Chapter 7 - Terms

Axial skeleton (80 bones)

Skull, vertebral column, thoracic cage, hyoid bone, and auditory ossicles

Appendicular skeleton (126 bones)

Pectoral girdle, upper limbs, pelvic girdle, and lower limbs

Cranial bones (8): function

Enclose and protect the brain; serve as attachment sites for muscles

Cranial bones (8): names

Frontal bone; parietal bones (2); temporal bones (2); occipital bone; sphenoid bone; ethmoid bone

Frontal bone

Forms forehead and roof of orbits. Superior to facial bones; anterior to parietal bones

Parietal bones (2)

Form superior and lateral sides of skull. Articulate anteriorly with frontal bone via coronal suture and with each other via sagittal suture

Temporal bones (2)

Form inferior lateral sides of skull and cranial floor. Inferior to parietal bones. Contain external auditory meatus, styloid process, and mastoid process; forms temporomandibular joint (TMJ) with mandible

Occipital bone

Forms base and posterior skull. Contains foramen magnum and occipital condyles

Foramen magnum

Spinal cord/vertebral arteries passage

Occipital condyles

Articulate with C1/atlas

Sphenoid bone

Keystone bone in middle cranial base; articulates with all other cranial bones

Ethmoid bone

Anterior cranial floor, between orbits; supports nasal cavity

Facial bones (14): names

Mandible; maxillae (2); zygomatic bones (2); nasal bones (2); lacrimal bones (2); palatine bones (2); inferior nasal conchae (2); vomer

Mandible

Lower jaw bone (only movable skull bone)

Maxillae (2)

Upper jaw bones; form floor of orbits and hard palate

Zygomatic bones (2)

Cheekbones; form zygomatic arch with temporal bone

Nasal bones (2)

Form bridge of nose

Lacrimal bones (2)

Medial wall of orbits

Palatine bones (2)

Posterior hard palate and nasal cavity

Inferior nasal conchae (2)

Independent bones on lateral walls of nasal cavity

Vomer

Inferior/posterior nasal septum

Overall function of the sphenoid bone

Articulates with all other cranial bones, providing considerable stability to the skull

Structure of the sphenoid bone that the optic nerve passes through

Optic canal (optic foramen)

Function of the sella turcica

A saddle-like depression that houses and protects the pituitary gland

Overall function of the ethmoid bone

Major support structure for the nasal cavity and makes up most of its surface area

Function of the crista galli

Serves as an attachment point for the membranes (dura mater/falx cerebri) that cover and anchor the brain

Functions of the nasal conchae

Swirl/turbulize incoming air to warm, humidify, and filter it before it reaches the lungs, and increase nasal surface area

The 7 bones that make up the eye orbit

Frontal bone; sphenoid bone; ethmoid bone; zygomatic bone; maxilla; lacrimal bone; palatine bone

Functions of the paranasal cavities

Lighten the skull; produce mucus (lined with mucous membranes); provide voice resonance

Fontanels: definition

Mesenchyme-filled spaces ("soft spots") between cranial bones present at birth that allow the skull to change shape during birth and accommodate rapid brain growth

Fontanels: fusion age

Most close completely 24 months (2 years) of age

Names of the 3 auditory ossicles

Malleus, incus, stapes

Location of the auditory ossicles

Found inside the middle ear cavity (within the temporal bone)

Auditory ossicles: size

The smallest bones in the body

Location of the hyoid bone

Anterior neck region, inferior to the mandible and superior to the larynx

What makes the hyoid bone special?

It does not articulate directly with any other bone in the skeleton; it is suspended purely by ligaments and muscles

The 5 major portions of the vertebral column

Cervical vertebrae; thoracic vertebrae; lumbar vertebrae; sacrum; coccyx

Cervical vertebrae: number of bones

7 bones (C1–C7)

Thoracic vertebrae: number of bones

12 bones (T1–T12)

Lumbar vertebrae: number of bones

5 bones (L1–L5)

Sacrum: number of bones

1 bone (formed by 5 fused sacral vertebrae; fuses between ~16–30 years old)

Coccyx: number of bones

1 bone (formed by 4 fused coccygeal vertebrae; fuses between ~20–30 years old)

Primary curvatures (present at birth)

Thoracic and sacral curvatures

Primary curvatures relative to the anterior side

Concave (curving inward anteriorly)

Secondary curvatures (develop postnatally)

Cervical and lumbar curvatures

Secondary curvatures relative to the anterior side

Convex (bulging outward anteriorly)

Scoliosis

An abnormal lateral (side-to-side) curvature of the spine

Kyphosis

An exaggerated thoracic curvature (posteriorly convex, "hunchback")

Lordosis

An exaggerated lumbar curvature (anteriorly convex, "swayback")

Herniated/slipped disc

Occurs when trauma or aging weakens the outer ring (annulus fibrosus), causing the inner gelatinous core (nucleus pulposus) to lose its cushioning properties and protrude/herniate outward, often pressing against spinal nerves

Function of the vertebral foramen

Provides an opening for the spinal cord to pass through

Function of the intervertebral foramen

Openings between adjacent vertebrae that allow spinal nerves to exit the spinal cord

Function of the intervertebral disc

Serves as a shock absorber between vertebrae and allows flexibility in the vertebral column

Tissue type of the intervertebral disc

Fibrocartilage (outer annulus fibrosus)

Cervical vertebrae (C1–C7): distinguishing characteristics

Smallest bodies, possess transverse foramina (for vertebral arteries), often bifid spinous processes

Thoracic vertebrae (T1–T12): distinguishing characteristics

Medium heart-shaped bodies, long downward-pointing spinous processes, possess costal facets for rib articulation

Lumbar vertebrae (L1–L5): distinguishing characteristics

Largest, thickest, kidney-bean-shaped bodies; short, blunt, hatchet-shaped spinous processes (built for weight-bearing)

Atlas (C1): shape

Ring of bone with no body and no spinous process

Atlas (C1): function

Articulates with the occipital condyles of the skull to support the head and permit nodding "yes"

Axis (C2): shape

Contains a peg-like vertical projection called the dens (odontoid process) on its body

Axis (C2): function

Acts as a pivot axis around which C1 rotates, allowing side-to-side rotation of the head ("no")

Manubrium

Superior portion of the sternum (contains suprasternal and clavicular notches)

Body of the sternum

Middle and largest portion

Xiphoid process

Inferior-most projection tip

True ribs

7 pairs (ribs 1–7). Direct attachment to the sternum via their own individual costal cartilage

False ribs

5 pairs (ribs 8–12). Indirect attachment to the sternum (costal cartilage of ribs 8–10 joins the 7th rib's cartilage) OR no anterior attachment at all

Floating ribs

2 pairs (ribs 11–12; a subset of false ribs). No anterior attachment to the sternum or other costal cartilages

Tissue type of costal cartilage

Hyaline cartilage