Clavicle Bone Anatomy Animation : Bony landmarks and Development

Summary

The clavicle, or collarbone, is a unique horizontal long bone located at the neck's root, forming part of the shoulder girdle. It's the first bone to ossify and has no medullary cavity. The clavicle's functions include keeping the arm away from the trunk for free movement and transmitting weight from the upper limb to the trunk. It features the sternal and acromial ends, with the latter articulating with the scapula. The bone develops from three centers of ossification, fusing by the mid-twenties.

Takeaways

• 🦴 The clavicle, also known as the collar bone, is a long bone that lies horizontally in front of the neck.
• 🔒 It plays a crucial role in the formation of the shoulder girdle and is the only long bone in the body that is subcutaneous.
• 🌀 The clavicle's unique feature is the absence of a medullary cavity.
• 🚫 It prevents the arm from swinging into the trunk, allowing free movement without contact.
• 🏋️‍♂️ It helps transmit weight from the upper limb to the trunk and assists in arm movement above shoulder level.
• 📏 The clavicle is divided into the shaft, acromial end, and sternal end, with the shaft further divided into lateral and medial thirds.
• 🔍 The lateral third has two surfaces and two borders, with the superior surface being subcutaneous and the inferior surface rough.
• 🔗 The medial two-thirds have four surfaces, including a rough and convex anterior surface and a smooth and concave posterior surface.
• 🔑 The acromial end is flat with an oval facet that articulates with the acromium process of the scapula.
• 📐 The sternal end is quadrangular, articulating with the clavicular notch of the manubrium sterni.
• 📈 The clavicle ossifies from three centers: two primary centers in the shaft and one secondary center, with fusion complete by the 25th year.

Q & A

What is the clavicle also known as?

The clavicle is also known as the collar bone.

What is the primary function of the clavicle?

The clavicle's primary function is to keep the arm away from the trunk, allowing it to swing freely without coming into contact with the trunk, and to transmit weight from the upper limb to the trunk.

How is the clavicle positioned in the body?

The clavicle lies horizontally in front of the root of the neck and is part of the shoulder girdle.

What makes the clavicle unique among long bones?

The clavicle is unique because it has no medullary cavity and is the only long bone in the body that lies horizontally.

What are the three main parts of the clavicle?

The clavicle consists of the shaft, the acromial end, and the sternal end.

How is the lateral 1/3 of the clavicle's shaft described?

The lateral 1/3 of the clavicle's shaft presents with two surfaces and two borders, with a subcutaneous superior surface, a rough inferior surface with the conoid tubercle, and a concave anterior border bearing the deltoid tubercle.

What is the significance of the trapezoid line on the clavicle?

The trapezoid line is an oblique ridge on the clavicle that runs forwards and laterally towards the acromial end, giving attachment to the trapezoid part of the coracoclavicular ligament.

What does the medial 2/3 of the clavicle's shaft present?

The medial 2/3 of the clavicle's shaft presents with four surfaces, including a rough and convex anterior surface, a smooth and concave posterior surface, and an inferior surface with the costal impression.

How does the acromial end of the clavicle articulate with the scapula?

The acromial end of the clavicle is flat and has an oval facet that articulates with the clavicular facet on the acromion process of the scapula.

What is the shape of the sternal end of the clavicle?

The sternal end of the clavicle is quadrangular and articulates with the clavicular notch of the manubrium sterni.

How can you determine the side of the clavicle?

The flattened acromial end is on the lateral side, the rounded sternal end is on the medial side, and the shaft is convex forwards in the medial 2/3 and concave forwards in the lateral 1/3.

How does the clavicle grow and develop during intrauterine life?

The clavicle starts to ossify from three centers: two primary centers in the medial and lateral regions of the shaft that begin to ossify by the fifth to sixth week of intrauterine life and fuse by the 45th day, and one secondary center that starts to ossify by 18 to 20 weeks of intrauterine life and fuses by the 25th year.