Help with Spinal Physiology - Anatomy

The dorsal column medial lemniscal pathway is the sensory pathway of the neural system that transports vibration, proprioception, two-point discrimmination, and fine touch.

The lateral spinothalamic pathway is the sensory pathway that transports pain and temperature sensation.

The corticospinal pathway is the motor control pathway that travels from the brain—specifically the precentral gyrus—to the spinal cord.

The corticobulbar pathway is the motor control pathway that travels from the brain, to the brainstem and the cranial nerves.

The anterior spinothalamic pathway is sensory pathway for crude touch and pressure.

The correct order of CSF flow is as follows:

Lateral ventricals, foramen of Monro, third ventricle, cerebrel aqueduct of Sylvius, fourth ventricle, foramen of Magendie (medial) and foramen of Lushka (lateral), central canal and subarachnoid space, superior sagittal sinus

The lateral spinothalamic tract is a sensory tract that conveys pain and temperature information. Although the tectospinal tract is a motor tract, it coordinates reflexive head movements in response to visual stimuli. The rubrospinal tract is also a motor tract, but it regulates activity of the upper extremity flexors. The fasciculus gracilis is a sensory tract carries proprioception, vibration, and light touch information, from the lower extremities.

Preganglionic neurons of the parasympathetic nervous system originate in the nuclei of the craniosacral region (cranial nerves and in the spinal cord segments of S2-S4). Those of the sympathetic nervous system originate in the thoracolumbar region (spinal cord segments of T1-L3).

The spinal cord consists of 31 segments/pairs. The cervical contains 8, thoracic contains 12, lumbar contains 5, sacral contains 5, and coccygeal contains 1.

The dorsal column track is an ascending system conveying somatic sensory information to the brain. The dorsal column tracts ascend in the fasiculus gracilis and fasiculus cuneatus. They synapse in the medulla so that signals from the left side of the body are transmitted to the right side, and vice versa.

The anterior roots are where outgoing instructions leave the spinal cord. The posterior roots are where incoming sensory information enter the spinal cord. Grey matter contains the cell bodies of neurons, while the white matter contains the axons of nerves.

The conus medullaris is the cone-shaped ending of the spinal cord and it is found at the level of the second lumbar vertebrae (L2). It is located superior to the cauda equina.

The cauda equina is the bottom of the conus medullaris. It extends from the conus medullaris and terminates at C0 vertebrae.

The Dorsal root is responsible for sensory information because it contains the somae of sensory neurons. The Ventral root, on the other hand, contains the somae of motor neurons and therefore is responsible for the motor division.

A delta fibers are responsible for signaling "new" sharp pain. The body sends this sensory information to Rexed Laminae I and II. *I and II are called the substantia gelatinosa.

Fasciculus gracilus is one of the component to the dorsal columns. Remember that anything that is dorsal of the spinal cord is associated with sensation. In addition, the dorsal columns control touch while the spinothalamic tract carries pain and temperature information.

Unlike the body, where the spinothalamic tract sends pain and temperature information, the trigeminal nerve does this for the face. This is processed through the trigeminal ganglion which then synapsis to the spinal trigeminal nucleus before going to the thalamus.

The face is unique in which the sensation of touch is processed through the trigeminal nerve through the trigeminal ganglion which later synapses to the chief nucleus. Don't confuse this with fasciculus gracilus, which transmits touch info from T8 and down and cuneatus that does T8 and up.

C fibers are the least myelinated fibers that carry sensory information. They are responsible for the "slow" more excruciating pain that people tend to experience after the initial pain occurs with an injury. They are known as the slow fibers because the less myelinated a fiber is the slower the conduction speed it has to send the information.

The somatic nervous system is the voluntary nervous system and part of the peripheral nervous system. It is associated with voluntary skeletal muscle control over body movements and is associated with involuntary reflex arcs. The somatic nervous system consists of afferent (relay sensations to central nervous system) and efferent (relays commands from central nervous system to the body) nerves stimulating muscle contractions. Thus muscle contraction ceases when neural stimulation ceases.

Visceral afferent and somatic afferent axons are found in the dorsal roots of spinal nerves. The dorsal root emerges directly from the spinal cord and travels to the dorsal root ganglion. It then joins fibers with the ventral root to make a mixed spinal nerve. The dorsal root relays sensory information (thus has afferent axons).

The cauda equina is the bottom of the conus medullaris. It extends from the conus medullaris and terminates at C0 vertebrae.

The spinal cord has both ventral and dorsal horns. The dorsal horns contain afferent neurons that receive sensory input from the environment, while the ventral horns contain efferent motor neurons that send impulses to the effector.

Nerves are separate structures that branch out from the spinal cord and central nervous system into the periphery. Cerebrospinal fluid surrounds the components of the central nervous system and acts to protect the brain and spinal cord, as well as regulate the environment of the central nervous system.