Osteology Exam I (sternum through skull) Flashcards
What two bones comprise the sternum?
The manubrium and corpus sterni.
Describe the costal notches and the sternum.
The first costal notch is inferior to the jugular notch (for the clavicle) on the manubrium. The second is found on the sternal angle, and the remaining 3-7 are found on the lateral sides of the corpus sterni. These are the sites of articulation of the rib heads.
What variably ossified featured is sometimes found inferior to the sternum?
The xiphoid process.
How is the sternum sided?
The anterior face of the sternum is convex; the posterior side is concave and dips inward.
How many ribs does an adult human have? Describe how they differ.
24: 12 on each side. Ribs 1-7 are “true” ribs and articulate directly with the sternum. Ribs 8-10 attach to the sternum through intermediate cartilage and are called “false ribs”. Ribs 11 and 12 have unattached distal ends and are called “floating ribs”.
Rib length typically increases from 1 to 7 and decreases from 7 to 12.
The head of the rib (proximal end) bears ______ for attachment to thoracic vertebrae bodies. Which ribs are unifaceted?
demifacets: two articular surfaces. Ribs 1, 10, 11, and 12 are unifaceted.
Describe features of the proximal rib head.
The head and neck: The crest of the rib head separates the two demifacets. The tubercle articulates with transverse process of thoracic vertebrae. The neck is the thinnest portion.
Describe the general features of a rib.
Sternal end, caudal edge, cranial edge, shaft, neck, head.
What features are unique to the first rib?
The scalene tubercle, on the cranial surface the groove for the subclavian artery and brachail plexus and the groove for the subclavian vein.
What is unique about the second rib?
It is intermediate in size between R1 and R3 and has a large tuberosity for the serratus anterior muscle in a cranial midshaft position.
What are the three major parts of the hyoid bone?
The body and the greater and lesser horns.
What encloses the spinal cord posterior to the vertebral body?
The vertebral arch.
The short segment of the vertebral arch near the body on the superior side is the
pedicle
Posterior to the pedicle is the
lamina
The three most prominent processes of a vertebra are the
spinous process and two transverse processes
Vertebrae articulate with one another through
pairs of superior and inferior articular facets
The transverse processes of cervical vertebrae are unique in that they have
transverse foramina that form a path for the vertebral arteries
The spinous processes of the cervical vertebrae are unique in that they are usually
bifurcated
The superior surface of the body of a cervical vertebrae is cup-shaped with the edges marked off by
uncinate processes
Describe three features of the lateral portions of cervical transverse processes
posterior and anterior tubercles and intertubercular lamina.
The ___ of the atlas are concave and elongate and receive the condyles of the occipital bone.
superior articular facets of the atlas.
In turning one’s head, the atlas pivots on the ___ of the ___.
dens/odontoid process of the axis.
C7 can be distriguished because it retains transverse foramina but has a
larger spinous process reminiscent of a thoracic vertebrae.
Give the numbers of the different vertebrae
7 cervical, 12 thoracic, 5 lumbar
Rib heads articulate to the transverse processes of most thoracic vertebrae through
costal facets formed by a pair of demifacets
Which thoracic vertebrae possess a full facet for rib articulation?
T1, T10, T11, and T12.
Describe the angle range for thoracic transverse processes
T1 is near 180 degrees and T10-12 near 90 degrees
Which thoracic vertebrae possesses a full facet and a demifacet?
T1
Describe the unique features of T10-T12
All have a complete, superiorly located costal facet. T10 has costal articulations on the transverse processes, T11 and 12 do not, and the inferior articular facets of T12 assume the lumbar pattern.
A hatchet shaped spinous process would belong to a
lumbar vertebrae
Two additional processes possessed by lumbar vertebrae are the
mamillary and accessory processes
The superior articular facets of lumber vertebrae are ___ while the inferior articular facets are ___
concave, convex
What happens to the sacral vertebrae during adolescence?
They fuse to form the sacrum.
