L2: Bones, ligaments and joints of the pectoral girdle

Question 1

clavicle

Answer 1

collar bone
articulates with sternum medially and scapula laterally
acts as strut, transferring forces between upper limb and axial skeleton

Question 2

clavicle shape

Answer 2

S - shaped
medial 2/3 curves anteriorly
lateral 1/3 curves posteriorly

Question 3

clavicle ends

Answer 3

medial end is bell-shaped and articulates with sternum - sternoclavicular joint

lateral end is flat and articulates with acromion - acromioclavicular joint

Question 4

clavicle surface

Answer 4

smooth superior surface
rough inferior surface - impression for costoclavicular ligament, groove for subclavius, conoid tubercle, trapezoid line

Question 5

clavicle weakest point

Answer 5

junction between medial 2/3 and lateral 1/3 - the straightest part of clavicle

typically fractures when excessive force transmitted through clavicle by upper limb

Question 6

scapula - shoulder blade

Answer 6

sits on posterior thorax at level of 2nd - 7th ribs

articulates with clavicle at the acromioclavicular joint and humerus at glenohumeral joint

triangular shape, medial, lateral and superior borders

inferior, superior and lateral angle

Question 7

scapula - anterior surface

Answer 7

subscapular fossa
coracoid process
acromion
neck

Question 8

scapula- posterior surface

Answer 8

supraspinous fossa
infraspinous fossa
scapular notch
spine and acromion

Question 9

scapula - lateral surface

Answer 9

glenoid fossa
supraglenoid tubercle
infraglenoid tubercle

Question 10

scapula fractures

Answer 10

not very common
usually happen only in high-energy impacts e.g. road traffic accident
direct blunt force trauma to the blade, or falling from a height

Question 11

humerus

Answer 11

long bone of the arm
articulates with scapular proximally - glenohumeral joint
articulates with bone of the forearm distally - ulna medially + radius laterally

Question 12

radial groove on humerus

Answer 12

on posterior surface of shaft of humerus
contains radial nerve

Question 13

sternoclavicular joint

Answer 13

articulation between clavicle, sternum and 1st costal cartilage

classified as an atypical saddle shaped synovial joint

Question 14

typical features include:

Answer 14

joint capsule with inner synovium
synovial fluid

Question 15

atypical feature

Answer 15

fibrocartilaginous disc in joint capsule between the bones - not hyaline

Question 16

sternoclavicular joint - ligaments

Answer 16

anterior sternoclavicular ligament
posterior sternoclavicular ligament
interclavicular ligament
costoclavicular ligament

these ligaments are exceptionally strong, explaining why the clavicle tends to fracture instead of dislocating

Question 17

acromioclavicular joint

Answer 17

*Articulation between lateral clavicle, and acromion of scapula
*Classified as atypical plane synovial join

Question 18

acromioclavicular joint - ligaments

Answer 18

AC Joint is stabilised by coracoclavicular ligament
*Coracoclavicular ligament has two components:
*Conoid ligament
*Trapezoid ligament
*These ligaments tether the scapula superiorly to the clavicle whilst…
*AC ligament counteracts rotary forces from weight of arm

Question 19

glenohumeral joint

Answer 19

classified as ball and socket synovial joint
most mobile joint of the body
unstable: sacrifices stability for mibility

Question 20

GH joint instability

Answer 20

Ball and socket joint
*Shallow bony socket (glenoid fossa)
*Large bony ball (head of humerus)

*Lax and loose joint capsule
*To allow for movement

*Passively reinforced
*Glenoid labrum
*Joint ligaments

*Actively reinforced
*Muscles – rotator cuff

Question 21

GH ligaments - passive stabilisers

Answer 21

glenohumeral ligaments
- superior
- middle
- inferior

coracohumeral ligament

Question 22

other ligaments in GH joint

Answer 22

*Coracoacromial Ligament
*Prevents superior displacement of humerus

*Transverse Humeral Ligament
*Forms a roof over the bicipital groove

*Coracoacromial Arch
*Prevents superior dislocation

Question 23

rotator cuff - active stabilisation

Answer 23

4 muscles that originate on scapula and insert on humerus
‘‘SITS’’
Supraspinatus
Infraspinatus
Teres minor
Subscapularis

Question 24

anterior GH joint dislocation

Answer 24

Most common dislocation because joint is least reinforced inferiorly

Antero-infero-medial displacement of humeral head

Question 25

posterior GH joint dislocation

Answer 25

Rare - usually only occurs in:
Electric Shock
Epileptic Seizure

*“Light Bulb” Sign

Question 26

what is a bursa

Answer 26

*A bubble of synovial membrane, contains synovial fluid

Acts as a soft cushion, preventing bone pressing against bone during moveme

Question 27

bursitis

Answer 27

inflammation of the bursa, usually from overuse or trauma