System interaction for locomotion:

• Thoracic sling syncarcosis joint = rotation and sliding movements of the scapula.
• Weight of the forelimb is transmitted by = Serratus Ventralis muscle, Deep Pectoral muscles and Superficial Pectoral muscles.
• Thoracic sling superficial muscles = Trapezius, Omotransversarius, latissimus Dorsi, Brachiocephalicus and Superficial Pectoral muscles.
• Thoracic sling deep muscles = Rhomboideus, Deep Pectorals and Serratus Ventralis.
• Lumbosacral plexus = (L4, L5, L6, S1 + S2), controls hindlimb innervation.
• Femoral nerves = hip flexors and stifle extension.
• Obturator nerves = hip flexor and limb adductor.
• Ischiatic nerve = innervates hamstring group.
• Brachial plexus = (C6, C7, C8, T1 + T2), innervates forelimb.
• Median nerve = carpal and digital flexor muscles.
• Ulnar nerve = carpal and digital flexor muscles.
• Radial nerve = extensor muscles of the elbow, carpus and the digit.
• Subscapular nerve = subscapular muscle.
• Suprascapular nerve = supraspinatus and infraspinatus.
• Musculocutaneous nerve = pectorals and shoulder flexors.
• Axillary nerve = flexor muscles of the shoulder.
• Lumbosacral junction = hinge joint, dorsal spinous processes face caudally, diverticulum and 20 degrees flexion mainly in canter/gallop.
• Diverticulum = direction change.
• Sacroiliac joint = ilium to sacrum, synovial, ligamentous, strong and can't be separated.
• Axial skeleton muscles = numerous separate units, span between 2-6 vertebrae each, for posture and enables horses to use themselves correctly.
• Longissimus Dorsi = C5 to the sacrum/pelvis, longest muscle, top line importance, back extension and needs to be elongated.
• Longissimus Copitis = skull end.
• Longissimus Atlantis = atlas.
• Longissimus Cevicus = cervical spine.
• Longissimus Thoracis = thoracic spine.
• Longissimus Lumborum = lumbar/sacral spine.
• Iliopsoas muscles = supports lumbar vertebrae/lumbosacral joint/sacroiliac joint, hip flexion/rotation and psoas + iliacus muscles involved (can't be palpated).
• Middle gluteal = hindlimb retraction, sacroiliac/lumbosacral joint extension and enables the hip joint (hindlimb propulsion).
• Axial skeleton ligaments = supraspinous, interspinous, ventral and dorsal.
• Nuchal ligament = supports head/neck, energy conservation, restrains DSP movement and has 2 parts - funicular + lamellar.
• Supraspinous ligament = more fibrous/less elastic than nuchal ligament, minimises DSP movement and works with nuchal ligament + abdominals.
• Muscle chains = coordinated actions and tension in one muscle can affect the whole chain.