Study sheet: Veterinary Musculoskeletal System

📋 Course Outline

1. Spinal Regions and Vertebrae
2. Horse Skeleton and Anatomical Terms
3. Bone Physiology and Remodeling
4. Muscle Tissue and Force Generation
5. Joint Types and Synovial Function
6. Connective Tissues and Locomotion
7. Veterinary Musculoskeletal Vocabulary

📖 1. Spinal Regions and Vertebrae

🔑 Key Concepts & Definitions

• Cervical vertebrae : the seven vertebrae in humans, dogs, and cats that support and rotate the skull and form the neck region

★ Must-know

• Thoracic vertebrae number 12 in humans and 13 in dogs and cats, articulate with the ribs, and have limited flexion.

• Lumbar vertebrae number five in humans and seven in dogs and cats, are large and weight-bearing, and permit the greatest range of flexion and extension.

📌 Sacral vertebrae are fused into the sacrum and connect the spine to the pelvic girdle, whereas caudal or coccygeal vertebrae are highly variable and form the tail in non-human mammals.

Further detail

• The intervertebral discs of the spine are cartilaginous joints.

💡 Memory Hook

Cervical → thoracic → lumbar → sacral → caudal

📖 2. Horse Skeleton and Anatomical Terms

★ Must-know

📌 The axial skeleton includes the neck vertebrae, ribs, and back vertebrae, whereas the appendicular skeleton includes the limb bones and the shoulder and pelvic girdles.

📌 The horse carpal joint is commonly called the knee, but its human anatomical equivalent is the wrist.

• 🔄 From proximal to distal, the bones are:
  1. cannon bone
  2. long pastern bone
  3. short pastern bone
  4. coffin bone

Further detail

• The horse sacrum is formed by five fused bones.

• In the horse forearm, the ulna is reduced in size and fused to the larger radius.

• The horse patella is the anatomical equivalent of the human kneecap, and the horse tibia is fused to the fibula in the lower hind leg.

💡 Memory Hook

Axial skeleton = central axis; appendicular skeleton = limbs and girdles

📖 3. Bone Physiology and Remodeling

🔑 Key Concepts & Definitions

• Cortical bone : the dense outer layer of bone that provides resistance to bending forces
• Trabecular bone : the lattice-like spongy bone inside the outer layer that dampens mechanical impacts
• Hematopoiesis : the formation of red blood cells, white blood cells, and platelets in bone marrow

📝 Essential Points

• Bone marrow acts as a reservoir for calcium and phosphorus homeostasis.

💡 Memory Hook

Remodeling and marrow activity → mechanical support, blood formation, and mineral homeostasis

📖 4. Muscle Tissue and Force Generation

🔑 Key Concepts & Definitions

• Skeletal muscle : voluntary, striated muscle whose organized actin and myosin proteins generate contraction for movement

★ Must-know

• The three types of muscle tissue are:
  • skeletal muscle
  • cardiac muscle
  • smooth muscle

📌 Muscles generate force by contracting and pulling rather than by actively pushing, so they operate in antagonistic pairs across joints.

• 🔄 During movement:
  1. the agonist contracts during flexion
  2. the antagonist relaxes during flexion
  3. the roles reverse during extension

Further detail

• Muscle contractions produce heat that helps keep the animal's body warm.

💡 Memory Hook

Agonist contracts while antagonist relaxes; extension reverses the roles

📖 5. Joint Types and Synovial Function

🔑 Key Concepts & Definitions

• Fibrous joint : an immovable joint held together by tough collagen, such as a skull suture
• Cartilaginous joint : a semi-flexible connection cushioned by cartilage, such as an intervertebral disc
• Synovial joint : a highly mobile articulation enclosed by a fibrous capsule and lined by a synovial membrane

📝 Essential Points

• 🔄 In a synovial joint:
  1. the synovial membrane secretes synovial fluid
  2. the fluid lubricates the joint
  3. friction is reduced
  4. hyaline cartilage is protected from wear

💡 Memory Hook

Fibrous joints are immovable, cartilaginous joints semi-flexible, and synovial joints highly mobile

📖 6. Connective Tissues and Locomotion

🔑 Key Concepts & Definitions

• Cartilage : an elastic connective tissue found at the ends of bones that protects articulations and also occurs in locations such as the tip of the nose
• Tendon : dense fibrous connective tissue made of parallel collagen fibers that anchors muscle to bone at the periosteum and stores elastic strain energy
• Ligament : tough, elastic connective tissue that links bone to bone and stabilizes the structural boundaries of a joint

📝 Essential Points

• Tendons release stored elastic strain energy during a stride to maximize locomotor energy efficiency.

💡 Memory Hook

Tendons connect muscle to bone, whereas ligaments connect bone to bone

📖 7. Veterinary Musculoskeletal Vocabulary

📝 Essential Points

• The plural of vertebra is vertebrae, and the adjective derived from vertebra is vertebral.

• The corresponding adjectives are:

  • cervical
  • thoracic
  • lumbar
  • caudal
  • sacral

📊 Synthesis Tables

Spinal Region Comparison

Region	Human vertebrae	Dog vertebrae	Cat vertebrae
Cervical	7	7	7
Thoracic	12	13	13
Lumbar	5	7	7
Sacral	5 fused	3 fused	3 fused
Caudal	3–5 fused	6–23	18–23

Joint Type Comparison

Joint type	Mobility	Held together by	Example
Fibrous	Immovable	Tough collagen	Skull sutures
Cartilaginous	Semi-flexible	Cartilage	Intervertebral discs
Synovial	Highly mobile	Joint capsule and synovial membrane	Shoulder, hip, and knee