Osteology of the upper limb - clavicle, scapula and humerus (dave's notes) Flashcards
How does the clavicle first appear?
Appears in membrane before there is any cartilage in the embryo.
What is notable about the clavicle’s development?
It is the first bone of the skeleton to develop.
When does ossification of the clavicle begin? What is the next stage of development?
Two centres ossify in the 5th week and rapidly fuse. Elongation occurs at the sternal end in secondary cartilage.
What development of the clavicle occurs in later life?
An epiphysis at the sternal end appears in the teens and fuses in the 20s.
What does the scapula arise from? In what weeks does it form cartilage and then bone?
Mesenchyme.
Cartilagenous in 6th week, boney centre in the 8th week.
How developed is the scapula at birth?
The blade and spine are ossified, but the acromion, coracoid and medial border are still hyaline cartilage.
When is the glenoid cavity formed? From what?
Secondary centres appear in the acrominon, coracoid and medial border, and the glenoid cavity is fused by 25.
What part of the scapula fuses at 10 years?
The centre at the base of the coracoid fuses at about 10 years.
At what weeks of development are the cartilaginous and ossifying stages of the humerus?
Cartilagenous at week 6
Primary centre appears in the middle in the 8th week.
Where are secondary centres in the humorous formed?
At both ends. These are cartilaginous at birth.
What does the secondary centre at the upper end of the humerus become, and when?
Head in the first year, greater tuberosity in the third hear, lesser tuberosity in the 5th year.
What stages of humerus development occur at 7 and 20 years?
The head, greater tuberosity, and lesser tuberosity fuse by the 7th year.
The epiphyseal line (growing end) skirts the bone with fusion at about 20 years.
What does the secondary centre at the lower end of the humerus become, and when?
4 centres appear; capitellum and lateral ridge (2nd year), medial epicondyle (5th year), trochlear (12 year), and lateral epicondyle (13th year)
When does the lower end of the humerus unite with the shaft?
At around 18 years.
