Biology 241 – Lab
LAB #7
(7th/21 Lab Sessions for Fall Quarter, 2008)
TOPICS TO BE COVERED
»Overview of how bones are classified.
»Review of the Significant Parts of a “Typical” Long Bone.
»General Terminology for Anatomical Features on the Surface of Bones (Boney Landmarks)
»Overview of the Axial & Appendicular Skeleton; the subdivisions of each Division; and names of
and number of bones in each subdivision.
»Introduction of Boney Landmarks of Axial Skeleton bones: Vertebrae
DESIRED OUTCOMES:
After completing the activities described for this lab session, students should:
»Be able to classify bones according to their shape giving appropriate reasons why the bone fits
into the particular classification.
»Be able to identify all parts of a “typical” long bone on a bone, model or diagram.
»Be conversant with definitions and examples of the various types of bone markings.
»Know the two Divisions of the Skeleton; the four sub-divisions of each division; and the
names of and number of bones in each sub-division.
»Know the general characteristics of all vertebra including how to name each vertebra
»Be able to identify vertebrae of the five regions of the vertebral column (including differential
characteristics)
MATERIALS NEEDED:
»Articulated Skeletons
» Bone Boxes: Disarticulated Skeleton
»Skulls
»Disarticulated skull in its own box
» Model: Articulated Vertebral Column
»Sets of Vertebrae (example vertebrae
from each vertebral region)
»Window Box: Various Sections through a Femur
»X-rays and Illuminating Light Boxes
»Other models as appropriate
»Wall chart of Human Skeleton
»Photographic Atlas, Ch. 5 and Ch. 6
Activity #1: Overview of how bones are classified
Almost all bones of the body can be classified into five main types based on shape: Long, Short, Flat,
Irregular, and Sesamoid. Please review the descriptions, including examples, given at the beginning of Chapter 7 of your textbook. Remember, an additional type of bone is classified by location rather than shape.
These are sutural bones (aka Wormian bones) that are small bones located within sutures (immovable joints) between certain cranial bones. (In the frontal suture, sagittal suture, and, most often, in the lambdoidal suture.)
Their number varies greatly from person to person; but statistically at least 30% of individuals have one or more
of these. (It is memorable to see them on an X-ray of the skull!)
Biology 241 – Lab #7 – continued
Page Two
Activity #2: Review of the Significant Parts of a “Typical” Long Bone
You are proceeding with a homework assignment in the Lecture portion of this class that requires of
you to study and write-up detailed description of the anatomical considerations of the 5 regions and 10 significant structures of a long bone, along with their functional contributions. These are listed here for you:
5 Regions: 1) Proximal epiphyseal region
2) Proximal metaphyseal region (What is this called/composed of in a child’s long bone?
What is this called/composed of in an adult’s long bone?)
3) Diaphyseal region
4) Distal metaphyseal region (Again, same questions as for the prox. metaphyseal region)
5) Distal epiphyseal region
10 Structures: 1) Articular cartilages (covering BOTH prox. and dist. articular surfaces)
2) Spongy (aka Trabecular) Bone
3) Red bone marrow (aka Myeloid)
4) Epiphyseal Plate/Line (depends on AGE of bone being described!)
5) Compact Bone
6) Periosteum
7) Medullary Cavity
8) Yellow bone marrow
9) Endosteum
10) Nutrient artery piercing through the Nutrient foramen
Now, in the Lab setting, you may be able to visualize many of these physical structures to more fully appreciate
how each contributes to the overall effectiveness of individual bones as organs of the Skeletal System.
Activity #3: General Terminology for Anatomical Features on Bone Surfaces (Boney Landmarks)
Each bone has certain anatomical features on the surface called bone markings (aka surface markings). A
particular bone marking may be unique to a single bone or may occur throughout the skeleton. (Your Instructor
may illustrate examples of generalized bone markings as follows:
ON A FEMUR: Head, Neck, Trochanter, Tuberosity, Tubercle, Condyle, Facet
ON A SKULL: Sinus, Fissure, Process, Foramen;
ON A PELVIC BONE: Crest, Spine, Line, Ramus, Fossa
The following TABLE organizes the markings into five groups. The first group includes general anatomical
structures; the second group lists specialized boney structures for attachment of tendons and ligaments; the
third group contains structures that enable articulation with other bones; and the last two groups include
depressions and openings.
