<Page>

EXHIBIT 3.73

- --------------------------------------------------------------------------------

-----------------------

CPA I, INC.

BYLAWS

-----------------------

Adopted as of October 20, 1999

- --------------------------------------------------------------------------------

<Page>

CPA I, INC.

BYLAWS

TABLE OF CONTENTS

<Table>
<Caption>
Page

ARTICLE I OFFICES............................................................................. 1
Section 1.1 Principal and Registered Office..................................................... 1
Section 1.2 Other Offices....................................................................... 1

ARTICLE II MEETINGS OF SHAREHOLDERS............................................................ 1
Section 2.1 Location............................................................................ 1
Section 2.2 Annual Meetings..................................................................... 1
Section 2.3 Notice of Annual Meetings........................................................... 1
Section 2.4 Special Meetings.................................................................... 1
Section 2.5 Notice of Special Meetings.......................................................... 1
Section 2.6 Business of Special Meetings........................................................ 2
Section 2.7 Shareholder List.................................................................... 2
Section 2.8 Quorum.............................................................................. 2
Section 2.9 Action by Shareholders.............................................................. 2
Section 2.10 Voting.............................................................................. 2
Section 2.11 Waiver of Notice.................................................................... 2
Section 2.12 Action Without a Shareholders' Meeting.............................................. 2

ARTICLE III BOARD OF DIRECTORS.................................................................. 3
Section 3.1 General Powers; Number, Tenure and Qualifications................................... 3
Section 3.2 Vacancies........................................................................... 3
Section 3.3 Location of Meetings...............,................................................ 3
Section 3.4 Organizational Meetings............................................................. 3
Section 3.5 Regular Meetings.................................................................... 3
Section 3.6 Special Meetings..,,................................................................ 3
Section 3.7 Meetings by Conference Telephone, etc............................................... 3
Section 3.8 Quorum.............................................................................. 3
Section 3.9 Action Without a Meeting............................................................ 4
Section 3.10 Committees.......................................................................... 4
Section 3.11 Committee Minutes and Reports....................................................... 4
Section 3.12 Compensation........................................................................ 4
Section 3.13 Transactions with Directors, etc.................................................... 4
Section 3.14 Removal of Directors................................................................ 5

ARTICLE IV NOTICES............................................................................. 5
Section 4.1 Manner of Giving Notice............................................................. 5
Section 4.2 Waiver of Notice.................................................................... 5

ARTICLE V OFFICERS............................................................................ 5
Section 5.1 Officers, Elections, Terms.......................................................... 5
Section 5.2 Duties of the Chairman of the Board................................................. 5
</Table>

<Page>

<Table>

Section 5.3 Duties of the President............................................................. 6
Section 5.4 Vice Presidents..................................................................... 6
Section 5.5 Treasurer........................................................................... 6
Section 5.6 Assistant Treasurer................................................................. 6
Section 5.7 Secretary........................................................................... 7
Section 5.8 Assistant Secretaries............................................................... 7
Section 5.9 Compensation........................................................................ 7
Section 5.10 Other Officers...................................................................... 7
Section 5.11 Vacancies........................................................................... 7
Section 5.12 Removal of Officers................................................................. 7

ARTICLE VI CONTRACTS, CHECKS, BANK ACCOUNTS, ETC............................................... 7
Section 6.1 Contracts, etc., How Executed....................................................... 7
Section 6.2 Checks, Drafts, etc................................................................. 8
Section 6.3 Deposits........,................................................................... 8
Section 6.4 General and Special Bank Accounts................................................... 8

ARTICLE VII SHARES.............................................................................. 8
Section 7.1 Certificates for Shares............................................................. 8
Section 7.2 Transfer of Shares..........:....................................................... 9
Section 7.3 Regulations......................................................................... 9
Section 7.4 Date for Determining Shareholders of Record......................................... 9
Section 7.5 Lost, Destroyed and Mutilated Certificates.......................................... 9
Section 7.6 Examination of Books by Shareholders................................................ 10

ARTICLE VIII INDEMNIFICATION..................................................................... 10
Section 8.1 Definitions and References.......................................................... 10
Section 8.2 Indemnification of and Advancement of Expenses to Directors......................... 10
Section 8.3 Indemnification of and Advancement of Expenses to Officers, Employees
and Agents.......................................................................... 10
Section 8.4 Liability Insurance...........................-..................................... 10
Section 8.5 Contract Rights..................................................................... 11
Section 8.6 Non-exclusivity..................................................................... 11
Section 8.7 Amendments.......................................................................... 11
Section 8.8 Severability........................................................................ 11

ARTICLE EX WAIVER OF NOTICE.......................,............................................ 11

ARTICLE X SEAL................................................................................ 11

ARTICLE XI FISCAL YEAR......................................................................... 12

ARTICLE XII AMENDMENTS.......................................................................... 12
</Table>

- ii -

<Page>

-----------------------

CPA I, INC.

