Anatomy Ch. 5 - 2 (Axial Skeleton)

How many Vertebrae are present before birth? How many fuse?

33, 9

How many vertebrae make up the cervical

7

How many vertebrae make up the thoracic

12

How many vertebrae make up the lumbar

5

Primary curvatures

curves of thoracic and sacral regions, present when born.

Secondary curvatures

curves of cervical and lumbar

Vertebrae Body (Centrum)

disc-like and weight bearing part, that sits anteriorly in the column.

Vertebral arch

formed from the joining of all posterior extensions (lamina and pedicle)

Vertebral foramen

canal through which the spinal cord passes

Transverse Processes

two lateral projections from the vertebral arch

spinous process

single projection arising from the posterior aspect of the cerebral arch (the 2 laminae fused together)

superior and inferior articular processes

paired projects lateral to the vertebral foramen, allowing a vertebra to form joints with adjacent vertebrae.

Cervical vertebrae (C1-C7)

Smallet, have small holes

Atlas (C1)

no body, superior surfaces of its transverse processes contain large depression that reive the occipital condyles of the skull.

Axis (C2)

has a large upright process, the odontoid process (or dens) which acts as a pivot for the rotation of the atlas and skull.

Thoracic vertebrae (T1-T12)

larger than the cervical vertebrae. Body is heart-shped and has two costal demifacets (articulation surfaces) on each side that reviece the heads of the ribs. Spinous process is long and hooks.

Lumbar vertebrae (L1-L5)

Have massive, block like bodies and short hatched-shaped spinous processes. Most stress of the spine occurs here, so they are the sturdiest.

Sacrum

Formed from the fusion of 5 vertebrae.

What does the Sacrum superiorly and inferiorly articulate with?

Superiorly articulates with L5, and inferiorly with the coccyx.

What articulates laterally with the hip bones forming the sacroiliac joints?

alae

The median sacral crest

Lies on its dorsal midline, aremnant of the fusion of the 5 vertebrae

Coccyx

Tailbone, formed from the fusion of 3-5 small vertebae.

Sternum (breastbone)

Flat bone, easy site for a bone marrow aspiration since it is a site of

hematopoiesis and is close to the surface of the body.

How many ribs are there (true and false)?

True ribs- pairs 1-7, false ribs- pairs 8-12.

True vs. false ribs

True attach directly to the sternum by costal cartilages

False attach indirectly or not at all to the sternum

What is special about pairs 11 & 12?

Floating ribs, do not attach anteriorly at all.

Cervical vs. Thoracic vs. Lumbar

Cervical- small, highly mobile, special holes (transverse forming).

Thoracic - medium, heart-shaped bodies, connect to ribs, less mobile.

Lumbar - largest, kidney-shaped, thickest, bearing most weight with wide, short processes for strength.

Scoliosis

Abnormal lateral curvature

Kyphosis

exaggerated thoracic curvature (convex)

Lordoisis

exaggerated lumbar curvature (concave)

Paranasal sinuses

Hollow portions of bones surrounding the nasal cavity

Functions of paranasal sinuses

Lighten the skull, amplify sounds made as we speak.

Name the 4 paranasal sinuses

Frontal, ethmoid, sphenoidal, maxillary

Hyoid bone

Closely talked to mandible and temporal bones. Does not articulate with another bone.

Fetal skull is ___ body length compared to adult skull, which is ___ body length

1/4, 1/8

Fontanels

fibrous membranes connecting the cranial bones. Convert to bone within 24 months after birth

Name the 8 cranial bones that make up the Adult skull

Frontal bone, occipital bone, ethmoid bone, sphenoid bone, parietal bones (pair), temportal bones(pair).

Name the 14 facial bones that make up the Adult skull

Maxilae (pair), palatine bones (pair), lacrimal bones (pair), zygomatic bones (pair), ansal bones(pair), vomer bone, inferior nasal concahe (pair), mandible.