Biology 241 – Lab #7 – continued
Page Three
TABLE of Terminology for Anatomical Features of the Bones of the Skeleton
General Description
Anatomical Term
Definition
Elevations and projections
(general)
Process
Ramus
Any projection or bump
An extension of a bone making an angle to the rest
of the structure
Processes formed where tendons
or ligaments attach
Trochanter
Tuberosity
Tubercle
Crest
Line (Linea)
A large, rough projection
A smaller, rough projection
A small, rounded projection
A prominent ridge
A low ridge
Processes specializeded for articulation
with adjacent bones
Head
Condyle
Epicondyle
Trochlea
Facet
Spine
The expanded articular end of an epiphysis, separated from the shaft by a narrower neck
A smooth, rounded articular process
A projection above a condyle
A smooth, grooved, “pulley-like “articular process
A small, flat, smooth articular surface
A prominent, pointed process
Depressions
Fossa
Fovea
Sulcus
Alveolus
A shallow depression – may be large or small
A small, sharp, cone-shaped depression
A narrow groove
A small, hollow cavity (as in a socket for a tooth)
Openings
Foramen
Fissure
Meatus
A rounded passageway for blood vessels / nerves
An elongated cleft
Opening of a canal-like structure leading through
the substance of a bone
A chamber within a bone, normally filled with air
Sinus (aka antrum)
Activity #4: Introduction to the Axial & Appendicular Divisions of the Skeleton
The human skeleton consists of 206 bones, 80 of which are in the Axial Division. The four subdivisions of the Axial Skeleton (and the number of bones per subdivision) are the Skull (22), Hyoid bone (1),
Vertebral Column (32), and Rib Cage (25).
The other 126 bones of the human skeleton are contained in the Appendicular Division. The four subdivision of the Appendicular Skeleton (and the number of bones per subdivision) are the Shoulder Girdles (4);
Upper Extremities (60); Pelvic Girdle (2); and Lower Extremities (60).
In today’s lab, we will begin the study of boney landmarks of the bones of the Axial Division by observing the vertebrae and identifying pertinent features of all vertebrae, in general, and certain ones specifically.
Please refer to the Osteology sheets which list all the landmarks for which you will be held responsible. Then,
using that as your “checklist”, use the Photographic Atlas and textbook’s photographs, as well as all the bones
and models available in Lab, on which to identify each landmark.
Biology 241 – LAB #7 – continued
Page Four
The vertebral column protects the spinal cord and provides attachment sites for back and abdominal
muscles. The curved vertebral column (aka backbone) is a flexible structure that can be bent, twisted, and
rotated, especially in the cervical region. The vertebral column consists of 5 regions: cervical, thoracic, lumbar,
sacral and coccygeal. (The sacral vertebrae are fused in the adult, into what is commonly called the sacrum, but it is still
composed of five vertebral bones. The coccyx (tailbone) is usually composed of four small, fused coccygeal vertebrae; but
the number varies between 1 and 6.) The vertebral column articulates with the skull, the ribs, and the pelvis.
The five regions of the vertebral column and the number of vertebrae in the adult, from superior to
inferior, are: cervical (7), thoracic (12), lumbar (5), sacral (5 fused) and coccygeal (≈4) for a total of 32
vertebrae. (To remember the number of vertebrae in the first three groups, students say they eat “breakfast at 7, lunch at
12, and dinner at 5!) Vertebrae are named according to the following scheme: (1) use the first letter (always a
capital letter) of the region from which the vertebra comes, except for the coccygeal region you use two letters;
(2) followed by a subscript of the number that vertebra is in the sequence of vertebra for its region.
Examples: The sixth cervical vertebra is C6, the eighth thoracic vertebra is T8, the third lumbar vertebra is L3,
the fourth sacral vertebra is S4, and the second coccygeal vertebra is Co2.
There are four normal curvatures that correspond with the regions of the vertebral column: cervical,
thoracic, lumbar, and sacral (aka pelvic) curvatures. A newborn has a single anteriorly concave primary curve
that will become the thoracic curvature and sacral curvature. Two anteriorly convex secondary curves, the
cervical curvature and lumbar curvature, develop several months later. The cervical curvature develops when
the baby can hold its head erect, while the lumbar curvature develops when the baby can stand.