BYLAWS

-----------------------

ARTICLE 1
OFFICES

SECTION 1.1 PRINCIPAL AND REGISTERED OFFICE. The Corporation's principal
office shall be in the City of Nashville, County of Davidson, State of
Tennessee. The Corporation's registered office in the State of Tennessee shall
be in the City of Nashville, County of Davidson.

SECTION 1.2 OTHER OFFICES. The Corporation may also have offices at such
other places both within and without the State of Tennessee as the Board of
Directors may from time to time determine or the business of the Corporation may
require to the extent not prohibited by law.

ARTICLE II
MEETINGS OF SHAREHOLDERS

SECTION 2.1 LOCATION. All meetings of shareholders shall be held at the
Corporation's principal office, or at such other place either within or without
the State of Tennessee as shall be designated from time to time by the Board of
Directors and stated in the notice of the meeting.

SECTION 2.2 ANNUAL MEETINGS. Annual meetings of shareholders shall be
held on the date and time as shall be designated from time to time by the Board
of Directors and stated in the notice of the meeting. At the annual meeting, the
shareholders shall elect a Board of Directors by plurality vote, and shall
transact any other business as may properly come before the meeting.

SECTION 2.3 NOTICE OF ANNUAL MEETING. Written notice of the annual
meeting stating the place, day and hour of the meeting shall be given to each
shareholder of record entitled to vote at such meeting not less than 10 days nor
more than two months before the date of the meeting.

SECTION 2.4 SPECIAL MEETINGS. Special meetings of shareholders, for any
purpose or purposes, unless otherwise prescribed by statute or by the Charter,
may be called by the Chairman or the President, or a majority of the Board of
Directors, or upon the written request of the holders of at least 10% of all of
the votes entitled to be cast on any issue proposed to be considered at the
proposed special meeting. Such request by the shareholders shall state
specifically the purpose or purposes of the proposed meeting.

SECTION 2.5 NOTICE OF SPECIAL MEETINGS. Written notice of a special
meeting stating the place, day and hour of the meeting and the purpose or
purposes for which the meeting is called, shall be given to each shareholder of
record entitled to vote at such meeting not less than 10 days nor more than two
months before the date of the meeting.

<Page>

SECTION 2.6 BUSINESS OF SPECIAL MEETINGS. Business transacted at any
special meeting of shareholders shall be limited to the purposes stated in the
notice.

SECTION 2.7 SHAREHOLDER LIST. The officer who has charge of the
Corporation's stock ledger shall prepare and make available for inspection by
any shareholder beginning two business days after the notice of the meeting is
given, and continuing through the time of the meeting, a complete, alphabetical
list of shareholders entitled to vote at the meeting, arranged by voting group,
and showing the address of each shareholder and the number of shares registered
in the name of each shareholder. Such list shall be available for inspection by
any shareholder during regular business hours either at the Corporation's
principal office or at a place within the city where the meeting is to be held,
which place is specified in the notice of the meeting. The list of shareholders
entitled to vote also shall be produced and kept at the time and place of the
meeting during the whole time thereof, and may be inspected by any shareholder
who is present.

SECTION 2.8 QUORUM. A majority of the votes entitled to be cast on a
matter by a voting group constitutes a quorum of that voting group for action on
that matter, except as otherwise provided by the Tennessee Business Corporation
Act (the "Act") or the Charter. If, however, a quorum of the shares entitled to
vote as a voting group is not obtained at any meeting of the shareholders, the
chair of the meeting or the holders of a majority of the shares of such voting
group who are present, in person or by proxy, may adjourn the meeting to another
place, date or time, and no notice of such place, date or time need be given;
PROVIDED, HOWEVER, that if a new record date for the adjourned meeting must be
set, notice of such adjourned meeting must be given to persons who are
shareholders as of the new record date. Every meeting of the shareholders may be
adjourned from time to time until its business is completed, and except as
provided herein or by applicable law, no notice need be given of such adjourned
meeting.

SECTION 2.9 ACTION BY SHAREHOLDERS. When a quorum is present at any
meeting, action on any matter, other than the election of directors, by a voting
group is approved if the votes cast within the voting group favoring the action
exceed the votes cast opposing the action, unless the question is one upon which
by express provision in the Charter or the Act, a different vote is required, in
which case, such express provision shall govern and control the decision of such
question.

SECTION 2.10 VOTING. Each shareholder shall at every meeting of the
shareholders be entitled to one vote in person or by proxy for each share having
voting power held by such shareholder, except as may otherwise be provided in
the Charter.

SECTION 2.11 WAIVER OF NOTICE. Whenever any notice is required to be
given to any shareholder, a waiver thereof in writing signed by the person or
persons entitled to such notice, whether before or after the time stated therein
shall be equivalent to the giving of such notice. Attendance of a person at a
meeting shall constitute a waiver of notice of such meeting, except when the
person attends a meeting for the express purpose of objecting, at the beginning
of the meeting, to the transaction of any business because the meeting is not
lawfully called or convened.

