Topic 1

Question 1

classify the humerus

Answer 1

long bone

Question 2

what type of bones are the clavicle and scapula

Answer 2

clavicle is a sigmoid shaped long bone and the scapula is a triangular shaped bone.

Question 3

list the joints of the shoulder and classify each joint

Answer 3

glenohumeral - synovial, multiaxial, ball and socket
sternoclavicular - synovial, multiaxial, plane
acromioclavicular - synovial, multiaxial plane

Question 4

what are the articular surfaces of the glenohumeral joint

Answer 4

humeral head (1/2 sphere) and glenoid fossa.

there is only approx. 25%-30% contact between the articulating surfaces.

Question 5

describe the joint capsule of the glenohumeral joint

Answer 5

• very thin and lax,

the joint capsule attaches medially to the margin of the glenoid fossa and glenoid labrum, laterally to the margin of the anatomical neck of humerus and reflected inferiorly onto the medial shaft of the humerus.

the joint capsule is reinforced by the rotator cuff tendons, long head of tricep tendon and glenohumeral & corahumeral ligaments.

the joint capsule communicates with the subscapular bursa and intertubercular groove.

Question 6

describe the synovial membrane of the glenohumeral joint

Answer 6

the S.M lines the joint capsule as well as the bony surfaces that are not covered by the labrum.

Question 7

what is the main intra-articular structure of the glenohumeral joint

explain it

Answer 7

glenoid labrum - a fibrocartilaginous structure around the glenoid fossa.

• facilitates mobility of the joint
• increases glenoid concavity up to 50%
• provides attachment for ligaments, muscles and joint capsule.

Question 8

describe the orientation of the glenoid fossa

explain why - significance

Answer 8

when arm is hanging the glenoid fossa faces:
- laterally
- slightly anterior,
- slightly superior

Since fossa is so shallow, just letting arm hang Given its weight)
would be enough to have it dislocate if vertical .
•
By facing -
laterally -
slightly anteriorly -
slightly superiorly
the humans cannot slide or dislocate down without first moving
laterally -
and we have tissues that prevent that moremerit.
↳ oovaco humeral ligament
↳ superior glenohumeral ligamen

Question 9

list and describe the mechanical functions of the ligaments for the glenohumeral joint

Answer 9

1. coracoacormial ligament - prevents superior dislocation of humerus.
2. coracohumeral ligament - prevents lateral and therefore inferior dislocation of humerus (glenoid fossa directed superiorly, upper limb pendent).
3. glenohumeral ligaments - inconsistent.
   
   • superior: prevents lateral and therefore inferior dislocation of the humerus.
   • middle - limits external rotation.
   • inferior - prevents anterior dislocation of humerus when fully abducted.
4. transverse humeral ligament - passes between humerus tubercles and holds long head of biceps bracchi in the bracchi groove.

Question 10

what bones form the pectoral girdle

what are the scapulothoracic movements that occur at the pectoral girdle

Answer 10

clavicle and scapula

• elevation/depression
• retraction/protraction
• abduction/ adduction
• upward and downward rotation
• anterior and posterior tilt.

Question 11

what are the articulating surfaces of the sternoclavicular joint

describes its joint capsule

Answer 11

sternal end of clavicle
clavicular notch of sternum
costal cartilage of rib 1.

strong joint capsule, reinforced by capsular ligaments.

Question 12

describe the synovial membrane of sternoclavicular joint

Answer 12

intra-articular disc - vertical disc dividing joint capsule into medial and lateral compartments.

functions - shock absorber, prevents superior dislocation of clavicle (thrusting forces and weight in hand).

Question 13

ligaments for sternoclavicular joint

Answer 13

1. costoclavicular ligament
   
   • bilaminar (two layers), running 90 degree to one another.
   • limits elevation of clavicle
   • limits protraction and retraction
   • acts as fulcrum/pivot around which movements occur.
2. anterior sternoclavicular - limits retraction
3. posterior sternoclavicular - limits protraction
4. interclavicular (between clavicles).

Question 14

acromioclavicular joint - articular surfaces and joint capsule

Answer 14

articular surfaces of the acromioclavicular joint are the acromial end of the clavicle and anterior, medial acromion.

joint capsule is loose and reinforced by capsule ligaments and intra-articular disc.

Question 15

ligaments of acromioclavicular joint

Answer 15

coracoclavicular ligament
- conoid part - attaches to conoid tubercle, vertical, limits protraction of scapula, produces axial rotation of clavicle.

• trapezoid part - attaches to trapezoid line, oblique, limits retraction of scapula, prevents medial dislocation of scapula.