint: ball and socket

Physiological coupling: scapulo-thoracic joint (depends on the SC and AC joints as well as muscles and bursae that separate them)
- Allows scapula to slide over thoracic cage

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3
Q

What muscles border the scapulothoracic joint?

A

Bordered by subscapularis posteriorly and serratus anterior anterior-medially

Scapulothoracic joint movements involve the subscapularis sliding over serratus anterior

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4
Q

Describe the 6 movements of the scapula

A
  • elevation
  • depression
  • retraction
  • protraction
  • medial rotation/downward rotation: inferior angle turns toward midline
  • lateral rotation/upward rotation: inferior angle turns away from midline
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5
Q

What muscles cause scapular elevation

A

Superior/descending portion of trapezius
Levator scapulae
Rhomboid major
Rhomboid minor

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6
Q

What muscles cause scapular depression

A

Inferior/ascending portion of trapezius
Pectoralis minor

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7
Q

What muscles cause scapular retraction

A

All parts of the trapezius
Rhomboid major
Rhomboid minor

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8
Q

What muscles cause scapular protraction

A

Pectoralis minor
Serratus anterior

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9
Q

What muscles cause medial rotation/ downward rotation of the scapulae

A

Levator scapulae
Rhomboid minor
Rhomboid major
Pectoralis minor

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10
Q

What muscles cause lateral rotation/ upward rotation of the scapulae

A

Superior/descending and inferior/ascending portion of trapezius
Serratus anterior

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11
Q

Trapezius
- origin
- insertion
- action
- innervation

A
  • origin:
    Superior/descending part: Superior nuchal line and external occipital
    protuberance

Middle part: Spinous
processes of T1-T4

Inferior/ascending part: Spinous processes of T5-T12

  • insertion:
    Superior part: Lateral third of clavicle

Middle part: Spine and acromion of scapula

Inferior part: Spine of scapula

  • action:
    all parts: retraction
    superior/inferior part: upward rotation of scapula
    superior part: scapular elevation
    inferior part: scapular depression
  • innervation: accessory nerve (CNXI)
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12
Q

Levator scapulae
- origin
- insertion
- action
- innervation

A
  • origin: Transverse processes of C1-C4
  • insertion: Medial border of the scapula
    (superior to the spine)
  • action:
    downward rotation of
    scapula, elevates scapula

if scapulae are fixed, levator scapulae will cause neck to flex laterally

  • innervation:
    dorsal scapular nerve
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13
Q

Rhomboid minor
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes of the C6-C7 (or C7-T1) vertebra
  • insertion: Medial border of the
    scapula (~at the level
    of the spine; superior to r. major)
  • action: Retraction, elevation and downward rotation of scapula
  • innervation: Dorsal scapular nerve
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14
Q

Rhomboid major
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes of the T2-T5
    vertebrae
  • insertion: Medial border of the
    scapula (below the
    spine; inferior to r.
    minor)
  • action: Retraction, elevation
    and downward
    rotation of scapula
  • innervation: Dorsal scapular nerve
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15
Q

Latissimus Dorsi
- origin
- insertion
- action
- innervation

A
  • origin: Spinous process of T7-T12,
    thoracolumbar fascia, iliac crest, ribs 9-12, inferior angle
    of scapula
  • insertion: Floor of intertubercular
    groove of humerus
  • action: Adduction, extension, medial rotation of humerus;

If humerus fixed: elevates the trunk (ex. pull-up);

moves trunk anteriorly (ex. cross-
country skiing)

  • innervation: Thoracodorsal nerve
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15
Q

Iliocostalis
- origin
- insertion
- action
- innervation

A
  • origin: Iliac crest, the sacrum, and the erector spinae
    aponeurosis
  • insertion: Angle of the ribs and the
    transverse processes of C4-C6
  • action: Extends and laterally flexes the spine
  • innervation: spinal nerves (many)
16
Q

Longissimus
- origin
- insertion
- action
- innervation

A
  • origin: Thoracolumbar fascia,
    sacrum, transverse processes of lumbar and thoracic vertebrae
  • insertion: Transverse processes of thoracic and cervical vertebrae, lower ribs (3-12)
  • action: Extends and laterally flexes the spine
  • innervation: Spinal nerves (many)
17
Q