SECTION 2.12 ACTION WITHOUT A SHAREHOLDERS' MEETING. Any action required
to be taken at any annual or special meeting of shareholders of the Corporation,
or any action which may be taken at any annual or special meeting of such
shareholders, may be taken without a meeting, without prior notice and without a
vote, upon the affirmative vote of the number of shares that would be necessary
to authorize or take such action at a meeting, provided that all shareholders
entitled to vote on the action consent to taking such action without a meeting.
The consent(s) must be in writing, setting forth the action so taken, and

-2-
<Page>

shall be signed by each of the holders of outstanding shares entitled to vote on
such matter, indicating each signing shareholder's vote or abstention on the
action. Any such consent shall be delivered to the Corporation for inclusion in
the minutes or filing with the corporate records.

ARTICLE III
BOARD OF DIRECTORS

SECTION 3.1 GENERAL, POWERS; NUMBER, TENURE AND QUALIFICATIONS. The
Corporation's business, properties and affairs shall be managed by its Board of
Directors (the "Board"), comprised of a number of directors determined from time
to time by resolution of the Board or the shareholders. Directors shall be
elected at each annual meeting of the shareholders, and shall hold office until
their successors are elected and qualified.

SECTION 3.2 VACANCIES. Vacancies in the Board may be filled by the
shareholders or the affirmative vote of a majority of the remaining directors
even though such remaining directors constitute less than a quorum of the Board.
If there are no directors in office, the shareholders may hold a special meeting
to elect directors.

SECTION 3.3 LOCATION OF MEETINGS. Meetings of the Board, regular or
special, shall be held at the Corporation's principal office unless otherwise
specified in the notice thereof, in which event the meeting shall be held where
specified in the notice, either within or without the State of Tennessee.

SECTION 3.4 ORGANIZATIONAL MEETINGS. The first meeting of each newly
elected Board shall be held on the day and time specified by the Corporation's
Board. No notice of such meeting shall be necessary to the newly elected
directors in order to legally constitute the meeting, provided a quorum is
present.

SECTION 3.5 REGULAR MEETINGS. Regular meetings of the Board shall be
held at such times and places as the Board by resolution may determine.

SECTION 3.6 SPECIAL MEETINGS. Special meetings of the Board may be
called by the Chairman, the President, or any two directors on 24 hours'
personal, telephonic, telegraphic, facsimile or written notice to each director.
Any notice or waiver thereof of a special meeting, whether personal, telephonic,
telegraphic or written, need not include a statement of the business to be
transacted at, nor the purposes of, such special meeting except as expressly
required by statute, the Corporation's Charter or these Bylaws. Meetings of any
committee of the Board may be called by the Chairman, the President or by the
chairman of the committee, at any time upon personal, telephonic, telegraphic or
written notice to each member of such committee and need not include a statement
of the business to be transacted at, nor the purposes of, such special meeting.

SECTION 3.7 MEETINGS BY CONFERENCE TELEPHONE, ETC. Meetings of the Board
and of any committee thereof, may be held by means of a conference telephone or
equivalent communication equipment by which all persons participating in the
meeting can hear each other simultaneously. Participation by such means shall
constitute presence in person at any such meeting.

SECTION 3.8 QUORUM. At all meetings of the Board, a majority of the
directors then holding office shall constitute a quorum for the transaction of
business, and the act of a majority of the directors present at any meeting at
which there is a quorum shall be the act of the Board, except as may otherwise

-3-
<Page>

specifically be provided by statute, the Charter or these Bylaws. If a quorum is
not present at any meeting of the Board, the directors present may adjourn the
meeting from time to time, without notice other than announcement at the
meeting, until a quorum shall be present.

SECTION 3.9 ACTION WITHOUT A MEETING. Any action required or permitted
to be taken at any meeting of the Board or of any committee thereof may be taken
without a meeting or vote, upon the affirmative vote of the number of directors
that would be necessary to authorize or take such action at a meeting, if a
written consent setting forth the action taken is signed by all members of the
Board or committee, as the case may be, and such written consent or consents are
filed with the minutes of proceedings of the Board or of such committee. Such
consents shall have the same effect as a meeting vote of the Board.

SECTION 3.10 COMMITTEES. The Board may, by resolution passed by a
majority of the whole Board, designate one or more committees, each committee to
consist of one or more of the directors of the Corporation. Any such committee,
to the extent provided in the resolution or resolutions of the Board, shall have
and may exercise all the powers and authority of the Board in the management of
the business and affairs of the Corporation during intervals between meetings of
the Board, except to the extent such power and authority may be prohibited or
restricted by the Act. Such committee or committees shall have such name or
names as may be determined from time to time by resolution adopted by the Board.

SECTION 3.11 COMMITTEE MINUTES AND REPORTS. Each committee shall keep
regular minutes of its meetings and report the same to the Board whenever
required or requested.

SECTION 3.12 COMPENSATION. The Board shall have the authority to fix the
compensation of directors. The directors may be paid a fixed sum for attendance
at each meeting of the Board and/or a stated salary as directors. No such
payment shall preclude any director from serving the Corporation in any other
capacity and receiving compensation therefor. Members of special or standing
committees may be compensated for attending committee meetings.

