The Brain and Cranial Nerves

Ch. 19

Major Brain Subdivisions

• Cerebrum• Diencephalon

– Hypothalamus and Thalamus

• Brain Stem – Midbrain, pons, medulla

oblongata

• Cerebellum

Cerebrum• Processes:

– motor control, thoughts, judgment, problem solving, memory, and language

• Left & Right Hemispheres– longitudinal fissure

separates hemispheres– Gyri: elevated ridges– Sulci: shallow grooves– Fissures: deeper grooves

Cerebrum• Corpus callosum:

– Bundle of axon fibers that enables communication between the hemispheres

• Cerebral cortex: outermost area of brain– cell bodies of cerebral

neurons (gray matter)• White matter:

– Made of fiber tracks carrying impulses to or from the cortex

Diencephalon

Consists of:• Thalamus

– Translates information for interpretation by cerebral cortex

• Hypothalamus– Translates electrical

signals into hormones

Brain StemConsists of:• Midbrain

– connects the pons below with the cerebrum above

• Pons– means bridge– motor and sensory fiber

tracts connecting or bridging the brain to the lower CNS

• Medulla oblongata– lowest brain stem region.

It is composed mainly of fiber tracts

Cerebellum

• Function:– Coordination and

integration of sensory input and motor control (controls balance and equilibrium)

Meninges• Brain and Spinal cord are protected by 3

connective tissue membranes– Dura Mater– Arachnoid Mater– Pia Mater

Cerebral Spinal Fluid • Fluid

– inside the brain found in ventricles– Outside the brain is found in arachnoid layer

• Prevent brain from collapsing in on itself• Shock absorption

Cranial Nerves

• Twelve pairs of cranial nerves arise from the brain

• They have sensory, motor, or both sensory and motor functions

• Each nerve is identified by a number (I through XII) and a name

Functions of NervesI. Olfactory - sense of smellII. Optic - visionIII. Oculomotor Nerve - movement of eyelid and eyeball, constriction of

pupil and accommodation of lens for near visionIV. Trochler Nerve - movement of eyeballV. Trigeminal - chewing (motor) and sensoryVI. Abducens Nerve - lateral movement of eyeballVII. Facial Nerve - Facial expression, taste, tearsVIII. Vestibulocochlear Nerve - hearing, equilibriumIX. Glossopharyngeal Nerve - taste, swallowing, speechX. Vagus Nerve - taste, swallowing, talkingXI. Accessory Nerve - swallowing, SCM, trapezius muscles (neck muscles)XII. Hypoglossal Nerve - tongue movement

Some Say Marry Money But My Brother Says Big Brains Matter Most

Mnemonics for Cranial Nerves

1) On occasion our trusty truck acts funny --very good vehicle anyhow

2) Oh oh oh to touch and feel very green vegetables ah

Summary of Function of Cranial Nerves

Figure 13.5b

Some Say Marry Money But My Brother Says Big Brains Matter Most