lecture 13

Question 1

Describe the vascular and nervous structures located deep to the pectoralis minor and give the clinical significance of this anatomical relationship.

Answer 1

(1) axillary artery and brachial plexus just deep to pectoralis minor
(2) tight pectoralis minor causes constriction of neurovasculature and restricts chest expansion

Question 2

list the four muscles of the brachium. give the origin, insertion and major action of each.

Answer 2

biceps brachii, coracobrachialis, brachialis, triceps brachii

Question 3

what are the four joints of the pectoral girdle?

Answer 3

sternoclavicular joint, acromioclavicular joint, glenohumeral joint, scapulothoracic joint

Question 4

describe the sternoclavicular joint

Answer 4

synovial joint between the medial end of the clavicle and the manubrium of the sternum

Question 5

describe the acromioclavicular joint

Answer 5

synovial type joint between lateral portion of the clavicle and the acromion of the scapula

Question 6

describe the glenohumeral joint

Answer 6

ball and socket articulation between head of humerus and glenoid cavity» favors mobility over stability

Question 7

describe scapulothoracic joint

Answer 7

scapula suspended on rib cage by muscles&raquo_space; highly mobile and movements increase range of motion at the shoulder joint

Question 8

Distinguish anatomically between a dislocated and a separated shoulder

Answer 8

dislocation of shoulder - head of humerus subluxes from glenoid fossa due to weakness of rotator cuff tendons and/or trauma

separated shoulder -dislocation of acromioclavicular joint

Question 9

what stabilizes the sternoclavicular joint?

Answer 9

stability provided by substantial ligaments and so dislocation seldom occurs

Question 10

what is the movement of the sternoclavicular joint?

Answer 10

allows significant movement in abduction and in and anterior/posterior plane

Question 11

the sternoclavicular joint is prone to dislocation, T/F?

Answer 11

F

Question 12

what is the sternoclavicular joint primarily due to?

Answer 12

the scapula

Question 13

what movement does the acromioclavicular joint provide?

Answer 13

a point of axis for movement of the scapula

Question 14

what ligaments stabilize the acromioclavicular joint?

Answer 14

acromioclavicular ligament and coracoclavicular ligament

Question 15

what is torn when separated shoulder occurs?

Answer 15

tearing of the acromioclavicular and/or coracoclavicular ligaments

Question 16

what does the clavicle do when separated shoulder occurs?

Answer 16

the clavicle overrides acromion

Question 17

what is the effect of separated shoulder?

Answer 17

weight of upper limb pulls scapula and acromion inferiorly below clavicle

Question 18

what are the structural components of the glenohumeral joint?

Answer 18

glenoid labrum, numerous bursa + tendinous sheaths, capsule

Question 19

how is the glenohumeral joint stabilized?

Answer 19

coracoacromial ligament, coracohumeral ligament, transverse humeral ligament and the glenohumeral ligament

Question 20

why is the coracoacromial ligament important in terms of stability?

Answer 20

it prevents superior dislocation of humerus

Question 21

what is the importance of the glenohumeral ligament in terms of joint stability?

Answer 21

it consists of 3 parts (superior, middle, inferior) and is the primary source of placement holding

Question 22

what are the active stabilizers of the shoulder joint throughout the entire range of motion

Answer 22

rotator cuff muscles

Question 23

what do the rotator cuff muscles do?

Answer 23

a. depress head of humerus in glenoid cavity when humerus moves
b. prevents compression of structures between humeral head and acromion

Question 24

when does the dislocation of shoulder occur?

Answer 24

when humerus is in position of abduction or flexion&raquo_space; least amount of contact between opposing bony surfaces

Question 25

how does the dislocation of the shoulder usually occur?

Answer 25

in an inferior direction which is the weakest region of the capsule

Question 26

what is the effect on the humerus when the shoulder is dislocated?

Answer 26

humerus pulled either anterior to or posterior depending upon which rotator cuff muscles are injured

Question 27

what is the appearance of the dislocated shoulder?

Answer 27

arm hangs limp at side with a prominent “step deformity” (space) between acromion and humeral head (now bony landmark)

Question 28

what nerves are of concern when the shoulder is dislocated?

Answer 28

the axial nerve and radial nerve

Question 29

what is impingement syndrome?

Answer 29

usually involves compression of supraspinatus tendon between head of humerus and acromion

Question 30

what is the activity of the shoulder like with impingement syndrome?

Answer 30

intense pain through partial range of motion and results in weakness or fatigue of rotator cuff muscles

Question 31

how is the scapulothoracic joint stabilized?

Answer 31

due to the action of the extrinsic muscles

Question 32

what movements does the scapulothoracic joint enable?

Answer 32

elevation and depression, protraction (abduction) and retraction (adduction), upward rotation and downward rotation

Question 33

what is the scapulohumeral rhythm? examples?

Answer 33

abduction of humerus;

1) 0-15o by supraspinatus
(2) 15-90o by deltoid
(3) 90-180o by deltoid (2/3) and upward rotation of scapula (1/3