SECTION 3.13 TRANSACTIONS WITH DIRECTORS, ETC. Insofar as not prohibited
by applicable law, no contract or other transaction between the Corporation and
one or more of its directors or officers or between the Corporation or any other
entity in which one or more of its directors or officers are directors, officers
or trustees, are general partners, or have a material financial interest, shall
be void or voidable because of such relationship or interest, or because such
director or officer is present at or participates in a meeting of the Board or a
committee thereof which authorizes, approves or ratifies such contract or
transaction, or solely because his or their votes are counted for such purpose,
if either:

(a) The material facts of the transaction and the director's or
officer's interest were disclosed or known to the Board or a committee of
the Board, and the Board or committee authorized, approved or ratified the
transaction by the affirmative vote of a majority of the disinterested
directors of the Board or the committee, even though the disinterested
directors are less than a quorum; or

(b) The material facts of the transaction and the director's or
officer's interest were disclosed or known to the shareholders entitled to
vote thereon, and such transaction was authorized, approved or ratified by
the vote of the disinterested holders of a majority of the shares entitled
to vote thereon; or

-4-
<Page>

SECTION 3.14 REMOVAL OF DIRECTORS. Any director may be removed from
office with or without cause.

ARTICLE IV
NOTICES

SECTION 4.1 MANNER OF GIVING NOTICE. Except as otherwise required by
law, whenever notice is required to be given to any director or shareholder,
such notice requirement can be satisfied by giving written notice by mail,
postage prepaid, addressed to such director or shareholder, at his address as it
appears on the records of the Corporation, and such notice shall be deemed to be
given at the time when the same is deposited in the United States mail. Notice
to directors may also be given in person or by telegram, facsimile or telephone.

SECTION 4.2 WAIVER OF NOTICE. Whenever any notice is required to be
given to any shareholder or director of the Corporation, a waiver thereof in
writing, signed by the person or persons entitled to said notice, whether before
or after the time stated therein, shall be deemed equivalent to the giving of
such notice.

ARTICLE V
OFFICERS

SECTION 5.1 OFFICERS, ELECTION, TERMS. The officers of the Corporation
shall be a President and a Secretary. The Board may also elect a Chairman of the
Board, a Treasurer and one or more Vice Presidents, Assistant Treasurers,
Assistant Secretaries and such other officers as the Board may from time to time
deem proper. The Corporation's officers shall be elected annually by the Board
at its regular annual organizational meeting to serve for a term of one year and
until their respective successors are elected and qualified. If the officers or
any of them for any reason should not be elected at the regular annual meeting
of the Board, they may be elected at any regular or special meeting of the
Board. Any person may hold two or more of the offices in the Corporation, except
the same person may not serve as President and Secretary (or Assistant
Secretary). The Board may in is discretion designate one or more of the Vice
Presidents as Executive or Senior Vice Presidents.

SECTION 5.2 DUTIES OF THE CHAIRMAN OF THE BOARD. The Chairman of the
Board shall preside at all meetings of the shareholders and Board. He shall have
authority to execute bonds, mortgages and other contracts requiring a seal,
under the seal of the Corporation; he shall have power to endorse, when sold,
assigned, transferred or otherwise disposed of by the Corporation, all
certificates or shares of stock, bonds or other securities issued by other
corporations, associations, trusts, whether public or private, or by any
government agency thereof, and owned or held by the Corporation, and to make,
execute and deliver all instruments or assignments of transfer of any of such
stocks, bonds or other securities. He may, with the approval of the Board, or
shall, at the Board's direction, delegate any or all of such duties to the
President.

SECTION 5.3 DUTIES OF THE PRESIDENT. The President shall be the
Corporation's chief executive officer, and shall be responsible for all of the
operations of the Corporation, and shall report to the Board.

The President shall be responsible to the Chairman and to the Board and
shall see that all orders and resolutions of the Board are carried into effect.
He shall, under the direction of the Board, have general

-5-
<Page>

supervision and direction of the other officers, employees and agents of the
Corporation and shall see that their duties, as assigned by the Board, are
properly performed. He shall designate and assign the duties of the officers
under his supervision, with the approval of the Board or at their direction.

The President shall have authority to execute bonds, mortgages and other
contracts requiring a seal, under the seal of the Corporation; he shall have
power to endorse, when sold, assigned, transferred or otherwise disposed of by
the Corporation, all certificates for shares, bonds or other securities or
evidences of indebtedness issued by other corporations, associations, trusts,
whether public or private, or by any government or agency thereof, and owned or
held by the Corporation and to make, execute and deliver all instruments or
assignments or transfers of any such stocks, bonds or other securities. In the
absence of the Chairman of the Board, the President shall have authority to do
any and all things delegated to the Chairman of the Board by the Board or by any
committee of the Board having authority.

The President shall have general authority over the Corporation's business
and shall have such other powers and perform such other duties as the Board may
from time to time prescribe.

