PT3 - The Shoulder Complex And Orientating The Hand Flashcards
1
Q
What are the functions of the shoulder?
A
- shoulder girdle => orientation of hand to any position
- CNS may sacrifice anatomical structure of shoulder to maintain hand dexterity
- upper limb has more mobility, but at the cost of structural stability
2
Q
What are the articulations of the shoulder?
A
- stenoclavicular
- acromioclavicular
- scapulothoracic
- glenohumeral (ball and socket)
- supra-humeral (sub-acromial)
- long head of biceps and Bicipital groove
3
Q
Describe the structure of the SC joint
A
- shallow, saddle shaped between manubrium and first costal cartilage
- sternal articular surface larger than sternum
- convex vertically + concave in sagittal plane
- lined with fibrocartilage + fibrocartilaginous disc => divides joint into 2 synovial cavities (each lined with it’s own membrane)
- fibrous capsule surrounds articular surfaces, thicken in front + behind but thin above and below
4
Q
Name the ligaments around the AC joint
A
From medial to lateral:
- conoid ligament = clavicle => scapula
- trapezoid ligament = clavicle => scapula
- acromioclavicular ligament = clavicle => acromion
- coracoacromial ligament = scapula => acromion
5
Q
How many bones meet at the AC joint?
A
- 2 bones = clavicle + scapula via acromion
6
Q
What are the movements available at the AC joint?
A
- plane synovial joint => gliding movements
7
Q
What happens when you get to the end of range of AC joint moment?
A
- AC becomes part of complex movement = global movement of shoulder complex
8
Q
How can this joint be injured?
A
- FOOSH
- landing direction on acromion
- disruption of ligamentus support
9
Q
How can you assess for AC injury?
A
- graded based on the number of ligaments disrupted
- might notice a step between clavicle and acromion
- might notice laxity in ligament
- common site of osteoarthritis
- end ranges of movement causes compression and degenerative changes
10
Q
What is the structure of the AC joint?
A
- planar synovial joint
- located between oval facet at lateral end of clavicle + facet at medial aspect of acromion
- articular surfaces lined with fibrocartilage
- wedged-shaped articular disc separates joint surfaces
- capsule is attached to articular margins + reinforced superior and inferior to AC ligaments
- coracoclavicular ligament (+conoid + trapezoid components) => major stability of joint
11
Q
What is the functional anatomy of the rotator cuff?
A
- dynamic stability of GH joint (unlike passive stability of ligaments in AC)
- maintaining integrity of glenoid in capsule
- combines with joint capsule
- less reliant on passive structures to support the shoulder
- RCM sometimes described as dynamic ligaments
12
Q
What are the muscles of the RC?
A
- teres minor
- infraspinatus
- supraspinatus
- subscapularis
13
Q
What is the functional anatomy of the rotator cuff?
A
- RC does not permit assessment of individual musculotendinous unit => think of them as a whole structure
- tendons fuse into 1 structure
- supraspinatus + infraspinatus fuse at insertion (greater tubercle of humerus)
- teres minor + infraspinatus fuse proximally to musculotendonous junction
- subscapularis + supraspinatus tendons fuse => sheath around bicep tendon
- RC tendons adhere to GH joint capsule
14
Q
What is the function of the RC?
A
- dynamic stability of huméral head in glenoid fossa
- blend with joint capsule => layers of fibres in different directions
- high muscle spindle control => act as ligaments
- support inferior glide of humeral head during abduction to maintain stable contact with glenoid (think patella in knee)
15
Q
What is the function of the long head of the bicep?
A
- attaches to scapula
- humerus glides along bicep => facilitates downward shift of humeral head
- bicep assists RC dynamic stabilisation
- triceps similar, but not as much involvement as biceps