Veterinary Nerve Damage

• Lateral epicondyle fractures commonly damage the radial nerve.
• Damage to the radial nerve results in knuckling, but the animal can still bear weight.
• Musculocutaneous nerve damage causes it to be impossible to flex the elbow.
• Median nerve damage causes trouble flexing the carpus.
• Thoracodorsal nerve damage, which affects the latissimus dorsi, causes trouble flexing the shoulder.
• Radial nerve: Proximal damage results in inability to bear weight, distal damage causes knuckling.

Additional Info on Radial Nerve Damage

• With damage, you can use the radial nerve to help flex the shoulder.
• Ulnar nerve damage may result in palmigrade stance
• Suprascapular nerve damage causes shoulder sweeney, with muscle atrophy evident
• Axillary nerve damage doesn't stop shoulder flexion because the long head of the triceps is still functional
• Femoral nerve damage results in the inability to bear weight; the saphenous nerve can be used
• Tibial nerve damage results in plantigrade stance
• Fibular nerve damage results in knuckling
• Sciatic nerve damage causes generalized weakness and unsteadiness in the hock, often from misplaced IM injections
• Obturator nerve damage results in the inability to adduct the limb and is common in large animal parturition
• Branches of the radial, median, ulnar, and musculocutaneous nerves innervate the distal limb

Cutaneous Autonomous Zones

• Cutaneous autonomous zones can be located via the ulnar and radial nerves.

Lateral Head of Triceps

• The lateral head of the triceps is innervated by the radial nerve.

Distal Branch of the Radial Nerve

• Distal branch is superficial.
• Knuckling is different from not bearing weight.
• Horse: the radial nerve does not innervate the digits and stops at the carpus
• Medial and lateral palmar metacarpal nerves exit buttons to innervate dorsal digital nerves in horses; metacarpal exit is distal to the fetlock joint
• Suprascapular nerve damage causes shoulder Sweeney, severe atrophy of the supraspinatus, and also affects the infraspinatus
• Panniculus reflex happens via lateral thoracic nerve and cutaneous trunci muscle
• Flexors that innervate muscles can still flex a joint: the shoulder and elbow are innervated by the musculocutaneous nerve or biceps brachii

Scapular and Shoulder Muscles

• Teres major is innervated by the axillary nerve and flexes the shoulder while medially rotating the arm
• Subscapularis is innervated by subscapular nerves, adducts/extends/stabilizes the shoulder
• Coracobrachialis is innervated by the musculocutaneous nerve & adducts/extends/stabilizes shoulder.

Cranial Forelimb Muscles

• Biceps brachii & brachialis are innvervated by the musculocutaneous nerve and flexes the elbow, extends the shoulder.

Caudal Forelimb Muscles

• Tensor fascia antebrachii is innervated by the radial nerve and extends the elbow
• Triceps brachii extends the elbow; the long head flexes the shoulder
• Anconeus extends the elbow

Cranial and Lateral Forelimb Muscles

• Extensor carpi radialis & common digital extensor are innervated by radial nerve and extend the carpus and the digits.
• Lateral digital extensor extends the carpus and lateral digit.

Additional Notes on Muscle Function

• Ulnaris lateralis extends the carpus
• The flexor carpi radialis is innervated by the median nerve and flexes the carpus
• Flexor carpi ulnaris is innervated by the ulnar nerve and flexes the carpus
• Superficial and deep digital flexors and innervated by the median and ulnar nerve, and each flex the carpus, digits, and the ulnar head.
• The animal can still flex the shoulder even if the axillary nerve is damaged due to the long head of the triceps being innervated by the radial nerve

Thoracic Limb - Extrinsic Muscles

• Superficial pectoral: Cranial pectoral (C7,C8) adducts when no weight bearing, prevents abduction when weight bearing
• Deep pectoral: Caudal pectoral (C8,T1): adducts limb, extend shoulder and pull trunk cranially when limb advanced
• Brachiocephalicus: nerves are accessory nerve and ventral branches of cervical spinal nerves; advances the limb and extends the shoulder
• Sternocephalicus: nerves are accessory nerve and ventral branches of cervical spinal nerves; Draw head and neck to side
• Omotransversarius: nerve is accessory, advance limb and flex neck laterally
• Latissimus dorsi: nerve is thoracodorsal, Draws the limb backward; flexes the shoulder
• Trapezius: nerve is accessory, Elevate and abduct limb
• Rhomboideus: nerves are ventral branches of cervical and thoracic spinal nerves; can elevate limb and draw scapula against trunk
• Serratus ventralis: nerves are ventral branches of cervical spinal and long thoracic (C7); can supports trunk and depress scapula