Of the 32 vertebrae (some books say 26 because they are counting the 5 sacral vertebrae as 1 and the ≈4
coccygeal vertebrae as 1) all share certain general features such as a single body, two pedicles, two transverse
processes, two laminae, a single spinous process, two superior articular processes and two inferior articular
processes. Collectively, the 2 pedicles, 2 transverse processes, 2 laminae and 1 spinous process are referred to
as the vertebral arch. (All of these general features can be easily recognized and identified from photos in your Atlas,
or on the actual vertebra themselves.) (See Fig. 5.28 and 5.29 in the Atlas)
In addition to the general features enumerated above, vertebrae of different regions share unique
regional characteristics that help one to identify a vertebra as cervical, thoracic, or lumbar.
A. Cervical vertebrae
(1) Share the following common features:
(a) Transverse foramina: Found only in the seven cervical vertebrae, these through-and-through openings
In the transverse processes permit passage of blood vessels called the vertebral artery and vertebral
vein. (In fact, the foramen are there because the blood vessels came first and already occupied that space as the
vertebrae ossified around them.)
(b) Bifid spinous processes: the ends of cervical vertebral spinous processes are often forked rather than
having a single, blunt tip.
(c) The body size : vertebral foramen ratio is less than 1 (that is, the surface area of the vertebral foramen
is larger than the surface area of the body for each of the cervical vertebrae.)
(2) Two cervical vertebrae are named separately from others because of their unique features:
(a) Atlas (C1): The first cervical vertebra articulates with the occipital bone at the occipital condyles. It is
easily identified because it is “ring-shaped”; has the largest vertebral foramen, a very rudimentary
body and spinous process. Its name comes from the Greek mythological strongman who was tasked
with holding up the world – in the same way that C1 “holds up the head”
(b) Axis (C2): The second cervical vertebra which articulates with C1 to form the atlantoaxial joint. It is
also easily identified by its modified ring-shape, a bit more well-defined body off of whose superior
surface arises a tooth-shaped projection called the odontoid process (aka the dens). The dens fits up
inside the atlas and its anterior surface articulates with the rudimentary body of C1, enabling rotation
of the head. The nickname of this vertebra comes from the fact that the dens of this vertebra sets up
the axis about which rotation can be accomplished.
Biology 241 – LAB #7 – continued
Page Five
B. Thoracic vertebrae share the following common features:
(1) The spinous processes are thin, delicate, somewhat sharp, and point inferiorly.
(2) All 12 thoracic vertebrae have two transverse articular costal facets, which are the site of articulation
with ribs bilaterally. (Remember, there are 12 pairs of ribs; each pair being associated with a particular
thoracic vertebra.)
(3) All have somewhat triangular vertebral foramina
(4) The bodies of these vertebrae, while prominent, are fairly delicate.
(5) The body size : vertebral foramen ratio is nearly 1 (that is, the surface area of the vertebral foramen is
approximately the same size as the surface area of the body for each of the thoracic vertebrae .)
(6) If you look at a thoracic vertebra from a posterior view, each one resembles a giraffe!
C. Lumbar vertebrae share the following common features:
(1) All have a very large, block-like body.
(2) The spinous processes are thick, blunt, and point directly posteriorly.
(3) The body size : vertebral foramen ratio is less than 1 (that is, the surface area of the vertebral foramen is
smaller than the surface area of the body for each of the lumbar vertebrae.)
(4) If you look at a lumbar vertebra from a posterior view, each one resembles a moose!
(First note: Bones of the Axial Skeleton whose boney landmarks still remain to be studied in Lab are:
(1) Each of the 22 Bones of the Skull,
(2) 1 Hyoid Bone,
(3) 25 Bones of the Rib Cage:
(a) 1 Sternum
(b) 24 Ribs
(Second note: Please refer to Lab #14 now for information about Lab Practical #2 (which is the one that will test
you on Osteology) so that you will have the “heads-up” information earlier rather than later on how you will be
tested on the bones. Paying attention to this information now will benefit you as you begin studying the boney
landmarks, the relationship of one bone to another, and all the information associated with Osteology.)