The President will perform all of the duties and have all of the authority
of the Chairman of the Board in the absence of the Chairman of the Board, or in
the event a Chairman is not elected.

SECTION 5.4 VICE PRESIDENTS. The Vice Presidents (in order of the
Executive Vice President, Senior Vice President and other Vice Presidents, each
class in order of the seniority of its respective members or as designated by
resolution of the Board) shall, in the absence or disability of the Chairman and
President, perform the duties and exercise the powers of said officers, and
shall perform such other duties and exercise such other powers as the Board, the
Chairman of the Board or the President may prescribe. One or more vice
presidents may be designated by the Board as either "Executive Vice President"
or "Senior Vice President."

SECTION 5.5 TREASURER. The Treasurer shall be the Corporation's chief
financial officer and shall have charge and custody of, and shall be responsible
for, all funds and securities of the Corporation, and shall deposit all such
funds in the name of the Corporation in such banks or other depositories as
shall be selected or authorized to be selected by the Board; shall render or
cause to be rendered a statement of the condition of the finances of the
Corporation at all regular meetings of the Board, and a full financial report at
the annual meeting of shareholders, if called upon so to do; shall receive and
give receipts for moneys due and payable to the Corporation from any source
whatsoever; and, in general, subject to the provisions hereof shall perform or
cause to be performed all the duties incident to the office of Treasurer and
such other duties as from time to time may be assigned to him by the Board.

SECTION 5.6 ASSISTANT TREASURER. The Assistant Treasurers shall perform
such duties as from time to time may be assigned to them by the Chairman of the
Board, the President, the Treasurer or the Board. At the request of the
Treasurer, or in case of his absence or inability to act, any Assistant
Treasurer may act in his place.

SECTION 5.7 SECRETARY. The Secretary, if present, shall act as secretary
at all meetings of the Board and of the shareholders and keep the minutes
thereof in a book or books to be provided for that purpose; shall see that all
notices required to be given by the Corporation are duly given and served; shall
be custodian of the seal of the Corporation and shall affix the seal or cause it
or a facsimile thereof to be affixed to all certificates representing shares of
the Corporation and to all documents the execution of which on behalf of the
Corporation under its seal shall be duly authorized in accordance with the
provisions of these Bylaws; shall have charge of the stock records of the
Corporation; shall see that all reports,

-6-
<Page>

statements and other documents required by law are properly kept and filed; may
sign, with any other proper officer of the Corporation thereunto authorized,
certificates for shares, securities or evidences of indebtedness of the
Corporation; and, in general, shall perform all the duties incident to the
office of the Secretary and such other duties as from time to time may be
assigned to him by the Chairman of the Board or the Board.

SECTION 5.8 ASSISTANT SECRETARIES. The Assistant Secretaries shall
perform such duties as from time to time may be assigned to them by the Chairman
of the Board, the President, the Secretary or the Board. At the request of the
Secretary, or in case of his absence or inability to act, any Assistant
Secretary may act in his place.

SECTION 5.9 COMPENSATION. The salaries of the Corporation's principal
officers shall be fixed from time to time by the Board, after taking account of
any recommendations by any committee to which the power to advise with respect
to salaries is delegated by the Board. The Board may from time to time delegate
to any principal officer or any committee power to fix the salaries of other
officers, agents and employees. No officer shall be prevented from receiving
such salary by reason of the fact that he is also a director of the Corporation
or a member of any committee contemplated by these Bylaws.

SECTION 5.10 OTHER OFFICERS. The other officers of the Corporation shall
perform such duties and shall exercise such powers as may be prescribed by the
Board, or by the Chairman of the Board, or the President acting under authority
delegated them by the Board.

SECTION 5.11 VACANCIES. Vacancies in office arising from any cause may be
filled by action of the Board at any regular or special meeting of the Board.

SECTION 5.12 REMOVAL OF OFFICERS. The Board may remove any officer from
office at any time by a majority vote of the whole Board of Directors.

ARTICLE VI
CONTRACTS, CHECKS, BANK ACCOUNTS, ETC.

SECTION 6.1 CONTRACTS, ETC., HOW EXECUTED. The Board may authorize any
officer(s) or agent(s) to enter into any contract or execute and deliver any
instrument in the name of and on behalf of the Corporation, and such authority
may be general or confined to specific instances and if the Board so provides
may be delegated by the person so authorized; and, unless so authorized by the
Board or these Bylaws, no officer, agent or employee shall have any power or
authority to bind the Corporation by any contract or engagement or to pledge its
credit or to render it liable pecuniarily for any purpose or to any amount. In
general, absent specific authorization of the Board of Directors, and then only
for the specific purposes and time set forth by the Board, no Treasurer,
Secretary, Assistant Secretary or Assistant Treasurer may enter into any
contract or instrument on behalf of the Corporation without the signature of the
President or the Senior Vice President; PROVIDED nothing herein shall prevent
such officers from attesting the signatures of other officers duly authorized to
execute documents.

