All posts by jtrister

By Jon Trister MD

Prolotherapy is an effective treatment for various wrist and hand issues associated with laxity, instability, and altered function in these areas. The following structures are commonly targeted for Prolotherapy injections:

Carpal Ligaments  

The carpal ligaments comprise both intrinsic (connecting carpal bones) and extrinsic (connecting forearm bones to carpal bones) structures.

Transverse Carpal Ligament (TCL)  

The TCL is a thick fibrous band that spans the volar aspect of the wrist, forming the roof of the carpal tunnel. It attaches medially to the pisiform and hook of the hamate, and laterally to the scaphoid tuberosity and trapezium. Its key functions include:

– Formation of the Carpal Tunnel: The TCL creates a fibro-osseous tunnel that houses the median nerve and flexor tendons, protecting these components from external forces while allowing for smooth tendon gliding during wrist and finger movements.

– Biomechanical Stability: The TCL stabilizes the carpal bones by maintaining their arch-like configuration, which helps distribute axial loads across the wrist during weight-bearing activities.

– Pulley Function: Acting as a pulley system for flexor tendons, it ensures efficient force transfer from forearm muscles to the fingers.

• Muscle Attachment Site: Portions of the thenar (e.g., abductor pollicis brevis) and hypothenar (e.g., flexor digiti minimi brevis) muscles originate from the TCL, contributing to movements of the thumb and little finger.

The transverse palmar ligament (also known as the deep transverse metacarpal ligament) and the carpal ligaments, including the transverse carpal ligament (TCL) and the palmar carpal ligament, play vital roles in maintaining the form and function of the wrist and hand. These ligaments provide stability, facilitate movement, and protect essential anatomical components such as nerves, tendons, and blood vessels.

Transverse Palmar Ligament  

The transverse palmar ligament (also known as the deep transverse metacarpal ligament)

The transverse palmar ligament connects the heads of the metacarpal bones of the second to fifth fingers on their palmar surfaces. It serves several important purposes:

– Stability of Metacarpophalangeal (MCP) Joints: It prevents excessive separation of the metacarpal heads during finger movements, ensuring proper alignment and stability of the MCP joints.

– Facilitation of Grip: By stabilizing the MCP joints, this ligament contributes to grip strength and precision during hand functions such as grasping or pinching.

– Protection of Soft Tissues: The ligament creates functional spaces that house blood vessels, nerves, and intrinsic hand muscles, shielding these structures during hand movements.

Functional Importance 

Together, these ligaments ensure:

1. Structural Integrity: They stabilize both the proximal (carpal) and distal (metacarpal) components of the wrist-hand complex.

2. Facilitation of Movement: They allow a wide range of wrist motions—flexion, extension, adduction, and abduction—while maintaining alignment.

3. Protection of Neurovascular Structures: By forming tunnels or compartments (such as the carpal tunnel), these ligaments shield critical nerves like the median nerve from compression or injury.

4. Force Transmission: They enable the efficient transfer of forces from forearm muscles to the fingers during activities that require strength or precision.

Damage or dysfunction in these ligaments can lead to conditions such as carpal tunnel syndrome (caused by compression of the median nerve due to TCL thickening) or instability in the MCP joints. Understanding the anatomy and biomechanics of these structures is crucial for accurately diagnosing and effectively treating wrist-related injuries.

The Supraspinatus muscle collaborates with several structures, including muscles and ligaments, to effectively stabilize and facilitate movement in the shoulder joint. Below is a detailed breakdown:

Muscles that Work with the Supraspinatus

1. Deltoid Muscle: The supraspinatus initiates arm abduction (0° to 15°) and works in concert with the deltoid to continue abduction beyond this range. As the angle increases, the deltoid becomes increasingly dominant in the abduction process.

2. Other Rotator Cuff Muscles:

   – Infraspinatus: Aids in external rotation and stabilizes the humeral head.

   – Teres Minor: Contributes to external rotation and stabilization of the humeral head.

   – Subscapularis: Helps stabilize the humeral head within the glenoid cavity, counteracting forces during movement.

Ligaments that Support the Supraspinatus

1.Inferior Glenohumeral Ligament (IGHL): Provides passive stabilization by limiting superior and anterior translation of the humeral head, enhancing the stabilizing role of the supraspinatus during abduction.

2. Coracohumeral Ligament: Assists in limiting inferior translation of the humeral head, especially when the arm is adducted, supporting the supraspinatus in maintaining joint stability.

Together, these muscles and ligaments ensure both dynamic and static stability of the shoulder joint while facilitating smooth movements such as abduction and external rotation.

