Skeletal Bones and Features Axial Skeleton Skull, Spine, Thoracic Cage

Skull 22 Bones: 8 Cranial & 14 facial

Cranial Bones (8) Frontal bone (1) – forehead, part of nose, superior portions of orbits Parietal Bones (2) – dorsal to frontal bone, form roof and part of sides of cranium Occipital Bone (1) Most dorsal part, base of cranium – Foramen magnum – opening through which spinal cord joins brain – Occipital condyles – rounded processes on either side of foramen magnum, articulate with first vertebra (atlas) Temporal Bones (2) – inferior to parietal bones, help form base of cranium – External Auditory meatus – leads to middle ear – Mandibular fossa – artyiculates with mandible – Mastoid process – attachment site for neck muscles – Styloid process – attachment of muscles of tongue and neck – Zygomatic process – helps form cheekbone Sphenoid Bone (1) sides and base of cranium, floors and sides of orbits – Sella turcica – superior depression, houses pituitary gland Ethmoid Bone (1) – part of roof of nasal cavity – Crista galli (cock’s comb) – triangular process, attachment site for dura mater – Cribiform plate – passage of olfactory nerves – Perpendicular plate – projects inferiorly, forms nasal septum

Facial Bones (14) Maxillae (2) – upper jaw – alveolar processes hold teeth – palatine processes form anterior hard palate – floors of orbits – sides and floor of nasal cavity Palatine Bones (2) – Posterior portion of hard palate, floor of nasal cavity (cleft palate) Zygomatic Bones (2) – sides of orbits and cheekbones Lacrimal Bones (2) – medial walls of orbits Nasal Bones (2) – form bridge of nose Vomer Bone (1) – joins perpendicular plate of ethmoid, forms nasal septum Inferior Nasal Conchae (2) – project into nasal cavities from lateral walls Mandible (1)

Fontanels

TMJ

Sphenoid (bat bone)

Cleft Palate

Lacrimal Bone

HYOID BONE – Attachment site for tongue, neck (larynx and pharynx) muscles; unique – only bone that does NOT articulate with any other bone; often fractured  strangulation!

Spine 26 bones 24 vertebrae 7 cervical (atlas, axis, 5) 12 thoracic 5 lumbar Sacrum Coccyx Supports weight of head neck, trunk & transfers to lower appendicular skeleton (limbs) Protects spinal chord helps maintain an upright posture

Scoliosis

Kyphosis

Lordosis

ANATOMICAL DIFFERENCES BETWEEN VERTEBRAE (ID Characteristics) Cervical – neck, “neck” – small; small; extra holes present; transverse foramina for vertebral arteries going to brain, have forked spinous processes

VERTEBRAL COLUMN (continued) UNIQUE CERVICAL VERTEBRAE “Atlas” (C-1); attaches to occipital condyles; spinous process & centrum Atlas, along with his brother Menoetius, sided with the Titans in their war against the Olympians, the Titanomachy. His brothers Prometheus and Epimetheus weighed the odds and betrayed the other Titans by forming an alliance with the Olympians. When the Titans were defeated, many of them (including Menoetius) were confined to Tartarus, but Zeus condemned Atlas to stand at the western edge of Gaia, the Earth and hold up Ouranos, the Sky on his shoulders, to prevent the two from resuming their primordial embrace. Thus, he was Atlas Telamon, "enduring Atlas." A common misconception is that Atlas was forced to hold the Earth on his shoulders, but this is incorrect. Classical art shows Atlas holding a Celestial Sphere, not a Globe.OlympiansTitanomachyTartarusZeus Gaia, the EarthOuranos, the SkyCelestial SphereGlobe

VERTEBRAL COLUMN (continued) UNIQUE CERVICAL VERTEBRAE “Atlas” (C-1); attaches to occipital condyles; spinous process & centrum? “Axis” (C-2); creates ‘pivot joint’ for rotation with atlas; has dens (odontoid process)

VERTEBRAL COLUMN (continued) Shake Head No Yes

VERTEBRAL COLUMN (continued) Shaken Baby Syndrome

VERTEBRAL COLUMN (continued) UNIQUE CERVICAL VERTEBRAE “Atlas” (C-1); attaches to occipital condyles; spinous process & centrum? “Axis” (C-2); creates ‘pivot joint’ for rotation with atlas; has dens (odontoid process) “ Vertebra Prominens ” (C-7); has large tubercle at end of spinous process that attaches to large elastic ligament running to base of occipital bone (which reduces strain on postural neck muscles)

ANATOMICAL DIFFERENCES BETWEEN VERTEBRAE (ID Characteristics) Thoracic – medium; mid- back Ribs Attach; FLAT superior articular facets;

ANATOMICAL DIFFERENCES BETWEEN VERTEBRAE (ID Characteristics) Lumbar – large; CUPPED superior articular facets

VERTEBRAL COLUMN (continued) II. SACRUM (5 FUSED)  complete age 25; protects organs; connection point to pelvic girdle SACROILIAC JOINT – joins iliac bones and sacrum

VERTEBRAL COLUMN (continued) COMPONENTS III. COCCYX ( 3-5 FUSED) “ Tail Bone ”

Spina Bifida

Disk issuesCompression Fracture

Spondylolysis

Spondylolithesis

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Manubrium

XIPHOID PROCESS – most inferior portion, sharp projection – attachment sight for diaphragm and abdominal muscles