ECC Equine Anatomy & Physiology 2 — Questions and Answers
Question 1: Which ligament runs along the dorsal aspect of the equine spine and plays a key role in the 'bow and string' mechanism?
- Supraspinous ligament
- Interspinous ligament
- Ventral longitudinal ligament
- Nuchal ligament (Correct answer)
Correct answer: Nuchal ligament
The nuchal ligament forms the 'string' of the bow-and-string mechanism, storing elastic energy during locomotion to support the head and neck.
Question 2: The cervical vertebrae of the horse number how many, and which is the most mobile segment?
- 6 vertebrae; C5-C6
- 7 vertebrae; C2-C3 (Correct answer)
- 7 vertebrae; C5-C6
- 8 vertebrae; C3-C4
Correct answer: 7 vertebrae; C2-C3
Horses have 7 cervical vertebrae, and the C2-C3 (axis-third cervical) junction exhibits the greatest range of lateral flexion.
Question 3: What is the primary function of the interosseous muscle (suspensory ligament) in the equine distal limb?
- Actively flex the fetlock during breakover
- Passively support the fetlock against hyperextension (Correct answer)
- Rotate the coffin bone within the hoof capsule
- Stabilize the proximal sesamoid bones during lateral movements
Correct answer: Passively support the fetlock against hyperextension
The suspensory ligament is a largely fibrous structure that passively suspends the fetlock, preventing hyperextension under weight-bearing.
Question 4: Which thoracic vertebrae in the horse are known as the 'anticlinal vertebrae' and what is their significance?
- T8, where spinous processes are shortest
- T14-T16, where spinous processes change direction (Correct answer)
- T10, where the spine is most rigid
- T12, where costovertebral joints are absent
Correct answer: T14-T16, where spinous processes change direction
The anticlinal vertebrae (typically T14-T16) are where spinous processes transition from caudally inclined to vertically or cranially inclined, marking a biomechanical transition zone.
Question 5: The equine atlantoaxial joint primarily permits which type of movement?
- Lateral flexion
- Ventroflexion and dorsiflexion
- Axial rotation (Correct answer)
- Protraction and retraction
Correct answer: Axial rotation
The atlantoaxial joint (C1-C2) is a pivot joint that primarily allows axial rotation of the head and atlas around the dens of the axis.
Question 6: Which muscle group is primarily responsible for dorsiflexion (extension) of the equine thoracolumbar spine?
- Rectus abdominis and oblique abdominals
- Longissimus dorsi and multifidus (Correct answer)
- Iliopsoas and quadratus lumborum
- Biceps femoris and semitendinosus
Correct answer: Longissimus dorsi and multifidus
The longissimus dorsi and multifidus muscles run along the dorsal spine and contract to extend (dorsiflex) the thoracolumbar region.
Question 7: How many lumbar vertebrae does the horse typically have, and how does this compare to cattle?
- 5 lumbar vertebrae; same as cattle
- 6 lumbar vertebrae; cattle have 5
- 5 lumbar vertebrae; cattle have 6 (Correct answer)
- 6 lumbar vertebrae; same as cattle
Correct answer: 5 lumbar vertebrae; cattle have 6
Horses typically have 5 (sometimes 6) lumbar vertebrae, whereas cattle typically have 6, reflecting differences in lumbosacral conformation.
ECC Equine Anatomy & Physiology 2
Which ligament runs along the dorsal aspect of the equine spine and plays a key role in the 'bow and string' mechanism?