Skeletal System (Part 3) - Vertebrae, ribs and sternum
Summary
TLDRThis module discusses the vertebral formula, structure, and classification of the vertebrae, ribs, and sternum in animals, with a focus on dogs. It explains the arrangement of vertebrae (cervical, thoracic, lumbar, sacral, caudal), the features of each type, and their role in supporting the body. The rib structure and their articulation with the thoracic vertebrae and sternum are also covered. Notable sections include descriptions of the atlas, axis, anticlinal vertebra, and the differences between sternal and floating ribs. A quiz is offered at the end of the module.
Takeaways
- đ The vertebral formula of a dog is C7, T13, L7, S3, and Ca 20-24, meaning 7 cervical, 13 thoracic, 7 lumbar, 3 sacral, and 20-24 caudal vertebrae.
- 𩮠Vertebrae are irregular bones that form the vertebral column, extending from the skull to the tail.
- đŠ The vertebrae are grouped by location: cervical (neck), thoracic (chest), lumbar (loin), sacral (pelvic), and caudal (tail).
- đâđŠș A typical vertebra has a body, an arc, and several processes; the sixth cervical vertebra is used as an example.
- đïž The first cervical vertebra, the atlas, supports the head, and the second cervical vertebra, the axis, forms a pivot joint with the atlas.
- đ§ The thoracic vertebrae are characterized by tall spinous processes and articulate with the ribs, with T11 serving as the anticlinal vertebra in dogs.
- đŸ There are 13 pairs of ribs in dogs, corresponding to the number of thoracic vertebrae, with 9 true ribs, 3 false ribs, and 1 floating rib.
- 𧩠The sternum is composed of 8 fused bones called sternebrae and is divided into the manubrium, body, and xiphoid process.
- đ© The ribs are divided into different types based on their attachment to the sternum: true ribs, false ribs, and floating ribs.
- đ Key processes on vertebrae include spinous, transverse, and articular processes, with additional features like transverse foramina in cervical vertebrae.
Q & A
What is the vertebral formula of a dog?
-The vertebral formula of a dog is C7, T13, L7, S3, Ca20-24. This means there are 7 cervical, 13 thoracic, 7 lumbar, 3 sacral, and 20-24 caudal vertebrae.
Where are the cervical vertebrae located, and how many are there in a dog?
-The cervical vertebrae are located in the neck region, and there are 7 cervical vertebrae in a dog.
What are the key characteristics of thoracic vertebrae?
-Thoracic vertebrae are characterized by tall spinous processes, short bodies, and transverse processes. They also articulate with the ribs.
What is the function of the atlas (C1) in the vertebral column?
-The atlas, or C1, supports the head and connects it with the rest of the body. It is morphologically unique, lacking a spinous process and having wing-like transverse processes.
How do the ribs articulate with the vertebral column in dogs?
-Ribs articulate with the thoracic vertebrae. The head of the rib connects with the costal fovea on the body of the vertebra, while the tubercle of the rib connects with the transverse fovea on the transverse process of the vertebra.
How are sternal and asternal ribs different in dogs?
-Sternal ribs, also called true ribs, directly articulate with the sternum via costal cartilages, while asternal ribs, or false ribs, do not directly attach to the sternum and are instead fused into the costal arch.
What is the role of the sacrum in the vertebral column?
-The sacrum is formed by the fusion of sacral vertebrae and articulates with the hip bones to form the sacroiliac joint, providing support to the pelvis.
What are the typical components of a vertebra?
-A typical vertebra consists of a body, an arc (composed of the lamina and pedicle), and various processes, including spinous, transverse, and articular processes.
What is the anticlinal vertebra, and where is it located in a dog?
-The anticlinal vertebra in a dog is T11, characterized by a vertically oriented spinous process, in contrast to the adjacent thoracic vertebrae that have spinous processes angled cranially or caudally.
What is the purpose of the hemal arches in the caudal vertebrae of dogs?
-Hemal arches are bony structures found on the ventral surface of the 4th to 6th caudal vertebrae in dogs. They protect the median caudal artery.
