GEP (Life structure) Week 3 Flashcards

Question

What is an Articular Capsule

Answer 1

The envelope surrounding a joint it is continuous with the periosteum of the two articulating bones. Made of 2 parts: The outer fibrous layer = Ligament The inner synovial layer = highly vascularised serous connective tissue that absorbs and secretes synovial fluid. Synovial fluid has 3 functions: Lubrications, nutrient distribution and shock absorption. If an articular capsule is ineffective or damaged this can result in physical findings such as crepitus, swelling, redness and reduced movement of the joint due to pain. ## Footnote A side note to the ligaments, these are made up of collagen and there are many conditions that affect the formation of collagen such as marfan’s syndrome, and ehlers danlos. This is why people with these conditions are more likely to get dislocations. 90% of collagen in the body is made up of type 1 collagen. But in conditions like Marfan’s and Ehlers Danlos there is a problem with collagen IV naturally this doesn’t suggest it should cause any problems with ligaments, however in actual fact collagen IV regulates the formation of collagen 1 which leads to the characteristic dislocations that occur in these conditions. So if you get a patient that is very tall with very slim long fingers and a high arched palate that it might be suggesting the patient is getting dislocations due to having Marfan’s syndrome. The other big condition that affects joints is the good old arthritis. The joint capsule ends up thickening due to wear and tear which decreases all the space needed for the synovial fluid, less synovial fluid = more rubbing and more pain!

Answer 2

The subacromial bursa acts as a cushion between the area of the rotator cuff tendons and the acromion preventing friction on arm movement. This is why bursitis of this bursa leads to anterior or lateral shoulder pain with difficulty lifting or reaching for things. The shoulder has five main bursae: Subacromial-subdeltoid bursa Subscapular recess Subcoracoid bursa Coracoclavicular Supra-acromial Medial extension of supra-acromial (Only some texts mention this) ## Footnote The good news is, even though there are 5 or in some books 6 of these the big bad problematic one is the subacromial bursa. As shown on the diagram. Luckily bursae aren’t too hard to understand they are a nice little pocket of softness to protect where bone meets bone and are held together by tendons. The main condition that comes up is simply bursitis. Which as always with world etymology itis = inflammation. An inflamed bursae becomes swollen due to injury or infection. If a bursae swells it puts pressure on all the nerves around it causing pain alongside the pain caused by the inflammation too. As this subacromial bursae is a cushion for the rotator cuff tendons when it becomes swollen then the rotator cuff muscles cannot lift the arm due to impingement and pain.

Answer 3

## Footnote This is the bit I honestly struggled with the most. It looks horrific and unless you can think in 3D space which I admit I can’t it is tricky to visualise it especially when they don’t give you images! But we’ll break it down step by step the brachial plexus is a complex set of nerves located around the shoulder joint it consists of nerves originating from the spinal roots C5, C6, C7, C8 and T1. This image on the left is a great way to visualise it when you think of doing sensory testing for your OSCE’s but I find the right image to make more sense to me.

Answer 4

3 Musketeers Assassinated (Finger gun) 5 Mice 5 Rats and 2 Unicorns ## Footnote This is a great diagram and a life saver for all those brachial plexus questions on what nerve has been pinched! 3 Musketeers assassinated 5 Mice, 5 Rats and 2 Unicorns. It is also a great way of remembering the terminal branches in order as you can see we go Musculocutaneous, Axillary, Median, Radial and finally Ulnar nerve

Answer 5

## Footnote Remember To Drink Cold Beer Two Peaks and Three horizontal lines Divisions In the Dark Dingy bowling alley we want strikes over spares Cords Lateral cord = 1 (Lateral pectoral) Posterior cord = 2 lines (Upper subscapular, Lower subscapular, Thoracodorsal Medial cord = 3 Medial pectoral, medial brachial cutaneous, medial antebrachial cutaneous Branches When we are at the beach we want two small waves and a big one MARMU Musketeers, Assassinated, Rats, Mice and Unicorns C5 Five branches = Lateral pectoral, dorsal scapular, Suprascapular, Subclavius and Long thoracic

Answer 6

Some dislocations of the shoulder can cause the humerus to snap separating the greater and lesser tuberosity. Why is this important? Remember in the earlier slides where I discussed the attachment sites of the muscles of the rotator cuff? This is when it is important to know this. These fractures result in an inability to do a lot of the arm movements as three out of four of the rotator cuff muscles are now unable to put the force on the humerus as this is now loose. Don’t worry too much about fractures though, this is just a nice sideline to remember why dislocations can damage or tear these muscles. If you get a strange question about a shoulder dislocation and it is discussing peripheral pulses disappearing an important thing to know is that within the shoulder joint the axillary artery is just superior to the axillary nerve which means it can be torn open during a dislocation. This means no peripheral pulses and possibly a big expanding haematoma. The most important thing to remember about the shoulder capsule is the positioning of the tendons of the rotator cuff. The subscapularis is anterior to the capsule the supraspinatus is superior to the capsule and the infraspinatus muscle is posterior to the capsule. It’s a good one to remember because dislocations of the shoulder are usually anterior so the subscapularis is the most commonly affected muscle

Answer 7

Due to the pathway of the axillary nerve it is easily injured in dislocations. This X-ray shows a very clear dislocation and the yellow line shows the axillary nerve which is being pulled away from its natural position. The other side of the coin is the risk of nerve damage. The axillary nerve originates from the posterior cord of the brachial plexus (C5 and C6 roots) its path then leaves the axilla and travels medially to the surgical neck of the humerus it then divides into three terminal branches The anterior branch. The posterior branch. The articular branch. The anterior branch winds around the surgical neck of the humerus, posteriorly, with the posterior circumflex humeral vessels and supplies the anterior aspect of the deltoid muscle. The posterior branch supplies the posterior aspect of the deltoid muscle as well as the teres minor. Following this, it passes around the lower border of the deltoid and is then referred to as the superior/upper lateral cutaneous nerve of the arm. This nerve supplies the skin over the lower part of the deltoid and over the upper part of the long head of triceps both anteriorly and posteriorly. The articular branch supplies the glenohumeral joint.