A&P Mini Practical 5 - Axial Skeleton: Hyoid, Vertebrae, Sacrum, Thoracic Cage

Hyoid bone

Hangs high in neck, floats

Cervical

7 vertebrae, anterior, bends inward toward front

Thoracic

12 vertebrae, posterior, curves outward toward back

Lumbar

5 vertebrae, anterior, curves inward toward front

Sacrum

5 fused vertebrae (1 bone), posterior, curves outward toward back

Coccyx

1-4 fused bones (1 bone), posterior, curves inward toward front

Cervical curvature

Lordosis, convex anteriorly, curves forward

Thoracic curvature

Kyphosis, concave anteriorly, curves outward

Lumbar curvature

Lordosis, convex anteriorly, curves forward

Pelvic curvature

Kyphosis, concave anteriorly, curves outward

Scoliosis

Lateral (S shape, side-to-side), thoracic region

Kyphosis

Exaggeration of thoracic curvature, overly rounded (shrimp posture)

Lordosis

Exaggeration of lumbar curvature, too far forward

Body/Centrum

Disk-shaped, largest part

Laminae

Posterior part of arch, bridge for spinous process

Pedicles

Feet of arch, little pillars, short thick bridges

Spinous Process

Pointy part, sticks out posteriorly, where 2 laminae join, can feel it

Transverse Process

Side wings, projections that stick out laterally

Superior/Inferior Articular Processes

Joint connectors

Superior Articular Process

Faces upward

Inferior Articular Process

Faces downward

Vertebral Foramen

Hole in center where spinal cord runs through

Features of Cervical (7)

• Support head, allow for movement

• C1: Atlas

• C2: Axis

  • Dens (Odontoid) Process

• Bifid spinous process

• Transverse foramen

C1: Atlas

1st, Atlas held up the world (holds skull)

C2: Axis

2nd, lets head rotate/spin around

Dens (Odontoid) Process

Tooth-like projection

Bifid spinous process

C2-C6, split/forked (2 projections)

Transverse foramen

Only in cervical, hole in transverse process

Features of Thoracic (12)

• Supports rib cage, protects heart & lungs

• Sharp downward spinous process

• Superior/Inferior/Transverse Costal Facet

Sharp downward spinous process

Long, downward, shark tooth

Superior Costal Facet

Top side of body

Inferior Costal Facet

Bottom side of body

Transverse Costal Facet

On transverse process

Features of Lumbar (5)

• Bears most weight, supports lower back

• Massive Centrum (Body)

• Short/wide spinous process

Massive Centrum (Body)

Large, thick because supports weight

Short/wide spinous process

Squarish for flexibility, movement, strength

Features of intervertebral disc

• Shock absorber

• Nucleus pulposus

• Anulus fibrosus

Nucleus pulposus

Internal, gel-like core, shock absorber

Anulus Fibrosus

External, tougher ring, strength

Features of Sacrum (5)

• Connects spine to pelvis, supports body weight

• Sacral Canal

• Sacroiliac joint

• Sacral Foramen

• Median Sacral Crest

• Sacral Promontory

• Ala

Sacral canal

Tunnel in middle of sacrum

Sacroiliac joint

Where sacrum meets ilium

Sacral Foramen

4 each side, 8 total, exit holes on anterior and posterior surface

Median Sacral Crest

Bumpy ridge that runs down middle of posterior side

Sacral Promontory

Sticks out at top of sacrum

Ala

Two broad, wing-like projections on superior lateral portion

Features of Coccyx (1-4)

• Supports sitting posture, muscle attachment

• Tailbone (tail-end of spine)

• Smallest part of vertebral column

Features of Sternum

• Breastbone, protects vital organs, aids in breathing

• Manubrium

• Body

• Xiphoid process

• Clavicular notch

Manubrium

Top, upper portion, broad, articulates w/ clavicles

Body

Middle, longest part of sternum

Xiphoid process

Bottom part, small, pointed structure at lower end of sternum

Clavicular notch

At sides of manubrium, where clavicles attach to sternum

True ribs (1-7)

Attached directly to sternum via individual costal cartilages

False - Vertebrochondral Ribs (8-10)

Indirectly attached to sternum by common cartilage

False - Floating Ribs (11-12)

Don’t attach to sternum, no cartilage

Rib 1

Head, Neck, Tubercle, shaft

Head

Rounded end, articulates w/ vertebral body

Neck

Narrow portion after head

Tubercle

Small bump, articulates w/ transverse process

Shaft (main body)

Long, curved portion, attaches to costal cartilage

Ribs 2-10

Articular Facets, Costal Groove

Articular Facets (2)

Flat surfaces where rib connects to vertebrae

Costal Groove (1)

Groove along inside surface of rib

Ribs 11-12 (Floating)

• Has all the parts of the rest of the ribs except the shaft

• Doesn’t connect to costal cartilage or sternum (hence “floating”)

• No articular facets or costal groove