axial skeleton
TRANSCRIPT
The Axial Skeleton
By- Dr. Armaan SinghBy- Dr. Armaan Singh
I highly recommend Professor Wissman’s sites For bones:
http://homepage.smc.edu/wissmann_paul/bones/EBbonestutorial.html Check out all his links:
http://homepage.smc.edu/wissmann_paul/anatomy1/
Also check out:
Site for xrays & other diagnostic procedures:
http://www.radiologyinfo.org/en/sitemap/category.cfm?category=diag
http://homepage.smc.edu/wissmann_paul/bones/EBbonestutorial.html
This is an example of Prof Wissman’s bone site; this doesn’t show the roll-over answers
THE SKELETAL SYSTEMThe Axial Skeleton
The skeleton consists ofBones (206)CartilagesJoints – also called articulations, are the
junctions between skeletal elementsLigaments – connect bones
Divided into axial and appendicular
Axial skeleton - forms long axis of bodySkullVertebral columnThoracic cage
Appendicular skeleton – appendages and what they attach toUpper limbs (arms)Pectoral girdle (shoulder)Lower limbs (legs)Pelvic girdle
Axial skeletonSkullVertebral columnThoracic cage
Axial skeleton is shown in green
The Skull Cranial bones (or cranium)
Enclose the cranial cavity, which supports and protects the brain
Attachment sites for some head and neck muscles
Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face
Cranium Vault – “calvaria” = skullcap
Forms superior, lateral and posterior aspects of skull, and forehead
Base or floor: inferior part Prominent bony ridges divide
cranial base into 3 “fossae” (steps) – anterior, middle and posterior
Anterior cranial fossa
Middle cranial fossa
Posterior cranial fossa
(looking down on the floor of the skull)
Cranial bones
Frontal bone Parietal bones (paired) Occipital bone Temporal bones (paired) Sphenoid bone Ethmoid bone
Cranial bones
parietal parietalfrontal
temporal
parietal
occipital
_______sphenoid_____ethmoid
occipital
Temporal bones
this is the right temporal bone looking at it from the right side
Sphenoid
Ethmoid Small cranial bones…
Sutures
Immovable, interlocking joints of flat bones of skull
Irregular, saw-toothed appearance Largest 4 skull sutures: where bones articulate
with parietal bones Coronal Sagittal Squamous Lambdoid (FIND THEM)
Find: coronal, squamous and lamboid sutures
Find: sagittal and lambdoid sutures
Cranial “cavity” – houses brain Smaller cavities
Housing middle and inner earNasal cavityOrbitsSinuses
Openings (foramina, canals, fissures) for:Spinal cordBlood vesselsTwelve cranial nerves: I-XII
Remember, the skull is composed of:
1. Cranial bones (or cranium)[these were just reviewed]
and
2. Facial bones (anterior aspect of skull) Form framework of face Form cavities for sense organs of sight, taste
and smell Provides openings for passage of air and food Hold the teeth Anchor the muscles of the face
Facial bones
Mandible Vomer Maxillae (paired) Zygomatics (paired) Nasal (paired) Lacrimal (paired) Palatines (paired) Inferior nasal conchae (paired)
MandibleVomerMaxillae (paired)Zygomatics (paired)Nasal (paired)Lacrimal (paired)Palatines (paired)Inferior nasal conchae (paired)
Facial bones:
Mandible (lower jaw)
Maxilla (there are 2 which fuse, forming the upper jaw)
Nasal cavity
Of bone and cartilage Roof is ethmoid’s
cribriform plate Floor formed by palatine
processes of the 2 maxillae and horizontal plates of palatine bones These nasal-floor
structures form roof of the mouth, called the hard palate
nasal bone
ethmoid
vomer
inf nasal concha
(part of slide 18)
maxilla___________
Nasal cavity
To left, bones forming the left lateral wall of the nasal cavity (nasal septum removed)
To right, nasal cavity with nasal septum in place, showing how the ethmoid bone, septal cartilage, and vomer make up the septum
OrbitCone-shaped bony cavities holding the eyes, muscles that move the eyes, some fat and tear-producing glands; you don’t need to know all these bones that form it, just realize how complex it is and recognize the optic canal (optic nerve passes out through it)
(right orbit shown)
Paranasal sinuses
Air-filled sacs in the bones “Paranasal” because they cluster around
and connect to the nasal cavity
Hyoid bone
Only bone which does not articulate with any other bone
Moveable base for the tongue
Points of attachment for neck muscles that raise and lower the larynx during swallowing
Remember that the Axial skeleton includes:
SkullVertebral columnThoracic cage
Axial skeleton is shown in green
The Vertebral Column
Fetus and infant: 33 separate bones, or vertebrae
Adult: 24 vertebrae Inferior 9 have fused forming
The sacrum (5) and The coccyx (4)
Vertebrae
Cervical – 7 Thoracic - 12 Lumbar - 5 Sacrum (5 fused) Coccyx (4 fused)
Spinal curvatures
Cervical and lumbar are concave posteriorly* (lordosis)
Thoracic and sacral are convex posteriorly* (kyphosis)
Abnormal (see lab book p120): Too much of either Scoliosis (more than 10 degrees
of lateral curvature)
*when viewed from the side
Abnormal curvatures
Non-bony parts Intervertebral
discs anulus fibrosis
and nucleus pulposus)
Anterior longitudinal ligament
Posterior longitudinal ligament
Ligamentum flavum
Anterior longitudinal ligament: wide, strong and attaches to vertebrae as well as discs (prevents hyperextension)Posterior longitudinal ligament: narrow and relatively weak, attaching only to discs
Note “intervertebral foramen” vs “vertebral foramen” on next slides
*
Structure of a typical vertebra
Cervical vertebrae (C1-C7)C1 (atlas)
C2 (axis)
Smallest Lightest Most flexible Triangular vertebral
foramen Transverse
processes have foramina (transverse foramen)
Spinous process bifid (forked) except for C7
Cervical Vertebrae
Heart shaped body
Additional small costal facets (costal=ribs)
Round or oval vertebral foramen
Form posterior part of rib cage
Thoracic Vertebrae T1-T12
Massive blocklike bodies
Short, thick hatchet-shaped spinous processes
Limited mobility
Lumbar Vertebrae L1-L5
The SacrumShapes posterior wall of pelvis
Composite bone of 5 fused vertebrae
Sacral foramina allow passage of vessels & nerves
Coccyx(the tailbone)
Remember that the Axial skeleton includes:
SkullVertebral columnThoracic cage
Axial skeleton is shown in green
The Thoracic Cage
Sternum Ribs
Manubrium
Body
Xiphoid process
True ribs 1-7
False ribs 8-12
Floating ribs 11,12
Vertebral and Sternal Articulations
Typical rib
Disorders of the axial skeleton
Scoliosis (over 10% curvature)
Kyphosis
Lordosis
Vertebral compression fractures
Spinal stenosis
Fontanels
Unossified remnants of membranes
Present at birth Anterior fontanel largest Called “soft spots” Ossify by 1 ½ - 2 years
Continue to ossify into adulthood; the sutures can become fused in old age
Some abnormalities (early fusion) of sutures: “craniosynostosis”Metopic Synostosis and trigonocephaly
A: Preop B: 2 years after
frontal orbital advancement
Pre-op CAT scan Diagram of surgery
2 years post-op
Sagittal synostosis and scaphocephalyThe most common suture to fuse is the middle or sagittal suture. Often the back or front of the skull will be worse but the overall shape is a long skull with a shortened distance from ear to ear.
From - http://www.ppsca.com/skull.htm