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pectoral girdle Flashcards

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1
Q

what does the pectoral girdle include? what are its signature characteristics and the function of these? where does it get support and stabilization?

A

clavicle and scapula in an incomplete ring (open posteriorly) to allow mobility +independent motion
-support and stabilization by axio-appendicular muscles

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2
Q

what is the sternoclavicular joint?

A

single articulation between the pectoral girdle and the axial skeleton. (scapula has no articulation w/ axial- only attached via muscles)

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3
Q

what are the 3 chief characteristics of the clavicle? expand on each.

A
  1. Elongated S shape
    - -Convex medially (curve protudes anteriorly)
    - -Concave laterally
  2. Enlarged sternal (medial) end
    - -Articulates with manubrium
    - -Sternoclavicular joint (SC)
  3. Flattened acromial (lateral) end
    - -Articulates with acromion process
    - -Acromioclavicular joint (AC)
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4
Q

when someone falls on an outstretched arm, where are they likely to have a fracture/break?

A

weak points: clavicle or wrist

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5
Q

when people fall on their shoulder, where will they have a fracture/break? why?

A

clavicle - it transmits force from the upper limb to the axial skeleton

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6
Q

what are the movements of the clavicle?

A

swinging strut, suspends scapula at corcacoid process . Allows scapula to “glide” on the thoracic wall (scapulothoracic joint)

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7
Q

what movements can the scapula do at the scapulothoracic joint?

A

elevation/depression
protraction/retraction
upward rotation/downward rotation

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8
Q

characteristics of scapula structure? Think medial/lateral, anterior/posterior, superior/inferior

A

Medial, lateral, superior borders
–Suprascapular notch
–Superior transverse scapular ligament
Superior, lateral, inferior angles

Posterior surface divided by spine
--Supraspinous fossa (above spine)
--Infraspinous fossa (below spine)
Acromion- lateral end of spine 
--Acromioclavicular (AC) joint

Anterior subscapular fossa: indented region
Coracoid process- looks like little thumb
–Coracoclavicular ligament
Lateral surface bears glenoid fossa
–“Socket” for much larger humeral head

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9
Q

what two features create a foramen on the superior border of the scapula?

A

suprascapular notch and superior transverse scapular ligament

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10
Q

how does the acromion project?

A

anterior and laterally

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11
Q

where is the weight of the scapula and upper limb suspended?

A

center of balance: the strong coracoclavicular ligament- which is attached to the coracoid process on the anterior surface of scapula

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12
Q

how does the scapula and humerus counterbalance each other?

A

the balance of the coracoclavicular ligament but also the pull of the rhomboids against the weight of the limb.

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13
Q

posterior axio-appendicular muscles…O,I,A? What do they include?

A

Originate on axial skeleton
Insert on appendicular skeleton
Move or stabilize pectoral girdle and/or humerus
includes: superficial and deep extrinsic shoulder muscles

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14
Q

superficial extrinsic shoulder muscles

A

trapezius and lat. dorsi

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15
Q

deep extrinsic shoulder muscles

A

rhomboids (major and minor) + levator scapulae

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16
Q

scapulohumeral muscles: O,I,A. which muscles are included?

A

the intrinsic should muscles. O&I on appendicular skeleton. predominantly O on scapula and I on humerus

Act: on glenohumeral (shoulder) joint

  • Deltoid
  • teres major
  • rotator cuff group
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17
Q

what muscles are in the rotator cuff group?

A 
"SITS"
supraspinatus
infraspinatus
teres minor
subscapularis
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18
Q

Deltoid features, O,I,A, Innerv.?

A

inverted triangle: anterior, middle, and posterior portions
O- lateral third clavicle, acromion, lateral scapular spine
I-deltoid tuberosity (prominence on humerus)
A-abducts arm after 15degrees
–anterior: flexes
–posterior:extends (when adducted)
innveration:axillary nerve C5, C6 - terminal branch of brachial plexus

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19
Q

what abducts arm the first 15degrees?

A

supraspinatus

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20
Q

Teres Major:general location, O,I,A, Innerv.

