3.1 Shoulder complex

Question 1

Bones of the pectoral girdle

• Clavicle
  
  • ossification
• articulates w/…

Answer 1

Clavicle is first bone to form ~6weeks

• lats to fuse (late 20s)
• forms anterior wall of cervicoaxillary canal
  - articulates w/ manubrium
  - anchor on 1st costal cartilage
  - articulates w/ scapula at acromion

Question 2

Scapula

- ossiffication
- body forms...

Answer 2

• begins at 2 mos. (fetal growth)
• final fusion in 20s
• body forms SCAPULOTHORACIC JOINT WITH THORAX (not articulation)

Question 3

Joints of Shoulder Complex (SAG)

Answer 3

• Sternoclavicular Joint
• Acromioclavicular Joint
• Glenohumeral Joint

Question 4

Sternoclavicular Joint

• connects..
• type of joint

Answer 4

• clavicle to manubrium
• synovial; saddle/gliding
  
  • functionally 3 degrees of freedom (ball and socket)

Question 5

Acromioclavicular Joint

• connects…
• type of joint

Answer 5

• clavicle to scapula!

- synovial; gliding

Question 6

Glenohumeral Joint

• connects
• type

Answer 6

glenoid fossa (scapula) to humeral head

• synovial; ball and socket
• triaxial (3 deg of freedom)

Question 7

Pectoral girdle: STERNOCLAVICULAR JOINT

Answer 7

• synovial; saddle/gliding
• functions as a ball and socket (unusual)
• BLOOD SUPPLY
  
  • internal thoracic a/v
  • suprascapular a/v
• Nerve supply
  
  • medial supraclavicular n.
  • subclavius n.

Question 8

Sternoclavicular Joint reinforced by:

Answer 8

• ant./post. sternoclavicular lig.

- interclavicular lig

Question 9

Sternoclavicular joint anchor reinforcement

Answer 9

• costoclavicular lig.
  
  • costal cartilage>costal tuberosity
  • limits elevation of clavicle

Question 10

Sternoclavicular joint is ______ but _______

Answer 10

highly mobile but strong (most movement comes from acromial end)

Question 11

Movements at SCJ

Answer 11

• Rotation (along long axis)
• Elevation-depression
  - acromial end of clavicle raised by ~60 degree angle
• Protraction-retraction
  - moves clavicle ~25-30 deg from neutral

Question 12

scapulothoracic joint

Answer 12

not a real joint

• anterior scapula to posterior thoracic wall
• muscular attachment; no bony articulation

Question 13

Movement of scapula (scapulothoracic joint)

Answer 13

• elevation-depression
• protraction-retraction
• upward rotation-downward rotation
• winging (pivot)-medial border sticks out
• tilt (inferior angle moves up and away)

Question 14

Scapulo-humeral rhythm

Answer 14

• 180 deg of Abduction (1:2 ratio)
  
  • ~60 deg. from scapula rotation
  • ~120 deg. from humerus
• humerus must lateral rotate
  
  • tubercles rotated posterior
• allows greater SA for movement