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Anatomy > Lec 9 Pec Region and Shoulder > Flashcards

Lec 9 Pec Region and Shoulder Flashcards

1
Q

Origin of dermatomes and myotomes of the limbs

A

3rd week of embryogenesis

day 20 - mesoderm differentiation, types are close to neural tube

after day 20 - mesoderm differentiates into 44 pairs of somite’s which change into 31 sets to correspond with the 31 spinal nerves from neural tube

somites subdivide into sclerotome (precursor to cartilage and bone) and the DERMOMYOTOME which will divide into myotome and dermatome creating segmental innervation

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2
Q

When does segmental distribution of myotomes occur?

A

6 weeks (embryogenesis)

fusion of myotomes extending into the limbs produces skeletal muscles with multisegmented innervation

what does this indicate?
If c5 where to be damaged, other spinal nerves innervated that muscle (that had fused together) can take over the motion

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3
Q

What happens at the fourth week of development?

A

upper limb buds start to appear as elevations of the C5-T1

the tip of the arm bud (elevation) is called the apical ectodermal ridge; AER)

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4
Q

What emerges after the arm buds?

A

About one week after later (week 5) starting from cranial to caudal the lower limb buds appear L2-S2 segments

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5
Q

How are the limbs oriented during early development?

A

distal limb buds flatten into paddle-like hand and foot plates with thumb and great toe cranially and palms and soles anteriorly

flexures - limbs bend anteriorly, the elbow and knee are directed laterally, causing palm and sole to be directed toward the trunk

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6
Q

What happens at end of 7th week of development? (Limb development)

A

proximal parts of the upper and lower limbs undergo 90 degree torsion around their long axis in OPPOSITE directions

elbow becomes directed caudally (elbow points down)
and knee cranially (knee points up)

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7
Q

What happens to the lower limb in addition to proximal segment torsion? (where the knee goes cranially)

A

Permanent pronation (twisting) of the leg = foot becomes oriented with the great toe on the medial side

AKA rotates foot to be flat on floor, great toe is now medial whereas the thumb still remains lateral in anatomical position)

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8
Q

Describe the formation of the digits process

A

as elgonation continues, the mesenchyme condenses into plates forming the cartilaginous models of the future digital bones

the AER then breaks up and is maintained only over the tips of the future digits

interdigital spaces are progressively made via cellular apoptosis

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9
Q

Syndactyly

A
  • dactyly

represents fusion of two or more digits, can be isolated finding or part of a syndrome

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10
Q

Polydactyly

A

extra digits, typically occurs bilaterally

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11
Q

Macrodactyly

A

enlarged digits

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12
Q

Adactyly

A

absence of digits

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13
Q

Ectrodactyly

A

lobster claw deformity, typically missing middle digit, typically unilaterally

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14
Q

Amelia

A

complete absence of one or more extremities

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15
Q

Meromelia

A

partial absence of one or more extremities

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16
Q

Phocomelia

A

shortened lower extremities

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17
Q

Radial longitudinal deficiency

A

radius is shortened (underdeveloped or absent)

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18
Q

What is a Synovial Joint vs Fxnal Joint?

A

Synovial
- distal end of two bones articulate
- articular cartilage
- articular capsule (outer fibrous layer and inner synovial membrane with synovial fluid)

Functional joint;
- no joint cavity
- held together by soft tissue

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19
Q

What are the 4 joints of the upper extremity?

A

Glenohumeral Joint (synovial)

Acromial clavicular (synovial)

Sternoclavicular (synovial)

Scapulothoracic joint (FUNCTIONAL), scapular and rib cgaes and joining muscles

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20
Q

Where is the subacromial space located? What is its significance?

A

Located under the acromion process of scap (if looking laterally, it will be the big open space)

Contains rotator cuff ligaments
Biceps tendon
Glenohumeral ligament
Shoulder joint capsule
Bursa

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21
Q

Where is the spinoglenoid notch located?

A

laterally on the posterior aspect of the scapula, just below the spine of the scapula, and leads into the glenoid fossa

(passage for the suprascapular nerve and the suprascapular artery)

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22
Q

Which end of the clavicle is flat?

A

Sternal end is flat, has the sternal facet

Acromial end is not flat

Know the other bony landmarks for clavicle

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23
Q

What is special about the 5 terminal branches of the brachial plexus?

A

All 5 are muscle AND skin innervated

Not referring to dermatomes and myotomes here, those are spinal levels. We are looking at peripheral nerves

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24
Q

Which 3 muscles attach to the coracoid process

A

pec minor
biceps brachii
coracobrachialis

25
Q

What ligament keeps the biceps in their groove?

A

Transverse humeral ligament

runs between greater and lesser tubercles of humerus creating a “bridge” over a the bicipital (intertubercular) groove

biceps long head (tendon) runs through the groove and under the ligament

26
Q

What muscles of the brachium are tricarticulate?

A

long head of triceps

biceps long and short head

27
Q

Know slide 28 - Vascular
What are the parent structures for the right and left common carotid arteries? Subclavian?

A

R common carotid - brachiocephalic trunk
L common carotid - aorta

28
Q

What arteries come off of the subclavian and at what landmarks do they change ?

A

Subclavian - axillary - brachial - deep brachial

Axilary starts at lateral border of 1st rib

Brachial starts at inferior border of trees major

29
Q

What structures create the arterial anastomoses and what does this structure allow?

A

Network of arteries supply blood to back and shoulder
Dorsal scapular artery comes off subclavian, thoracodorsal artery, subscapular artery, posterior and anterior humeral circumflex

This structure allows blood to flow around the scapula into the scapular muscles even if one of the arteries is damaged, pinched or occluded this ensures that the muscles receive enough nutrients that the circulation is adequate

30
Q

What is the parent structure of the circumflex scapular branch of subscapular artery

A

Subscapular artery

31
Q

What does the subclavian vein break into?

