Joints and ligaments of the upper limb

Interclavicular ligament

The sternoclavicular junction is the primary point of bony interaction between the upper axial skeleton and the upper limb. As such, the ligaments associated with this articulation will be discussed. The first to be encountered is the interclavicular ligament. It attaches to the roughened upper border of the sternal end of the clavicle, crosses along the sternal notch and inserts on the same area of the contralateral clavicle.

Costoclavicular ligament

Emerging from a rough area on the ventral surface of the sternal end of the clavicle is the costoclavicular ligament. The inverted cone-shaped band helps to anchor the clavicle to the axial skeleton by inserting on the costal cartilage of the first rib.

Sternoclavicular ligaments

The anterior and posterior sternoclavicular ligaments also contribute to the stability of the sternoclavicular joint. Each one arises from the anterosuperior and posterosuperior (respectively) aspect of the sternal head of the clavicle and insert lateral to the jugular notch. While the posterior sternoclavicular ligament is relatively weaker than its anterior counterpart, both ligaments take an inferomedial course to insert in the manubrium.

For a quick recap, the ligaments of the pectoral girdle associated with the upper limb are the:

• Interclavicular Ligament
• Anterior Sternoclavicular Ligament
• Posterior Sternoclavicular Ligament
• Costoclavicular Ligament

Suprascapular ligament

The glenohumeral joint is the most mobile polyaxial joint in the body. Its articulating surface involves three bones – the scapula, acromion and humerus. The scapula has ligamentous attachments with the acromion and with other aspects of the scapula. The “intrascapular” attachments include the suprascapular (superior transverse scapular) ligament and the inconstant spinoglenoid (inferior transverse scapular) ligament. The suprascapular ligament extends from the medial aspect of the scapular notch on the superior surface of the scapula to the base of the coracoid process; thus converting it into the scapular foramen. The scapular foramen serves as a conduit for the suprascapular nerve, while the corresponding vasculature travels superior to the ligament.

Use the following mnemonic to easily remember the neurovasculature arrangement passing through the suprascapular notch.

Airforce above, Navy below

• Artery (suprascapular) runs above the ligament
• Nerve (suprascapular) runs below the ligament

Spinoglenoid ligament

On the other hand, the spinoglenoid ligament extends from the lateral aspect of the scapular spine to insert in the margin of the glenoid cavity. It also forms a conduit through which the suprascapular neurovasculature enters the infraspinous fossa.

Coracoacromial ligament

Arising near the clavicular articulating surface of the acromion is the coracoacromial ligament. It has its insertion along the lateral aspect of the coracoid process. It is a triangular ligament with its apex situated at its origin and the base along its insertion. The ligament subsequently forms the coracoacromial arch, which sits over the head of the humerus.

Coracoclavicular ligaments

The clavicle also articulates with the acromion (at its most lateral (acromial) end) and the coracoid process. The pair of ligaments known as the trapezoid (located anterolaterally) and conoid (located posteromedially) ligaments is collectively referred to as the coracoclavicular ligaments.

They attach the clavicle to the coracoid process of the scapula by extending from the medial region of the coracoid process to the lateral aspect of the subclavian groove (on the clavicle).

Acromioclavicular ligament

The quadrangular acromioclavicular ligament arises from the superior part of acromial end of the clavicle and attaches to the superior aspect of the acromion, interlacing with the aponeuroses of deltoid and trapezius along the way.

Glenohumeral ligaments

Deep to the glenohumeral joint capsule is a group of three ligaments known as the glenohumeral ligaments. There is a superior, middle and inferior ligament that gives additional anteroinferior support to the joint capsule. Unlike traditional ligaments, the glenohumeral ligaments are not purely tensile. Instead, like reins used in horse racing to steer the horses, the tenacity of the ligaments change when the humerus is rotated or the shoulder is abducted.

The superior glenohumeral ligament has its attachments apically on the supraglenoid tubercle and medially on the lesser tubercle of the intertuberculous groove (bicipital sulcus). The middle glenohumeral ligament has its origin caudal to its previously mentioned counterpart, as well as along the anterior and inferior part of the glenoid rim. It subsequently attaches deep to subscapularis tendon on the lesser tubercle. The largest and longest of the three ligaments is the inferior glenohumeral ligament. It has a relatively wide range of attachment along the glenoid labrum and extends to the inferomedial part of the surgical neck of the humerus.

Coracohumeral ligament

The last two ligaments to be discussed are the coracohumeral and transverse humeral ligaments. Both are superficial with respect to the glenohumeral ligaments. The coracohumeral ligament consists of two bands that bridges the coracoid process (dorsolaterally at its base) to the lesser and greater humeral tubercles. Part of the ligament integrates with the superior glenohumeral ligament inferiorly, while another portion covers the biceps tendon anterior to the joint.

Transverse humeral ligament

The transverse humeral ligament transforms the bicipital groove into a canal as it travels in the groove, above the long biceps tendon.

Just to ensure everything is clear, the ligaments associated with the shoulder joint include the:

• Coracoacromial Ligament
• Superior Transverse Scapular Ligament
• Inferior Transverse Scapular Ligament
• Acromioclavicular Ligament
• Coracoclavicular Ligament
  • Trapezoid Part
  • Conoid Part
• Glenohumeral Ligaments
  • Superior
  • Middle and
  • Inferior
• Coracohumeral Ligament
• Transverse humeral ligament

Ulnar collateral ligament

At the humeroulnar joint, the ulnar collateral ligament is a three-part triangular structure whose anterior component is stronger and more taut than the posterior part. The anterior part attaches apically to the anterior surface of the medial epicondyle and basally at the medial coronoid margin.

