Comprehensive Anatomy and Clinical Insights of Clavicle and Scapula.

  

 

The upper limbs have up to 64 of the 206 bones in the human body. There are 32 bones on each side, which is the distribution. Only 32 of the 64 bones in total need to be learned because the bones of the two upper limbs are similar. This also holds true for supple areas. Only one upper limb is taught; the other upper limb develops on its own. This applies to the entire body, with the exception of the abdomen. In actuality, only 50% of the body needs to be mastered; the remaining 50% learns this on its own. We shall go over each of the upper limb's bones individually. Before beginning the dissection of the relevant portion, their features and attachments should be compared to the bones. The attachments paragraphs ought to be updated upon the completion of a specific region's dissection.

CLAVICLE

The clavicle is a long bone, meaning "small key" in Latin. It provides shoulder support, allowing the arm to swing freely away from the trunk. The weight of the limb is transferred from the clavicle to the sternum. The lateral and medial ends of the bone are joined by a curved section known as the shaft.

Determination of the Side

The following characters indicate which side of the body a clavicle belongs to.

1. The medial end is broad and quadrilateral, whereas the lateral end is flat.
2. The shaft has a modest curvature, with its medial two-thirds convex and its lateral one-third concave forwards.
3. The center third of the inferior surface has a longitudinal groove.

Strangeness’s in the Clavicle

• The only long bone with horizontal orientation is this one.
• The entire thing is subcutaneous.
• It is the initial bone to begin ossification.
• The ossification of a long bone in a membrane is unique to it.
• It is the only long bone with two main ossification centers.
• There is no medullary cavity.
• Occasionally, the middle supraclavicular nerve pierces it.
• It transfers the weight of the upper limb to the axial skeleton via the medial two-thirds portion after receiving the lateral one-third through the coracoclavicular ligament.

Characteristics

Shaft

There are two halves to the shaft: the medial two-thirds and the lateral one-third.
The lateral portion of the shaft is compressed downward from above. Its anterior and posterior margins are two. The front edge has a forward concavity. The rear border of the posterior region is convex. There are two surfaces on this portion of the bone: superior and inferior. The inferior surface has a ridge known as the trapezoid ridge and an elevation known as the conoid (Greek cone) tubercle. The superior surface is subcutaneous.

There are four surfaces in the rounded medial two-thirds of the shaft. The front surface has a forward convexity. The rear surface is flat. The medial portion of the superior surface is rough. At the medial end of the inferior surface, there is a rough oval indentation. This surface features a longitudinal subclavian groove on its lateral side. At the lateral end of the groove is the nutritional foramen.

Medial and Lateral Ends

1. The acromial, or lateral, end of the shoulder is flattened downward from above. It has a facet that forms the acromioclavicular joint by articulating with the scapula's acromion process.
2. The sternoclavicular joint is formed by the articulation of the quadrangular medial or sternal end with the clavicular notch of the manubrium sterni. In order to articulate with the first costal cartilage, the articular surface extends to the inferior aspect.

Attachment

1. The joint capsule is attached to the lateral end of the articular surface of the acromioclavicular joint by its border.
2. At the medial end, the sternum's articular surface border provides connection to: 
   a. The sternoclavicular joint's whole fibrous capsule
   b. Superiorly, the articular disc;
   c. Superiorly, the interclavicular ligament.
3. The lateral third of the shaft
   a. The anterior boundary is where the deltoid muscle begins.
   b. The posterior border is where the trapezius muscle inserts.
   c. The conoid and trapezoid portions of the coracoclavicular ligament are attached to the conoid tubercle and trapezoid ridge.
   
   
   
4. Two-thirds of the shaft's middle
   a. The pectorals major derive from the majority of the anterior surface.
   b. It is the clavicular head of the sternocleidomastoid that originates from half of the rough superior surface.
   c. The costoclavicular ligament attaches to the inferior surface at the medial end through an oval indentation.
   d. The subclavius muscle inserts into the subclavian groove. The clavipectoral fascia is attached to the groove's edges.
   e. The sternohyoid muscle originates on the posterior side toward the medial end.
5. The subclavian vessels and the size of the brachial plexus trunks flow through the axilla, which is located between the first rib's upper side and the clavicle's inferior surface. The subclavius muscle serves as a support. A branch of the suprascapular artery is transmitted by the nutritional foramen.

Ossification

The clavicle is the body's first ossified bone. It ossifies in membrane except for its medial end. It ossifies from one minor center and two main centers.
Between the fifth and sixth weeks of intrauterine development, the two main centers form in the shaft. They merge about day forty-five. The medial end secondary center emerges between the ages of 15 and 17 and merges with the shaft between the ages of 21 and 22. Periodically, the acromial end could have a secondary center.

Anatomy in Clinical Practice

Falling onto an outstretched hand frequently results in a cracked collarbone (indirect violence). The weakest area of the bone, the intersection of its two curvatures, is where fractures most frequently occur. Because the trapezius muscle cannot sustain the weight of the upper limb on its own, the lateral fragment is forced downward by the weight of the limb. The condition known as cleidocranial dysostosis can cause the clavicles to develop incorrectly or not at all at birth. The shoulders droop in this condition, and they can be roughly measured anteriorly in front of the chest.

SCAPULA

Located on the posterolateral part of the thoracic cage, the scapula, also known as the Latin shoulder blade, is a slender bone. Three borders, three angles, two surfaces, and three processes make up the scapula.

