Axial Skeleton
1. Identify and name the bones of the skull
2. Compare and contrast the fetal and adult skulls and explain the role of the fontanels
3. Identify and distinguish between bones from the different vertebral regions
4. Explain how and why bones from different vertebral regions are structured differently
5. Explain how a spinal tap is used to diagnose spinal cord and brain imbalances
6. Compare different spinal abnormalities
7. Explain how the structure of the ribs and sternum enables the functioning of the thoracic cavity

1. Identify and name the bones of the skull

human skull bones
human skull bones

human cranium
human cranium

Diangram Of Skull Broken Down In 5 Pieces

angle of jaw or mandible
back of jaw
the corner of the jaw where the mandible body turns upwards into the ramus
aveolar process
maxilla, root of teeth
rugosities associated with tooth development
condyle of mandible
top of ramus of mandible
a ball-like end to the ramus of the mandible that forms a hinge with the temporal bone
coronal suture
top of head between frontal and parietal cranial bones
one of the major joints or sutures between the plates of the frontal and parietal cranial bones
external acoustic meatus
between ramus of mandible and mastoid process
a hole in the temporal cranial bone allowing the passage of sound to enter the inner ear
ethmoid bone
eye cavity
a cranial bone forming part of the eye cavity
forehead boss or frontal tuberosity
a feature of the frontal bone that forms the "bumps" in the forehead above the eyebrows
frontal bone
top of face (forehead) and front top of head
one of the major cranial bones that forms the forehead and front top of the head; roughly
covers the frontal lobes of the brain
center of forehead
an area in the center of the forehead, between the eyebrows, that assumes various shapes on different individuals
lacrimal bone
inner corner of eye socket
a small bone forming a cavity for the tear gland
lambdoid suture
back of head
suture or joint between the occipital and parietal cranial bones
mandible or jaw bone
lower part of jaw
the lower jaw bone is the only skull bone that moves, i.e., during mastication, speech, and expression; carries the lower teeth
upper part of jaw
the two maxillae form the center of the face with many attaching muscles; carry the upper teeth; form part of the eye orbit; act like keystones into which the other facial bones fit
mastoid process
lower part of temporal bone, behind ramus of jaw
built up area of the lower temporal bone where important neck muscles attach
mental protuberance
chin boss
a feature of the mandible at the lower front part of the chin which underlies part of the chin boss
mental tuberosities
chin boss
a dual bulbous formation of the mandible that underlies part of the chin boss
nasal bone
forms the upper part of the nose and nasal bridge; the lower part of the bridge is formed of cartilage
nasal concha
nasal cavity
formations creating part of the nasal cavity
nasal spine
center of nose
feature of maxilla facial bone at center of nose to which septum is attached
occipital bone
the lower rear of the head
a major cranial bone at the lower back of the head; covers occipital lobe of the brain
parietal bone
top and side of head
a major cranial bone that forms part of the top, back, and side of the head and roughly covers the parietal lobe of the brain
ramus of mandible
back part of the mandible
the more vertical part of the mandible
sphenoid bone
temple and eye orbit area
a cranial bone that forms part of the eye cavity
squamosal suture
side of head between parietal and temporal bones
one of the major joints or sutures between the parietal and temporal cranial bones
supraorbial foramen
upper orbit of eye
a hole in the frontal bone where nerves and blood vessels pass through; forms a notch in the orbit of the eye
supraorbital process
a formation of the frontal bone above the orbit of the eye, under and above the eyebrows that affects the appearance of the eyebrows
temporal bone
side of the head, above the ear
a cranial bone on the side of the head that roughly covers the temporal lobe of the brain; it extends down behind the ear towards the jaw
temporal lines
front part of temple and lower part of frontal bones
lines in the frontal bone around the temple
nasal cavity
a facial bone on the centerline of the nose that forms part of the nasal cavity
zygomatic bone
the principal cheek bone; origin of zygomatic and other facial muscles
zygomatic process
bones bordering zygomatic bone
the temporal and maxilla bones have areas next to the zygomatic bone
Great interactive tutorial:

Video: The Facial Bones

Shows the different sutures

2. Compare and contrast the fetal and adult skulls and explain the role of the fontanels

Fontanels are soft spots on a baby's head which, during birth, enable the bony plates of the skull to flex, allowing the child's head to pass through the birth canal. The fontanels also allow a baby's brain to grow and develop (increase in size) during the first two years of life. The ossification of the bones of the skull cause the fontanels to close over by a child's second birthday. Parents may worry that their infant may be more prone to injury at the fontanels. In fact, although they may colloquially be called "soft-spots", the membrane covering the fontanels is extremely tough and difficult to penetrate. However, the fontanels allow the infant brain to be imaged using ultrasonography. Once they are closed, most of the brain is inaccessible to ultrasound imaging, as the bony skull presents an acoustic barrier.
The fetal skull consists of 5 bones: two frontal bones, two parietal bones, and one occipital bone. As stated above, it is important for these bones in the head to be flexible so childbirth can be possible. This is accomplished by fibrous membranes called sutures that connect the bones and allow growth at the edges of the bones. As sutures expand and create wide gaps at birth, fontanels are formed. There are 6 fontanels, but the two more important ones, the posterior and anterior, are described here. The triangular, small posterior fontanel, located where the two parietal bones adjoin the occipital bone at the lambda towards the back of the skull, clsoes within the first few months of infancy. The diamond-shaped, large anterior fontanel, located where the two frontal bones adjoin the two parietal bones at the bregma towards the top of the skull, is arguably the more important fontanel. It doesn't close till about 2 years after birth, except in cleidocranial dysostosis, which means the anterior fontanel is either late in closing or never will. It is important clinically and is examined in infant check-ups; a depressed anterior fontanel indicates dehydration and a tight or bulging one indicates intracranial pressure.
Compared to the fused adult skull, a fetal skull is smaller, thinner, and is composed of many deformable bones. They also have different proportion face sizes or cranium ratios. Many fetal bones contain multiple ossification centers; the joints between bones enable growth. Unlike the adult skull, none of the fetal skull bones are pneumatized (they have no air-filled cavities).

Fetal Skull
Adult Skull
1. Face is much smaller than cranium.
2. Bones are still in cartilage form at soft spots (fontanels).
3. Skull is ¼ of body length.
1. Cranium and face are more in proportion.
2. Soft spots no longer exist because the bone has fused together at sutures.
3. Skull is 1/8 of body length.

external image 2547_f1.gif

Fetal Skull

external image f7-27at_fetal_skull_lat_c.jpg

Lateral View of Adult Skull

external image A4skull.jpg
Link to website with animation on fetal skeleton development, featuring fetal skull and fontanel info.

3. Identify and distinguish between bones from the different vertebral regions

The spine consists of 26 bones. Each of these bones are connected by a number of ligaments and provide support for the upper body. It also provides protection for the Spinal Cord. The vertebral column provides attachment points for the ribs and the muscles of the back.
The spine has 5 regions and each has varying characteristics: Cervical, Thoracic, Lumbar, Sacrum, and the Coccyx.

Cervical Vertebrae:The Cervical region consists of seven bones and are the smallest bones of the spine. They are numbered 1 to 7, starting from the top and working down. The first two also have another name: the Atlas and the Axis.
- The Atlas is the first Cervical Vertebrae (C1) and essentially allows the head to nod "Yes". The atlas contains a superior articular surface, which allows it to support the weight of the skull.
- The Axis is the second Cervical Vertebrae (C2) and allows the head to shake "No". The axis contains an odontoid process (dens), which allows it to fit in place with the atlas to allow for the movement of the head.
- The main functions of the cervical vertebrae are to support the weight of the head and to form a flexible framework for the neck
- It also plays a big role in the rotation of the head (side to side/ foward and backwards).
- Link to video on website discussing the anatomy of the cervical vertebrae.
LINK to website with information/videos about atlas/axis vertebrae disorder

Thoracic Vertebrae:The Thoracic region consists of 12 vertebrae that are larger than Cervical Vertebrae and increase in size from top to bottom.These bones move with the ribs to form the rear anchor of the rib cage.

Lumbar Vertebrae (the lower back):The Lumbar region consists of 5 vertebrae. This region receives the most stress because it supports most of the body's weight and is attached to many of the back muscles; this is why the lumbar vertebae are much larger.

Sacrum: The Sacrum consists of five fused vertebrae. It is a triangular shaped bone that connects the two Coxal bones (Pelvis), forming the back wall of the pelvic girdle. It articulates with the fifth lumbar vertebrae, the Coxal bones on each side, and the Coccyx at the bottom. In children, it consists of four or five sacral vertebrae which become fused into one after the age of 26.

