MSK 3

Question 1

Insertions of BBC muscles

Answer 1

Brachialis - coronoid process of ulna
Biceps brachii - radial tuberosity
Coracobrachialis - Coracoid process

Question 2

Attachments of long and short head of biceps brachii

Which tendon is most likely to rupture and what is this called

Answer 2

Short head into Coracoid process
Long head into superglenoid fossa of scapula

Long head most likely to rupture - called Popeyes sign

Question 3

Names of the heads of triceps brachii - nerve innervation with roots

Answer 3

Medial, short and lateral

Innervated by radial nerve C5-T1 and long head also innervated by Axillary nerve C5 and C6

Question 4

What nerve root does the triceps tendon hammer reflex test for

Answer 4

C7

Question 5

Where does the long head of the triceps originate from?

Answer 5

Infraglenoid fossa of the scapula

Question 6

Borders of the cubital fossa

Answer 6

Superior - imaginary line between the medial and lateral epicondyles
Medial - lateral border of pronator teres
Lateral - medial border of brachioradialis

Question 7

Contents of the cubital fossa

Answer 7

Tendon of biceps brachii
Brachial artery
Median nerve

Question 8

2 ways that the glenohmeral joint is made stable

Answer 8

Ligaments

• glenohumeral ligament
• transverse humeral ligament
• coracohumeral ligament
• Coracoacromial ligament

Tonic tone of the SITS muscles

Glenoid labrum making the joint deeper

Fibrous capsule

Question 9

What are the two bursae of the glenohumeral joint

Answer 9

Sub acromial bursae - between Supraspinatous tendon and acromion
Subscapular bursae - bursae between the subscapular tendon & scapula

Question 10

Ligaments of the glenohumeral joint. Briefly describe their location and where they span between

Answer 10

1. Transverse humeral ligament.
   
   • across the greater and lesser tubercle of humerus and holds tendon of long head of biceps in place during movement
2. Coracoacromial ligament
   
   • across the Coracoid process and acromion
   • ligament plus acromion and Coracoid process form an arch
     
     • Coracoacromial arch - prevents superior displacement of humerus
3. Glenohumeral ligament
   
   • from glenoid fossa to the anatomical neck of humerus
4. Coracohumeral
   
   • from Coracoid process to the anterior surface of greater tubercle

Question 11

Painful arc - what is it and how is it tested

Answer 11

Subacromial bursitis - inflammation of this bursae. Supraspinatus tendon becomes irritated and degeneration occurs of the tendon

Upon abduction, when the affected portion of the tendon comes into contact with the acromion, it hurts - hence painful arc.

Question 12

Why are most shoulder dislocations anterior and inferior?
What structures are at risk in these dislocations.
What is it anterior and inferior in relation to?

Answer 12

Location is in relation to infraglenoid fossa.
This dislocation is more common because there are no SITS muscles here to stabilise it and this is the weakest part of the joint capsule.
Axillary nerve runs here as well as anterior and posterior circumflex arteries so these structures are at risk.

Question 13

Describe the major land marks for the arterial supply of the upper limb

Answer 13

Left hand side

• subclavian artery direct branch off the aortic arch
• becomes the Axillary artery as it passes the lateral border of 1st rib
• Axillary artery passes the into upper limb in the axillary sheath below pec minor
• surgical neck of humerus - anterior and poster Cx artery arise
• lower border of teres major, Axillary becomes brachial artery
• gives off profunda brachii for the posterior supply of the arm
• brachial artery bifurcates into radial and ulna artery as it crosses cubital fossa

Question 14

Where do the limb buds appear in the foetus? Put timings on it

Answer 14

End of week 4, upper limb buds appear on the ventrolateral body wall.
A few days later the lower limb buds appear too, a bit lower down.

Question 15

From which embryonic tissues do the limbs generate from

Answer 15

Mesoderm (flexible)

Question 16

What covers the the distal borders of the limb buds and what structure does this become

Answer 16

Ectoderm

Forms the Apical Ectodermal Ridge

Question 17

What is the function of the AER?

Answer 17

• keeps the adjacent mesenchyme undifferentiated but they proliferate.
• proliferation = growth so the cells get further away from the AER
  
  • AER becomes more distal and loses its effect on the proximal cells
• the more proximal cells then differentiate into cartilage and muscle.

Question 18

How do fingers and toes form from the hand and foot plates

Answer 18

Cell death occurs which separates them into fingers as we know them

Question 19

What marks the boundary between dorsal and ventral ectoderm?

Answer 19

AER

Question 20

What is the zone of polarising activity and what does it do

Answer 20

It is a cluster of cells that is located on the posterior base of the limb bud.
It is responsible for asymmetry of the limb (eg ensures the thumb is lateral in the hand) and ensures an anterior posterior axis.
It also maintains the AER.

Question 21

Which weeks of the foetal development are the most critical for limb defects?

Answer 21

4 to 6

Question 22

What is syndactyly

Answer 22

Fusion of digits.
Occurs when the apoptosis in the cartilaginous digital rays fails.
Fusion can be due to skin, connective tissue or even bone.

Question 23

What is polydactyly

Answer 23

Extra digit (s)

Question 24

What is Amelia

Answer 24

A complete absence of a limb

Question 25

What is meromelia

Answer 25

Partial absence of a limb

Question 26

What is phocomelia

Answer 26

This is a subset of meromelia. | Rudimentary hands and feet are connected to the truth via weak, misshaped bones.

Question 27

Name a drug that is known to have caused phocomelia.

Answer 27

Thalidomide

Question 28

Explain how in the upper limb, the thumb is lateral and the extensors are posteriorly, but in the lower limb the great toe is medial and the extensors are anterior

Answer 28

Limb rotation occurs - UL rotates 90 degrees laterally - LL rotates 90 degrees medially

Question 29

Name the positions of the muscles in the anterior compartment of the arm, relative to each other

Answer 29

Coracobrachialis - medial and deepest Biceps brachii - most superficial Brachialis - deep to biceps and more distal