Brain lab - written

Cerebral hemispheres (Cerebrum)

• 83% of brain mass

• forms superior portion of the brain

• surface marked by gyri (tissue ridges) and sulci (shallow grooves). 

• conscious mind. 

• It enables us to communicate, remember, understand, be aware of ourselves and sensations, and initiate voluntary movements.  

• divided into five lobes and three basic regions.

frontal

• Primary motor cortex

• precise movements of skeletal muscles; Broca’s area 

• special motor speech area (located only in one hemisphere, usually the left

parietal

• primary somatosensory cortex

• receive information from sensory receptors in skin and from proprioceptors (position sensors) in skin, joints and tendons.     Neurons can identify body area stimulated (spatial discrimination)

Temporal

auditory areas; olfactory cortex 

occipital

visual areas 

insula

taste, visceral sensation (ex. full bladder), equilibrium 

cerebral cortex

• thin, outer layer of gray matter.

• Speech, evaluation of stimuli, conscious thinking, and control of skeletal muscles occur here. 

• grouped into motor areas, sensory areas, and association areas

cerebral white matter

underneath cerebral cortex, contains myelinated axons  

commissural fibers

• myelinated axons that connect gray areas of the cerebral hemispheres

corpus callosum

nerve tract consisting of commissural fibers that connects the two cerebral hemispheres and allows for communication between the two hemispheres

association fibers

myelinated axons that connect gyri within the same hemisphere 

projection fibers

myelinated axons that connect the cerebrum to the spinal cord. 

Basal nuclei

• pockets of gray matter within the cerebral white matter. 

• play a role in motor control, regulating attention and cognition. 

• important in starting, stopping and monitoringmovements executed by the cerebral cortex (arm-swinging). 

• the intensity of these movements. Disorders can result in too little or too much movement (Parkinson’s disease and Huntington’s disease). 

Diencephalon

• core of forebrain surrounded by the cerebral hemispheres, encloses 3rd ventricle, gray matter.

• A choroid plexus is located here.

Epithalamus

• most dorsal portion of the diencephalon, makes up the roof of the 3rd 

ventricle

• location of the pineal gland, which aids in regulating sleep-wake cycle and mood.

Thalamus

• 80% of the deiencephalon;

• plays a role in mediating sensation, motor activities, cortical arousal, learning and memory. 

• “gateway to the cerebral cortex”

• relay station for sensory nerve impulses evaluation of pain, pressure and temperature.

• Comprises superolateral wall of the third ventricle

Hypothalamus

• visceral control center, essential in maintaining homeostasis 

• autonomic control center; center for emotional response; regulation of body temperature, food intake, and thirst

• an important component of the endocrine system, as it produces regulating hormones and the hormones ADH (antidiuretic hormone) and oxytocin.

• comprises inferolateral wall of 3rd ventricle

Brain Stem

located between the diencephalon and spinal cord; produces the programmed, automatic behaviors needed for survival

The brain stem is comprised of the?

Midbrain, pons & medulla oblongata

Midbrain

• located between the diencephalon and the pons; comprised of the cerebral peduncles and the corpora quadrigemina.

• The cerebral aqueduct runs through the midbrain 

Pons

• bulging area between midbrain and medulla oblongata

• contains respiratory centers

Medulla oblongata

blends into the spinal cord; contains cardiac centers, respiratory centers,and a Bp center (the vasomotor center)

Cerebellum

• 11% of brain mass

• dorsal to pons and medulla oblongata

• activities occur subconsciously

• Processes inputs from cerebral motor cortex, brain stem nuclei, and sensory receptors to allow for accurate timing of skeletal muscle contraction.

• Evaluates and coordinates motor movements; compares actual skeletal movements to the movement that was intended

Ventricles of the brain

• Location - in the cerebrum (one in each hemisphere)

  1) Lateral ventricles - where most CFS producation

  • interventricular foramen (foramen of munro)

  2) 3rd ventricles (more CSF added)

  • cerebral aqueduct

  Location - in between the pons and cerebellum (looks like indentation in cerebellum)

  3) 4th ventricle - more CSF is added

  a) most CSF enter the subarachnoid space and circulated around the brain (eventually the CSF is reclaimed by the arachnoid villi)

  b) Some CSF enter the central canal of the spinal cord

Meninges Layers in order

1) Dura matter - Outermost

• between: subduer space

2) Arachnoid - middle

• between: subarachnoid space

  • most CSF is located

3) Pia matter - innermost

Spinal Cord

• ends around L1- L2 

• coverings: single layer dura mater- spinal dural sheath, arachnoid, pia mater (epidural space – between vertebra and spinal dural sheath)  CSF fills the subarachnoid space

ventral root  

Contains motor nerve axons (impulses from spinal cord to effectors) 

Dorsal root

contains sensory nerve fibers (impulses to spinal cord from sensory  

receptors)

Reflex arc

• Reflex arc — Sensory receptors (modified dendritic ending of a sneery neuron)

• PNS — Sensory neurons (located in the corals roots ganglion)

  • goes along the dorsal root (sensory)

• CNS (spinal cord) — where interactions takes place (located in the posterior horns)

• Relays to the motor neurons (located in the anterior horns)

  • from there goes to the mental roots

• ventral root (motor)

• ending in the effectors

Gray matter

regions of the brain and spinal cord containing neuron cell bodies and unmyelinated fibers.  

gray commissure

Cross-bar of H

anterior (ventral) horns

cell bodies of motor neurons that stimulate skeletal muscles 

Posterior (dorsal) horns

• contain mainly interneurons that synapse with sensory neurons lateral horns (only in thoracic and lumbar regions)

• small projections of gray matter at sides of the H – containbodies of motor neurons of sympathetic division of ANS  central canal – hole in center of H, connects with 4th ventricle of brain, contains CSF 

White matter

funiculi (anterior, lateral, posterior) 

Ascending tracts (sensory)

sensory info from body to brain 

Descending tracts (motor)

motor impulses from brain to muscles and glands (the effectors)

Cranial Nerves I (1)

Cranial Nerves I (1)

Cranial Nerves II (2)

Optic - vision (only pair that crosses)

Cranial Nerves III (3)

Oculomotor - controls most of the eye movement (controls 4/6 eye muscle)

Cranial Nerves IV (4)

Trochlear - Controls one eye muscle

Cranial Nerves V (5)

Trigeminal

• Motor - Muscles of chewing

• sensory - face

• Largest

Cranial Nerves VI (6)

Abducens - Controls one eye muscle

Cranial Nerves VIII (8)

Vestibulocochlear - hearing and equilibrium (balance)

Cranial Nerves X (10)

Vagus

• only cranial never pairs to leave head and neck area

• innervates many body organs including heart (aids in maintaining resting heart rate) ; longest