Coccyx (Tail-Bone): The Coccyx usually consists of 4 fused vertebrae but can sometimes vary between 3 and 5. It is a triangular shaped bone that offers a small amount of support for the pelvic region
external image spineanterior.jpg
A: coccyx

B: Sacrum

C: L5 (lowest vertebrae of the lumbar spine)

D: L1 (highest vertebrae of the lumbar spine)

E: intervertebral disc

F:C7 (lowest vertebrae of the cervical spine)

G: axis (also known as C2)

H: atlas (also known as C1)

I: T1 (highest vertebrae of thoracic spine)

J: T12 (lowest vertebrae of the thoracic spine)

K: transverse process

4. Explain how and why bones from different vertebral regions are structured differently


Critical Attributes of Vertebral bones

Atlas: only vertebrae with no body, large landing pads/articular surfaces for skull
Axis: odontoid process
- small body.
- 3 foramen (1 central foramen, 2 transverse foramina). The foramina allow the vertebral arteries to pass through on their way to the foramen magnum to end in the circle of Willis.
- short spinous process that maybe split at ends (with the exception of C2 and C7, which have obvious spinous processes).
- allow for the neck and head movement. For the most part, the atlanto-occipital joint allows the skull to move up and down, while the atlanto-axial joint allows the upper neck to twist left and right.
- triangular-shaped foramen.
- overall smallest, lightest vertebrae.
- Cervical Vertebrae video :
- heart shaped body
- 2 coastal facets on each side to articulate with the ribs
- spinous process may hook down (giraffes neck)
- Some rotation can occur between the thoracic vertebrae, but their connection with the rib cage prevents much flexion or other excursion. They may also be known as 'dorsal vertebrae', in the human context.

vertebrae.jpg- Thoracic video:
- large, block-like body
- short 'hatchet-shaped' spinous process
- must support more weight than other vertebrae
- allow for significant flexion and extension, moderate lateral flexion (sidebending), and a small degree of rotation
- Lumbar video:
- five smaller bones which are naturally fused together forming a triangle
- do not look like the other vertebrae
- The pair of nerve endings in this area are responsible for the action of the pelvic organs and the buttock muscles
- does not have intervertebral discs
- Sacrum video:
- tailbone made up for 4 little bones fused together
- do not look like the other vertebrae
The pair of nerve endings in this area are responsible for the action of the pelvic organs and the buttock muscles
- does not have intervertebral discs

5. Explain how a spinal tap is used to diagnose spinal cord and brain imbalances-also called lumbar puncture

spinaltapp.jpg1. Doctors look at cerebrospinal fluid (brain fluid) by removing it from spinal canal.
2. Doctors can use the fluid to find infections, multiple sclerosis, brain hemorrhaging, cause of seizures, and causes of headaches.
3. Cerebrospinal fluid contains glucose, proteins, and other substances that are also found in the blood.
4. Analysis of the fluid includes looking at the number and types of white blood cells, the level of glucose, the types and levels of various proteins (especially immune system proteins called antibodies and testing for bacteria, fungus, or other abnormal cells).
Link to spinal tap video

external image JAMA_Medical_Tests_LumbarPuncture_JPP_01.jpg&usg=AFQjCNFueQMqLlnd_aTh_-gWY2z3P7SnFw

6. Compare different spinal abnormalities

To See How Such a Phenomeon is Repaired in the Cervical Vertibrae Go To:
To See How Such a Phenomeon is Repaired in the Cervical Vertibrae Go To:
Herniated Disks: Extremely common, especially in the lumbar and cervical regions of the spine. Herniated discs are often caused by other completely normal degenerative processes. Common back pain can be a result of a herniated disk. Herniated disks are also commonly referred to as having a slipped or ruptured disk. When you get a herniated disc, a small portion of the intervertebral disks is pushed into the spinal cavity causing a great deal of pain. For most cases, surgury is not necessary.
Watch Bone Graft Surgery--Part of a Treatment for Herniated Disk

Degenerative Disc Disease: The discs naturally lose moisture and shrink as we age and since the disks are composed of mostly water, its quiet a substantial problem. Although they "degenerate" at different rates, most people as they grow older will suffer from some degree of degenerative disc disease. This sometimes creates the perfect scenario for a herniation to occur. These two conditions often exist simultaneously in the same patient, at the same vertebral levels. Degenerative disc disease makes the disks smaller, then they have a better chance to "slip" into the spinal cavity.
external image Cervical_Spine_MRI.jpg
Spinal Arthritis: A normal part of aging. Cartilage and joint breakdown is normal throughout the body. It can cause some aches and pains, but is rarely to blame for severe chronic back pain. It is not abnormal to have evidence of arthritis or facet joint syndrome and not even know it. Almost everyone develops the physical manifestations of the condition, but only a minority develops associated symptoms.

