Now let's look at the shoulder joint. To understand the shoulder joint, let's get acquainted with the upper half of the humerus. This is the head of the humerus. The articular surface is half of a sphere. On the anterior aspect is a well marked groove known as the bicipital groove, because the tendon of the long head of the biceps runs in it. At the proximal end of the groove are the lesser tubercle, and the greater tubercle. Because it's between two tubercles, the bicipital groove is also known as the inter-tubercular groove. Down here on the lateral aspect of the humerus, almost halfway down the bone, is a rough spot, the deltoid tuberosity.
现在，让我们学习肩关节。为了了解肩关节，首先需要熟悉肱骨上半部分的解剖。这里是肱骨头，接合的关节呈半球形。在前方，有一个明显的沟，叫做二头肌沟，二头肌长腱从此经过。在二头肌沟的近测是小结节和大结节。因为二头肌沟位于两个结节之间，所以二头肌沟也叫做结间沟。在肱骨外侧下方，差不多一半的位置，有一个粗糙的点，叫做三角肌粗隆。
Here's the shoulder joint, also known as the gleno-humeral joint. This loose sleeve of tissue which encloses the joint is the joint capsule. The capsule doesn't hold the bones together, it's quite a weak structure. What it does is to permit movement. The structures which hold the two bones together are muscles, as we'll see. Here's the tendon of one of those muscles.
这里是肩关节，也叫做盂肱关节。疏松的袖状组织环绕关节，称为关节囊。关节囊不连接骨头，它是非常力量非常虚弱的结构。它允许一定的关节活动度。连接两块骨头的结构是肌肉，正如我们所见。这里是其中一块肌肉的肌腱。
Let's look at the movements that can occur at the shoulder joint. Movement forward and upward is called flexion. Movement downward and backward is called extension.
Movement away from the side of the body is ab-duction. The opposite movement is ad-duction. Rotation which moves the front of the arm towards the body, is internal rotation. Rotation the other way is external rotation.
Now that we've taken a look at the bones, joints and ligaments, let's spend about a minute reviewing what we've seen so far.
Here's the clavicle, for an easy start. On the scapula here's the blade, the glenoid fossa, the supraglenoid, and infraglenoid tubercles, the spine of the scapula, the
supraspinous and infraspinous fossa the acromion, and the coracoid process.
Here's the proximal humerus, with the head, the greater tubercle and lesser tubercle, the bicipital groove, and the deltoid tuberosity.
Here's the sterno-clavicular joint, and here's the acromio-clavicular joint, with the conoid ligament and the trapezoid ligament.
On the scapula, here's the glenoid labrum, and the coraco-acromial ligament.
Lastly, here's the capsule of the shoulder joint.
