lecture 3- muscles that move the scapula Flashcards

1
Q

what is the shoulder/ pectoral girdle?
features?
why do we care?

A

the shoulder girdle is the attachment point of the upper-limb to the axial skeleton
features: high mobility
why do we care? the shoulder girdle is a complex structure, efficient in the performance of many movements yet vulnerable to injury because of the many and varied stresses it encounters

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2
Q

joints/ articulations of the pectoral girdle 7

A

sternocostal
sternoclavicular
acromioclavicular
glenohumeral (shoulder joint)
costovertebral
Scapulothoracic
interclavicualr

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3
Q

joints

A

1acromioclavicular
2glenohumeral
3sternoclavicular

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4
Q

articulations

A

1vertebroclavicular
2vertbroscapular
3costoclavicular

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5
Q

joints

A

1.acromioclavicular
2.glenohumeral
3.sternoclavicular
4.sternocostal

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6
Q

articulations

A

1.vertebroclavicular
2.costoclavicular
3.costoscapular

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7
Q

sternoclavicular joint movement

A

synovial joint
movements:
-full elevation ~60 degrees
-anterior and posterior movement
-20-30 degrees occurs with protraction and retraction
-also allows for small amount of rotation

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8
Q

sternoclavicular joint: ligaments

A

interclavicular
-limits superior and lateral displacement of clavicle
costoclavicular
-main support limits all ROM except depression
sternoclavicular
-limits anterior and posterior glide of clavicle

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9
Q

acromioclavicular joint: movements

A

synovial place joint
serves as restriction to overhead movements
the motions of AC joint are described as scapular movement with respect to the clavicle
-upward/downward rotation at an axis directed perpendicular to the scapular plane facing interiorly and medially
-int and external rotation about an approximate vertical axis
-anterior/ posterior tripping or tilting about an axis directed laterally and anteriorly

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10
Q

acromioclavicular joint: ligaments

A

coracolavicular ligament
-conoid
-trapezoid
acromioclavicular ligament
-prevents separation of clavicle and scapula
-prevents posterior and anterior displacement
coracoacromical ligament
-forms roof over glenohumeral joint
-protection for bursa and suprapinatus tendon
-provides limit to superior humeral head

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11
Q

Scapulothoracic joint: scapula

A

physiologic articulation between the rib cage and the scapula

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12
Q

scapularthoacic joint: movements

A

physiology joint (not a typical articulation of bone to bone)
contains muscular and bursal structures to allow smooth movement
function- allows arm to abduct beyond the 120degree allowed by the glenohumeral joint alone (1 degree of scapular rotation for every 2 degrees of humeral abduction)
-movement in three directions
protraction & retraction (30-60)
superior & inferior rotation (60)
elevation &depression (30)

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13
Q

pectoral gridle: layout and movement

A

arm in anatomical position:
clavicle is 20-30 degrees posterior to frontal plane
scapula is oriented 35 degrees anterior to the frontal plane

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14
Q

protraction and retraction of the scapula

A

protraction:
-serratus anterior
-pectoralis major
-pectoralis minor
retraction:
-trapezius (middle part)
-rhomboids

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15
Q

serratus anterior: origin, insertion, action

A

origin: external surfaces of the lateral parts of ribs 1-8
insertion: anterior surfaces of the medial border of the scapula
action: Protracts the scapula and
holds it against the
thoracic wall; rotates the
scapula in an upward
direction

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16
Q

pectoralis major

A

Origin - Clavicular Head: Anterior surface of the medial half of the clavicle
Sternocostal head: anterior surface of the sternum, superior six costal cartlidges , aponeurosis of the
external oblique muscle.
Insertion - Lateral lip of the intertubercular groove
of the humerus .
Actions - Adducts and medially rotates the humerus; draws the scapula anteriorly and inferiorly. Acting alone the clavicular head flexes the humerus, and the sternocostal head will extend the humerus from a flexed position

17
Q

pectoralis minor

A

origin-ant. surface of ribs 3,4, &5
insertion- coracoid process of the scapula
action- anchors, depresses and protracts the scapula

18
Q

Middle Fibers of Trapezius

A

Origin: Spinous processes of the first-
fifth thoracic vertebrae.
* Insertion: Medial margin of the
acromion and superior lip of the spine of the scapula.
* Action: Retracts the scapula
* Innervation: Spinal Accessory
Nerves (CN XI)

19
Q

rhomboids major

A

origin: spinous processes of the thoracic vertebrae 2-5
insertion: by fibrous attachment to the medial border of the scapula between the spine and inferior angle
action: adducts and elevates the scapula

20
Q

what muscles elevate the scapula

A

levator scapula
trapezius
rhomboids

21
Q

upper fibers of the trapezius

A

Origin: External occipital
protuberance, medial 1/3 of the
superior nuchal line, ligamentum
nuchae and spinous process of the 7th
cervical vertebrae.
* Insertion: Lateral 1/3 of the of the
clavicle and acromion process of the
scapula.
* Action: Elevates the scapula
* Innervation: Spinal Accessory
Nerves (CN XI)

22
Q

levator scapula

A

Origin:
– Transverse processes of the first 4
cervical vertebrae.
* Insertion:
– Medial border of the scapula,
between the superior angle and the
root of the spine.
* Action:
– Elevates scapula and assists with
downward rotation of the scapula.
– Can also assist with lateral flexion of the c-spine (unilaterally) or extension of the c-spine (bilaterally), if the scapula is stabilized by other
muscles.
* Innervation:
– Cervical 3 & 4, and Dorsal Scapular
nerve (C4, C5)
Levator Scapulae

23
Q

what muscles would cause depression of the scapula

A

lower trapezius
subclavius
pectoralis minor
gravity

24
Q

lower trapezius

A

Origin: Spinous processes of the 6th-12th thoracic vertebrae.
* Insertion: Tubercle at the apex of the spine of the scapula.
Action: Depresses the scapula and
retracts scapula
* Innervation: Spinal Accessory
Nerves (CN XI)

25
Q

subclavius

A

Origin – Junction of 1st rib and its costal cartlidge
Insertion – Inferior surface of the middle third of the clavicle
Action – Anchors and depresses the scapula Innervation – Nerve to subclavius (C5, C6)

26
Q

what muscles rotate the scapula upward/downward?

A

upward: trapezius upper and lower fibers
serratus anterior
downward:
levator scapulae
rhomboids
pectoralis minor
gravity

27
Q

rhomboids minor

A

origin: ligamentous nuchal, spinous process of the 7th cervicle and 1st thoracic vertebrae
insertion: medial border of the scapula, at the root of the spine of the scapula
action: adducts and elevates scapula