The Scapula: How It Can Make or Break You | Breaking Muscle
This consists of two bones, the scapula and clavicle (Figure 2). The clavicle ( collarbone) is an S-shaped bone located on the anterior side of the shoulder. The shoulder girdle consists of the scapula at the back and the clavicle anteriorly. The shoulder girdle is also referred to as the pectoral girdle. Together with the. The bones that attach each upper limb to the axial skeleton form the pectoral girdle (shoulder girdle). This consists of two bones, the scapula and clavicle ( Figure.
Cartilage can be hyaline, fibrocartilage and elastic and differ based on the proportions of collagen and elastin. Cartilage is a stiff but flexible tissue that is good with weight-bearing which is why it is found in our joints. Cartilage has almost no blood vessels and is very bad at repairing itself. Bone is full of blood vessels and is very good at self repair. It is the high water content that makes cartilage flexible. The muscles on the lateral side of the shoulder allow movement and stabilize the joint.
These muscles are strong on the upper and back sides of the arm, but not on the underside. A strong outside force in this area can cause the head of the humerus to slip out of the glenoid socket, called dislocation.
Since there is little bony stability in this joint, a number of ligaments and other soft tissues stabilize this joint. The superior AC ligament is the most important horizontal stabilizer. The coracoclavicular ligaments help stabilize the clavicle vertically.
The Sternoclavicular Joint SC Most of the rotation occurs at the sternoclavicular joint and joint stability comes from the soft tissues. The posterior sternoclavicular joint capsule is the most important structure for preventing forward and backward displacement of the medial clavicle. The Rotator Cuff The rotator cuff consists of four muscle-tendon units that originate on the scapula and attach to the tuberosities of the humerus. The rotator cuff is the primary stabilizer during movement of the GH joint.
Both overuse and traumatic injuries to the rotator cuff are the most common problems in the shoulder girdle. The Subacromial Space The subacromial space is beneath the acromion and above the rotator cuff.
The subacromial bursa outlines this space and provides frictionless gliding of the rotator cuff beneath the arch formed by the acromion and coracoacromion.
Bone spurs on the underside of the acromion narrow this space, irritate the bursa and contribute to tears in the rotator cuff. Bones of the Shoulder Girdle Click on image for larger labeled, picture.
The bones of the shoulder girdle include the humerus, the scapula, and the clavicle. There are four articulations movements in the shoulder named for their anatomic locations: The scapula is the most complex of the bones in the shoulder and is part of the shoulder girdle.
The scapula floats on the rib cage, and is attached to it only with muscles.
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There are three landmarks on the scapula; the spine, acromion and coracoid processes. The roof of the glenohumeral joint is formed by the acromion. The acromion articulates with the clavicle forming the acromioclavicular AC joint.
A spine divides the back of the scapula into two sections. The muscles that attach below this spine are called infraspinatus muscles; the ones that attach above this spine are called supraspinatus muscles.
The Pectoral Girdle | Anatomy & Physiology
The humerus is the ball part of the ball-and-socket joint. The head ball of the humerus articulates within the glenoid fossa. Below the humeral head is the anatomic neck which separates the head ball from the tuberosities. Each tuberosity provides a place for the attachment for the anterior muscles of the rotator cuff—the 4 rotator cuff muscles originate from the scapula and their tendons attach at the humerus.
The bicipital groove separates the tuberosities. Just below the tuberosities is the surgical neck of the humerus and is the most common area for fractures of the proximal humerus. Clavicle Shoulder Blade — lateral view Clavicle collar bone. The clavicle originates at the sternum breastbone just above the first rib, and is held in place by the acromioclavicular ligament, several muscles and the coracoclavicular ligament.
The clavicle helps hold the shoulder out to the side while allowing the scapula to move around. Shoulder Ligaments Click on image to see larger picture. There are several important ligaments about the shoulder girdle. Ligaments are soft tissue structures that connect bones to bones.
Ligaments are strong, tough bands that are not particularly flexible. Once stretched, they tend to stay stretched and if stretched too far, they snap. Ligaments, along with muscles and tendons, are the main source of stability for the shoulder. Shoulder ligaments also form the joint capsule that surround the glenohumeral joint.
These passive stabilizers serve to keep the joints of the shoulder from dislocating. It's the articular surface for the shoulder joint. Above and below the glenoid fossa are the supraglenoid tubercle, and the infraglenoid tubercle, where two tendons are attached, as we'll see.
A prominent bony ridge, the spine A prominent bony ridge, the spine of the scapula, arises from the dorsal surface, and divides it into the supraspinous fossa, and the infraspinous fossa. At its lateral end the spine gives rise to this flat, angulated projection, the acromion, which stands completely clear of the bone. The clavicle articulates with the scapula here, at the tip of the acromion. This other projection, looking like a bent finger, is the coracoid process.
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- The Scapula: How It Can Make or Break You
Here's how the clavicle and the scapula look in the living body. Round the edge of the shallow glenoid fossa, a rim of fibrocartiilage, the glenoid labrum, makes the socket of the shoulder joint both wider and deeper.Scapula and Clavicle - Shoulder Girdle - Anatomy Tutorial
This flat ligament, the coraco-acromial ligament, joins the coracoid process to the acromion. Here's the acromio-clavicular joint. Two strong ligaments, the trapezoid in front and the conoid behind, fix the underside of the clavicle to the coracoid process. There's very little movement at the acromio-clavicular joint.
As we've seen, the medial end of the clavicle articulates with the sternum at the sterno-clavicular joint. Strong ligaments between the clavicle and the sternum, and between the clavicle and the underlying first rib, keep the two bones together but permit an impresssive range of motion: