The cord is segmentally organized. There are 31 segments, defined by 31 pairs of nerves exiting the cord. These nerves are divided into 8 cervical, 12 thoracic, 5 lumbar, 5 sacral, and 1 coccygeal nerve (Figure 3.2).
How many sensory nerves enter the spinal cord?
Thirty-one pairs of spinal nerves (sensory and motor) branch from the human spinal cord. Each spinal nerve is formed from the combination of nerve fibers from its posterior and anterior roots.
Where do sensory nerves enter the spinal cord?
Sensory spinal nerves enter the spinal cord on the back (dorsal) side, whereas motor spinal nerves exit the spinal cord on the front (ventral) side. The cell bodies of sensory nerves lie outside the spinal cord within the dorsal root ganglia, whereas the cell bodies of motor nerves lie within the spinal cord.
Which spinal nerves affect which parts of the body?
The nerves of the cervical spine go to the upper chest and arms. The nerves in your thoracic spine go to your chest and abdomen. The nerves of the lumbar spine then reach to your legs, bowel, and bladder. These nerves coordinate and control all the body’s organs and parts, and let you control your muscles.
What are two examples of nerves that carry only sensory information?
The somas of sensory neurons are located in dorsal root ganglia. The somas of motor neurons are found in the ventral portion of the gray matter of the spinal cord. Some cranial nerves transmit only sensory information. For example, the olfactory nerve transmits information about smells from the nose to the brainstem.
What are the three areas of the spine?
The spine has three normal curves: cervical, thoracic and lumbar. There are seven cervical vertebrae in the neck, 12 thoracic vertebrae in the torso and five lumbar vertebrae in the lower back.
What are the 12 cranial nerves and what do they do?
Overview of the 12 CNs
|I—olfactory nerve (smell)||Transmits signals from the olfactory organ (nose) to the brain||Somatosensory and afferent|
|II—optic nerve (vision)||Transmits visual signals from the retina to the brain||Somatosensory and afferent|
When a neurologist asks a patient to smile which cranial nerve is being tested?
Cranial Nerve VII – Facial Nerve
Ask the patient to smile, show teeth, close both eyes, puff cheeks, frown, and raise eyebrows. Look for symmetry and strength of facial muscles. See Figure 6.18 for an image of assessing motor function of the facial nerve.