Outlines
𩮠Introduction to Vertebrae and Skeletal Anatomy
This paragraph introduces the vertebral column, ribs, and sternum, explaining their location and function in the body. It describes how the vertebrae are classified into different groups based on their location (cervical, thoracic, lumbar, sacral, and caudal) and highlights the vertebral formula for a dog: C7, T13, L7, S3, and Ca20-24. The paragraph also mentions that vertebrae are classified as irregular bones, sharing a common structure with a body, arc, and processes. It concludes by describing the basic parts of a typical vertebra and their respective roles.
đ Anatomical Characteristics of the Atlas and Axis
This paragraph focuses on the first two cervical vertebraeâthe atlas and axis. The atlas holds the head and is unique in its structure, lacking a spinous process and featuring modified wings. The axis, on the other hand, has a tooth-like projection called the 'dens,' which forms a pivot joint with the atlas. Additionally, the thoracic vertebrae are discussed, characterized by their tall spinous processes and articulation with the ribs, with specialized structures for rib attachment, such as the transverse fovea and costal fovea.
đ Overview of Rib Types and Sternum Structure
This paragraph explains the structure and function of the ribs and sternum, highlighting that there are 13 pairs of ribs corresponding to the number of thoracic vertebrae. Ribs are classified as sternal (true ribs), asternal (false ribs), and floating ribs, with dogs having 9 pairs of sternal ribs and 3 pairs of asternal ribs. The sternum is described as consisting of eight individual bones (sternebrae), with the manubrium as the first segment and the xiphoid process as the last. The paragraph ends with a brief mention of a quiz on this section and an introduction to the next module covering the bones of the thoracic limb.
Mindmap
Keywords
đĄVertebrae
đĄVertebral Formula
đĄCervical Vertebrae
đĄAtlas and Axis
đĄThoracic Vertebrae
đĄLumbar Vertebrae
đĄSacral Vertebrae
đĄRibs
đĄSternum
đĄCaudal Vertebrae
Highlights
Introduction to the vertebrae, ribs, and sternum in the skeleton.
The vertebral formula of a dog includes seven cervical, 13 thoracic, seven lumbar, and three sacral vertebrae, with 20 to 24 caudal vertebrae.
Vertebrae are classified as irregular bones due to their shape, but share common structural parts.
The cervical vertebrae, located in the neck region, include C1 (atlas) and C2 (axis), which are atypical compared to the others.
C1, or the atlas, supports the head and lacks a spinous process, with transverse processes modified into wings.
C2, or the axis, has a tooth-like projection called the 'dens' or 'odontoid process,' which articulates with the atlas to form a pivot joint.
Thoracic vertebrae are characterized by tall spinous processes, short bodies, and articulate with the ribs.
The anticlinal vertebra in a dog is T11, where the orientation of the spinous process changes direction.
Lumbar vertebrae, located in the loin area, have large, flat transverse processes and include accessory processes.
The sacrum, composed of fused sacral vertebrae, forms the sacroiliac joint by articulating with the hip bones.
Caudal vertebrae, forming the tail, range from 6 to 24 in number and become rod-like distally.
Ribs are long, curved bones that form the lateral walls of the thorax, and the number of ribs corresponds with the thoracic vertebrae.
In dogs, there are nine pairs of sternal ribs and three pairs of asternal (false) ribs.
The sternum, made up of eight segments called sternebrae, forms the ventral part of the thorax and supports the ribs.
The manubrium is the first and longest segment of the sternum, while the xiphoid process is the last segment, holding the xiphoid cartilage.