The broad anterosuperior surface of the sacrum that articulates with L5 is the
sacral plateau
The anterior midline projection of the sacral plateau is the
sacral promontory
The parts of the first sacral element that sweep out laterally from the centrum are the
alae
The lines of fusion of the sacral vertebrae are the
transverse ridges
The lateral aspects of the sacrum that contributes to the sacroiliac joint are the
auricular surfaces
The roughened area posterior to the auricular surface of the sacrum that attaches the sacroiliac muscles is the
sacral tuberosity
Viewing the sacrum anteriorly, it can be divided into __, __, and ___.
lateral part, centrum, and lateral part.
The ___ allow for the passage of the sacral nerves
sacral foramina
What allows for articulation with the inferior articular processes of the 5th lumbar vertebrae
The superior articular processes and facets of the sacrum that project up on the posterior border.
The rough, convex, posterior-facign surface of the sacrum is the. At the center of this is the
dorsal surface; median sacral crest.
Internal passages formed by the fusion of superior and inferior sacral vertebral notches are the
intervertebral foramina.
The feature located just laterally to the sacral foramina is the
lateral sacral crest
The feature found just medial to the sacral foramina but before the median sacral crest is the
intermediate sacral crest
The three crests found on the posterior portion of the sacrum are the
median sacral crest, intermediate sacral crests, and lateral sacral crests.
The vertebral foramen pathway is continued in the sacrum as the
sacral canal.
The protion most inferior on the posterior side of the sacrum where the dorsal wall is absent is the __ and is bounded by the
sacral hiatus; sacral cornu
The narrow inferior tip of the sacrum that includes the articular facet for the coccyx is the
apex of the sacrum
The suture between the temporal and parietal bones is the
squamos suture
The two sutures of the cranium that form the bregma are the
coronal and sagittal sutures
The suture between the occipital and parietal bones is the
lambdoid suture
The suture that lies between the occipital and sphenoid is the
basilar suture
The osteological term for the forehead is the
frontal squama
The original centers of ossification of the frontal bone are the
frontal eminences, tubers, or bosses.
The attachment for the temporalis muscle on the lateral ectocranial side of the frontal bone is the
temporal line
The most lateral and anterior corners of the frontal bone are the
zygomatic processes
Describe features around the upper eye orbits.
A supraorbital foramen (or notch) exists on the supraorbital margin. The supracilliary arches are superior to this (where the eyebrows are).
The suture connecting the right and left frontal halves (sometimes obliterated in adults) is the
metopic suture
The vertical groove running down the midline of the endocranial surface is the
sagittal sulcus
At its most inferior and anterior region, the sagittal sulcus becomes the
frontal crest
A foramen of varying size found at the root of the frontal crest is the
foramen cecum.
The endocranial portion of the frontal bone bears various
meningeal grooves
The horizontal portion of the frontal bone which on its inferior ectocranial side borders the eye is the
pars orbitalis (orbital plate)
The gap that separates the two orbital plates of the frontal bone is the
ethmoid notch
The features found at the lateral, inferior parts of the inferior orbital surfaces of the frontal are the
lacrimal fossae
Features anterior to the ethmoid notch that may be used for forensic identification due to their variation are the
frontal sinuses
Describe the angles present on the parietal bones
Frontal angle (at bregma), sphenoidal angle (at pterion), occipital angle (at lambda), and mastoid angle (at asterion).
Siding parietal bones can be accomplished by observed what near the mastoid angle on the endocranial surface?
The sigmoid sulcus (posterior and inferior).
Located near the sagittal suture near lambda on parietal bones.
Parietal foramen.
The ___ ___ is a continuation of the same feature on the frontal bone when two parietal bones are articulated together
Sagittal sulcus
Parietal bones on the ectocranial surface inferior side possess
parietal striae
An endocranial feature of parietal bones near the frontal angle is the
archanoid fovea
Running across the ectocranial surface of parietal bones are
the superior and inferior temporal lines
The ectocranial surface of the temporal bone bears the ___ which articulates with the parietals along the squamous suture.
temporal squama
The superior root of the zygomatic process is the ___ ___, which becomes the ___ ___ posteriorly.
suprameatal crest; supramastoid crest.
The thin, pointed bony rod that points anteroinferiorly from teh base of the temporal bone
styloid process
Foramen between the mastoid and styloid process
styloidmastoid process
The three auditory ossicles are the
incus, malleus (hammer), and stapes (staple)
