7. Upper Limb Flashcards
What makes up the shoulder girdle?
- Clavicle
- Scapula
By what form of ossification does the clavicle develop?
Intramembraneous ossification
Describe the articulations and ligamental attachments of the clavicle.
Articulations:
- Medially -> With manubrium of the sternum (sternoclavicular joint)
- Laterally -> With acromion of scapula (acromioclavicular joint a.k.a. AC joint)
Ligaments:
- Coracoclavicular ligament -> Connects the clavicle to the coracoid process of the scapula. Made up of the trapezoid and conoid ligaments.
- Costoclavicular ligament -> Connects the medial clavicle to the first costal cartilage and first rib.
Where does the clavicle most commonly fracture?
- In the middle third.
- Following fractures, the medial portion is pulled superiorly by sternocleidomastoid whilst the lateral portion is pulled inferiorly by the weight of the upper limb.
Is this the anterior or posterior view of the scapula?
Posterior
Draw the coracoid process.
What does the scapula articulate with and what are the names of these joints?
- Humerus -> Glenohumeral joint
- Clavicle -> Acromioclavicular joint
What is involved in the glenohumeral joint?
- Glenoid fossa of the scapula
- Head of humerus
What is the glenoid labrum?
A fibrocartilaginous structure that deepens the glenoid fossa, stabilising the shoulder joint.
Describe the attachements of the capsule in the glenohumeral joint.
The joint capsule’s fibrous layer attaches to the circumference of the glenoid cavity and inserts into anatomical neck of the humerus. Inferiorly, near the armpit region, the capsule is lax, minimising impingement to motion.
How is the scapula involved in limb mobility?
Scapular movements assist the optimal movement of the glenohumeral joint as a result of interactions between the scapula and humerus (scapulohumeral rhythm).
What are the 4 rotator cuff muscles?
Subscapularis, infraspinatus, supraspinatus, teres minor
Where do the rotator cuff muscles attach?
- Supraspinatus, infraspinatus and teres minor attach to the greater tuberosity of the humerus
- Subscapularis attaches to the lesser tuberosity of the humerus (only one)
The other ends of the muscles attach to the scapula.
What movement does supraspinatus aid?
Assists with initial arm abduction.
What movement do infraspinatus and teres minor aid?
Lateral shoulder rotation
What movement does subscapularis aid?
Medial shoulder rotation
Draw the attachments of the rotator cuff muscles.
What muscles act at the glenohumeral joint?
- Trapezius -> Elevation, rotation (during abduction) and retraction of the scapula.
- Pectoralis major -> Flexes, adducts and medially rotates the upper limb.
- Latissimus dorsi -> Extends, adducts and medially rotates the upper limb.
- Serratus anterior -> Retracts the scapula against the chest wall.
- Deltoid -> Functions to flex (anterior fibres) and extend (posterior fibres) the arm at the glenohumeral joint. Middle fibres are the major shoulder abductors, taking over from the supraspinatus muscle after the first 15°.