A&P exam 2

Name the four major regions and two enlargements of the spinal cord

The spinal cord is divided into four major regions: cervical, thoracic, lumbar, and sacral. Think of these regions as the floors of a tall building, each serving different parts of the body. The cervical and lumbosacral enlargements are like bustling lobbies, where nerves branch out to the upper and lower limbs, respectively. This structure ensures efficient communication between the brain and various body parts.

Describe the distal end of the spinal cord and the contents of the vertebral canal from level L2 to S5

The distal end of the spinal cord tapers to the medullary cone, below the lumbosacral enlargement. From L2 to S5, the vertebral canal contains the cauda equina, a bundle of nerve roots resembling a horse's tail, which innervates pelvic organs and lower limbs. This structure is crucial for transmitting nerve signals to and from these regions.

Describe an anatomical reason why a stroke in the right cerebral hemisphere would paralyze the limbs of the left side of the body

Strokes in the right cerebral hemisphere can paralyze the left limbs due to decussation, where nerve tracts cross from one side of the brain to the opposite side of the body. Thus, the right brain controls the left side, and damage to its motor centers results in contralateral paralysis, affecting the limbs on the left side.

Identify the spinal tracts and there main functions and locations

The gracile fasciculus is an ascending tract originating below T6, carrying sensory signals like limb position and vibration. The lateral corticospinal tract descends from the cerebral cortex, controlling fine limb movements. The lateral reticulospinal tract is also descending, aiding in balance and posture. The spinothalamic tract ascends, transmitting sensations like light touch and temperature. Think of these tracts as highways, each with specific routes and destinations, carrying sensory or motor information across the nervous system.

Afferent fibers

Carry sensory signals from receptors to CNS

Efferent fibers

Carry motor signals from the CNS to effectors

Somatic fibers

Innervate skin, skeletal muscles, bones, and joints

Visceral fibers

Innervate blood vessels, glands, and viscera

General fibers

Innervate widespread organs such as muscles, skin, glands, viscera, and blood vessels

Special fibers

Innervate more localized organs in the head, including the eyes, ears, and olfactory and taste receptors, and muscles of chewing, swallowing and facial expressions