SECTION 6.2 CHECKS, DRAFTS, ETC. All checks, drafts or other orders for
the payment of money, notes or other evidences of indebtedness issued in the
name of the Corporation shall be signed by such officer or officers or agent or
agents, as shall from time to time be determined by resolution of the Board.

-7-
<Page>

SECTION 6.3 DEPOSITS. All funds of the Corporation not otherwise
employed shall be deposited from time to time to the credit of the Corporation
or otherwise as the Chairman of the Board, the President, or any other officer
or officers authorized by the Board shall direct in such banks, trust companies
or other depositories as may be selected by the Chairman of the Board, the
President or any other officer or officers or agents or agents to whom power in
that respect shall have been delegated by the Board. For the purpose of deposit
and for the purpose of collection for the account of the Corporation, checks,
drafts and other orders for the payment of money which are payable to the order
of the Corporation may be endorsed, assigned and delivered by such officer or
officers or agent or agents as shall be determined by the Chairman of the Board,
the President or any other officer or officers designated by the Board.

SECTION 6.4 GENERAL AND SPECIAL BANK ACCOUNTS. The Board or the Chairman
of the Board, the President or any other officer or officers designated by the
Board may from time to time authorize the opening and keeping of general and
special bank accounts with such banks, trust companies or other depositories as
may be selected by the Board. The Board may make such special rules and
regulations with respect to such bank accounts, not inconsistent with the
provisions of these Bylaws, as it may deem expedient.

ARTICLE VII
SHARES

SECTION 7.1 CERTIFICATES FOR SHARES. Every holder of shares shall be
entitled to have a certificate, in such form as the Board shall prescribe,
certifying the number and class of Corporation shares owned by him. Each such
certificate shall be signed in the name of the Corporation by the Chairman or
Vice Chairman of the Board, the President or an Executive Vice President or a
Vice President, and by the Treasurer or an Assistant Treasurer or the Secretary
or an Assistant Secretary. The signature of any such officer may be a facsimile.
In case any officer, transfer agent or registrar who has signed, or whose
facsimile signature has been placed upon, any such certificate shall cease to be
such officer, transfer agent or registrar, before such certificate shall have
been issued by the Corporation, such certificate may nevertheless be issued by
the Corporation with the same effect as if such person were such officer,
transfer agent or registrar at the date of issue. A record shall be kept of the
respective names of the persons, firms or corporations owning the shares
represented by certificates, respectively, and the respective dates thereof,
and, in case of cancellation, the respective dates of cancellation. Every
certificate surrendered to the Corporation for exchange or transfer shall be
cancelled, and a new certificate or certificates shall not be issued in exchange
for any existing certificates until such existing certificate shall have been so
cancelled, except in cases otherwise provided for in this Article VII.

SECTION 7.2 TRANSFER OF SHARES. Each transfer of Corporation shares
shall be made only on the books of the Corporation by the registered holder
thereof, or by his attorney thereunto authorized by power of attorney duly
executed and filed with the Secretary of the Corporation, or with a transfer
agent appointed as provided in this Article VII, upon the payment of any taxes
thereon and the surrender of the certificate or certificates for such shares
properly endorsed and in good delivery form. The person in whose name
Corporation shares stand on the books of the Corporation shall be deemed the
owner thereof for all purposes as regards the Corporation; PROVIDED that
whenever any transfer of shares shall be made for collateral security and not
absolutely, such fact, if known to the Corporation or to any such transfer
agent, shall be so expressed in the entry of transfer if requested by both the
transferor and transferee.

SECTION 7.3 REGULATIONS. The Board may make such rules and regulations
as it may deem expedient, not inconsistent with these Bylaws, concerning the
issue, transfer and registration of certificates

-8-
<Page>

for Corporation shares. It may appoint, or authorize the Chairman or President
to appoint, one or more transfer agents and one or more registrars, and may
require all certificates for shares of the Corporation to bear the signature or
signatures of any such transfer agents or registrars.

SECTION 7.4 DATE FOR DETERMINING SHAREHOLDERS OF RECORD.

(a) In order that the Corporation may determine the shareholders
entitled to notice of or to vote at any meeting of shareholders or any
adjournment thereof or entitled to receive payment of any dividend or other
distribution or allotment of any rights, or entitled to exercise any rights
in respect to any change, conversion or exchange of shares or for the
purpose of any other lawful action, the Board may fix in advance, a record
date, which record date shall not precede the date upon which the
resolution fixing the record date is adopted, and which shall not be more
than 70 days before the date of such meeting or action. If no record date
is fixed by the Board, the record date shall be at the close of business on
the day on which notice is given, or, if notice is waived, at the close of
business on the day on which the meeting is held, or, in the case of a
distribution (other than one involving the repurchase or reacquisition of
shares), the day on which the Board authorizes such distribution. A
determination of shareholders of record entitled to notice of or to vote at
a meeting of shareholders shall apply to any adjournment of such meeting;
PROVIDED, HOWEVER, that the Board may fix a new record date for the
adjourned meeting and must fix a new record date if the meeting is
adjourned to a date more than four months after the date for the original
meeting.