A

Axillary (medial) and cephalic (lateral)

Axillary splits into brachial (lateral) and basilic (medial)

At the elbow (cubital fossa), the median cubital vein, which is a common site for venipuncture (drawing blood) connects cephalon and basilic

32
Q

Shoulder flexion movers GHJ

A

Prime: anterior deltoid, coracobrachialis

Secondary: pec major, long head biceps

33
Q

Horizontal abduction

A

Posterior delt, infraspinatus, trees minor, teres major

34
Q

Horizontal Adductors

A

Pec major both heads

Secondary: anterior delt, coracobrachialis

35
Q

What nerve can become impinged/entrapped at the top of the scapula? What ligament is involved?

A

Suprascalular nerve travels through supra scapular notch but NOT THE ARTERY

Nerve is held in place by superior transverse scapular ligament

Can occur because a thickened ligament

Common in athletes

Atrophy?

36
Q

What are the three types of acromion and the associated condition?

A

Flat, Curved and Hooked

Hooked acromion due to bone spurs developed or you can be born with it

It can squeeze the contents of the subacromial space (tendons and ligaments) and cause subacromial impingement

37
Q

What is the most commonly torn rotator cuff muscle?

A

Supraspinatus

38
Q

What are the three ways a RCT can occur?

A

Articular Side - underside where it would mee the greater tubercle is torn

Bursal Side tear - Top side is torn

Full thickness tear

39
Q

When is a Rotator Cuff Repair done?

A

If the edges of the tear can not be brought together, notch is creates in humerus just beneath articular surface to allow attachment of tendon through drill holes in bone using strong sutures

40
Q

What is the glenoid labrum and what does it do

A

Fibrocartilage O ring that deepens a shallow socket (for the GHJ joint)

Connected to the long head of biceps = “stem” of the pear shaped labrum

41
Q

What is a SLAP injury?

A

Superior Labrum anterior posterior

injured labrum

biceps pulls labrum off the bone

common in athletes

can begin as Long head of Biceps tendinitis and progress to SLAP

42
Q

Scapulohumeral Rhythm SHR

Joint movements

A

coordinated movement between the scapulothoracic joint and the glenohumeral joint during arm elevation

STJ upwardly rotates, protracted and posterior tilts

GHJ externally rotates for greater tubercle to clear the acromion

Clavicle elevates and rotates backwards

43
Q

SHR ratios

A

Early phase - initial 30 degrees of abduction is little to no ST motion

Mid phase (30-120) is 1:1 (so 90 degrees of motion, 45 is GHJ, 45 is STJ)

Late phase (120-180) is 2-3:1, so every 3 degrees GHJ, 1 degree STJ

The first 30 degrees of the ST ROM needs 30 degrees of clavicular elevation through A-P axis of SC joint

Second 30 degrees of ST ROM needs to have 50 degrees of clavicular rotation through longitudinal axis of clavicle at AC joint

44
Q

What ligaments exist in the GHJ capsule and what movements do they limit

A

Coracohumeral - greatest stiffness

Glenohumeral ligament

Superior GHL limits inferior translation and ER

Middle GHL limits anterior translation

Inferior GHL is the hammock

Redundant capsule

45
Q

At what angle is the GHJ capsule the tightest? What happens if the capsule is not tight?

A

90/90

Shoulder instability can result if the capsule is born loose or torn loose, becomes stretched out

46
Q

How and where does Bursa emerge?

A

The synovial membrane protrudes through aperture in fibrous membrane to form bursa, exists between tendons and fibrous membrane

Subacromial or subdeltoid bursa

If this becomes inflamed in can take up more space

47
Q

Sternoclavicular joint (type and degrees of freedom)

A

Synovial SADDLE

Head of clavicle with clavicular notch of manubrium

Contains a fibrocartilage disc

3 DF:
Elevation/depression
Protraction/retraction
Posterior/Anterior Rotation

48
Q

SCJ ligaments

A

Anterior and posterior SC ligament - checks excessive A/P motion

Costoclavicular ligament - checks clavicular elevation and superior glide

Interclavicular ligament - checks excessive depression/downward glide

Use names and locations to remember movements

49
Q

Acromioclavicular joint type and DF

A

Synovial plane joint

3 DF

weak joint capsule

50
Q

Coracoid ligaments

A

Coracoacromial ligament

Acromioclavicular ligament

Coracoclavicular ligmanets:
- trapezoid more lateral guides during rotation

  • conoid more medial prevents vertical displacement
51
Q

Separated shoulder

A

can fall and have;

dislocation of acromioclavicular joint without ligament rupture

dislocation of acromioclavicular joint AND rupture of coracoclavicular ligament

52
Q

Piano key

A

results from acromioclavicular injury where the clavicle pops up, you can push it back down but it will pop up again

instability of the ligament or injury

53
Q

Bankart injury

A

damage to the labrum with anterior shoulder dislocation

54
Q

Shoulder extension

A

Prime: posterior delt, lat, teres major

Secondary : pec major sternal head, long head triceps

55
Q

Shoulder abduction

A

Middle deltoid and supraspinatus

56
Q

Shoulder adduction

A

Lat, teres major, coracobrachialis, long head of triceps

57
Q

Shoulder ER and IR

A

ER: infraspinatus and teres minor

IR: lat, teres major, subscapularis, pec minor

58
Q

Shoulder ER and IR

A

ER: infraspinatus and teres minor

IR: lat, teres major, subscapularis, pec minor

Anatomy (23 decks)

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