8- Tendon Notes

Tendons

Function of Tendons

  • Tendons function to attach muscles to bone or cartilage.

  • Muscle attachments can vary considerably in shape and how they attach to bone, cartilage (or muscle).

    • They range from a flattened fibrous sheet (aponeurosis) to a fibrous cord-like structure (tendon).

Types of Tendons

  • Aponeurosis: A type of tendon consisting of fibrous connective tissue arranged as a thin sheet of tissue.

    • Serves as a wide attachment for muscles to bone or other muscles.

  • Raphe: A seam or line of union between halves of symmetrical parts.

    • Example: Dorsal raphe of the neck where several cervical muscles attach.

    • Example: Linea alba (white line) where the aponeuroses of the abdominal wall muscles meet.

Tendon Attachments

  • Tendon of origin (Proximal attachment): Usually the fixed point.

  • Tendon of insertion (Distal attachment): Usually the point moved by muscle contraction.

Characteristics of Tendons

  • Originates from the muscle, passes over a joint, and attaches to the bone.

  • Brilliant white color.

  • Great resistance to mechanical loads.

  • Low metabolic needs.

  • Poorly vascularized.

  • Do not hemorrhage when cut.

  • Damaged tendons are inevitably slow to heal.

  • A tendon is a dense, connective tissue structure.

Protection of Tendons

  • Tendons may be damaged by excessive pressure or friction, particularly when they change direction over bony prominences or are shifted over hard tissues.

  • Deep digital flexor tendon has a cushion when it glides over the distal sesamoid bone.

  • Tendon sheath: If a greater part of the circumference is vulnerable, the cushion wraps around the tendon.

  • Synovial bursa: Present only when one side of the tendon comes in contact with the bone.

  • Protective Structures:

    • Tendon

    • Bursa

    • Retinaculum

    • Tendon sheath

Tendon Injuries

  • Tendinopathies may be caused by several factors.

    • Intrinsic factors: Age, body weight, and nutrition.

    • Extrinsic factors: Often related to sports and include excessive forces or loading, poor training techniques, and environmental conditions.

  • Excessive tension can detach a fragment of bone at the insertion = avulsion

    • Old avulsion fracture of the calcaneus of a 6-year-old mare.

Treatment and Recovery

  • Tendon tissues have limited healing capacity.

  • Rehabilitation time: 8 to 16 months.

  • Treatment and recovery process:

    • Reducing inflammation with ice, bandages