(b) If no record date has been fixed by the Board, the record
date for determining shareholders entitled to consent to corporate action
in writing without a meeting, when no prior action by the Board is required
under the Act, shall be the first date on which a signed written consent
setting forth the action taken or proposed to be taken is delivered to the
Corporation by delivery to its registered or principal office. Delivery to
the Corporation's registered office shall be by hand or by certified or
registered mail, return receipt requested.

SECTION 7.5 LOST, DESTROYED AND MUTILATED CERTIFICATES. The holder of
any Corporation shares or other securities shall immediately notify the
Corporation of any loss, destruction or mutilation of the certificate(s)
therefor, and the Board may, in its discretion, and after the expiration of such
period of time as it may determine to be advisable, cause to be issued to him a
new certificate or certificates for shares, upon the surrender of the mutilated
certificate, or in case of loss or destruction of the certificate, upon proof
satisfactory to the Board of such loss or destruction, and the Board or its
delegee may, in its discretion, require the owner of the lost, destroyed or
mutilated certificate, or his legal representatives, to give the Corporation a
bond, in such sum and with such surety or sureties as it may direct, or to
indemnify the Corporation against any claim that may be made against it on
account of the alleged loss, destruction or mutilation of any such certificate
or the issuance of such new certificate.

SECTION 7.6 EXAMINATION OF BOOKS BY SHAREHOLDERS. The Board shall,
subject to any applicable statutes, have the power to determine, from time to
time, whether and to what extent and at what times and places and under what
conditions and regulations the accounts and books and documents of the
Corporation, or any of them, shall be open to the inspection of the
shareholders; and no shareholder shall have any right to inspect any account or
book or document of the Corporation, except as conferred by any such statute,
unless and until authorized so to do by resolution of the Board or of the
shareholders of the Corporation.

-9-
<Page>

ARTICLE VIII
INDEMNIFICATION

SECTION 8.1 DEFINITIONS AND REFERENCES. Terms used in this Article shall
have the meanings assigned such terms in Part 5 of Chapter 18 of the Act.
Whenever in this provision reference is made to a specific section of the Act,
such reference shall be deemed to refer to such section as amended from time to
time or any successor provision.

SECTION 8.2 INDEMNIFICATION OF AND ADVANCEMENT OF EXPENSES TO DIRECTORS.
The corporation shall indemnify and advance expenses to its directors to the
full extent and under the conditions that a Tennessee corporation is permitted
to indemnify and advance expenses to its directors under Part 5 of Chapter 18 of
the Act, as amended from time to time, other than the provisions of Section
48-18-509 thereof.

SECTION 8.3 INDEMNIFICATION OF AND ADVANCEMENT OF EXPENSES TO OFFICERS,
EMPLOYEES AND AGENTS. The corporation shall indemnify and advance expenses to
its officers who are not directors (and may, if authorized for a specific
proceeding, indemnify and advance expenses to its employees and agents who are
not officers or directors) to the same extent and under the same conditions as
to directors. No advancement or reimbursement of expenses to officers, employees
or agents in accordance with the foregoing sentence shall be made unless the
proposed indemnitee furnishes the Corporation a written affirmation of his or
her good faith belief that he or she has met the standard of conduct set forth
in Section 48-18-502(a) of the Act, and he or she furnishes the Corporation a
written undertaking, executed personally or on his or her behalf, to repay any
advances if it is ultimately determined that he or she is not entitled to
indemnification under this Article or Part 5 of Chapter 18 of the Act.

SECTION 8.4 LIABILITY INSURANCE. The corporation may purchase and
maintain insurance on behalf of an individual who is a director, officer,
employee or agent of the Corporation or who, while a director, officer, employee
or agent of the Corporation, serves at the Corporation's request as a director,
officer, partner, trustee, employee or agent of another domestic or foreign
corporation, partnership, joint venture, trust, employee benefit plan, or other
entity against liability asserted against or incurred by him or her in that
capacity or arising from his or her status as a director, officer, employee, or
agent, whether or not the Corporation would have power to indemnify or advance
expenses to him or her against the same liability under this Article or under
Part 5 of Chapter 18 of the Act.

SECTION 8.5 CONTRACT RIGHTS. The right to indemnification and
advancement of expenses conferred hereunder to directors and officers shall be a
contract right and shall not be affected adversely to any director or officer by
any amendment of these Bylaws with respect to any action or inaction occurring
prior to such amendment; provided, however, that this provision shall not confer
upon any indemnitee or potential indemnitee (in his or her capacity as such) the
right to consent or object to any subsequent amendment of these Bylaws.

SECTION 8.6 NON-EXCLUSIVITY. The rights of a director or officer
hereunder shall be in addition to any other rights with respect to
indemnification, advancement of expenses or otherwise that he or she may have
under contract or the Act or otherwise.

SECTION 8.7 AMENDMENTS. No amendment, modification or rescission of this
Article, or any provision hereof, the effect of which would diminish the rights
to indemnification or advancement of

-10-
<Page>

expenses as set forth herein shall be effective as to any director or officer of
the Corporation with respect to any action taken or omitted by such person prior
to such amendment, modification or rescission.

