I'd like to review this idea of efferent versus a parent function of the peripheral nervous system okay and we can do that by including an image of the spinal cord so let me draw the spinal cord or at least a half of the spinal cord I have my dorsal root for my dorsal horn my ventral lateral horn and my ventral horn which make up the gray matter I also have where all these fiber tracks are going in the white matter now when we talk about P&S we're talking about the peripheral nervous system and sensory and motor function and the sensory and motor function come off of the spinal cord the spinal cord is CNS or an integration Center so by add-on here my dorsal root and my ventral root of the spinal cord now I have my peripheral nervous system and this ventral root or this dorsal root are going to come together to form a typical spinal nerve that's all we would see emerge from the vertebral column now if I wanted to go out and do some motor function and innervate this muscle out here and its associated fibers or muscle cells I would send out a nerve called the alpha motor neuron from that ventral horn through the ventral root and the typical spinal nerve to throw up acetylcholine all over the muscle fibers that I was interested in getting to get contracted to get them contracted this is motor function this is motor or what we call efferent signaling because we're reaching the effector organ and getting it to respond now if I took my finger or a finger and I tricked this person's finger with a sharp needle saying I would get some blood I'd draw some blood and they would feel this prick on their finger because they have sensory receptors here in the dermis and those sensory receptors stimulate a neuron that traveled back and enter into through the typical spinal nerve past the dorsal root ganglia into the dorsal root to reach and synapse on a cell of the dorsal Horn and then that information can be carried up to the thalamus or to the brain this would be sensory information or what we know as a parent coming in signals signals entering into the CNS or the integration center so when we talk about motor function or sensory function word this is what we're referring to and other terms for motor is efferent that's coming in that's sorry that's going out from the central nervous system and a current information is coming in to the central nervous system now we can expand this when we think of the cranial nerves if I took a brainstem because that's where most of the cranial nerves arise from and I take this brainstem and I look at the cranial nerves coming off now we have little factory bulbs and cranial nerve one the optic chiasm and cranial nerve to the optic nerve we have ocular motor cranial nerve three cranial nerve for the trochlear there cranial nerve five that big trigeminal nerve six we have abducens that's even bigger seven it's like sorry abducens here seven we have facial nerve eight vestibular cochlear nine glossopharyngeal the vagus nerve 10 accessory number eleven and then twelve the hypoglossal nerve is good is going to be coming off somewhere here along the midline when we consider these cranial nerves which are coming off of the brainstem we can consider that whether or not they're a parent or efferent and a really good way to remember which ones are a parent or a parent is to use some kind of a mnemonic and the one that I original and goes some say Merry money but my brother says big brains matter most and what this scene does is it matches up the cranial nerve with its function there's 12 cranial nerves and some of them are only sensory some are only motor and some of them are like this typical spinal nerve here at this location mixed they carry both efferent and afferent information remembering this mnemonic can help us coordinate it cranial nerve one cranial nerve - cranial nerve debris for cranial nerve five cranial nerve 6 cranial nerve seven cranial nerve eight cranial nerve nine ten eleven and twelve cranial nerve one will Factory is sensory cranial nerve to the optic nerve is sensory cranial nerve three ocular motor is motor for the trochlear is motor five trigeminal carries both six carries motor seven both eight sensory nine both 10 of 11 carries motor 12 the hypoglossal nerve carries motor function so we take the first letter of our saying or our mnemonic or acronym and we associated with that nerve and whether it's sensory or motor so this is a very quick way of learning that say abducens cranial nerve six is motor six is motor cranial nerve one some that's all factory that's going to be sensory cranial nerve to the optic nerve is going to be sensory and I match up the number with my saying and the first letter with whether it's sensory both sensory and motor or just motor