Posterior Triangle of Neck and the Axilla

Question 1

List the boundaries of the posterior triangle.

Answer 1

Anterior - SCM
Posterior - trapezius
Inferior
Middle 1/3 of clavicle
Apex - where trapezius and SCM meet on occipital bone
Roof - layer of deep cervical fascia
Floor - muscles covered by deep cervical fascia

Question 2

What are the two segments of the posterior triangle and what divides them?

Answer 2

Occipital triangle
Supraclavicular triangle
Inferior belly of omohyoid

Question 3

What are the boundaries of the axilla?

Answer 3

Anterior - Pectoralis major and pectoralis minor
Posterior - Subscapularis, latissimus dorsi and teres major
Medial - serratus anterior and intercostal spaces
Lateral - Humerus, biceps brachii, coracobrachialis
Apex - entrance from neck to axilla
Base - skin and fascia between chest wall

Question 4

What is Hilton’s Law?

Answer 4

States that nerves supplying a joint also supplies the muscles moving the joint and the skin covering their attachments

Question 5

What is the axillary sheath?

Answer 5

Connective tissue sheath which forms a sleeve enclosing the axillary artery, vein and cords of brachial plexus

Question 6

Where does the axillary artery begin and end?

Answer 6

Lateral border of 1st rib and ends at inferior border of teres major

Question 7

What are branches of the axillary artery?

Answer 7

Anterior and posterior circumflex arteries

Question 8

Is the axillary vein medial or lateral to the axillary artery?

Answer 8

Medial

Question 9

Where does the axillary vein become the subclavian vein?

Answer 9

Lateral border of 1st rib

Question 10

What are the names of the groups of axillary lymph nodes and where do they get lymph from?

Answer 10

Anterior - Anterior thorax wall incl. breast
Posterior - upper quadrant of back
Infraclavicular - lymphatics w/ cephalic vein
Central - anterior, posterior and lateral
Apical - all groups (empties into right lym. duct)
Lateral - Lymph from UL except cephalic vein

Question 11

How is the SCM used to detect respiratory distress?

Answer 11

Contraction visible during forced inspiration

Question 12

What muscles are physical signs of respiratory distress?

Answer 12

SCM
Anterior scalene
Posterior scalene
Middle scalene

Question 13

Which muscle is used as an intramuscular injection site?

Answer 13

Deltoid

Question 14

What may travel along the axillary sheath?

Answer 14

Pus

Question 15

What does the external jugular vein drain?

Answer 15

Scalp and face

Question 16

What is subclavian vein catherisation?

Answer 16

Method of placing a central line to administer drugs or intravenous nutrition

Question 17

Where is the most superficial part of the subclavian artery located?

Answer 17

Posterior triangle

Question 18

How do we evaluate the accessory nerve?

Answer 18

Ask the patient to shrug their shoulders while you try to push their shoulders down and ask the patient to push their head against your hand

Question 19

What happens if there’s damage to C5/C6?

Answer 19

Traction injury - excessive increase in angle between shoulder and neck stretches/tears nerves due to motorbike RTA
- Childbrith

Question 20

What is Erb-Duchenne palsy?

Answer 20

Injured C5 and C6
UL hangs limply by the side
UL medially rotated
Elbow extended and forearm pronated
Loss of sensation of lateral arm

Question 21

How can a traction injury (lower lesion) occur in the UL?

Answer 21

Falling from height and clutching to object
Breech delivery at childbirth
Invasion of malignant metastases from lung to lower deep cervical LNs

Question 22

What is Klumpke palsy?

Answer 22

Ulnar claw
Loss of sensation of medial arm and medial side of forearm, hand and medial 1.5 fingers
C8 and T1 affected