Neck in Motion

Question 1

Describe the differences between Hyracotherium and the modern horse and the significance of these differences. (Lumbars, neck, hindlimbs, forearms, carpi, tarsi, toes)

Answer 1

• Lumbars – back flatter, transverse processes became larger/more lateral, stiff spine transfers energy better, better for running in straight lines, joint capsule smaller, decreased ROM
• Neck – longer
• Hindlimbs – shorter
• Forearm – longer, fused radius and ulna to prevent supination
• Carpi –
• Tarsi –
• Toes – regressed to one weight bearing digit

Question 2

Know the 3 types of neck and describe each.

Answer 2

1. Arched – medium primary curve, medium middle section and a short shallow secondary curve
2. Straight – medium primary curve, long middle, and short shallow secondary curve
3. Ewe – short primary curve, long middle, long deep secondary curve; tend to carry head higher/face in front of vertical

Question 3

Describe the motion of the head at a walk

Answer 3

Nose figure 8, move slightly side to side and C0-C1 slightly flex and extend

Question 4

What areas might be affected if a horse is reluctant to bring his nose down close to his fetlocks? (2)

Answer 4

Neck or back issue

Question 5

Know when the splenius, sternocephalicus and brachiocephalicus contract at a walk.

Answer 5

• Splenius – just before the beginning of the stance phase of each front limb
• Sternocephalicus – before and during the first half of the stance phase (reciprocal action to the splenius)
• Brachiocephalicus – ipsilaterally during the second half of the stance phase and during the suspension to protract the limb

Question 6

Know the motion and rotation of the head and neck during stance and suspension phases of the walk.

Answer 6

Stance – 1st part – neck and trunk rotate upward, middle – neck lowers, end – neck and trunk rotate downward

Suspension – neck comes up

Question 7

Know the effect of flexion and extension on the diameter of the spinal canal and the IVF.

Answer 7

Flexion – decreases diameter of spinal canal, increases diameter or IVF

Extension – decreases diameter of both the canal and the IVF

Question 8

Which muscle “flattens” the secondary curve?

Answer 8

Scalenus, Serratus Ventralis, Longus Colli

Question 9

Know the importance of using the scalenes instead of the brachiocephalicus and the sternocephalicus. (2)

Answer 9

Closes the airway and restricts the hyoid apparatus

Question 10

If the horse uses the brachiocephalicus and the sternocephalicus instead of the scalenes and the larynx is pushed into the base of the tongue, what other structures can be affected?

Answer 10

Hyoid restrictions, can lead to lesions of the TMJ which can lead to upper cervical lesions

Question 11

Know correct and incorrect appearance of the neck musculature

Answer 11

Countours should be smooth, muscles soft and relaxed, no sharp muscle definition

Question 12

Know correct and incorrect lateral bend.

Answer 12

Upper cervical restriction – tension lines, no lateral bend at C0-C1, head tilt

Lower cervical restriction – substituting rotation

Question 13

Flexion of the lower cervical involves (4) muscles

Answer 13

Scalenus
Longus colli
Sternocephalicus
Serratus ventralis

Question 14

Flexion of the upper cervicals involves (2) muscles

Answer 14

Longus capitus, Sternochephalicus

Question 15

Rotation of the neck involves (4) muscles

Answer 15

• Obliqus capitus cranialis and caudalis,
• rectus capitus lateralis, dorsalis
• major, brachicephalicus