Spinalis
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes of T11-L2
  • insertion: Dorsal spinous processes of
    T1-T8 (cervicis inserts higher on cervical vertebrae as well)
  • action: Extends and the spine; laterally flexes thoracic/cervical spine
  • innervation: Spinal nerves (many)

connect dorsal spinous processes with caudal origins and rostral insertions

17
Q

Serratus posterior superior
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes of C7-T3
  • insertion: Upper borders of ribs 2-5
  • action: Elevates ribs (contributes to inhalation); proprioception in posterior thoracic cage (contains high density of proprioceptors)
  • innervation: Intercostal nerves (many)
17
Q

Serratus posterior inferior
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes of T11-L2
  • insertion: Inferior borders of ribs 9-12
  • action: Depresses ribs (contributes to exhalation); proprioception in posterior thoracic cage (contains high density of proprioceptors)
  • innervation: Intercostal nerves (many)
18
Q

Multifidus
- origin
- insertion
- action
- innervation

A
  • origin: Sacrum and transverse processes of thoracic vertebra (+ articular processes of C4-C7)
  • insertion: Dorsal spinous processes of
    vertebrae superior to origin
  • action: Extends and laterally flexes the spine; also active in
    rotation and proprioceptive
    feedback; stabilizer of the vertebral column
  • innervation: Spinal nerves (many)

Multifidus: fibres are obliquely oriented;

19
Q

Splenius capitus and cervicis
- origin
- insertion
- action
- innervation

A
  • origin: Dorsal spinous processes C7-
    T3 (up to T6)
  • insertion: Mastoid
    process of the temporal bone (capitus); transverse
    processes of the superior cervical vertebrae (cervicis).
  • action: Extends,
    rotates, and
    laterally flexes
    the neck
  • innervation: Spinal nerves (cervical)
19
Q

Pectoralis major
- origin
- insertion
- action
- innervation

A
  • origin: Clavicular part: medial half of the clavicle;
    Sternal part: sternum and the costal cartilages of the 2nd to 7th ribs, aponeurosis of the external oblique
  • insertion: Lateral border of the
    intertubercular (bicipital) groove of the humerus
  • action:
    All fibres: horizontal
    flexion, adduction, medial rotation of humerus

Clavicular part: flexion of humerus

Sternal part: extension of
humerus (from flexed
position)

  • innervation: Lateral pectoral nerve (clavicular); Medial pectoral nerve
    (sternal)
20
Q

Pectoralis minor
- origin
- insertion
- action
- innervation

A
  • origin: body of ribs 3-5
  • insertion: coracoid process of scapula
  • action: Protracts, depresses and
    downwardly rotates
    scapula
  • innervation: Lateral and medial pectoral
    nerves (mostly the medial
    one)
21
Q

Serratus anterior
- origin
- insertion
- action
- innervation

A
  • origin: Body of ribs 1-9
  • insertion: Medial border of scapula, anterior side
  • action: Protracts, and upwardly rotates
    scapula
  • innervation: Long thoracic
    nerve
22
Q

Diaphragm
- origin
- insertion
- action
- innervation

A
  • origin: Lumbar vertebrae, ribs 7-12, and xiphoid process
  • insertion: All fibres converge to insert on a central tendon
  • action: Flattens in
    inhalation to
    increase volume of
    the thoracic cavity
    (when relaxes,
    decreases volume
    to promote
    exhalation)
  • innervation: Phrenic nerve
23
Q

External intercostals
- origin
- insertion
- action
- innervation

A
  • origin: Inferior border of the upper rib
  • insertion: Superior border of inferior rib
  • action: Elevates lower rib to promote
    inhalation during
    quiet breathing
  • innervation: Intercostal nerves
24
Q

Internal intercostals
- origin
- insertion
- action
- innervation

A
  • origin: superior border of the inferior rib
  • insertion: inferior border of superior rib
  • action: Depresses ribs during forced
    exhalation (not
    involved in quiet
    breathing)
  • innervation: Intercostal nerves
25
Q

Give the overall action of the erector spinae group

A

Bilateral contraction produces spinal extension
Unilateral contraction produces lateral flexion

26
Q

Identify the pectoralis major and its divisions

A
27
Q

Identify the pectoralis minor

A
28
Q

Identify the serratus anterior

A
29
Q

Identify intercostal muscles (all 3 layers)

A

326 (32 decks)

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