Transcripts
welcome to part three of module two
after identifying the bones of the head
let us now continue discussing other
parts of the actual skeleton
like the vertebrae the ribs and the
sternum
at the end of this presentation you
should be able to write the vertebral
formula of dog
identify the total number of free pairs
present
and its relation to the number of sterne
braid
first let us see the general arrangement
of the vertebrae
ribs and sternum in the body of an
animal
the vertebrae are located at the dorsal
midline
the rib forms a lateral bony structure
supporting the thorax
while the sternum are located at the
ventral midline
the vertebral column is composed of a
number of unpaired bones
called vertebrae arranged in a series
along the midline of the body
and extending from the base of the skull
to the tip of the tail
the vertebrae can be grouped based on
their location
cervical vertebrae are located at the
neck region
the thoracic vertebrae are located at
the level of the chest
lumbar vertebrae are those present at
the loin area
sacral vertebrae are the fused vertebrae
at the level of the pelvic area
and finally the caudal vertebrae which
supports the tail
vertebral formula represents the number
of specific
vertebrae in an animal the number is
constant except for the caudal vertebrae
take note that the number varies per
species
in dog the vertebral formula is c7
t13 l7 s3
ca 20-24 this means
that the dog has seven cervical
vertebrae
13 thoracic vertebrae 7 lumbar vertebrae
3 sacral vertebrae and around 20 to 24
caudal vertebrae
remember that vertebrae are classified
as irregular bones because of their
irregular shape
however most of the vertebrae have the
basic parts in common
a typical vertebra has a body an arc
and number of processes let's identify
the parts of a vertebra
this is the sixth cervical vertebra
the body is a cylindrical mass forming
the ventral part of the vertebra
and the floor of the vertebral foramen
it is
convex cranially as shown here and
concave
caudally the vertebral art completes the
vertebral foramen dorsally
the arc is composed of a lamina and
pedicle
the lamina forms the roof of the ark
while the pedicle forms the wall of the
arc
on the average there are seven processes
present at the vertebral arc
there is a single spinous process that
projects
dorsally from the arc of the vertebra
the paired transverse processes project
laterally from the arc
there are also four articular processes
two cranial and two codal articular
processes
they form joints between adjacent
vertebrae
the vertebral foramen is the space
formed by the vertebral arc and the body
the vertebral foramina of all vertebrae
form the vertebral canal
the paired transverse foramen is an
opening
present at the transverse process
through which vertebral
artery passes there are seven
cervical vertebrae in mammals these are
the vertebrae at the neck region
they are characterized by a massive
appearance and by the presence of
transverse foramen as discussed
previously
this slide shows examples of the
cervical vertebrae
note that they have different views of
presentation
c1 or atlas and c2 or axis
are considered as atypical meaning they
are not
similar in appearance with the rest of
the cervical vertebrae
third to fifth cervical vertebrae are
almost the same with the sixth cervical
vertebra
the seventh cervical vertebra locks the
transverse foramen
and has a tall spinous process we will
just
focus on the first and second cervical
vertebrae
the first cervical vertebra is the atlas
the name of this bone was derived from
the greek mythology character atlas
which was given the task of holding up
the heavens
the same with the first cervical
vertebra it is holding the head in place
with the rest of the body
morphologically the atlas is a typical
it does not follow the same structures
present in most vertebrae
some books considered the body of atlas
to be absent
but in some it is described as a thin
structure
forming the ventrum of the bone this is
in contrast to the bulky body of other
vertebrae
here is a dorsal and caudal view of the
atlas
take note that it lacks spinous process
the transverse processes are modified
into wings
it has a transverse foramen and lateral
vertebral foramen
the alar foramen is modified into our
notch
the presence of allah notch is
characteristic of a dog atlas
the axis or epistrophuse is the second
cervical vertebra
it has a tooth like bony projection at
the cranial end
called dense or odontoid process which
articulate with the atlas forming a
pivot joint
take note that it has a large ridge-like
spinous process
the thoracic vertebra is characterized
by the tall spinous process short body
and transverse processes the thoracic
vertebrae articulate with the rib
thus it has structures specialized for
such
the transverse fovea is a plane surface
at the transverse process of the
vertebra
that articulates with the tubercle of
the rib
on the other hand the costal fovea is a
