Simone Lawson
The pectoral girdle is a part of the human skeleton that connects the upper limbs to the trunk. It is composed of two bones: the clavicle (collarbone) and the scapula (shoulder blade). The clavicle is an S-shaped bone that lies horizontally across the upper chest, connecting to the sternum (breastbone) at its medial end and the scapula at its lateral end. The scapula is a flat, triangular-shaped bone located at the back of the shoulder, providing structural support and facilitating movement of the upper limbs. Together, the clavicle and scapula enable essential functions such as lifting, throwing, and pushing.
| Characteristics | Values |
|---|---|
| Composition | Clavicle (collarbone) and scapula (shoulder blade) |
| Clavicle shape | S-shaped |
| Clavicle location | Anterior side of the shoulder |
| Clavicle function | Provides structural support for the shoulder and transmits forces from the upper limb to the sternum and axial skeleton |
| Scapula shape | Flat and triangular |
| Scapula location | Posterior side of the shoulder |
| Scapula function | Anchors the upper limb to the body |
| Joint | Acromioclavicular joint formed by the articulation of the clavicle and scapula |
| Ligament | Coracoclavicular ligament provides support for the acromioclavicular joint |
| Injury | Clavicle fracture is a common injury caused by a fall onto an outstretched hand |
Explore related products
What You'll Learn
The clavicle (collarbone)
The clavicle, or collarbone, is a thin, slightly curved bone that connects the sternum (breastbone) to the scapula (shoulder blade). It is located at the base of the neck and runs horizontally across the upper chest, with one clavicle on each side. The medial (central) end of the clavicle articulates with the sternum, forming the sternoclavicular joint, while the lateral end joins with the scapula just above the shoulder joint. This lateral articulation is known as the acromioclavicular joint and is supported by ligaments, including the coracoclavicular and acromioclavicular ligaments.
The clavicle plays a crucial role in shoulder and arm movement, providing stability and support for the shoulder joint. It helps to keep the scapula in the correct position during movement and transmits forces acting on the upper limb to the sternum and axial skeleton. Additionally, the clavicle protects the underlying nerves and blood vessels as they pass between the trunk and the upper limb.
The clavicle is one of the most commonly fractured bones due to its thin structure and proximity to the skin. Clavicle fractures often occur when an individual falls on their outstretched hand or shoulder, transmitting a significant force through the scapula to the clavicle, causing it to break. Treatment for a fractured clavicle typically involves wearing a sling to immobilize the arm and shoulder, allowing the bone to heal. In some cases, surgery may be required to realign the clavicle and hold the bone fragments in place with metal plates and screws.
The clavicle is derived from the Latin word "clavicula," meaning "little key," as the bone resembles an old-fashioned key in shape. It is one of the bones that constitute the pectoral girdle, along with the scapula. The pectoral girdle is the bony structure on either side of the body that connects the upper limbs to the axial skeleton, providing structural and functional support for the shoulders.
Stapling Documents: A Single Contract or Separate Agreements?
You may want to see also
The scapula (shoulder blade)
The scapula, commonly known as the shoulder blade, is a flat, triangular bone located at the back of the shoulder. It is one of three bones that make up the shoulder joint, along with the clavicle (or collarbone) and the humerus (upper arm bone). The scapula forms part of the shoulder's socket and enables movement and use of the shoulder.
The scapula is surrounded and supported by a complex system of muscles, tendons, and ligaments that work together to facilitate arm movement. These include the muscles of the rotator cuff (subscapularis, supraspinatus, infraspinatus, and teres minor), as well as the biceps, triceps, and deltoid muscles. The scapula is also connected to nerves, with the clavicle serving to protect the underlying nerves and blood vessels as they pass between the trunk and the upper limb.
The scapula has three surfaces: the costal (anterior) surface, the lateral surface, and the posterior (inferior) surface. The costal surface, which faces the rib cage, features a slightly indented cup (the subscapular fossa) that supports one of the rotator cuff muscles. The lateral surface includes the glenoid fossa, an indentation that forms the back of the shoulder socket. The scapula's triangular shape gives rise to three borders: the superior border, the medial border, and the lateral border.
The scapula plays a crucial role in anchoring the upper limb to the body. It articulates with the clavicle, forming the acromioclavicular joint, which helps form the upper part of the shoulder socket. This articulation is supported by ligaments such as the coracoclavicular and acromioclavicular ligaments. The clavicle braces the shoulder, distributing weight from the arm and shoulder to the axial skeleton, while the scapula provides structural and functional support for the shoulder.
The scapula is susceptible to injuries, and alterations in its positioning or motion can affect arm movement. A common condition is scapular dyskinesis, which can cause weakness in the affected arm, fatigue with repetitive activities, and a limited range of motion. Treatment for scapular disorders typically involves physical therapy to strengthen the muscles and restore proper scapular positioning and motion.
Fed Action: What Policy Does It Constitute?