The Subscapularis muscle, an essential component of the rotator cuff, also works synergistically with various muscles and ligaments to stabilize and facilitate movement in the shoulder joint.

Muscles that Work with the Subscapularis

1. Rotator Cuff Muscles:

   – Supraspinatus: Helps stabilize the humeral head within the glenoid fossa and complements the subscapularis during shoulder movements.

   – Infraspinatus and Teres Minor: Serve as antagonists to the subscapularis by providing external rotation, balancing its internal rotation force. Together, these muscles form a force couple that stabilizes the glenohumeral joint by compressing the humeral head into the glenoid cavity.

2. Latissimus Dorsi: Works synergistically with the subscapularis during internal rotation and adduction of the shoulder, particularly when the function of the subscapularis is compromised.

3. Pectoralis Major: Aids in internal rotation and adduction of the shoulder, complementing the subscapularis during these movements.

4. Deltoid (Anterior Fibers): Contributes to internal rotation alongside the subscapularis and assists in arm elevation.

Ligaments that Support the Subscapularis

1. Coracohumeral Ligament: Reinforces the area between the subscapularis and supraspinatus tendons, providing added stability to the anterior shoulder.

2. Glenohumeral Ligaments (especially the Anterior Band of IGHL): These ligaments limit excessive anterior translation of the humeral head, complementing the stabilizing role of the subscapularis during shoulder movements.

Functional Synergy

– The subscapularis primarily provides internal rotation and prevents anterior displacement of the humeral head while working in conjunction with other rotator cuff muscles to maintain dynamic stability.

– Additionally, it plays a role in “concavity compression,” where opposing forces from the subscapularis (anterior) and infraspinatus/teres minor (posterior) help stabilize the humeral head within the glenoid cavity.

In summary, the subscapularis muscle synergizes with the other rotator cuff muscles—particularly the supraspinatus, infraspinatus, and teres minor—as well as larger muscles such as the latissimus dorsi and pectoralis major. Ligaments like the coracohumeral and glenohumeral ligaments further support its stabilizing functions. Together, these structures ensure proper shoulder mechanics and joint stability during movement.

The Infraspinatus and Teres minor muscles.

This muscles are components of the rotator cuff, primarily function as external rotators of theshoulder joint. They collaborate with various other muscles and ligaments to stabilize and mobilize the shoulder joint effectively.

Synergistic Muscles

1. Rotator Cuff Muscles:

   – Supraspinatus: Initiates arm abduction and stabilizes the humeral head, complementing the actions of infraspinatus and teres minor by preventing superior translation of the humeral head.

   – Subscapularis: Provides anterior stabilization and counteracts excessive anterior displacement, coordinating with infraspinatus and teres minor to maintain joint stability during movement.

2. Deltoid Muscle: 

   – The deltoid works alongside the rotator cuff muscles during shoulder abduction. Infraspinatus and teres minor counterbalance the upward pull of the deltoid, preventing superior displacement of the humeral head.

3. Teres Major: 

   – Although not a rotator cuff muscle, teres major aids with shoulder adduction and internal rotation, complementing the stabilization provided by infraspinatus and teres minor.

4. Trapezius and Serratus Anterior: 

   – These muscles stabilize the scapula, providing an optimal base for infraspinatus and teres minor to act on the humerus effectively during external rotation and other movements.

Synergistic Ligaments

1. Glenohumeral Ligaments: 

   – The superior, middle, and inferior glenohumeral ligaments provide passive stability to the shoulder joint. They work alongside the active stabilization role of infraspinatus and teres minor to limit excessive translation of the humeral head.

2. Capsular Mechanoreceptors: 

   – Mechanoreceptors within the glenohumeral capsule interact with rotator cuff muscles through reflex arcs, enhancing their synergistic action to stabilize the joint during dynamic movements.

Functional Roles

– Infraspinatus and teres minor work together to externally rotate the humerus, stabilize the glenohumeral joint by compressing the humeral head into the glenoid cavity, and counteract anterior or superior translation forces during arm movements.

– During overhead activities, these muscles help clear the greater tuberosity from impinging under the coracoacromial arch by externally rotating the humerus.

In summary, infraspinatus and teres minor synergize with other rotator cuff muscles (such as supraspinatus and subscapularis), larger movers like the deltoid and trapezius, and passive stabilizers like the glenohumeral ligaments to guarantee stability, mobility, and proper biomechanics of the shoulder joint.

