Clavicle
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The clavicle is an S-shaped bone commonly known as the collar bone. When palpating the collar bone, you are feeling the shaft of the clavicle bone.
The medial side of the clavicle articulates with the sternum at the sternoclavicular joint via the sternoclavicular ligament, the rib cage via the costoclavicular ligament, and the other clavicle via the interclavicular ligament.
The lateral side of the clavicle articulates with the coracoid process of the scapula at the coracoclavicular joint via the coracoclavicular ligament, and with the acromion of the scapula at the acromioclavicular joint via the acromioclavicular ligament.
Muscles including the deltoid and pectoralis major originate from this bone.
The medial side of the clavicle articulates with the sternum at the sternoclavicular joint via the sternoclavicular ligament, the rib cage via the costoclavicular ligament, and the other clavicle via the interclavicular ligament.
The lateral side of the clavicle articulates with the coracoid process of the scapula at the coracoclavicular joint via the coracoclavicular ligament, and with the acromion of the scapula at the acromioclavicular joint via the acromioclavicular ligament.
Muscles including the deltoid and pectoralis major originate from this bone.
Scapula
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The scapula, commonly known as the shoulder blades, are much more complicated than the clavicle.
The coracoid process is on the anterior side of the scapula and articulates with the clavicle at the coracoclavicular joint. There are three ligaments connecting the coracoid process to other bones, the coracohumeral, coracoclavicular, and the coracoacromial ligaments. The coracoid process is also the origin of the coracobrachialis.
The subscapular fossa is the surface along the anterior side of the scapula. This surface is where the subscapular muscle of the rotator cuff originates.
The coracoid process is on the anterior side of the scapula and articulates with the clavicle at the coracoclavicular joint. There are three ligaments connecting the coracoid process to other bones, the coracohumeral, coracoclavicular, and the coracoacromial ligaments. The coracoid process is also the origin of the coracobrachialis.
The subscapular fossa is the surface along the anterior side of the scapula. This surface is where the subscapular muscle of the rotator cuff originates.
This image, similar to the previous one, illustrates the scapula bone, but from the posterior view. From this vantage point, you can see the spine of the scapula which is where the posterior head of the deltoid originates. At the distal end of the scapular spine is the acromion.
The acromion is a process on the posterior side of the scapula which articulates with the clavicle at the acromioclavicular joint. There are two ligaments from the acromion. The first connects the acromion with the clavicle called the acromioclavicular ligament. The second connects the acromion to the coracoid process called the coracoclavicular ligament. The middle head of the deltoid has its origin on the acromion. Above the spine of the scapula, is the supraspinous fossa where the supraspinatus muscle originates. Below the spine of the scapula is the infraspinous fossa where the infraspinatus muscle originates. |
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This image shows the scapula bone from the lateral side.
This angle allows the best view of the glenoid fossa. The glenoid fossa is an important structure because it is where the head of the humerus sits. This fossa is not very deep which helps allow great range of motion in the shoulder joint. This motion is limited by the rotator cuff muscles which function to create motion and keep the humerus from becoming dislocated from the joint.
This angle allows the best view of the glenoid fossa. The glenoid fossa is an important structure because it is where the head of the humerus sits. This fossa is not very deep which helps allow great range of motion in the shoulder joint. This motion is limited by the rotator cuff muscles which function to create motion and keep the humerus from becoming dislocated from the joint.
Humerus
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The third bone that makes up the shoulder complex is the humerus. The most important structure of the humerus, in regards to the shoulder complex, is the humeral head which sits within the glenoid fossa.
The humerus also serves as a great place for shoulder muscle insertions. The deltoid tuberosity is the location of insertion for the deltoid muscle. The greater tuberosity, also known as the greater tubercle, is the location of insertion for infraspinatus, pectoralis major, and teres minor. Finally, the lesser tuberosity, also known as the lesser tubercle, is the location of insertion for the subscapularis, supraspinatus, and teres major muscles.
The humerus also serves as a great place for shoulder muscle insertions. The deltoid tuberosity is the location of insertion for the deltoid muscle. The greater tuberosity, also known as the greater tubercle, is the location of insertion for infraspinatus, pectoralis major, and teres minor. Finally, the lesser tuberosity, also known as the lesser tubercle, is the location of insertion for the subscapularis, supraspinatus, and teres major muscles.