You may want to see also
The humerus (arm bone)
The humerus is a long bone in the upper arm that runs from the shoulder to the elbow. It is the largest bone in the upper extremity and is one of the longest bones in the body. The bone connects the scapula (shoulder blade) to the two bones of the lower arm, the radius and ulna. The humerus is divided into three sections: the upper extremity, the shaft, and the lower extremity.
The upper extremity of the humerus consists of a rounded head, a narrow neck, and two short processes called tubercles (sometimes referred to as tuberosities). The head of the humerus articulates with the glenoid cavity on the scapula, forming a ball-and-socket joint known as the glenohumeral joint. This joint allows for a large range of motion in the shoulder. The anatomical neck of the humerus is an indentation distal to the head, and it is a common site of fracture. Below the head of the humerus are the greater and lesser tubercles, which serve as attachment points for muscles such as the supraspinatus, infraspinatus, teres minor, and subscapularis. These muscles help with movements like abduction and extension of the shoulder.
The shaft of the humerus is cylindrical in its upper portion and more prismatic towards the lower end. It contains a deltoid tubercle on its lateral aspect and a radial groove on its posterior aspect, also known as the spiral groove. The shaft is prone to fractures, especially in its narrow middle portion known as the surgical neck.
The lower extremity of the humerus consists of two epicondyles, two processes (trochlea and capitulum), and three fossae (radial fossa, coronoid fossa, and olecranon fossa). The distal humerus articulates with the radius and ulna at the elbow joint, forming a hinge joint that allows for flexion and extension of the forearm. The ulnar nerve is located at the distal end of the humerus near the elbow, and it is commonly referred to as the "funny bone" due to the tingling sensation felt when struck.
The humerus plays a crucial role in providing structural support and serving as an insertion point for many important muscles, including the pectoralis major ("pecs"), latissimus dorsi ("lats"), deltoids, and several other muscles that provide motion for the arm and upper body. Additionally, the humerus is associated with various medical conditions, such as humerus varus, Charcot arthropathy, osteochondrosis, and proximal humeral fractures, especially in elderly individuals who fall on their outstretched arms.
The US Constitution: Political Parties' Legal Status
You may want to see also
Explore related products
The acromioclavicular joint
The AC joint is a planar joint, allowing two bones to glide smoothly past each other. It helps in the rotation of the shoulder and enables movements such as tilting the arms up and down and moving them front to back. The AC joint is also responsible for transmitting forces from the upper arm to the rest of the skeleton. This transmission of forces is an important protective mechanism, as it helps distribute impact forces away from vulnerable underlying blood vessels and nerves.
The AC joint is supported and stabilized by several ligaments, including the coracoclavicular and acromioclavicular ligaments. The coracoclavicular ligament complex consists of the conoid and trapezoid ligaments, which provide vertical stability and contribute to the overall stability of the AC joint. The acromioclavicular ligament, on the other hand, reinforces the joint capsule and restricts certain movements, such as anterior-posterior translation and posterior axial rotation.
Injuries to the AC joint are common and can result from sports, accidents, or falls on an outstretched hand or elbow. These injuries can range from sprains to frank tears and may occasionally require surgery. AC joint arthritis can also develop, although it may not always cause noticeable symptoms. Due to the complexity of the shoulder joint and the surrounding anatomy, it can be challenging to pinpoint the exact source of shoulder pain. Therefore, it is important to seek medical advice for proper evaluation and treatment.
In summary, the acromioclavicular joint is an important component of the shoulder, facilitating stability and movement. It is supported by several ligaments and plays a key role in transmitting forces throughout the skeleton. The AC joint is susceptible to various injuries, which can be managed through conservative treatment or, in more severe cases, surgical intervention.
The Constitution: Supreme Law of the Land?
You may want to see also
The sternoclavicular joint
The vascular supply of the sternoclavicular joint comes from the internal thoracic artery and the suprascapular artery, which are branches of the subclavian artery. The joint is directly innervated by the medial supraclavicular nerve (C3-C4) and the nerve to the subclavius (C5-C6).
While injuries to the sternoclavicular joint are not common, they typically result from high-energy injuries such as motor vehicle collisions or contact sports. Most injuries are relatively minor and do not require surgery. However, a hard blow to the shoulder can, in rare cases, damage the vital organs and tissues nearby, such as the main blood vessels from the heart, the trachea, and the oesophagus. This type of injury requires immediate medical attention.
Corporate Power: Australia's Constitutional Conundrum
You may want to see also
Frequently asked questions
The pectoral girdle consists of the clavicle (collarbone) and the scapula (shoulder blade).
The pectoral girdle provides attachment points for the upper limbs to the axial skeleton, allowing for extensive mobility of the shoulder and upper limb.
The pectoral girdle is susceptible to injuries, particularly fractures of the clavicle, which can occur from a hard fall onto an outstretched hand. The force from the fall is transmitted through the scapula to the clavicle, causing a fracture.
The clavicle is an S-shaped bone located on the anterior side of the shoulder, while the scapula is a flat, triangular-shaped bone located on the posterior side. The clavicle is attached to the sternum of the thoracic cage, while the scapula articulates with the humerus (upper arm bone) to form the shoulder joint.
