Axial Skeleton Lecture Notes

Vocabulary flashcards detailing the anatomical structures, bone counts, and clinical considerations of the axial skeleton based on Chapter 8 lecture notes.

Axial Skeleton

The central framework of the body composed of $80$ bones, including the skull, vertebral column, ribs, and sternum.

Appendicular Skeleton

The division of the skeletal system consisting of $126$ bones, including the upper and lower limbs and the bones that attach them to the axial skeleton.

Skeletal System

A system consisting of bones, cartilage, and ligaments that supports the body, protects organs, helps movement, and stores calcium; adults have $206$ bones.

Skull

A structure composed of $22$ bones (divided into $8$ cranial and $14$ facial bones) that protects the brain and forms the face.

Mandible

The only movable bone of the skull which forms the lower jaw and allows for chewing and speaking.

Maxilla

The bone that forms the fixed upper jaw, the roof of the mouth, the floor of the orbit, and the sides of the nose.

Foramen magnum

The large opening in the occipital bone that allows the spinal cord to pass into the skull, connecting the brain and spinal cord.

Sella turquica

A depression in the sphenoid bone that houses the pituitary gland.

Cribriform plate

A structure of the ethmoid bone that allows the olfactory nerves (cranial nerve $I$) to pass for the sense of smell.

Lacrimal bones

The smallest facial bones, which help form the eye socket and are associated with tear drainage.

Zygomatic bones

Commonly called cheekbones, these bones give shape to the face and help form the eye socket.

Vomer

The bone that forms part of the nasal septum.

Sutures

Immovable fibrous joints that connect the cranial bones, including the sagittal, coronal, lambdoid, and squamous sutures.

Paranasal sinuses

Air-filled spaces inside skull bones (frontal, maxillary, ethmoid, and sphenoid) that lighten the skull and produce voice resonance.

Fontanels

The soft spots between the skull bones of an infant that allow the brain to grow rapidly and facilitate childbirth.

Ossification

The biological process by which bone is formed from connective tissue.

Craniosynostosis

A developmental disorder characterized by the premature fusion of skull sutures.

Hyoid bone

A unique $U$-shaped bone in the neck that does not articulate with any other bone and serves as an attachment site for muscles involved in swallowing and speaking.

Vertebral column regions

The five regions of the spine consisting of cervical ($7$), thoracic ($12$), lumbar ($5$), sacral ($5$ fused), and coccygeal ($4$ fused) vertebrae.

Kyphosis

An abnormal spinal curvature abnormality characterized by an excessive thoracic curvature, also known as hunchback.

Lordosis

An abnormal spinal curvature abnormality characterized by an excessive lumbar curvature, also known as swayback.

Scoliosis

A lateral or sideways curvature of the spine.

Atlas ($C_1$)

The first cervical vertebra that supports the skull and allows for the 'yes' movement of the head.

Axis ($C_2$)

The second cervical vertebra that contains the dens, a projection that allows for the 'no' movement of the head.

Nucleus pulposus

The inner soft center of an intervertebral disc that absorbs shock and allow movement of the spine.

Annulus fibrosus

The outer layer of an intervertebral disc.

Sternum

Commonly called the breastbone, it consists of three parts: the manubrium, the body, and the xiphoid process.

True ribs

Ribs $1$ through $7$ that attach directly to the sternum through costal cartilage.

False ribs

Ribs $8$ through $12$ that attach to the sternum indirectly or not at all.

Floating ribs

Ribs $11$ and $12$ which have no attachment to the sternum.