BIO 252 EXAM 2 REVISED 2025

BIO 252 EXAM 2 Total number of spinal nerves - -31 pairs How many cervical nerves are there? - -8 (C1-C8) How many thoracic nerves? - -12 (T1-T12) How many lumbar nerves? - -5 (L1-L5) How many sacral nerves? - -5 (S1-S5) How many coccygeal nerves? - -1 (Co1) Dorsal root (posterior root) - -Sensory neuron (afferent), dorsal root ganglia (cell body) Carry sensory information to spinal cord Ventral root (anterior) - -Motor neuron (efferent) Carry motor signal to distant part of body Spinal nerves contains which two neurons? - -Motor and Sensory Neurons Myotomes - -specific MUSCLE GROUPS innervated by specific levels of spinal nerves Dermatomes - -Specific PATCHES OF SKIN innervated by specific levels of the spinal column Endoneurium - -Connective Tissue surrounds each individual Axon (Stuck to Axon) Perineurium - -covers fascicles (found in middle) Epineurium - -surrounds spinal nerve (Found outside) Cervical plexus - -C1-C5 Phrenic nerve (C3-C5) (play role with breathing) Serves head and neck Notable nerves Roots and nerves Brachial plexus - -C5-T1 nerves to upper limbs, neck, & shoulder muscles Roots,Trunks, Division,Cords, & Branches (complex arrangement) Notable Nerves (radial, Median, & Ulnar) Bio 252 Bio 252 What does accronym R.T.D.C.B stand for? - -Roots Trunks Divisions Cords Branches Lumbar plexus - -L1-L4 (lumbar region and femoral nerve) Nerves to abdominal wall, genitals, and lower limb Roots and divisions Notable nerves, Radial, Median, and Ulnar Sacral and coccygeal plexus - -L4-Co1 Nerves to the buttock, perineum and lower limb Roots and divisions Notable Nerves- Sciatic nerve (tibial and common fibular) Reflex - -A fast, involuntary and predictable sequence of events that function in an are Sensory receptors, sensory neurons, interneuron, motor neuron, effector, Effector - -The muscles that carry out response Sensory receptors - -neurons that respond to stimuli and trigger electrical signals Sensory neurons (afferent neurons) - -neurons that carry incoming information from the sensory receptors to the brain and spinal cord Interneurons - -link between sensory and motor neurons, found in the brain and spinal cord Motor neurons - -carry signals from the spinal cord to the muscles to produce movement Ipsilateral - -same side Contralateral - -opposite side Monosynaptic - -one synapse Polysynaptic - -multiple synapses(multiple neurons stimulated) Sensory tracts - -afferent (ascending tracts) (to the brain) Spinothalamic (antero and lateral) Posterior (Dorsal) Columns- (Cuneate and Gracile) Spinothalamic - -spinal cord to thalamus Bio 252 Bio 252 Bio 252 Pain, temperature, itch and tickle to thalamus, crossing over in the cord upon level of entry Posterior (dorsal) columns - -(Cuneate and Gracile) takes touch, pressure, and vibration to the thalamus; decussates in the medulla Motor tracts - -descending tracts Starts at cortex Voluntary movement of distal extremity Autonomic nervous system - -A subdivision of the peripheral nervous system. Controls involuntary activity of visceral muscles and internal organs and glands. Somatic nervous system - -A subdivision of the peripheral nervous system. Enables voluntary actions to be undertaken due to its control of skeletal muscles Cholinergic receptors - -bind ach Adrenergic receptors - -receptor sites for the sympathetic neurotransmitters norepinephrine and epinephrine Alpha and Betas Autonomic reflexes - -smooth muscle regulation, heart and blood pressure regulation, regulation of glands, digestive system regulation Autonomic Dysreflexia - -patients with spinal cord injuries are at risk for developing autonomic dyreflexia (T-7 or above) Makes blood pressure dangerously high Can lead to stroke, seizures, or cardiac Parasympathetic - -rest and digest Symphatetic - -fight or flight Somatic reflex arc - -1. Somatic receptors (skin, muscles, and tendons) 2. Afferent nerve fibers (carry info from these receptors to the posterior horn of the spinal cord or to the brainstem) 3. Integrating center point of synaptic contract between neurons in gray matter of the cord or brainstem) 4. Efferent nerve fibers ( carry motor impulses to the muscles) 5. Effectors ( muscles that carry out the response) Ascending tracts of the spinal cord - -First order neuron- detects a stimulus & transmits a signal to the spinal cord or brainstem Second order neuron- continues as far as a "gateway" called the thalamus at the upper end of the brainstem Bio 252 Bio 252 Third order neuron- carries the signal to the rest of the way to the cerebral cortex The brain is protected by: - -Bones of the skull Spinal meninges Cerebrospinal fluid Spinal Meninges are: - -dura mater, arachnoid mater, pia mater Dura matter - -most superficial, forms loose fitting sleeve called DURAL SHEATH around the spinal cord, tough collagenous membrane Arachnoid space - -middle layer of three meninges that surround the brain and spinal cord Just deep to the dura matter. Next is the subarachnoid space that is filled with CSF Pita mater - -thin, delicate inner membrane of the meninges Lies directly on the brain Blood flow to the brain is supplied by the? - -internal carotid artery and vertebral artery Any disruption in oxygen or glucose can damage the? - -Brain Cerebrospinal fluid (CSF) - -Starts with the cho