Must Know
- Clavicle is the first bone to start ossifying, in membrane from two centres at about week five.
- A clavicular secondary centre appears at the sternal end in the late teens and fuses fast.
- Clavicular articular surfaces are fibrocartilage, in keeping with membranous ossification.
- Humeral head is about one third of a sphere and four times the glenoid area.
- Shoulder capsule runs about 2 cm down the medial shaft and encloses the epiphyseal line there.
- Surgical neck carries the axillary nerve and posterior circumflex vessels behind it.
- Scaphoid waist is non-articular. Vascular foramina cluster distally, so proximal supply is retrograde.
- Scaphoid is the commonest carpal fracture and second only to the femoral head for traumatic osteonecrosis.
- Lunate is the commonest carpal dislocation. It moves forwards and can compress the median nerve.
Clavicle Attachments
| Site | Attachment |
|---|
| Upper surface, medial third | Clavicular head of sternocleidomastoid |
| Anterior, medial half | Pectoralis major |
| Anterior, lateral third | Deltoid |
| Posterior, lateral third | Trapezius |
| Inferior, medial end | Costoclavicular ligament |
| Inferior, middle third | Subclavius groove with clavipectoral fascia and nutrient foramen |
| Junction of lateral quarter | Conoid tubercle |
| Lateral inferior ridge | Trapezoid ligament |
Humerus Attachments
| Site | Attachment |
|---|
| Greater tubercle facets, top to back | Supraspinatus, infraspinatus, teres minor |
| Lesser tubercle | Subscapularis |
| Lateral lip of sulcus | Pectoralis major |
| Floor of sulcus | Latissimus dorsi |
| Medial lip of sulcus | Teres major |
| Mid lateral shaft | Deltoid tuberosity |
| Mid medial shaft | Coracobrachialis |
| Above radial groove | Lateral head of triceps |
| Below radial groove | Medial head of triceps |
| Lateral supracondylar ridge | Brachioradialis upper two thirds, ECRL lower third |
- Nutrient foramen lies anteromedially at the lower deltoid tuberosity and points to the elbow.
- Anterior shaft approach splits brachialis, with the lateral part retracted to cover the radial nerve.
- Posterior approach uses the long and lateral head interval and splits the medial head.
Humeral Ossification
| Centre | Fusion |
|---|
| Shaft | Primary centre at week eight |
| Proximal (head, greater and lesser tubercles) | Unite as one epiphysis, join shaft at about 20 years |
| Distal (capitulum, trochlea, lateral epicondyle) | Unite, then join shaft at about 15 years |
| Medial epicondyle | Separate, joins shaft at about 20 years |
- Proximal humerus is the growing end.
- The late medial epicondyle centre can mimic a fracture in adolescent radiographs.
- Volar scaphoid approach runs between FCR medially and the radial artery laterally.
Numbers to Remember
- Clavicle. Ossifies from week five.
- Humeral head. Four times the glenoid area.
- Medial capsule. About 2 cm below the articular margin.
- Humeral fusion. Distal about 15 years, proximal about 20.
Memory Aids
- Lady between two majors. Latissimus in the sulcus floor between pectoralis major and teres major.
- SIT on the greater tubercle. Supraspinatus, infraspinatus, teres minor from top to back.
Exam Traps
- Clavicle ossifies in membrane, not cartilage.
- Proximal humeral epiphysis fuses after the distal one.
- The medial proximal humeral physis is intracapsular.
Source
Sinnatamby CS. Last’s Anatomy. Regional and Applied. 12th ed. Edinburgh, Churchill Livingstone Elsevier, 2011. Chapter 2, Upper limb.
Reviewed by Professor Phong Tran, Head of Orthopaedic Surgery, Western Health. Last updated 17 October 2026.
