M2s3 Axial Skeleton Flashcards
4 sections of axial skeleton (skull)
Skull (bones of the skull)
-22 bones
-2 sets of bones make up skull: the cranial (above nose, brain aspect) and facial bones (face area bones)
Cranial bones of skull
-8 bones
-provides protection for the brain
-responsible for knowing 7 of these bones that form a roof (cranial vault) and floor (cranial base), enclosing the brain in a space called the cranial activity
Frontal: single bone, forms the forehead and roof of the orbits (eye sockets)
Temporal bones: paired and form the lateral and inferior walls of the skull (features include zygomatic process, external auditory (acoustic) meats (ear hole), mastoid process). You can palpate your own mastoid process by touching behind and slightly superior to your ear lobes. You should feel two lumps on either side of the inferior-lateral portion of your skull
Sphenoid Bone: single bone known as the “keystone” of the skull as it joins the cranium and facial bones by attaching with almost every other bone of the skull (shape resembles bat with wings extended)
Parietal Bones: paired and form superior and lateral surfaces of the skull
Occipital bone: single and forms posterior wall of the base of the skull. 2 features 1. Foramen magnum (big hole) which allows the spinal cord to exit the cranial cavity 2. Occipital condyles which articulate with the first bone in the neck
Sutures
-attachments or articulations between the flat bones of the skull
Include:
Coronal: junction between frontal and parietal bones
Sagittal: Junction between parietal bones
Lambdoid: Junction between the occipital and parietal bones
Squamous: Junction between temporal and parietal bones
Cranial vault
-dome-shaped bony roof of the skull that encases the brain
-formed by the frontal, parietal and occipital bones which are flat bones
-sometimes called the skullcap
Cranial Base
-fossa is defined as a depression in a bone
-floor of the cranium (cranial base), on which the brain sits, contains three fossae: anterior cranial fossa, middle cranial fossa, posterior cranial fossa
Facial bones of the skull
-14 bones
-know 7
Maxillary bones (maxillae): paired, upper jaw bones
Nasal Bones: paired, articulate with the frontal bone which form a bridge do the nose. Only a small portion of the nose that you can see and feel on your face is made of the bone. The most superior portion is the nasal bones, while the rest is cartilage
Zygomatic bones: Paired and form the cheekbones. A feature of these bones is the temporal process, which articulates with the zygomatic process of the temporal bone to form the zygomatic arch
Mandible: single and forms the lower jaw. Three parts of the mandible include body, ramus, angle. Only moving bone in the face. You can palpate the angle of your mandible on either side of your face by starting at your ear lobes and moving your fingers downwards
*look at good notes for photos and labels
Another of the 4 sections of axial skeleton (vertebral column) (spine)
- look at good notes for images
Adult spine made up of 26 bones: 24 vertebrae, 1 sacrum, 1 coccyx
-like skull one purpose is to protect spinal cord
-vertical column is approximately 70 cm long in the average adult
Divisions of the spine
(From top to bottom)
Cervical- 7 vertebrae
Thoracic- 12 vertebrae
Lumbar- 5 vertebrae
Sacrum- 5 fused vertebrae
Coccyx- 4 fused vertebrae
Vertebrae structure
-although cervical, thoracic, lumbar all different from each other, they all have the same basic structure
1. Body (anterior)
2. Vertebral arch (posterior): extends into the spinous and traverse processes. Spinal process- extending posteriorly, traverse process- paired, extending laterally
3. Vertebral foramen (canal): houses the spinal cord. All the vertebral foramina stack together to form the vertebral canal, which houses the spinal cord
Atypical vertebrae
-not all vertebrae the same, there are distinct regional differences observed in the three regions of the vertebral column
-examples include: C1 (atlas) and C2 (axis), which are the first and second cervical vertebrae
C1:
Two features that are important for articulation with other bones:
Anterior arch: provides surface for articulation with the dens (a feature of C2) (more so middle)
Lateral masses: provide surface for articulation with the occipital condyles of the occipital bone (more so ends)
C2:
-main feature is the dens which rests within the anterior arch of C1
Movement of C1 and C2:
-skull rests on top of the lateral masses of C1 via the occipital condyles And these joints allow for the “yes” movement of the head
-underneath C1, the dens of C2 articulates, or attaches, with the anterior arch of C1 which allows for the “no” movement of the head from side to side
Vertebral articulations
-individual vertebrae articulate (or join) to stack on top of one another
-vertebral articulations give rise to two structures
1. Intervertebral disc
-think of as “jelly filled donut” located between two vertebrae
-acts as a shock absorber
2. Intervertebral Foramina
-these are lateral openings between adjacent vertebrae that allow for the passage of spinal nerves
Cartilage of Intervertebral Discs
-tough cartilaginous layers that serve to resist compression on the spine so then can identify fibrocartilage is found between the intervertebral discs
Sacrum and Coccyx
-unlike the other 3 divisions of the vertebral column that are composed of individual vertebrae, the sacrum and coccyx are located inferiority and are formed from fused vertebrae
Sacrum- fusion of 5 vertebrae
Coccyx- fusion of three to five vertebrae although usually 4
Ribs section of the axial skeleton
- check goodnotes for diagrams and images
-12 ribs
3 types:
True ribs - pairs 1 to 7 which articulates directly (individually) with the sternum
False ribs - pairs 8 to 10 which don’t have direct articulation with the sternum, they join rib 7 to indirectly articulate with the sternum
Floating ribs - pairs 11 to 12 which have no articulation with the sternum
Structure of a typical rib
-typically long, flat and twisted
-consisting of head, neck, tubercle, shaft (body), and angle (where the shaft is bent sharply anteriorly)
-shaft has a sharp inferior border which is grooved (costal groove)
-head typically articulates with the bodies of two thoracic vertebrae which the tubercle of the rib has a facet for articulation with the traverse process of one vertebra
Sternum section of axial skeleton
- check goodnotes for images
-aka breastbone
-makes up the anterior portion of the thoracic cage
Three parts:
Manubrium - Articulation with rib 1
Body - Articulates with ribs 2 - 7
The xiphoid process
The thoracic Cage
-made of thoracic vertebrae posteriorly, ribs laterally, and the sternum anteriorly
Scoliosis
-a lateral curvature of the spine, forming what appears to be an “S” shape of the vertebral column
-aka “twisted disease”
Remember that the thoracic vertebrae attach to the sternum via the ribs to create the thoracic cage. One function of the thoracic cage is to house and protect the lungs
Why do patients with scoliosis often have breathing problems
The lateral curvature places the thoracic vertebrae in an atypical position
-causes abnormal development and placement of the ribs and thoracic cavity
-abnormal form of the thoracic cavity can compress the lungs, causing breathing problems