  • The most common form of arthritis
  • Most often occurs in middle-aged and older people
  • Doesn't go away
  • May involve many joints in the body
  • Wears away the tough tissue (cartilage) that keeps the joints in place
  • Causes bone spurs and problems with joints.

external image OsteoarthritisKnee1.jpg

Rheumatoid Arthritis:
  • Affects most people at a younger age than osteoarthritis
  • Causes the soft tissues of the joints to swell and can affect the internal organs and systems
  • Is not a common cause of spinal stenosis
  • Can cause severe damage, especially to joints.

external image rheumatoid-arthritis-17890.jpgexternal image Rheumatoid%20Arthritis.jpg

Medications to Relieve Arthritis Pain

Spinal Stenosis:
Spine Conditions
Spine Conditions
external image pinched_nerve.gif
external image degenerative-disc-disease_clip_image001.jpg

Shape of Spine

Curves are a normal part of the spine's structure. Looking at the spine from the side (lateral), several curves can be seen (Figure 1-A). From this angle, the spine almost resembles a soft 'S' shape. When viewing the spinal column from the rear (posterior), the spine appears vertically straight -- from the neck to the tailbone (Figure 1-B). The normal curves are termed lordosis and kyphosis. However, the natural curves should not be mistaken for spinal disorders also called Lordosis and Kyphosis

Adolescent idiopathic scoliosis is the most common case of scoliosis, but there is no clear cause of the deformity. Various causes have been suggested, but none has consensus among scientists as the cause of scoliosis. Scoliosis is more often diagnosed in females and is often seen in patients with cerebral palsy or spina bifida. In some cases, scoliosis exists at birth due to a congenital vertebral anomaly. Occasionally, development of scoliosis during adolescence is due to an underlying anomaly such as a tethered spinal cord, but most often the cause is unknown. Some therapists like the referenced Hanna Somatic therapist believe that trauma to an adult can cause, not just asymmetry but an actual curve to the spine visible on x-ray, but no documentation is offered in her article. Scoliosis often presents itself, or worsens, during the adolescence growth spurt.
In April 2007, researchers at Texas Scottish Rite Hospital for Children identified the first gene associated with idiopathic scoliosis, CHD7. The medical breakthrough was the result of a 10-year study and is outlined in the May 2007 issue of the American Journal of Human Genetics.
credit to
File:Wiki pre-op.jpg
File:Wiki pre-op.jpg
external image Scoliosis.gif

Kyphosis is also known as "hunch back" or "hunchbackism" or "hunchbackedness." In general terms, is a common condition of a curvature of the upper (thoracic) spine. It can be either the result of bad posture, such as slouching or a structural, muscular abnormality in the spine. In the sense of a deformity, it is the pathological curving of the spine, where parts of the spinal column lose some or all of their lordotic profile. This causes a bowing of the back, seen as a slouching back and breathing difficulties. Severe cases can cause great discomfort and even lead to death.
credit to

Lordosis: A longitudinal curve, starting at the top of the thoracic region and ending at the coccyx. This abnormality affects the lower back, and pushes the spinal column into the stomach. Patients with excessive lumbar lordosis may appear swayback, the buttocks more prominent, and in general their posture appears exaggerated. Lordosis affects people of all ages and when it affects the low back, it can cause back pain making movement difficult and painful. Spondylolisthesis, osteoporosis, and even obesity may lead to abnormal lordosis.

external image thoracic_scheuermanns_anatomy01.jpg

7. Explain how the structure of the ribs and sternum enables the functioning of the thoracic cavity

In this inspiratory movement(inhalation), the thorax is enlarged in each of its three dimensions: in depth from before backwards, in width from side to side, and in length or height from above downwards enlargement in depth, from the spine to the sternum, is accomplished by the elevation of the ribs, which being movably articulated with the vertebral column behind, and continued on, by their cartilages, to the sternum in front, and having, moreover, an oblique direction from their posterior to near their anterior extremities, necessarily cause an elevation and projection forwards of the sternum, when they are slightly lifted upon their posterior points of attachment, to a less oblique position. The point of support or fulcrum of each rib, is the vertebral column; whilst the connection of the upper ten ribs in front, directly or indirectly with the sternum, enables them to elevate and push forward that bone, and thus to increase the antero- posterior diameter of the chest.