Determination of the Side

• The glenoid cavity is located in the big lateral or glenoid (Greek socket) angle.
• The triangular spine separates the convex dorsal surface into the supraspinous and infraspinous fossae. The concave subscapular fossa occupies the costal surface in order to fit on the convex chest wall.
• From the inferior angle below to the glenoid cavity above, the thickest lateral border is seen.

Characteristics

Surfaces

1. The concave costal surface, also known as the subscapular fossa, faces medially and forward. Three longitudinal ridges identify it. The lateral border is adjacent to another thick ridge. This portion of the bone resembles a rod. When the arm is abducted overhead, it serves as a lever for the serratus anterior.
2. Attachment to the scapula's dorsal surface occurs via the spine, which separates the surface into a larger infraspinous fossa and a smaller supraspinous fossa. The spinoglenoid notch, which is located lateral to the spinal root, connects the two fossa.

Borders

Limitations

1. The border on top is the shortest. It exhibits the suprascapular notch close to the root of the coracoid process.
2. There is a thick lateral border. It displays the infraglenoid tubercle at the higher end.
3. There is a thin medial boundary. It reaches the inferior angle from the superior angle.

Angles

• The trapezius covers the superior angle.
• The latissimus dorsi covers the inferior angle. As soon as the arm is abducted, it advances and around the chest.
• The glenoid cavity, also known as the fossa, is located in the broad lateral or glenoid angle and faces forward, laterally, and slightly upward. Above the glenoid cavity, there is a supra-glenoid tubercle.

Procedures

• The spine, also known as the spinous process, is a triangular bone plate with two sides and three edges. It separates the supraspinous and infraspinous fossae from the scapula's dorsal surface. The crest of the spine is the term for its posterior edge. The lips on the crest are upper and lower.
• The acromion process has a facet for the clavicle, two surfaces superior and inferior and two borders medial and lateral.
• The coracoid process, which bears Greek resemblance to a crow's beak, faces forward and slightly laterally. It resembles a crooked finger. This particular epiphysis is atavistic.

Attachments

The medial two-thirds of the subscapular fossa give rise to the multipennate subscapularis muscle.

• The medial two-thirds of the supraspinous fossa, which includes the upper surface of the spine, give rise to the supraspinatus.
• The medial two-thirds of the infraspinous fossa, which includes the lower surface of the spine, give birth to the infraspinatus.
• The lateral border of the acromion and the lower border of the spinal crest are the sources of the deltoid. Acromial fibers have several pennants.
  
• The trapezius is inserted into the medial border of the acromion process and into the upper border of the spinal crest.
• One digitation from the superior angle to the spine's root, two digitations to the medial border, and five digitations to the inferior angle are where the serratus anterior is inserted along the costal surface's medial border.
• The biceps brachii's long head originates from the supraglenoid tubercle, while the short head originates from the lateral portion of the coracoid process' tip.
• The medial portion of the coracoid process tip is where the coracobrachialis originates.
• The superior surface and medial border of the coracoid process receive the insertion of the pectoralis minor.
• The infraglenoid tubercle gives birth to the triceps brachii's long head.
• Two slips from the top two-thirds of the rough strip on the dorsal surface along the lateral border give origin to the phrase. Scapula artery circumflex is located in between the two slips.
  
• On the dorsal face of the lateral border, the teres major originates from the lower third of the rough strip. The inferior angle gives rise to the latissimus dorsi.
• From the superior angle to the toot of the spine, the levator scapulae are inserted along the dorsal aspect of the medial border.
• The insertion of the rhomboid minor occurs on the dorsal aspect of the medial border, in opposition to the spinal root.
• Between the inferior angle and the root of the spine, at the medial border (dorsal aspect), is where the rhomboid major is inserted.
• The omohyoid inferior bells emerge from the upper border close to the suprascapular notch.
• The glenoid cavity edge provides connection to the glenoidal labrum and the shoulder capsule.
• The acromioclavicular joint capsule is attached to the facet's border on the medial aspect of the acromion process.
  
• The ligament coracoacromial is joined.
  (a) to the coracoid process's lateral edge
  (b) to the side of the acromion process that is medial.
• The coracoid process root is where the coracohumeral ligament is attached.
• The coracoid process is joined to the coracoclavicular ligament. The conoid portion close to the root and the trapezoid portion on the superior aspect.
• The suprascapular nerve is transmitted through a foramen formed by the transverse ligament, which spans the suprascapular notch. The ligament is situated above the suprascapular vessels.
• The notch in the spinoglenoid may be bridged by the spinoglenoid ligament. It is deeply penetrated by the suprascapular vessels and nerve.

Ossification

The scapula ossifies from one primary center and seven secondary centers. The first secondary center emerges in the middle of the coracoid process during the first year and fuses by the 15th year. The primary center appears at the glenoid cavity during the eighth week of development. By the sixteenth or eighteenth year, the sub coracoid center fuses, having first appeared in the coracoid process' root during the tenth year. 

The remaining centers, which include two for the acromion process, one for the medial border, one for the inferior angle, one for the lower two-thirds of the glenoid cavity boundary, and one for the medial border, emerge throughout puberty and unite by the time a person is 25 years old. The acromion process is the fact of practical significance. In the event that the two acromion process centers do not merge, a radiological examination could diagnose a fracture. In these situations, a radiograph of the opposing acromion process will typically show a comparable union failure.

Anatomy in Clinical Practice

Winging of the scapula is caused by paralysis of the serratus anterior. The arm cannot be abducted over 90 degrees because of the excessive prominence of the bone's medial border. The medial edge of the scaphoid scapula, a developmental abnormality, is concave.