A

Forms posterior lateral boundary of axilla, runs very close to latissimus dorsi.
O-posterior surface of inferior scapular angle
I-intertubercular groove of humerus (posteromedial to latissimus dorsi)
Adducts & medially rotates arm
Innervated by lower subscapular nerve (C5, C6)
–(Collateral/preterminal branch of brachial plexus)
NOT THORACODORSAL NERVE

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21
Q

what does “teres” mean?

A

“round” - cylindrical shape of muscle

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22
Q

what type of baseball pitch would the teres major help in?

A

screwball, medial/internal rotation

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23
Q

which muscle is not part of the rotator cuff group but does serve to rotate the humerus?

24
Q

what do the rotator cuff muscles do?

Study These Flashcards
A

all 4 form a tendinous cuff around glenohumeral joint that stabilizes the oversized humeral head into undersized glenoid fossa - think of thumb and first three finger grabbing onto humeral- they form “ the cuff “

  • -3 of the 4 serve to rotate the humerus. (supra only ABducts)
  • -4 muscles provide tendinous support- support on all sides except inferiorly - plays a role in shoulder dislocation
25
what are the placement of the rotator cuff muscles in the finger model?
holding the head of the humerus with the palm as the glenoid fossa thumb: subascapularis pointer: supraspinatus middle: infraspinatus ring: teres minor
26
supraspinatus: O,I,A, Inner,Blood?
``` O-supraspinous fossa I-greater tubercle (superior portion) A: First 15° abduction of arm Innervated: suprascapular nerve (C4-6) ---Collateral/preterminal branch of brachial plexus -blood: suprascapular artery ```
27
what is the general location of the supraspinatus?
passes under the acromion and under the acromion ligament "bridge"
28
infraspinatus: O,I,A, blood?
O-infraspinous fossa of scapula I-greater tubercle of humerus (posterior portion) A: Laterally rotates arm Innervated: suprascapular nerve (C5-6) ----Collateral/preterminal branch of brachial plexus blood: suprascapular artery
29
what muscle aids in the curveball pitch?
infraspinatus (lateral rotation)
30
suprascapular nerve and artery: general location
both originate in neck go into the pectorogirdle region
31
suprascapular artery: originates where? goes where? supplies what?
-O: thyrocervical trunk "army": Passes OVER superior transverse scapular ligament Passes deep to acromion -Forms scapular anastomoses with intercostal arteries (backup if occlusion of vessel occurs) -supplies both spinatus muscles
32
suprascapular nerve:
O:superior trunk of brachial plexus "navy":Passes UNDER superior transverse scapular ligament -Passes deep to acromion- through the suprascapular notch/ "foramen" -Innervates supraspinatus & infraspinatus
33
Teres minor: O,I,A, Inner.?
O-lateral border of scapula (mid-portion) I-greater tubercle of humerus (posterior portion) Laterally rotates arm Innervated by axillary nerve (C5-6) --Terminal branch of brachial plexus
34
what muscle does the teres minor often blend with?
infraspinatus
35
what nerve serves both the teres minor and deltoid?
axillary C5,C6
36
subscapularis: O,I,A, Innerv?
O-anterior surface of scapula I-lesser tubercle of humerus Forms portion of posterior wall of axilla A: Medially rotates arm (screwball), anterior support Innervated: upper & lower subscapular nerves (C5-7) --Collateral branches of brachial plexus
37
which muscle of pectoral girdle will we not see in lab b/c it is located on the anterior surface of the scapula?
subscapularis - occupies subscapular foss | - we will see serratus anterior
38
what makes up the quadriangular space?
``` -Communicate with axilla S-inferior border of teres minor L-surgical neck of humerus I-superior border of teres major M-lateral border of long head of triceps brachii ```
39
what muscle bisects the teres major from minor?
longhead of the triceps brachii | major is anterior to it, minor is posterior
40
what nerve and artery pass through the quadriangular space?
Axillary nerve & posterior circumflex humeral artery (brachial plexus) pass through here
41
what makes up the triangular space ?
communicate w/ axilla S-inferior border of teres minor L-medial border of long head of triceps brachii I-superior border of teres major
