Exercises 27 and 28

1
Exercises 27 and 28

• Reflex arc and reflexes
• Brain and Cranial Nerves

2
Ex. 27

• Objectives
• to describe a reflex arc
• distinguish between a reflex and a reflex arc
• identify the reflexes listed in the following
  slides

3
Information

• A reflex is an automatic response to a stimulus
• The parts of the reflex arc include receptor,
  sensory or afferent neuron, interneuron, motor or
  efferent neuron, and effector
• go to for a diagram of the reflex arc
  http//education.vetmed.vt.edu/Curriculum/VM8054/L
  abs/Lab9/Examples/exsomarc.htm
• reflexes are an important tool to help determine
  spinal cord damage

4
Links to help

• http//www.merck.com/mmhe/sec06/ch077/ch077c.html
  MMHE_06_077_01

5
Procedure Work with a partner to demonstrate
each reflex using the reflex hammer provided

• 1. Knee jerk reflex (or patellar reflex)-sit on
  table with legs crossed and relaxed (you can also
  do this without crossing the leg)
• -gently strike the patellar ligament just below
  the patella with the rubber percussion hammer
• -normal response is slight extension of the leg
• 2. Ankle-jerk reflex
• -kneel on a chair and hand feet over the edge
  (relaxed)
• -gently strike the Achilles tendon
• -the foot should plantar flex

6
continued

• 3. Biceps-jerk reflex
• -bend elbow as shown in figure 27.2 c.
• -press thumb on the tendon of the biceps brachii
  in elbow
• -strike your thumb
• -should show slight flexion of the arm
• 4. Triceps-jerk reflex
• -you can place arm over the back of a chair or
  hold arm in position for this one. (your TA will
  demonstrate)
• -tap the tendon of the triceps near the
  olecranon process
• -the triceps brachii should extend the arm
  slightly

7
continued

• 5. plantar reflex-take off your sock and shoe
• Draw the metal tip of the rubber hammer over the
  from the sole of the heel to the base of your big
  toe
• Your toes should curl and the foot plantar flexes
• If your toes spread apart and your foot
  dorsiflexes you are showing the Babinski reflex
  which is ONLY in newborns.
• In an adult this could indicate damage to the
  spinal column

8
Brain and Cranial Nerves

• Exercise 28

9
Objectives

• Identify the major structures of the human brain
• Locate major functional regions of the human
  brain
• Identify the cranial nerves
• List functions of the cranial nerves (go to this
  web site). There is a paragraph first, so scan
  down to the bottom and click next for the table
  
• http//www.meddean.luc.edu/lumen/MedEd/GrossAnatom
  y/h_n/cn/cn1/mainframe.htm

10
Procedure A Human Brain

• Using the human brain models and diagrams locate
  all the following structures
• cerebrum
• cerebral hemispheres
• corpus callosum (white matter tract that connects
  the two cerebral hemispheres)
• convolutions (also called gyri)
• sulci (central sulcus and lateral sulcus)

11
insula
12
Structures to learn continued

• fissures (longitudinal and transverse fissures)
• lobes (frontal, temporal, parietal, occipital)
  (the fifth lobe is called the INSULA)
• cerebral cortex (outer layer of cerebrum)
• ventricles (lateral, third, fourth, choroid
  plexus, cerebral aqueduct)
• extra information the lateral ventricles are
  separated by the septum pellucidum.
• Also see the intermediate mass in the middle of
  the area of the 3rd ventricle

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More structures

• Hypothalamus
• Thalamus
• Fornix
• Midbrain
• Pons
• Medulla oblongata
• Pituitary gland

• Mammillary bodies
• Corpora quadrigemina
• Pineal gland
• Cerebellum
• Arbor vitae (tree of life)

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fornix
Intermediate mass
Corpora quadrigemina
Pituitary gland
cerebellum
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Corpus callosum
Lateral ventricles
Choroid plexus
hypothalamus
Midbrain
4th ventricle
Pons
Medulla oblongata
Page 412 in text
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Cranial Nerves Procedure B
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Objectives

• Identify the cranial nerves
• List functions of the cranial nerves (go to this
  web site). There is a paragraph first, so scan
  down to the bottom and click next for the table
  
• http//www.meddean.luc.edu/lumen/MedEd/GrossAnatom
  y/h_n/cn/cn1/mainframe.htm
• http//www.gwc.maricopa.edu/class/bio201/cn/crania
  l.htm

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Cranial nerves

• Using the models supplied or the diagrams,
  located each cranial nerve and know the functions
  (you can get this information from your book or
  the web sites indicated)
• olfactory (I)
• optic (II)
• oculomotor (III)
• trochlear (IV)
• trigeminal (V)
• abducens (VI)

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Cranial nerves continued

• facial (VII)
• vestibulocochlear (VIII)
• glossopharyngeal (IX)
• vagus (X)
• accessory (XI)
• hypoglossal (XII)
• A way to remember these Oh Oh Oh To Touch And
  Feel Very Good Velvet AH
• http//faculty.washington.edu/chudler/cranial.html
  

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Another good link

• http//www.gwc.maricopa.edu/class/bio201/cn/crania
  l.htm
• This is a good site!! It has functions listed
  too.

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Mammillary bodies
p. 418 text
22
Cranial nerve one (olfactory) is not on this
diagram
Pituitary gland
Optic
thalamus
Pineal gland
Pons
4th ventricle
p. 409 text