On the other hand, the posterior part (of a similar shape) connects the back of the medial epicondyle to the medial part of the olecranon. The inferior part travels diagonally between the coronoid process and the olecranon above the trochlear notch (transforming it into the trochlear foramen).

Radial collateral ligament

The humeroradial articulation is stabilized by the radial collateral ligament. It is a ‘Y’ shaped structure that connects to the lateral epicondyle via the long arm of the ‘Y’, and the annular ligament of the radius by the short arms of the ‘Y’. Some fibers extend to the proximal portion of the supinator crest.

Annular ligament

Support to the proximal radioulnar joint is provided in part by the annular and quadrate ligaments. The annular ligament of the radius (as the name suggests) partly circumscribes the proximal head of the radius and inserts in the anterior and posterior margins of the radial notch of the ulnar at the points of discontinuity. Proximally, the annular border blends with the joint capsule, while distally it attaches to the neck of the radius.

Quadrate ligament

The quadrate ligament is a small structure that runs from the radial neck to the proximal area of the supinator fossa of the ulna. It is always taut when the forearm is supinating or pronating.

Palmar radioulnar ligament

At the distal articulation of the joint are three other ligamentous attachments that aids in stabilizing the joint. On the palmar surface of the wrist is the palmar radioulnar ligament. It is a narrow fibrous band that courses from the radial ulnar notch to the head of the ulna.

Dorsal radioulnar ligament

Dorsally, the dorsal radioulnar ligament also extends from the ulnar notch of the radius to the head of the ulna.

Articular disk

Finally, the triangular fibrocartilaginous articular disk extends via a thick base from the styloid process of the ulna to the radius (near the radiocarpal articulation). It is a biconcave band of tissue that gradually becomes thinner moving from its periphery to the center.

So let’s review the ligaments of the elbow one more time:

• Proximally
  • Ulnar Collateral Ligament
  • Radial Collateral Ligament
  • Annular Ligament Of Radius
  • Quadrate Ligament
• Distally
  • Palmar radioulnar ligament
  • Dorsal radioulnar ligament
  • Articular disk (triangular fibrocartilage)

Radioscaphocapitate ligament

A tripartite ligament arising for the styloid process and palmar lip of the radius is the radioscaphocapitate ligament, which be observed on the palmar surface of the wrist. The first band is relatively short and inserts into the proximal aspect of the scaphoid bone, while the second extends further to attach to the distal pole of the same bone. The third part however, traverses the proximal pole of the scaphoid to insert in the capitate bone, while contributing to the formation of the arcuate ligament of the palmar surface of the capitate bone.

Long radiolunate ligament

Another ligament arises from the palmar lip of the radius next to the radioscaphocapitate ligament, known as the long radiolunate ligament, traverses the scaphoid bone in order to insert in the palmar horn of the lunate bone. It is distinctly separated from the radioscaphocapitate ligament and as such, an obvious space called the interligamentous sulcus (which is continuous with the space of Poirier between the inferior border of the radioscaphocapitate ligament and the palmar horn of the lunate) can be seen.

Short radiolunate ligament

The palmar lip of the lunate fossa of the radius serves as a point of origin for the short radiolunate ligament. It subsequently inserts in the palmar horn of the lunate bone.

Palmar ulnocarpal ligaments

The palmar ulnocarpal group of ligaments include the ulnotriquetral, ulnocapitate and ulnolunate ligaments. As implied by the nomenclature, these ligaments help to stabilize the triquetrum, lunate and capitate bones by anchoring them to the palmar region of the ulna. The ulnotriquetral ligament inserts on the medial side of the triquetrum, while the ulnolunate ligament attaches to the palmar horn of the lunate. The latter also contributes to the formation of the arcuate ligament.

Intrinsic carpal ligaments

The intrinsic carpal ligaments are further sub classified as proximal and distal interosseous and palmar and dorsal midcarpal ligaments. Not only do they offer stability to the carpal bones, but in some instances they act as partitioning barriers that create the different hand spaces. The proximal row of interosseous ligaments is integral in the hinge mechanism observed with flexion and extension of at the carpometacarpal junctions. The distal row of interosseous ligaments is stronger than those of the proximal row and as such, they are less susceptible to injury than the proximal ligaments.

Dorsal ligaments

The ligaments of the dorsum of the hand are thinner and more superficial than those on the palmar region. Additionally, the ligaments are arranged in a ‘Z’ pattern, with the dorsal intercarpal ligament superiorly, the dorsal radiocarpal ligament in the middle, and the dorsal radioulnotriquetral ligament inferiorly.  

So the take home message for the ligaments of the palmar aspect of the wrist is that they can be divided into two groups:

• Palmar
  • Extrinsic:
    • Radioscaphocapitate Ligament
    • Palmar Radiolunate Ligament
    • Long Radiolunate Ligament
    • Short Radiolunate Ligament
    • Palmar Ulnocarpal Ligaments
      • Ulnotriquetral
      • Ulnocapitate
      • Ulnolunate
  • Intrinsic:
    • Proximal Row Interosseus Ligaments
      • Lunotriequetral Ligament
      • Scapholunate Ligament
    • Palmar Midcarpal Ligaments
      • Scaphotrapeziotrapezoid Ligament
      • Scaphocapitate Ligament
      • Triquetrohamate Ligament
      • Trapeziocapitate Ligament
    • Distal Row Interosseous Ligaments
      • Capitohamate Ligament
      • Trapeziotrapezoid Ligament
      • Pisometacarpal Ligament
      • Pisohamate Ligament
      • Triquetrocapitate Ligament
• Dorsal
  • Dorsal Radiolunotriquetral Ligament
  • Dorsal Radial Metaphyseal Arcuate Ligament
  • Dorsal Radiocarpal Ligament
  • Dorsal Intercarpal Ligament