The clavicle has multiple attachments for musculature that should be considered anatomically.  

• Superior surface: The anterior deltoid originates on the anterior aspect and assists in flexion of the shoulder while one of the insertion sites for the trapezius muscle is located at the posterior aspect. The trapezius predominantly is responsible for stabilizing the scapula.[12]
• inferior surface: The subclavius muscle resides in the subclavian groove of the clavicle and functions to depress the shoulder as well as pull the clavicle anteroinferiorly. The coracoacromial ligament is located laterally and provides support from the coracoid residing below. The medial component of the CA ligament is the conoid ligament which inserts onto the conoid tubercle, and the lateral component is the trapezoid ligament which inserts onto the trapezoid line.
• Anterior surface: The clavicular part of the pectoralis major muscle originates from the medial clavicle anteriorly. The clavicular head contributes to flexion, horizontal adduction, and inward rotation of the humerus.
• Posterior surface: As mentioned, the trapezius inserts posterosuperior on the clavicle. The clavicular head of the sternocleidomastoid (SCM) also has a similar location but is found along the medial third of the clavicle. The SCM, when contracting alone, causes the head to rotate to the opposite side and laterally side bend ipsilaterally. When both SCM contract, this causes head flexion.

The sternohyoid muscle has fibers originating inferomedially along the posterior surface of the clavicle in addition to the manubrium and posterior sternoclavicular ligament. Contraction of the sternohyoid causes hyoid bone depression.

Compared to other long bones, the clavicle has shown to exhibit varying features. Thickness and length can both vary depending on the sex, with males having longer and thicker bone morphology than females. Males also have a greater degree of curvature in the bone compared to females. Cadaveric studies also revealed left clavicles were substantially longer than the contralateral.[13] A rare, but clinically relevant genetic disease, cleidocranial dysplasia, can present with absent or partially absent clavicles bilaterally. Dental abnormalities, delayed fontanel closure, and cranial sutures that have failed to fuse are other features that can be present in this disease.[14]

One of the most common fractures to occur is a clavicular fracture, more typically in the middle third of the bone. While most medial and lateral fractures can be managed non-operatively if they remain stable, mid-shaft fractures can potentially have a higher degree of displacement with an increased incidence of malunion or non-union. Depending on the displacement and possible shortening of the involved fragments, surgery may be warranted. Additionally, neurovascular compromise may also be an indication for operative management. Pediatric injury typically occurs in physeal regions of the clavicle, and due to the healing potential of these regions, non-operative treatment can be pursued.[15] 

Operative management has shown to improve short-term functional outcomes; however, long-term shoulder function difference compared to non-operative management has proven unremarkable. Open reduction with internal fixation using plate and screws as well as intramedullary nails have been used to reduce these fractures.[16] Increased patient satisfaction and earlier return to physical activity have been seen with surgical management when compared to the non-operative approach. Cost-effectiveness was also surprisingly advantageous for operative patients. Current recommendations suggest a patient-tailored approach when considering surgery which may involve multiple parameters.[17]

The mid-clavicular line is a landmark on the clavicle that is used for multiple reasons. This landmark provides a general location for cardiac apex beat as well as appreciating the liver size. It also can be used to locate the gallbladder which is located between the mid-clavicular line and transpyloric plane. Accurate location assessment can vary, however, depending on the user.[18] 

• Clavicle fractures are responsible for 10% of all fractures and are the most acute of issues when dealing with injuries of the clavicle.[19] Depending on comminution, displacement, and shortening, surgery may be warranted. The level of superior displacement of the medial fragment seen in midshaft fractures may be due to SCM tension leading to further instability. The injury typically occurs due to trauma, such as falling directly on the shoulder laterally in 87% of cases. The injury also may be a result of falling outward onto an outstretched hand or due to contact directed medially onto the clavicle.[19]
• AC joint (ACJ) dislocation is common in contact sports and represents 9% of all traumatic shoulder girdle injuries [20]. The joint injury can be appreciated via X-ray imaging and is classified into six types. The injury severity increases with injury type and is dependent on the amount of gapping between acromioclavicular articulation.[21] 
  • Type I and II injuries are managed nonoperatively.  The former manifest solely as ACJ tenderness but no instability.  Type II injuries exhibit horizontal instability only, as the ACJ is disrupted and coracoclavicular distance is increased by less than 25% compared to the contralateral extremity.
  • Type III injuries are often managed nonoperatively as well, albeit slightly more controversial.  For example, as surgical techniques have improved over the years, a survey of 28 Major League Baseball team orthopedic surgeons resulted in 72% (20/28) reporting nonoperative treatment as the preferred management modality [22].  Interestingly enough, the aforementioned study from 2018 closely echoed the previous classic report 20 years earlier from McFarland and colleagues, when 69% of team physicians reported favoring nonoperative management of type III AC separations [23].  Thirty years earlier, however, there was an overwhelming preference for treating acute, complete ACJ separation with surgical repair.  A study from the 1970s by Powers and Bach consisted of a163 chairmen-survey of United States orthopedic programs, with 92% advocated for surgical treatment [24].
  • Type IV injuries through VI are typically managed with surgery. [25]  Type IV consists of lateral clavicular posterior displacement through the trapezial fascia.  Type V is an increase in CC distance greater than 100% compared to the contralateral.  Type VI consists of inferior dislocation of the lateral clavicle (in the subacromial or subcoracoid positions)[25].
• AC joint osteoarthritis has multiple etiologies including degenerative, posttraumatic, septic, and inflammatory arthritis.  Being the most common disorder of the AC joint, it can be quite debilitating for patients in their daily activities, especially with overhead activity. Clinical management can consist of the use of anti-inflammatory medication, intra-articular injections, and physical therapy. If symptoms persist, some patients may be candidates for AC joint resection.[26]
• SC joint injuries can also occur; however, they are less common. Anterior dislocations can occur with an anterolateral loading of the distal clavicle; posterior dislocations occur with posterolateral loading. An even less common mechanism of posterior SC joint dislocation can be due to significant posteriorly directed force to the medial head of the clavicle. Females with ligamentous laxity have a higher incidence of SC joint injuries and can also be associated with trapezius nerve palsy.[27]