Sievert: Shoulder, Pectoral Region, Axilla, Arm Flashcards
It is important to consider if a muscle is attaching close to or far away from a joint. If the muscle attaches close to a joint, will it provide speed or power? If a muscle attaches further from the joint, will it provide speed or power?
speed; power
It is important to understand how a muscle attaches relative to its axis of (blank)
rotation
The shoulder girdle, including the arm and the scapula, has only one bony attachment. What is it?
sternoclavicular joint
Why is it important for the inferior angle of the scapula to move laterally?
for full abduction of the arm
What is different between the superior surface and the inferior surface of the clavicle?
superior surface is smooth, while the inferior surface is rough for attachment of ligaments
This is the first bone to ossify and the last long bone to fuse
clavicle
Most long bones undergo endochondral ossification, in which they begin with a cartilage model before laying down bone. How is the clavicle an exception?
The clavicle undergoes membranous ossification
At what two joints does the clavicle articulate?
At the acromioclavicular joint
and the sternoclavicular joint
On what axis does the scapula protract and retract (move anteriorly and posteriorly)?
vertical axis
As you protract the clavicle, the scapula can undergo about (blank) degrees of gliding movement as the scapula glides along the posterior chest wall.
15 degrees
The position of the scapula on the chest wall requires some mobility at the (blank) joint
acromioclavicular joint
What is the main stabilization of the scapula?
acromioclavicular joint
When there is a blow to the clavicle, where does it usually occur?
usually fractures just proximal to the coracoclavicular ligaments - near the middle and lateral third of the clavicle
What is a ligament that goes between the coricoid process (bony protrusion of the scapula anteriorly) and the acromion?
coracoacromial ligament
This ligament forms a roof for the glenohumeral joint, and helps rest the head of the humerus when weight is borne on an extended arm
coracoacromial ligament
Can the AC joint separate without tearing the coracoacromial ligament?
Yes, a shoulder separation is when some laxity is created in the AC joint. Does not have to be a complete tear.
What is more serious? Separation of AC joint or shoulder dislocation?
Shoulder dislocation, because the head of the humerus is forced out of the glenoid fossa
When you dislocate a shoulder, in what direction does it generally occur?
inferiorly and anteriorly
When would a shoulder dislocation most likely occur?
When you are abducted, because the head of the humerus is rotated outward and is making little contact with the glenoid fossa. Very little of the articular joint is intact, so the join will be relatively unstable.
T/F: There is a lot of blood flow and innervation that pass through the area where a shoulder dislocation occurs, and these vessels can be damaged or compressed.
True
The sternoclavicular joint is a typical synovial joint with two exceptions. What is its disc made of?
has an articular disc with two synovial cavities; made of fibrocartilage
In general, the upper extremities are designed for (blank), while the lower extremities are designed for (blank)
speed; power
What two bones make up the shoulder girdle? Where do the two bones articulate
scapula; clavicle; at the acromion
When does the clavicle ossify? When does it fuse?
week 5-6; fuses at 25 years
Where is the only bony attachment of the upper limb to the axial skeleton?
at the sternum
Two important ligaments of the shoulder
coracoclavicular ligament
coracoacromial ligament
Shoulder separation occurs at the (blank) joint, while shoulder dislocation occurs at the (blank) joint.
AC joint; glenohumeral joint
On what axis does the sternoclavicular joint protract and retract? Elevate and depress? Rotate medially and laterally?
vertical; AP; oblique
Movement of the inferior angle of the scapula medially or laterally
medial/lateral rotation
What portion of the abduction of the shoulder takes place at the glenohumeral joint? What portion takes place at the sternoclavicular joint? What is this combination of movements called?
120 degrees; 60 degrees; scapulohumeral rhythm
During abduction of the arm, you can only get 120 degrees of rotation at the glenohumeral joint. What is this assisted by? The last 60 degrees comes from lateral rotation at the sternoclavicular joint.
the deltoid
Can the arm fully abduct when the palms are facing medially?
No - arm must be laterally rotated to get full abduction
This muscle has an origin up the spinous processes of the vertebral column to the superior nuchal line of the head.
trapezius
There are three different parts of the trapezius. Upper, middle, and lower. On the vertical axis, what do each of these muscles cause? On the oblique axis, what do each of these muscles cause? On the AP axis, what do superior fibers do? What do inferior fibers do? Alas, what innervates the trapezius?
vertical axis: retraction
oblique axis: lateral rotation
AP axis: superior elevates, inferior depresses; innervation by CN XI
What nerve supplies motor function to the trapezius? What nerve segments supply proprioceptive innervation to the trapezius?
spinal accessory nerve (XI); cervical segments C3 and C4
This is a superficial (extrinsic) back muscle whose primary action is at the glenohumeral joint
latissimus dorsi
If you stabilize the glenohumeral joint, the latissimus dorsi will assist in retracting and depressing the shoulder girdle at the (blank) joint
sternoclavicular joint
The latissimus dorsi performs what actions? What’s its nerve supply? Where does it attach after leaving the thoracolumbar fascia?
adduction on AP axis
extendor of arm on transverse axis
medial rotator on the vertical axis;
nerve supply from thoracodorsal nerve (middle subscapular); attaches to the humerus
What do the rhomboids minor and major do? What’s their nerve supply?
retract the scapula
medially rotate scapula
elevate;
dorsal scapular nerve
What does the levator scapulae do? What’s its nerve supply?
elevates and medially rotates the scapula (pulls toward the midline); dorsal scapular nerve
Two other muscles that have an action at the SC joint
pec minor
serratus anterior
What’s the action of the pec minor on the coricoid process? What innervates the pec minor?
depressed
protracts
medially rotates;
medial pectoral nerve
Innervation to serratus anterior? What is unique about this?
Has a prominent nerve supply on its superficial surface – long thoracic nerve. Most muscles have their nerve supply on the deep side, but this nerve is on the superficial side. Can lead to nerve damage, which results in winging**
What is the main action of the serratus anterior?
Attaches to medial border but hugs the chest wall the whole way. Its major action is to hold the scapula tight against the body wall. If you push against something, it keeps the scapula from popping out.
Three actions of serratus:
AP axis
vertical axis
oblique
depression on AP axis
protraction on vertical axis
lateral rotation on oblique axis
Arm movements occur at the glenohumeral joint. But if you fix this joint, arms still need (blank) to facilitate all range of motion. In other words, movements of the (blank) are transmitted to the humerus.
the scapula; the…scapula
At the glenohumeral joint, what occurs along the horizontal transverse axis? The horizontal AP axis? The vertical axis?
flexion/extension
abduction/adduction
rotation
The glenohumeral joint is inherently unstable, because it allows for a lot of motion. It has a glenoid fossa and the articular surface of the head of the humerus. How much of the articular surface is in contact with the glenoid fossa?
only about half!
This tendon blends with the capsule of the glenohumeral joint, and helps hold the head of the humerus tightly against the glenoid fossa.
supraspinotis
This muscle comes off of the acromion, and a bit from the scapula. It is a prominent shoulder muscle that is unique, because it can perform every movement in the shoulder. It has anterior, middle, and posterior fibers (like the trapezius)
deltoid muscle
What movements do rotator cuff muscles allow for?
internal/external rotation and abduction/adduction