Brain Orientation, THE PERIPHERAL NERVOUS SYSTEM

Dorsal

spinal cord—> toward the back of body/top of head

Ventral

spinal cord, toward the belly

Anterior

• Toward the front of face (like the nose or forehead).

Posterior

• spinal cord—> Toward the back (lower spinal cord). down

Medial ←-

Toward the midline (nose/ ears)

Lateral —>

Away from midline (forehead area)

Proximal

Near origin

Distal

Far from origin

Origin

The CNS

Ipsilateral

Same side of body

Contralateral

Opposite sides of body

Axial Slice

slice the top of brain

Sagittal Slice

• slice brain in the middle, fingers facing sky

Coronal Slice

“slice your face off”

Contralateral Function

2 hemispheres (Left and Right) are connected by bundles of axons called the Corpus callosum

Contralateral Function: Split Brain Patient (Joe)

his corpus callosum split in half and no longer has contralateral functioning

Left Visual Field → Can't name it, but can draw it.

Right Visual Field → Can name and draw it.

THE NERVOUS SYSTEM

Peripheral Nervous System (PNS)

🔹 Connects the brain & spinal cord to the body
🔹 Communicates via cranial & spinal nerves

Spinal Nerves

• 31 pairs of spinal nerves (from spinal cord)

• 12 pairs of cranial nerves (from brain)

  🔹 Emerge from the vertebral column
  🔹 Carry signals to muscles from sensory receptors

Dorsal Root

• Allows sensory neurons to enter the spinal cord
  - Contains afferent axons (admits signals to the cell)

Dorsal Root GANGLION

HOUSES the cell bodies of sensory neurons

Ventral Root

Contains motor neurons

• spinal cord TO muscles
  No ganglion (cell bodies are in the spinal cord)

12 Cranial Nerves

Somatic Nervous System (CNS)

🔹 Controls skeletal muscle movement
🔹 Sends sensory info to CNS (skin & sense organs)
🔹 Includes cranial & spinal nerves

AUTOMATIC NERVOUS SYSTEM (part of PNS)

Autonomic Nervous System (PNS)

Part of the PNS that controls involuntary (vegetative) functions
🔹 Regulates smooth muscle

Sympathetic Nervous System

“Fight or Flight" response

• Increases heart rate, blood pressure, & epinephrine release

• Prepares body for energy expenditure & action

Sympathetic Nervous System (NEURONS)

• Preganglionic Neurons → Short, synapse in ganglia near spinal cord

• Postganglionic Neurons → Long, extend to target organs

Parasympathetic Nervous System

“Rest & Digest" response
- Conserves & restores energy
- Increases salivation, digestion, & blood flow to GI tract

Parasympathetic Nervous System (NEURONS)

• Preganglionic Neurons → Long, from cranial nerve region

• Postganglionic Neurons → Short, near or in target organs