Meninges. The cord is surrounded by dura, arachnoid, and pia mater, which are continuous with the corresponding layers of the cerebral meninges at the foramen magnum. The spinal dura mater,…

From the jugular foramen, the nerve arches forward between the internal jugular vein and internal carotid artery, then passes deep to the styloid process, and curves behind the stylopharyngeus muscle…

The principal sensory nucleus, which is located in the lateral pons, receives tactile and proprioceptive sensation. It gives off fibers that travel in the trigeminal lemniscus and the uncrossed dorsal…

The external vertebral plexus consists of anterior and posterior parts, which anastomose freely. The veins forming the anterior external plexus lie in front of the vertebral bodies, from which they…

Some of the filaments passing through the superior orbital fissure form the sympathetic root of the ciliary ganglion; their contained fibers pass through it without relaying to become incorporated in…

The trigeminal nerve emerges from the anterolateral aspect of the upper pons. The large sensory root conveys sensation from most of the face and scalp; parts of the auricle; and…

MOTOR IMPAIRMENT The degree of motor dysfunction depends on the extent of the spinal cord lesion. Complete lesions destroy all function below the affected level. Incomplete lesions cause partial weakness,…

As shown in the illustration, rubrospinal fibers decussate almost immediately on leaving the red nucleus to descend through the lateral part of the brainstem to the spinal cord. In the…

OLFACTORY PATHWAY Olfactory Bulb. About 100 million olfactory afferent fibers enter the olfactory bulb, a flattened, oval mass lying near the lateral margin of the cribriform plate of the ethmoid…

The posterior funiculus, made up of the fasciculus gracilis and the fasciculus cuneatus, carries fibers that signal discriminative touch or pressure, muscle length and tension, and joint position. Some afferent…