Chapter 69 - Anatomy of the Shoulder, Arm, and Elbow

Question 1

what is the first bone in the body to ossify?

Answer 1

clavicle - 5th week of gestation

it is also the last bone in the body to fuse at like 25 yo

Question 2

what is the only long bone to ossify via intramembranous ossification?

Answer 2

clavicle

intramembranous ossification occurs without a cartilage precursor

Question 3

normal shoulder motion is what percentage glenohumeral vs scapulothoracic

Answer 3

2/3 vs 1/3

Question 4

when does the scapular body ossify?

Answer 4

8th week of gestation

Question 5

three ossifications centers of the acromion

Answer 5

Meta (base)
meso (middle)
preacromion (tip)

Question 6

what attaches to the coracoid process?

Answer 6

• coracobrachialis
• short head of the biceps
• pectoralis minor inserts onto the base of the coracoid

Question 7

what is the average orientation of the glenoid?

Answer 7

5degrees retroverted

Question 8

average orientation of the humerus

Answer 8

19 degrees of retroversion, 41 degrees of inclination (neck-shaft angle)

Question 9

primary blood supply to the greater tuberosity

Answer 9

arcuate a via the ascending branch of the anterior humeral circumflex a

Question 10

primary blood supply to the humeral head

Answer 10

posterior circumflex humeral a (previously thought to be the ascending branch of the anterior circumflex humeral a)

Question 11

what are the primary SC joint stabilizers to AP translation?

Answer 11

posterior SC joint ligaments

Question 12

What are the primary SC joint stabilizers to superior/inferior translation?

Answer 12

anterior SC joint ligaments

Question 13

What ligaments are the primary restraints to AP translation of the AC joint

Answer 13

posterior and superior AC ligaments

Question 14

what ligaments are the primary restraints to vertical translation of the distal clavicle

Answer 14

coracoclavicular ligaments
- conoid medial
- trapezoid lateral

Question 15

rotator interval is composed of what?

Answer 15

base of coracoid medially
supraspinatus
subscap

contains: SGHL, Long head of the biceps

Question 16

what ligament is most active in the position of apprehension for anterior instability (90 abduction, ER)

Answer 16

anterior band of the inferior gleno humeral ligament

primary restraint to anterior-inferior dislocation

Question 17

role of the posterior band of the IGHL

Answer 17

primary static restraint against posterior inferior translation with the arm internally rotated and adducted

Question 18

long thoracic nerve palsy

Answer 18

results from axillary dissection or aggressive scalene retraction

-> serratus anterior palsy -> MEDIAL scapular winging (scapular elevstion with medial translation and medial rotation of the inferior pole of the scapula)

Question 19

spinal accessory nerve palsy

Answer 19

cranial nerve XI

from radical neck dissection or lymph node biopsy

-> trapezius palsy -> LATERAL scapular winging (scapular depression with lateral translation and lateral rotation of the inferior pole of the scapula)

Question 20

posterior approach to the shoulder

Answer 20

interval:
- teres minor: axillary n
- infraspinatus: suprascapular n

Question 21

what is buford complex

Answer 21

a cord like MGHL with a sublabral foramen anterosuperiorly just distal to the biceps insertion

Question 22

what is idiopathic osteonecrosis of the capitellum called?

Answer 22

Panner diesase

Question 23

Supinator crest

Answer 23

insertion point for the LUCL

on posterolateral ulna

and origin for supinator muscle

Question 24

sublime tubercle

Answer 24

insertion point for the anterior bundle of medial collateral ligament aka anteromedial facet of the coronoid

Question 25

Lateral collateral ligament of the elbow

Answer 25

primary restraint to varus force at the elbow

Question 26

lateral ulnar collateral ligament

Answer 26

primary restraint to posterolateral rotatory instability

Question 27

Medial collateral ligament - which band primarily resists valgus

Answer 27

anterior band

Question 28

medial collateral ligament - which band is most dominant in elbow contractures

Answer 28

posterior band also forms floor of cubital tunnel

Question 29

name the major arm nerves and the corresponding cords of the brachial plexus

Answer 29

axillay - posterior cord median - lateral and median cord musculocutaneous - lateral cord radial - posterior cord ulnar - meddial

Question 30

first motor branch of the ulnar nerve branches where?

Answer 30

distal to the. cubital tunnel branch to the FCU

Question 31

median nerve

Answer 31

is medial to the brachial artery lies anterior to the brachialis at the antecubital fossa

Question 32

where does the blood supply to the lateral condyle come from?

Answer 32

posterior

Question 33

what is the only direct source of oxygenated blood to the ulnar n proximal to the cubital tunnel?

Answer 33

inferior ulnar collateral a

Question 34

kocher approach

Answer 34

between anconeus (radial n) and extensor carpi ulnaris (PIN) preserve the LCL buy doing your arthroptomy above the equatorial line

Question 35

what percentage of an axial load goes through the radial head v the ulna

Answer 35

60% radiohumeral, 40% ulnohumeral

Question 36

most common neurologic complication of elbow arthroscopy?

Answer 36

ulnar nerve palsy

Question 37

dangers with proximal anterolateral portal

Answer 37

radial n

Question 38

dangers with proximal anteromedial portal?

Answer 38

medial antebrachial cutaneous n (medial cord, brachial plexus)

Question 39

what nerve lies close to the anterior capsule at the mis aspect of the radiocapitellar joint?

Answer 39

radial n

Question 40

where does the ulnar nerve lie in elbow arthroscopy?

Answer 40

directly superficial to the capsule in the posteriomedial gutter