Week 8 & 9- The Nervous System

Question 1

Describe the facial nerve

Answer 1

• located on the lateral sides of the face.
• Cranial nerve VII
• Damage causes paralysis of the facial muscles on the affected side. Characterized by a drooping lip or nostril. Drooping ear and a weak palpebral reflex may also be seen. Often results in small animals from head trauma or facial surgery.

Question 2

Describe the vagus nerve.

Answer 2

• Cranial nerve X.
• longest nerve in the body, originates from the medulla oblongata, travels to the colon.
• supplies motor impulses to the pharynx, larynx, trachea, lungs, heart, esophagus, and the rest of the digestive tract. Brings sensory impulses from the ear, tongue, pharynx and larynx back to the brain.
• in the neck area, runs parallel to the carotid artery and the jugular vein.

Question 3

Describe the brachial plexus.

Answer 3

• is a group of nerves in the armpit (axillary region)
• Formed from branches of the sixth cervical to second thoracic nerve roots.
• forms many branches, including the radial nerve, median nerve and ulnar nerve.

Question 4

Describe the radial nerve.

Answer 4

• largest nerve branch from the brachial plexus
• passes between the triceps muscle and the humerus
• supplies motor impulse to muscles of the elbow, carpus, and digits.
• carries sensory impulses to the brain from the dorsal and lateral forearm and dorsal area of the paw.
• damage results in loss of ability to extend the paw and loss of sensation on the dorsal surface of the paw, causing it to be dragged.

Question 5

Describe the femoral nerve.

Answer 5

• on the medial surface of the thigh, is found running with the femoral artery and vein.
• supplies motor function to the muscles of the thigh
• carries sensory impulses from the skin of the hip, thigh, leg and knee.
• damage results in an inability to extend the stifle joint to support weight. (occurs in calves and foals if strong traction is applied to the hind limbs during a difficult birth)

Question 6

Describe the sciatic nerve.

Answer 6

• found on the lateral thigh beneath the biceps femurs muscle.
• carries motor impulses to the flexor muscles of the stifle joint and the digits, and the flexor muscles of the hock.
• can be injured by pelvic or femoral fractures, during surgery to repair femoral fractures, or by improper intramuscular injections.
• damage results in knuckling on dorsal aspect of foot. hock aimlessly or passively flexes and extends as weight is shifted. straightening the entire leg makes weight bearing impossible.