The Skeletal System: The Axial Skeleton

Flashcards related to the axial skeleton, including bone types, surface markings, skull components, and vertebral column.

Axial Skeleton

Consists of 80 bones including skull bones, auditory ossicles, hyoid bone, ribs, sternum, vertebrae, and sacrum.

Appendicular Skeleton

Consists of 126 bones including bones of the upper and lower extremities and the bones forming the girdles that connect the limbs to the axial skeleton.

Long Bones

Bones that have a greater length than width.

Short Bones

Bones that are cube-shaped.

Flat Bones

Bones that are thin layers of parallel plates.

Irregular Bones

Bones with complex shapes.

Sesamoid Bones

Bones shaped like a sesame seed.

Sutural Bones

Small, extra bone plates located within the sutures of cranial bones.

Sutures

Jointed areas where flat bones come together.

Fissure

Narrow slit between adjacent parts of bones through which blood vessels or nerves pass.

Foramen

Opening through which blood vessels, nerves, or ligaments pass.

Fossa

Shallow depression in a bone.

Sulcus

Furrow along bone surface that accommodates blood vessel, nerve, or tendon.

Meatus

Tubelike opening in a bone.

Condyle

Large, round protuberance with a smooth articular surface at end of bone.

Facet

Smooth, flat, slightly concave or convex articular surface.

Head

Usually rounded articular projection supported on neck (constricted portion) of bone.

Crest

Prominent ridge or elongated projection on a bone.

Epicondyle

Typically roughened projection above condyle.

Line

Long, narrow ridge or border (less prominent than crest).

Spinous Process

Sharp, slender projection on a bone.

Trochanter

Very large projection found only on the femur.

Tubercle

Variably-sized rounded projection.

Tuberosity

Variably-sized projection that has a rough, bumpy surface.

Skull

Contains 22 bones, not including the 3 middle ear bones in both ears.

Temporomandibular Joint (TMJ) Dysfunction

Dull pain around ear, tender jaw muscles, clicking noise when opening/closing mouth. Caused by improperly aligned teeth, grinding of teeth, trauma to the head, arthritis, etc. Treatment includes moist heat or ice, soft foods and pain relievers.

Deviated Nasal Septum

Occurs when septum does not run along the midline of nasal cavity. Caused by trauma to the nose or developmental abnormality. May lead to infection, inflammation, congestion, headaches and nosebleeds. May require surgery to fix.

Mandible

The lower jawbone, is the largest and strongest facial bone and the only moveable skull bone (other than auditory ossicles).

Suture

An immoveable joint found in the skull holding bones together.

Paranasal Sinuses

Mucous membrane-lined cavities in the frontal, maxillary, sphenoid and ethmoid bones. Used as resonating chambers to enhance the voice, increase the surface area of the nasal mucosa and help to moisten it as well.

Fontanels

Areas of a fetus/baby where unossified mesenchyme develops into dense connective tissue. They close up through intramembranous ossification by 2 years of age.

Hyoid Bone

Does not articulate with any other bone, supports the tongue and provides an attachment site for some muscles of the neck and pharynx.

Vertebral Column

Also known as the spinal column, backbone or spine. Composed of 26 vertebrae divided into 5 regions and protects the spinal cord.

Intervertebral Discs

Located between the bodies of the vertebrae from the second cervical to the sacrum. Composed of an outer ring of fibrocartilage (annulus fibrosus) and an inner, soft nucleus (nucleus pulposus) with a layer of hyaline cartilage on the top and bottom of each disc. Absorb shock and separate the vertebrae from one another.

Thorax

The entire chest region. The bones that compose the thoracic cage are the sternum, ribs and costal cartilages.

Sternum

Composed of 3 segments: the upper manubrium, the middle body, and the lower xiphoid process. The sternum articulates with the clavicles and the costal cartilages.

True Ribs

First 7 pairs of ribs; their cartilage is directly connected to the sternum.

False Ribs

Next 5 pairs of ribs; cartilage is indirectly connected to the sternum.

Floating Ribs

Last 2 pairs of ribs; these are not connected to the sternum.

Scoliosis

Increased lateral curvature of the spine.

Kyphosis

Increased thoracic curve (bent forward).

Lordosis

Increased lumbar curve (bent backwards).

Spina Bifida

A congenital defect of the vertebral column where the laminae do not develop normally.