Pectoral girdle (Shoulder girdle)
The pectoral girdle consists of the clavicle and scapula. Compared to the pelvic girdle, the pectoral girdle is less loosely connected to the trunk and limbs (free upper limbs), thus allowing greater freedom of movement. In mammals, the clavicle is well developed in primates, but lacking in dogs.
Let us consider the significance of the pectoral girdle in terms of the form of locomotion of both animals.
- 1. Clavicle
- ・What is the shape?
- How touchable is the living body?
- ・What happens if the clavicle is not present?
- ・Fusion of the epiphyseal line is not seen until adulthood (after age 20), do not mistake the radiograph for a fracture line!
- ・The ossification style is?
- ・Sternal end (1) ---- sternoclavicular joint (2)
- What is the cross-sectional shape?
- ・Acromial end (3) ---- acromioclavicular joint (4)
- What is the cross-sectional shape?
- ・Conoid tubercle (5);It is an indicator for determining the upper and lower surfaces.
- 2. Scapula
- ・What is the shape?
- ・How thick is it?
- ・The position of the scapula in relation to the rib cage is?
- ・The relationship between free upper extremity motion and scapular motion is (To what extent does the scapula move when the upper limb is abducted)?
- ・What is a winged (alar) scapula in living body?
- ・Costal surface (7-1), Distinguish the Posterior surface (7-2),Medial border (7-3),Lateral border (7-4),Lateral angle (7-5),Superior angle (7-6),Inferior angle (7-7).
- ・Glenoid cavity (8)
- Supraglenoid tubercle (9),Infraglenoid tubercle
(10);What attaches to?
- This part of the shoulder joint is very shallow (compared to the hip joint) and is reinforced by ligaments and muscles. In particular, the four rotator cuff musclesqs (Subscapularis, Teres minor, Supraspinatus and Infraspinatus) does not act as a reinforcement in a static state (such as when a weight is hanging down), but it shows remarkable function during exercise.
- Find out where these muscles attach.
- ・Suprascapular notch (11);What passes?
- ・Spine of scapula (12)
- Supraspinous fossa (13),Infraspinous fossa (14);What fits in a living body?
- ・Acromion (15);Touch it with your own body.
- The width of the acromion (shoulder width) can be measured by connecting these points on both sides with a straight line.
- ・Coracoid process (16)
- What will attache?
- Can it be touched by a living body?