plane surface that articulates with the
head of the ribs
they are located at the body of the
vertebra
in dogs there are 13 number of repairs
look at this schematic drawing of the
thoracic vertebrae of dog
observe that the spinous processes are
oriented caudally
until one spinous process is vertically
inclined
this vertebra is called the anticlinal
vertebra
in contrast the spinous processes of the
vertebrae cuddle to the anticlinal
vertebra
is oriented cranially the anticlinal
vertebra of dog is t11
as you recall the lumbar vertebrae are
located at the loin area
the lumbar vertebrae can be
distinguished from the rest of the
vertebrae
because of its large flat or plate-like
transverse
processes that project laterally
in addition to other processes present
in other vertebrae
the lumbar vertebrae has an accessory
process
note that this are present from the mid
thoracic vertebrae to the lumbar
vertebrae
this should not be confused with a
ruptured intervertebral disc
they also have mammiliary process which
are present at the cranial articular
processes
and the processes of the three sacral
vertebrae fuse to form the sacrum
here is a lateral dorsal
and ventral view of the sacrum
the median sacral crest is the fused
spinous processes
present at the dorsal surface of the
suck room
the wing forms the lateral parts of the
sacrum
that articulates with the hip bone to
form the sacroiliac joint
you can also observe paired openings
seen at the dorsal and ventral views
this are the dorsal and ventral sacral
foramina
these are for the passage of the spinal
nerves
the promontory is a transverse ridge at
the cranioventral part of the base
this can be best seen on a cranial or
ventral view
the vertebrae of the tail has an average
number of 20
but may range between 6 to 24.
they became smaller distally until it
become a rod-like structure
hemal arches are present as a separate
bone that articulates with the ventral
surface of the fourth
fifth and sixth caudal vertebrae in life
this structure is protecting the median
caudal artery
again here are the segments of the
vertebral column
cervical thoracic lumbar
sacral and caudal vertebrae
take note that in writing the vertebral
formula
it must be written in chronological
order
after finishing the bones of the
vertebral column
let us now discuss the bones of the
thorax
this is a bony cavity formed by the
sternum
ribs costal cartilages
and the bodies of the thoracic vertebrae
this bones support and protect the soft
tissues and organs of the thoracic
cavity
like the lungs and the heart ribs
are longed curved bone forming the
lateral walls of the thorax
usually the number of pairs of ribs is
the same with the number of the thoracic
vertebrae
remember that the thoracic vertebrae is
13 in number
thus the number of rib bears is also 13.
ribs can be classified depending on
their articulation with the sternum
sternal or true ribs truribs articulates
with the sternum by means of its costal
cartilage
the costal cartilages are cartilaginous
cylindrical
distal continuation of the bony rib
sternal ribs are also known as immobile
ribs
there are nine pairs of sternal ribs in
dog
asternal or false ribs have no direct
attachment with the sternum
however their cartilages are fused to
form the costal arc
they are also called the respiratory rib
because they are mobile
there are three pairs of external ribs
in dog
here is the coastal ark it is formed by
the costal cartilages
of the 10 11 and 12 rib
with the last segment of the sternum
the last is the floating rib it has no
connection with the sternum
and no cartilage is present it is
usually the last stream
and found only in dog and man
let us then discuss the parts of a rib
the head of the rib articulates with the
costal fovea of the thoracic vertebrae
the neck of the rib connects the head to
the body
or shaft of the rib the tubercle of the
rib
is a bony small prominence lateral to
the head
that articulates with the transverse
fovea of the thoracic vertebrae
the sternum forms the ventrum of the
bony thorax
and gives attachment to the coastal
cartilages
of the ribs as well as providing a bony
origin for the pectoral muscles
the sternum is consists of eight
individual bones called sterne bray that
tend to fuse as age advances
manubrium is the first segment of the
sternum
it is longer than the other sternobray
the body is the middle portion composed
of several sterner brain
and finally the siphoid process is the
last segment of the sternum
it is wide and flat and it holds the
siphoid cartilage
that ends our lecture on the remaining
parts of the actual skeleton
i hope you are now able to differentiate
vertebrae from one another
familiar with the vertebral formula of
dog the number of rib pairs
and segments of the sternum a short quiz
on this part module is prepared for you
to answer
after that you may now proceed to part 4
of module 2
which is the bones of the thoracic limb
5.0 / 5 (0 votes)