Key Components of the Elbow Joint

Bones: Humerus, Ulna, Radius 

Ligaments:

Ligaments are tough connective tissues that stabilize the elbow by connecting bones to bones. The primary ligaments of the elbow include:

• Medial (Ulnar) Collateral Ligament (MCL): Provides stability on the inner side of the elbow, resisting valgus forces.
• Lateral (Radial) Collateral Ligament (LCL): Stabilizes the outer side of the elbow, resisting varus forces.
• Annular Ligament: Encircles the radial head, holding it against the ulna and allowing smooth rotation during pronation and supination.
• Joint Capsule: A fibrous capsule reinforced by ligaments that encloses the elbow joint and contains synovial fluid for lubrication.

Tendons

• Biceps Tendon: Attaches the biceps muscle to the radius, enabling flexion and forearm supination.
• Triceps Tendon: Connects the triceps muscle to the ulna, enabling extension of the elbow.
• Forearm Muscle Tendons: Attach to the medial and lateral epicondyles of the humerus.

Muscles

Muscles crossing the elbow provide dynamic stability and enable movement:

• Biceps Brachii: Facilitates flexion and supination.
• Triceps Brachii: Enables extension.
• Forearm Flexors (e.g., Flexor Carpi Ulnaris): Attach to the medial epicondyle, aiding in wrist flexion.
• Forearm Extensors (e.g., Extensor Carpi Radialis Brevis): Attach to the lateral epicondyle, aiding in wrist extension.

Synergy Between Ligaments, Tendons, and Muscles

1. Stabilization:
   • Ligaments act as static stabilizers, maintaining joint congruency and preventing excessive motion. For example, collateral ligaments resist side-to-side instability during activities like throwing or lifting.
   • Muscles serve as dynamic stabilizers, contracting to counteract external forces. For instance, forearm muscles stabilize the elbow during gripping or lifting tasks.
2. Movement Coordination:
3. Tendons transmit muscular forces to bones, enabling precise movements such as flexion, extension, pronation, and supination. The biceps tendon works with the biceps muscle for bending and rotating the arm, while the triceps tendon facilitates straightening
4. Stress Dissipation:
5. The enthesis plays a important  role in dissipating mechanical stress. This reduces wear on individual structures during repetitive or high-stress activities such as throwing or lifting.
6. Load Sharing:
7. Structures like tendons and ligaments often merge or overlap at their attachment sites. For example, components of the lateral collateral ligament complex share loads with adjacent tendons like those of the extensor muscles.During dynamic activities like pitching or racquet sports, specific muscle groups (e.g., forearm flexors) activate to counteract valgus stress on ligaments like the MCL. This synergy minimizes strain on static stabilizers while maintaining joint integrity.

Clinical Implications

In summary, ligaments provide static stability while tendons and muscles dynamically control movement at the elbow joint. Their synergy ensures a balance between mobility and stability, enabling efficient function during complex activities while protecting against injury.

Supinator Muscle  and Ligaments in the elbow: functional synergy

The supinator muscle and the ligaments of the elbow joint work in functional synergy to enable and stabilize forearm supination, a key movement that rotates the palm upward. This coordination involves both dynamic and static elements, ensuring effective motion while maintaining joint integrity.

Supinator Muscle and Its Role

The supinator muscle is a spiral-shaped muscle located in the posterior forearm. It wraps around the proximal radius and is primarily responsible for forearm supination. Unlike the biceps brachii, which also assists in supination but requires a flexed elbow, the supinator can perform this action regardless of elbow position. It originates from multiple structures around the elbow, including:

• Lateral epicondyle of the humerus
• Radial collateral ligament
• Annular ligament
• Supinator crest of the ulna

Its insertion on the proximal radius allows it to rotate the radius laterally during supination. The muscle is innervated by the deep branch of the radial nerve (posterior interosseous nerve) and is most active during slow or unresisted supination, while the biceps brachii takes over during forceful or resisted movements.

Ligaments, Lateral elbow:

Several ligaments in the elbow joint contribute to stability during supination:

• Annular Ligament: Encircles the radial head, securing it against the ulna while allowing rotational movement. This ligament provides a stable axis for the radius to rotate during pronation and supination.
• Jaap van der Wal, a Dutch anatomist, provided a unique perspective on the anatomy of the annular radial ligament. According to his observations, the so-called “annular ligament” is not an independent structure as traditionally described in anatomy. Instead, Van der Wal argued that it is an integrated part of the aponeurotic connective tissue layer through which the fibers of the supinator muscle insert into the lateral epicondyle of the humerus. He suggested that most collagenous fibers in the proximal lateral cubital region are interposed between skeletal tissue and muscle fascicles, making it difficult to identify separate ligamentous entities such as the annular ligament or even the radial collateral ligament as distinct structures.
• Van der Wal’s connective tissue-focused dissections highlighted how these anatomical components are interconnected within the lateral ligamentous complex of the elbow. This perspective challenges traditional anatomical descriptions and underscores the functional integration of ligaments, muscles, and connective tissues in this region. His work sheds light on how these structures collectively contribute to elbow stability rather than functioning as isolated components
• Radial Collateral Ligament: Works with the annular ligament to stabilize lateral elbow structures and prevent excessive varus forces.
• Quadrate Ligament: Located distal to the annular ligament, it limits excessive supination and helps maintain alignment between the radial head and ulna.

