Nerve Pathways Through the Body

Nerve pathways through the body

• In your lab envelope you have many pieces of yellow mason line – these will be used to model the pathways that nerves travel through the body. PLEASE be careful with them, as the ends fray easily and other groups will need to use them!
• There are six total nerves; two cranial and four major nerves that are parts of the nerve plexuses of the body. Some of the nerves have more than one ending – these will represent attachment points to spinal nerves. Those that have multiple endings thus are spinal nerves, and those with a single ending are cranial nerves. It is up to you to figure out which nerve to use for the following exercises. Examine their lengths and number of endings to figure out which is which.
• NOTE: this model will not be completely accurate, as we are not modeling the nerve plexuses; rather the nerves will attach directly to the spinal nerves. Also remember that each nerve is paired – there is a left and right of each nerve. You are only going to model the left or the right, not both.

• Spread your six nerves out on your lab bench and compare their lengths and number of spinal nerve attachment points. Can you tell which ones are cranial nerves and which ones are spinal nerves?

• Optic nerve
• Take the brain from the torso and identify the origination point of the optic nerve.
• Identify the optic nerve from the envelope of nerves and tape one end to the attachment point on the brain.
• Where does the optic nerve originate from the brain? Optic chiasma / thalamus
• Remove the skullcap from the human skeleton skull model, and identify the foramen that the optic nerve passes through.
• What foramen does the optic nerve pass through? ___Optic canal____
• Carefully place the brain in the cranial fossa and thread the cranial nerve through its foramen.
• Remove the left eye from the torso and carefully place it in the left orbital socket of the skull. The optic nerve is now “attached” to the eye!

• Vagus nerve
• Remove the brain from the skull and identify the origination point of the vagus nerve. (leave the optic nerve attached!)
• Where does the vagus nerve originate from the brain? Medulla oblongata
• Identify the vagus nerve from the envelope of nerves and tape one end to the attachment point on the brain.
• In the skull model, identify the foramen that the vagus nerve passes through.
• What foramen does the vagus nerve pass through? _Jugular foramen_
• Carefully place the brain in the cranial fossa and thread the cranial nerve and vagus nerve through their foramina.
• Thread the vagus nerve to the approximate location where it would innervate the heart.

Show your instructor your optic and vagus nerves before moving on. Do not remove the nerves until the end of the lesson.

• Phrenic nerve
• Identify the phrenic nerve from the envelope of nerves.
• Which spinal nerves make up the phrenic nerve? ___C3, C4, C5____
• What plexus does the phrenic nerve originate from? ____Cervical____
• On the human skeleton model, identify the spinal nerves that make up the phrenic nerve.
• Tape the ends of the phrenic nerve to its appropriate spinal nerves.
• Thread the phrenic nerve from its attachment points at the spinal nerves to its most distal point – use tape to help keep it in place.

• Ulnar nerve
• Identify the ulnar nerve from the envelope of nerves.
• Which spinal nerves make up the ulnar nerve? _____C8, T1_____
• What plexus does the ulnar nerve originate from? ____Brachial___
• On the human skeleton model, identify the spinal nerves that make up the ulnar nerve.
• Tape the ends of the ulnar nerve to its appropriate spinal nerves.
• Thread the ulnar nerve from its attachment points at the spinal nerves to its most distal point – use tape to help keep it in place.

Show your instructor your phrenic and ulnar nerves before moving on. Do not remove the nerves until the end of the lesson.

• Obturator nerve
• Identify the obturator nerve from the envelope of nerves.
• Which spinal nerves make up the obturator nerve? ____L2, L3, L4___
• What plexus does the obturator nerve originate from? ___Lumbar_____
• On the human skeleton model, identify the spinal nerves that make up the obturator nerve.
• Tape the ends of the obturator nerve to its appropriate spinal nerves.
• Thread the obturator nerve from its attachment points at the spinal nerves to its most distal point – use tape to help keep it in place.

• Tibial nerve
• Identify the tibial nerve from the envelope of nerves.
• Which spinal nerves make up the tibial nerve? ___L4, L5, S1, S2, S3__
• What plexus does the tibial nerve originate from? ___Sacral____
• On the human skeleton model, identify the spinal nerves that make up the tibial nerve.
• Tape the ends of the tibial nerve to its appropriate spinal nerves.
• Thread the tibial nerve from its attachment points at the spinal nerves to its most distal point – use tape to help keep it in place.

Show your instructor your obturator and tibial nerves before moving on. Take a photo of your completed skeleton model before removing your nerves.

Answer the questions on the worksheet and turn it in as a group to complete this lesson.