SECTION 8.8 SEVERABILITY. To the extent that the provisions of this
Article are held to be inconsistent with the provisions of Part 5 of Chapter 18
of the Act, such provisions of such Act shall govern. In the event that any of
the provisions of this Article (including any provision within a single section,
subsection, division or sentence) is held by a court of competent jurisdiction
to be invalid, void or otherwise unenforceable, the remaining provisions of this
Article shall remain enforceable to the fullest extent permitted by law.

ARTICLE IX
WAIVER OF NOTICE

Whenever any notice whatever is required to be given by these Bylaws or by
statute, the person entitled thereto may in person, or in the case of a
shareholder by his attorney thereunto duly authorized, waive such notice in
writing (including, telegraph, cable, radio or wireless), whether before or
after the meeting, or other matter in respect of which such notice is to be
given, and in such event such notice, and any action to be taken after such
notice or after the lapse of a prescribed period of time may be taken without
such notice and without the lapse of any period of time.

ARTICLE X
SEAL

The seal of the Corporation shall be in the form of a circle and shall bear
the name of the Corporation, the year of its incorporation and the word
"Tennessee" as impressed to the margin hereof. It need not be affixed to
contracts and other agreements to which the Corporation is a party for such
contracts and agreements to be binding.

ARTICLE XI
FISCAL YEAR

The fiscal year of the Corporation shall be determined by resolution of the
Board.

ARTICLE XII
AMENDMENTS

These Bylaws may be amended or repealed, or new Bylaws may be adopted, by
the affirmative vote of a majority of the Board at any regular or special
meeting of the Board, unless the Charter or applicable law reserve this power to
the shareholders.

-11-
<Page>

EXHIBIT 3.73

- --------------------------------------------------------------------------------

-----------------------

CPA I, INC.

BYLAWS

-----------------------

Adopted as of October 20, 1999

- --------------------------------------------------------------------------------

<Page>

CPA I, INC.

BYLAWS

TABLE OF CONTENTS

<Table>
<Caption>
Page

<Page>

<Table>

ARTICLE EX WAIVER OF NOTICE.......................,............................................ 11

ARTICLE X SEAL................................................................................ 11

ARTICLE XI FISCAL YEAR......................................................................... 12

ARTICLE XII AMENDMENTS.......................................................................... 12
</Table>

- ii -

<Page>

-----------------------

CPA I, INC.

BYLAWS

-----------------------

ARTICLE 1
OFFICES

ARTICLE II
MEETINGS OF SHAREHOLDERS

<Page>

SECTION 2.6 BUSINESS OF SPECIAL MEETINGS. Business transacted at any
special meeting of shareholders shall be limited to the purposes stated in the
notice.

-2-
<Page>

ARTICLE III
BOARD OF DIRECTORS

SECTION 3.5 REGULAR MEETINGS. Regular meetings of the Board shall be
held at such times and places as the Board by resolution may determine.

-3-
<Page>

SECTION 3.11 COMMITTEE MINUTES AND REPORTS. Each committee shall keep
regular minutes of its meetings and report the same to the Board whenever
required or requested.

-4-
<Page>

SECTION 3.14 REMOVAL OF DIRECTORS. Any director may be removed from
office with or without cause.

ARTICLE IV
NOTICES

ARTICLE V
OFFICERS

-5-
<Page>

The President shall have general authority over the Corporation's business
and shall have such other powers and perform such other duties as the Board may
from time to time prescribe.

The President will perform all of the duties and have all of the authority
of the Chairman of the Board in the absence of the Chairman of the Board, or in
the event a Chairman is not elected.

-6-
<Page>

SECTION 5.11 VACANCIES. Vacancies in office arising from any cause may be
filled by action of the Board at any regular or special meeting of the Board.

SECTION 5.12 REMOVAL OF OFFICERS. The Board may remove any officer from
office at any time by a majority vote of the whole Board of Directors.

ARTICLE VI
CONTRACTS, CHECKS, BANK ACCOUNTS, ETC.

-7-
<Page>

ARTICLE VII
SHARES

SECTION 7.3 REGULATIONS. The Board may make such rules and regulations
as it may deem expedient, not inconsistent with these Bylaws, concerning the
issue, transfer and registration of certificates

-8-
<Page>

SECTION 7.4 DATE FOR DETERMINING SHAREHOLDERS OF RECORD.

-9-
<Page>

ARTICLE VIII
INDEMNIFICATION

SECTION 8.7 AMENDMENTS. No amendment, modification or rescission of this
Article, or any provision hereof, the effect of which would diminish the rights
to indemnification or advancement of

-10-
<Page>

ARTICLE IX
WAIVER OF NOTICE

ARTICLE X
SEAL

ARTICLE XI
FISCAL YEAR

The fiscal year of the Corporation shall be determined by resolution of the
Board.

ARTICLE XII
AMENDMENTS

-11-