Functional Synergy

1. Stabilization During Supination:
   • The annular ligament anchors the radial head, ensuring smooth rotation within the radial notch of the ulna.
   • The radial collateral ligament supports lateral stability, preventing dislocation or misalignment during rotational movements.
2. Force Transmission:
3. The supinator muscle generates rotational force on the radius for forearm supination. Its attachment to ligaments like the annular ligament integrates muscle action with ligamentous stability, ensuring efficient motion without compromising joint integrity.
4. Load Sharing:
5. The close anatomical relationship between the supinator muscle and ligaments like the annular ligament allows these structures to share mechanical loads. For instance, parts of the supinator originate from or are embedded in collagenous tissue associated with these ligaments, creating a functional unit that stabilizes and moves the joint simultaneously.
6. Prevention of Excessive Motion:
7. Ligaments such as the quadrate ligament act as passive restraints against excessive rotational forces, complementing the dynamic control provided by muscles like the supinator.
8. Developmental Interplay:
9. During fetal development, parts of the supinator muscle are closely integrated with collagenous tissue forming ligaments like the annular ligament. This suggests a developmental synergy where muscle contraction may influence ligament formation, although excessive ligament growth can impair some muscle fibers.

Clinical Relevance

The interplay between these structures highlights their importance in maintaining elbow function:

• Injuries to ligaments (e.g., annular ligament tears) or nerve compression affecting the supinator can impair forearm rotation.
• Conditions like “pulled elbow” (radial head subluxation) involve entrapment of structures such as the annular ligament and may disrupt normal synergy between muscles and ligaments.
• Rehabilitation often focuses on restoring both dynamic (muscle) and static (ligament) stability to ensure proper joint mechanics.

In summary, the supinator muscle works synergistically with elbow ligaments to facilitate controlled forearm supination while stabilizing joint structures. This collaboration ensures smooth movement and protects against injury during complex rotational tasks.

Mechanical properties of the skin are changed with time. Altered pre-stress changes first defenses of the immune system-physical barriers-Epidermis and dermal layers of the skin. Reduced functional capacity and increased susceptibility of the skin with development of dermatoses such as dry skin, itching, ulcers, dis-pigmentation,  wrinkles, fungal infections, as well as benign and malignant tumors are the most common skin conditions in aged population. In turn altered appearance, dry skin, chronic wounds, and other conditions decrease general health and reduce the likelihood for healthy and active aging. Ability of the skin to carry out multiple and wide-ranging roles is very closely related to its structure, which is composed of an outer epidermis overlying an inner dermis, separated by a basement membrane.

Relevant Histology:

Stratum Corneum

Stratum Granulosum

Stratum Spinosum

Stratum Basale

Skin perform barrier function for invaders:

Physical barriers: terminally differentiated epidermal keratinocytes. 

Biochemical barriers: acidic, hydrolipidic nature of the skin, as a result of sweat, sebum, lipids, and antimicrobial peptides (AMPs).Any changes in lipid composition and epidermal differentiation lead to a disturbed skin barrier, which plays a role in the pathogenesis of several immune-mediated skin  pathologies, such as atopic dermatitis and ichthyosis vulgaris .

The epidermis is a host to keratinocytes, melanocytes and immune cells such as Langerhans cells (LCs) and T lymphocytes, nerve-ending cells (Merkel cells).The dermis is composed of an upper papillary (stratum papillare) and lower reticular (stratum reticulare) dermis containing thin and thick collagen fibers, respectively. The collagen fibers offer a mechanical barrier as well as a structural environment  in which to host blood vessels and many immune cells such as dermal dendritic cells (DDCs), ab T cells, gd T cells, natural killer (NK) cells, B cells, mast cells, and macrophages can perform their function.

More recently, it was proposed a sentinel role in health and disease for a spectrum of skin-resident cells ( with keratinocytes involved in sensing pathogens and danger signals, migratory DCs capable of initiating a diverse range of immune responses, and tissue-resident memory T (Trm) cells performing crucial effector functions.

Skin-associated lymphoid tissue (SALT) participates in  trafficking of immune cells between the skin, draining lymph nodes (LNs), and the peripheral circulation (Streilein, 1983).