lecture 13 Flashcards
chest arm and shoulder
Describe the vascular and nervous structures located deep to the pectoralis minor and give the clinical significance of this anatomical relationship.
(1) axillary artery and brachial plexus just deep to pectoralis minor
(2) tight pectoralis minor causes constriction of neurovasculature and restricts chest expansion
list the four muscles of the brachium. give the origin, insertion and major action of each.
biceps brachii, coracobrachialis, brachialis, triceps brachii
what are the four joints of the pectoral girdle?
sternoclavicular joint, acromioclavicular joint, glenohumeral joint, scapulothoracic joint
describe the sternoclavicular joint
synovial joint between the medial end of the clavicle and the manubrium of the sternum
describe the acromioclavicular joint
synovial type joint between lateral portion of the clavicle and the acromion of the scapula
describe the glenohumeral joint
ball and socket articulation between head of humerus and glenoid cavity» favors mobility over stability
describe scapulothoracic joint
scapula suspended on rib cage by muscles»_space; highly mobile and movements increase range of motion at the shoulder joint
Distinguish anatomically between a dislocated and a separated shoulder
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
what stabilizes the sternoclavicular joint?
stability provided by substantial ligaments and so dislocation seldom occurs
what is the movement of the sternoclavicular joint?
allows significant movement in abduction and in and anterior/posterior plane
the sternoclavicular joint is prone to dislocation, T/F?
F
what is the sternoclavicular joint primarily due to?
the scapula
what movement does the acromioclavicular joint provide?
a point of axis for movement of the scapula
what ligaments stabilize the acromioclavicular joint?
acromioclavicular ligament and coracoclavicular ligament
what is torn when separated shoulder occurs?
tearing of the acromioclavicular and/or coracoclavicular ligaments
what does the clavicle do when separated shoulder occurs?
the clavicle overrides acromion
what is the effect of separated shoulder?
weight of upper limb pulls scapula and acromion inferiorly below clavicle
what are the structural components of the glenohumeral joint?
glenoid labrum, numerous bursa + tendinous sheaths, capsule
how is the glenohumeral joint stabilized?
coracoacromial ligament, coracohumeral ligament, transverse humeral ligament and the glenohumeral ligament
why is the coracoacromial ligament important in terms of stability?
it prevents superior dislocation of humerus
what is the importance of the glenohumeral ligament in terms of joint stability?
it consists of 3 parts (superior, middle, inferior) and is the primary source of placement holding
what are the active stabilizers of the shoulder joint throughout the entire range of motion
rotator cuff muscles
what do the rotator cuff muscles do?
a. depress head of humerus in glenoid cavity when humerus moves
b. prevents compression of structures between humeral head and acromion
when does the dislocation of shoulder occur?
when humerus is in position of abduction or flexion»_space; least amount of contact between opposing bony surfaces
how does the dislocation of the shoulder usually occur?
in an inferior direction which is the weakest region of the capsule
what is the effect on the humerus when the shoulder is dislocated?
humerus pulled either anterior to or posterior depending upon which rotator cuff muscles are injured
what is the appearance of the dislocated shoulder?
arm hangs limp at side with a prominent “step deformity” (space) between acromion and humeral head (now bony landmark)
what nerves are of concern when the shoulder is dislocated?
the axial nerve and radial nerve
what is impingement syndrome?
usually involves compression of supraspinatus tendon between head of humerus and acromion
what is the activity of the shoulder like with impingement syndrome?
intense pain through partial range of motion and results in weakness or fatigue of rotator cuff muscles
how is the scapulothoracic joint stabilized?
due to the action of the extrinsic muscles
what movements does the scapulothoracic joint enable?
elevation and depression, protraction (abduction) and retraction (adduction), upward rotation and downward rotation
what is the scapulohumeral rhythm? examples?
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