42
what artery goes through the triangular space?
Circumflex scapular artery (branch of subscapular)
43
longhead of the triceps: anterior and posterior to what? originates where? what does it separate?
Separates two spaces: quadrangular from triangular O: at inferior glenoid tubercle Anterior to teres minor Posterior to teres major
44
triangular interval
S-inferior border of teres major M-lateral border of long head of triceps brachii L-medial border of lateral head of triceps brachii Radial nerve & profunda (deep as in "profoundly deep person" brachii artery --Both course in radial (spiral) groove
45
what is the largest branch of the brachial plexus?
radial nerve
46
structures that cross triangular interval..pass in what way?
pass in radial/spiral groove of humerus - an oblique/diagonal groove - nerve passes in this - groove spirals to lateral aspect of humerus and we see nerve there again. important landmark in understanding triceps muscle
47
anterior and posterior compartments of the arm- muscles and nerves
Anterior - -Flexors of forearm & arm (biceps brachii, brachialis, coracobrachialis) - -Musculocutaneous nerve (term branch of brachial plexus) Posterior - -Extensors of forearm- (triceps brachii) - -Radial nerve
48
Triceps Brachii: O,I,A, Innerv?
Long, lateral, & medial heads O-inferior lip of glenoid fossa (long head); posterior humerus, above radial groove (lateral head); posterior humerus, below radial groove (medial head) I-olecranon process (of ulna) A:Extends forearm, long head also extends & adducts arm (b/c it crosses the shoulder joint) Innervated by radial nerve (C6-C8)
49
what are the variances in strength/activity of the different parts of triceps brachii?
Long head-least active Medial head-most active Lateral head-strongest, only used against resistance
50
anconeus: O,I,A, Innerv.?
small "cone" on the ulna, just distal from elbow joint O-lateral epicondyle of humerus I-lateral olecranon process & proximal ulna A: Assists in extension of forearm Innervated by radial nerve (C7-T1)
51
what are the three major clinical correlations we talk about with the rotator cuff/posterior arm?
axial nerve injury, rotator cuff injury, glenohumeral dislocations
52
4 Causes of axial nerve injury? What will result from this injury?
1. Surgical neck (of humerus) fractures: axillary nerve wraps around this part of the humerus 2. Glenohumeral dislocations 3. Improper crutch fitting/use: should be 2 inches below axillary floor 4. Improper IM injections: IM should be 2 fingerbreadths below acromion these can lead to: Deltoid atrophy & Lateral shoulder numbness
53
where is the surgical neck of the humerus?
just below tubercles
54
what causes Degenerative Tendonitis? what are the symptoms?
Repetitive/forceful use of upper limb above horizontal plane Supraspinatus tendon & humeral head grate on coracoacromial arch/"bridge"/ligament (Supraspinatus tendon relatively avascular- doesnt heal well w/out blood supply) symptoms: Shoulder stiffness & Pain on initiating abduction or reaching behind back
55
what causes rotator cuff tear? what are the symptoms?
Usually supraspinatus tendon Usually preceded by degenerative tendinitis Fall on shoulder Forceful lifting motion symptoms: Unable to resist gravity from 90° abduction & Can’t initiate/maintain abduction
56
Glenohumeral Dislocation
joint: Highly mobile but unstable- head too big for socket and no inferior support cause: Forceful extension & lateral rotation MO: Nearly always inferior head of humerus displaces into Quadrangular space and pinches Axillary nerve Clinically described by location of dislocated humeral head - -either Anterior (pulled by pectoralis) or posterior (pulled by latissimus and teres major) to glenoid fossa - -Anterior most common (pectoralis is stronger so it Wins)
57
how are the radial and axillary nerves oriented in the arm?
posterior cord of brachial plexus comes under the lateral end of the clavicle, anteriorly into the glenohumeral( glenoid fossa/humerus) joint. just under the head of the humerus it branches laterally (axillary nerve) and wraps around humerus posterior then anteriorly. the larger part of the cord follows inferiorly (radial nerve) down the arm.

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