BIOL 212 Exam 4 SDSU Questions with
Complete Solutions
No plexus intercostal nerves (via dorsal ramus) : skin and muscles of back
intercostal nerves (via ventral ramus): skin and muscles of thoracic and abdominal wall
Lumbar plexus (T12-L4) obturator nerve, femoral nerve, saphenous nerve
Obturator nerve Skin of mid-medial surface of thigh, addductor muscles of the thigh
(adductor magnus, gracilis)
Femoral nerve Skin over anteromedial surface of thigh, leg, and ankle. Muscles of
anterior medial surface of thigh (iliacus, sartorial, quads)
Saphenous Skin of medial surface of leg, ankle, and foot; knee joint
Sacral plexus (L4-S5) Gluteal nerve, sciatic nerve, tibial nerve, common fibular
,Gluteal nerve Muscles of buttocks - abductor and extensor muscles of thigh (gluteal
muscles; tensor fasciae latae)
Sciatic nerve Combined tibial and fibular nerves - skin of leg, ankle, and foot except that
supplies by saphenous; all posterior muscle of thigh and leg (hamstring, plantarflexors)
Tibial nerve skin of posterior surface of leg and plantar surface of foot; flexor muscles of
leg and plantar flexor muscles of foot
Common fibular nerve Skin of anterolateral surface of leg, ankle, and dorsal lateral foot;
muscles of anterolateral muscles of leg (dorsiflexor and fibular mucles)
Reflex arc 1. receptor
2. sensory neuron
3. interneuron
4. motor neuron
5. effector
, step 1: receptors in skin or organs are stimulated
step 2: impulse for pain travels along sensory neuron to spinal cord
step 3: impulse travels to interneuron within spinal cord
4: impulse arcs back out of spinal cord to travel away from cord along the motor neuron
step 5: impulse travels to effector to stimulate or inhibit
Pyramidal system The voluntary motor path to skeletal muscles
Corticospinal tract Describes the path from the motor cortex to the spinal cord and nerves
General somatic motor tract tracing Motor cortex of cerebrum (frontal lobe) > internal
capsule > mesencephalon > pons > medulla oblong at a > ventral horn (synapse) > ventral root >
ramus > plexus > nerve (s) > muscle (synapse)
General somatic sensory tract tracing Receptor > nerve(s) > plexus > ramus > dorsal root
ganglion > dorsal root > dorsal horn (synapse) > thalamus (synapse) > internal capsule > sensory
cortex of cerebrum (parietal lobe)
You step bare foot on warm sand. Trace
Complete Solutions
No plexus intercostal nerves (via dorsal ramus) : skin and muscles of back
intercostal nerves (via ventral ramus): skin and muscles of thoracic and abdominal wall
Lumbar plexus (T12-L4) obturator nerve, femoral nerve, saphenous nerve
Obturator nerve Skin of mid-medial surface of thigh, addductor muscles of the thigh
(adductor magnus, gracilis)
Femoral nerve Skin over anteromedial surface of thigh, leg, and ankle. Muscles of
anterior medial surface of thigh (iliacus, sartorial, quads)
Saphenous Skin of medial surface of leg, ankle, and foot; knee joint
Sacral plexus (L4-S5) Gluteal nerve, sciatic nerve, tibial nerve, common fibular
,Gluteal nerve Muscles of buttocks - abductor and extensor muscles of thigh (gluteal
muscles; tensor fasciae latae)
Sciatic nerve Combined tibial and fibular nerves - skin of leg, ankle, and foot except that
supplies by saphenous; all posterior muscle of thigh and leg (hamstring, plantarflexors)
Tibial nerve skin of posterior surface of leg and plantar surface of foot; flexor muscles of
leg and plantar flexor muscles of foot
Common fibular nerve Skin of anterolateral surface of leg, ankle, and dorsal lateral foot;
muscles of anterolateral muscles of leg (dorsiflexor and fibular mucles)
Reflex arc 1. receptor
2. sensory neuron
3. interneuron
4. motor neuron
5. effector
, step 1: receptors in skin or organs are stimulated
step 2: impulse for pain travels along sensory neuron to spinal cord
step 3: impulse travels to interneuron within spinal cord
4: impulse arcs back out of spinal cord to travel away from cord along the motor neuron
step 5: impulse travels to effector to stimulate or inhibit
Pyramidal system The voluntary motor path to skeletal muscles
Corticospinal tract Describes the path from the motor cortex to the spinal cord and nerves
General somatic motor tract tracing Motor cortex of cerebrum (frontal lobe) > internal
capsule > mesencephalon > pons > medulla oblong at a > ventral horn (synapse) > ventral root >
ramus > plexus > nerve (s) > muscle (synapse)
General somatic sensory tract tracing Receptor > nerve(s) > plexus > ramus > dorsal root
ganglion > dorsal root > dorsal horn (synapse) > thalamus (synapse) > internal capsule > sensory
cortex of cerebrum (parietal lobe)
You step bare foot on warm sand. Trace