The enlargement of the thorax in width is likewise accomplished by the elevation of the curved and obliquely attached ribs, which are not merely lifted, but slightly rotated on their hinder attached extremities; their sides are thus carried outwards, their outer surfaces being turned somewhat upwards, and their inner surfaces downwards. The total result, as it affects all the ribs, is to expand the thorax in its transverse diameter.

Lastly, the increase in the height of the thorax is accomplished by the action of the arched or vaulted diaphragm, which forms the base of the thorax.

The central tendinous expansion, the diaphragm, is drawn down by the contraction of its circumferential muscular parts; and this movement, named the descent of the diaphragm, causes an important elongation of the thoracic space. The elevation of the ribs in inspiration is accomplished, in ordinary breathing, by the co-operation of a number of small muscles placed deeply between and upon the ribs, first, more especially concerned, are the external intercostal muscles. These occupy the interspaces between all the ribs, extending, in each intercostal space, from close to the vertebral column to the neighborhood of the costal cartilages; their fibers pass downwards and forwards, from one rib to another.

Expiration (exhalation) As the muscles of inspiration cease to act, the tendinous part of the diaphragm, the chief of those muscles, ascends into the thorax, followed by the abdominal viscera, which are supported in their upward movement by the cooperation of the muscles of the abdominal walls. At the same time the ribs and the sternum, which were elevated, descend and fall back, while the effects of the rotation of the ribs are counteracted by the elastic recoil of the costal cartilages.


More general explanation:
Fundamentally the sternum is a large bone that provides a wide area of protection - significantly, most of the heart is found behind the sternum. However, it also provides a point of contact for the ribs to aid their movement.

It is said that the superior (upper) ribs have a pump handle movement. The idea of the ribs moving is to increase the volume of the thoracic cavity (i.e. to increase the volume inside the rib cage), so you need to increase the dimensions somehow. The pump handle movement of the superior ribs increases what is called the anterior-posterior dimension of the thoracic cavity, i.e. it increases the distance between the sternum and the vertebral column (spine). The distance front-to-back is increased, leading to an overall increase in volume.

external image upperribs.gif

bucket handle


external image lowerribs1.gif

The sternum:
Sternum2.pngIs also called the breastbone. It is classified as a flat bone and has three different sections; the manubrium or the handle, the sternum body or the corpus sterni and the xyphoid process or the processus xiphoideus. This bone is located in the middle of the chest along with the ribs.

The Manubrium: Is located at the top of the sternum, Moves slightly and it’s connected to the first two ribs.
· Jugular notch: You can feel it at the base of your throat
· Clavicular notches: These two bones form an articulation called the sternoclavicular joint. There is a right and a left sternoclavicular joint.
· Costal notches: These are small notches at the lower end of the manubrium that are attachments for the first ribs on the right and on the left side.
Sternum body: Is located in the middle of the sternum, connects the third up to the seventh ribs directly. Also connects the eight to the tenth ribs indirectly
The Xyphoid process: Is located at the bottom of the sternum, it’s usually made of cartilage that becomes
bone in later years.
These three parts are separated during childhood by fibro cartilage zones and become together during adulthood.
Function:The function of the sternum is to form the ribs cage, protecting the heart, lungs and major blood vessels from damage.
Form follows function:
The ribs are connected to the sternum by the costal cartilage. Without it there would be an open area in the middle of our chest leaving open the rib cage. The sternum is designed to protect the thoracic cavity in which the heart lungs and some blood vessels are found, the cartilages attached to first seven ribs allows a slightly movement in the chest are when breathing. The sternum completes the rib cage making the thoracic cavity more protected from damage.
The sternum articulates with the cartilage of the first seven ribs and with the clavicle on both sides. Ii is larger in man than women.
The pectoralis major is located at the front of the sternum and the external intercostals, adjacent to the ribs and makes the elevation in the rib cage when inhalation.
STERNUM1.gif Some articulations and cartilages: Arthro-dial joints (articulation) Anterior Costo-Sternal,
Posterior Costo-Sternal, Capsular and Synovial Membranes are ligaments. The third rib has two
synovial membranes; and that of the fourth, fifth, sixth, and seventh, eich a single synovial
membrane. In old age, the articulations do not exist, the cartilages of most of the ribs becoming
firmly united to the sternum.