Scapula and Shoulder Muscles

• Supraspinatus is innervated by the suprascapular nerve and stabilizes and extends the shoulder joint
• Infraspinatus is innervated by the suprascapular nerve and laterally rotates and flexes the shoulder Deltoideus is innervated by the axillary nerve and abducts and flexes the shoulder
• Teres minor is innervated by the axillary nerve; flexes shoulder and rotate arm medially

Fibular and Tibial Nerve Function

• Fibular nerve flexes hock (anterior, lateral, dorsiflexion)
• Tibial nerve extends hock (plantarflexion, posterior)
• The Obturator nerve is otherwise known as the PAGE nerve: pectineus, adductor, gracilis, external obturator

Saphenous Nerve

• The saphenous branch is the most superficial branch of femoral nerve.
• The hamstrings are innervated by the sciatic nerve and include the biceps femoris, semitendinosus, and semimembranosus
• The cutaneous autonomous zone involves the tibial and fibular nerve.
• Injury resulting in knuckling means there's fibular or radial nerve damage
• Injury causing a palmigrade stance means there's tibial or ulnar nerve damage

Nerve Damage

• Hindlimb: The femoral nerve causes non-weight bearing
• Forelimb: The radial nerve causes non-weight bearing
• Medial and lateral plantar nerves can be blocked via metatarsal/digital blocks
• Misplaced IM injections in groove between the hamstrings damages the sciatic nerve
• Infraorbital canal is associated with the maxillary/infraorbital foramen and is associated with maxillary/infraorbital foramen.
• The ethmoid bone holds the ethmoidal labyrinth where cranial nerve 1/olfactory nerve run through it
• The internal occipital fissure is where the occipital bone meets the temporal bone where nerves go through

Acoustic Meatus

• Internal acoustic meatus: facial, vestibulocochlear nerves
• External acoustic labyrinth: the tube: extends from the base of the auricle to the tympanic membrane & no nerves go through

Mandibular Nerves

• Mandibular foramen = inferior alveolar nerve/ mandibular nerve, artery, vein
• Mental foramen = mental nerve, artery, vein passes through
• Temporal occipital fissure: glossopharyngeal, vagus, and spinal accessory come out
• Stylomastoid foramen: just facial nerve comes out

Hyoid Bones

• Focus on knowledge of them

Epaxial Muscles

• Splenius: support vertebra through movement
• Complexus + biventer cervicis = capitis
• Transverse: supports lateral movement
• Longissimus: extend the neck, can flex it
• Iliocostalis: aid flexion

Cervical Vertebrae

• C6 has a large transverse process
• C7 has no transverse foramen, so no cranial nerves pass through it.
• Cervical vertebrae can have intervertebral, transverse, and lateral foramina.

Costal Fovea

• The costal fovea is where the ribs articulate.
• Dorsal and ventral longitudinal ligaments, Dorsal, ventral, interspinous, interarcuate
• Intervertebral discs are not present in between C1 and C2, or in the tail
• NP= nucleus pulposus
• Transition zone
• Annulus fibrosis

Processes of The Mandible

• Condylar, coronoid, angular

Articulation

• Occipital condyles and bone Articulates at atlanto-occipital joint
• Attachment of nuchal ligament in equine (where?) In horses, it is a highly developed, elastic structure extending from the skull to the withers Attaches at back of skull on nuchal crests: In dogs, it's less developed and extends only to the second cervical vertebra
• Zygomatic bone/ arch (accidents) fracture? Eye protrude out.
• Vertebral body of C1-C7 on MRI Nerve tumor case at brachial plexus that affects all forelimb nerves: musculocutaneous, radial, ulnar, median, axillary

Exit Point for Cranial Nerves

• Cribriform plate - Olfactory
• Optic canal - Optic
• Orbital fissure - Oculomotor
• Orbital fissure - Trochlear
• Orbital fissure - Trigeminal A-Opthalmic
• Round foramen, Alar canal = Trigeminal B - Maxillary
• Oval foramen = Trigeminal C- Mandibular
• Orbital fissure = Abducens
• Internal acoustic meatus, Stylomastoid foramen = Facial
• Internal acoustic meatus = Vestibulo-cochlear
• Jugular foramen, Tympano-occipital fissure = Glossopharyngeal
• Jugular foramen, Tympano-occipital fissure = Vagus
• Jugular foramen, Tympano-occipital fissure = Spinal Accessory
• Hypoglossal canal = Hypoglossal