Human Anatomy & Physiology I: The Brain and Spinal Cord Overview (copy)

Spinal nerves

31 pairs that attach to the spinal cord by paired roots.

Cervical and lumbar enlargements

Sites where nerves serving the upper and lower limbs emerge.

Cauda equina

Collection of nerve roots at the inferior end of the vertebral canal.

Conus medullaris

Terminal portion of the spinal cord.

Filum terminale

Fibrous extension of the pia mater that anchors the spinal cord to the coccyx.

Denticulate ligaments

Delicate shelves of pia mater that attach the spinal cord to the vertebrae.

Gray matter

Consists of soma (cell bodies), unmyelinated processes, and neuroglia (glial cells).

Gray commissure

Connects masses of gray matter and encloses the central canal.

Posterior (dorsal) horns

Contain interneurons.

Anterior (ventral) horns

Contain interneurons and somatic motor neurons.

Lateral horns

Contain sympathetic nerve fibers.

Dorsal half of gray matter

Contains sensory roots and ganglia.

Ventral half of gray matter

Contains motor roots.

Dorsal and ventral roots

Fuse laterally to form spinal nerves.

Somatic sensory (SS)

One of the four zones evident within the gray matter.

Visceral sensory (VS)

One of the four zones evident within the gray matter.

Visceral motor (VM)

One of the four zones evident within the gray matter.

Somatic motor (SM)

One of the four zones evident within the gray matter.

Ascendign fiber directions

Fibers in the spinal cord run in three directions: ascending, descending, and transversely.

White matter funiculi

Divided into three columns: posterior funiculus, lateral funiculus, anterior funiculus.

Fiber tracts composition

Composed of axons with similar functions.

Pathways decussate

Most pathways cross over to the opposite side.

Neuron composition

Most consist of two or three neurons.

Somatotopy

Exhibit precise spatial relationships.

Pathways are paired

One on each side of the spinal cord or brain.

Spinothalamic ascending tract

Decussates in the spinal cord and involves touch, temperature, pain, and pressure sensations.

Decussation of spinocerebellar tract

Pathway does not decussate, usually a two-neuron pathway.

Functions of cuneate fasciculus

Involved in sensations of limbs and trunk position and movement, deep touch, visceral pain, and vibration above T6.

Primary motor area

Region of the brain responsible for initiating voluntary movement.

Premotor cortex

Involved in planning and coordination of movement.

Frontal eye field

Controls voluntary eye movement.

Central sulcus

Separates the primary motor cortex from the primary somatosensory cortex.

Primary somatosensory cortex

Processes tactile information from the body.

Somatosensory association area

Integrates sensory information for spatial tasks.

Broca's area

Executive area for task management in language production.

Prefrontal cortex

Involves solving complex, multitask problems.

Gustatory cortex

Involved in the sense of taste.

Wernicke's area

Associated with language comprehension.

Primary somatosensory cortex homunculus

A cartoon representation illustrating sensory processing areas.

Primary motor cortex homunculus

Represents body areas concerning motor control.

Lateral corticospinal tract

Pathway that decussates in the medulla and is involved in fine motor control of limbs.

Anterior corticospinal tract

Pathway that decussates in the spinal cord and is involved in fine motor control.

Paralysis

Loss of motor function.

Flaccid paralysis

Results from damage to the ventral root or anterior horn cells, leading to loss of muscle control.

Spastic paralysis

Caused by damage to upper motor neurons, resulting in irregular muscle stimulation.

Paraplegia

Transection of the spinal cord between T1 and L1 leading to loss of function in the lower body.

Quadriplegia

Transection of the spinal cord in the cervical region leading to loss of function in all four limbs.

Dermatome

Specific area of skin receiving sensory input from a pair of spinal nerves.

Shingles

Localized disease caused by varicella-zoster virus reactivating along sensory nerves.

Cervical plexus

Formed by ventral rami of C1-C5, primarily consisting of cutaneous nerves.

Brachial plexus

Formed by C5-T1, gives rise to nerves innervating the upper limb.

Thoracic outlet syndrome (TOS)

Compression of the Brachial Plexus and subclavian artery causing pain and numbness.

Radial nerve paralysis

Results in symptoms like pain, weakness, and numbness due to nerve compression.

Sciatic nerve paralysis

Caused by compression, resulting in sharp pain down the back of the thigh and leg.

Reflex arc

A rapid and predictable motor response to a stimulus.

Components of a reflex arc

Somatic receptor, afferent fiber, integration center, efferent fiber, effector.

Withdrawal (flexor) reflex

Quick contraction of flexor muscles to withdraw a limb from a stimulus.

Superficial reflexes

Initiated by cutaneous stimulation, such as the plantar reflex.

Cerebrospinal fluid (CSF)

Provides buoyancy, protects the CNS, nourishes the brain, and carries chemical signals.

Hydrocephalus

Condition in which excessive CSF leads to swelling and pressure on the brain.

Meningitis

Inflammation of the meninges, commonly caused by bacterial or viral infections.

Cerebral edema

Swelling of the brain due to excess fluid accumulation.

Traumatic brain injury (TBI)

Results from localized and ricocheting injuries to the brain.