Chapter 08 Skeletal System: Axial and Appendicular Skeleton

Vocabulary flashcards covering the axial and appendicular skeletal systems, including bone markings, clinical conditions, developmental milestones, and sexually dimorphic features.

Axial skeleton

Consists of bones along the central axis of the body, including the skull ($22$ bones), associated bones of the skull ($7$), vertebral column ($26$), and thoracic cage ($25$), totaling $80$ bones.

Appendicular skeleton

Includes the bones of the pectoral girdle, pelvic girdle, and the upper and lower limbs, totaling $126$ bones ($63$ per side).

Condyle

A large, smooth, rounded, oval articulating structure found on bones such as the occipital bone and femur.

Foramen

A general anatomical term for an opening or hole in a bone, such as the foramen magnum.

Fissure

A narrow, slitlike opening through a bone, such as the superior orbital fissure in the eye socket.

Cleft palate

A congenital fissure in the palate midline caused by the incomplete fusion of the left and right maxillary and palatine bones.

Craniosynostosis

The premature fusion of one or more cranial sutures, which results in an atypical craniofacial shape.

Paranasal sinuses

Air-filled cavities located within the frontal, ethmoid, sphenoid, and maxillary bones that help lighten the skull and humidify air.

Auditory ossicles

Three tiny bones housed within the petrous part of each temporal bone: the malleus, incus, and stapes.

Hyoid bone

A slender, curved bone located inferior to the skull between the mandible and larynx that does not articulate with any other bone.

Fontanelles

Flexible areas of dense regular connective tissue between infant cranial bones, often called "soft spots," that ease passage through the birth canal and allow for rapid brain growth.

Anterior fontanelle

The largest fontanelle in an infant skull, which typically closes at around $15$ months of age.

Primary curves

The thoracic and sacral curvatures of the spine that are present at birth and result in a C-shaped column.

Secondary curves

The cervical curvature (appearing at $3\,\text{to}\,4$ months) and lumbar curvature (appearing by the first year) that help shift trunk weight over the legs.

Hyperkyphosis

An exaggerated convex thoracic curvature of the spine, often associated with osteoporosis.

Nucleus pulposus

The inner gelatinous region of an intervertebral disc that acts as a shock absorber.

Scaphoid bone

The most commonly fractured carpal bone, which can suffer from avascular necrosis due to inadequate blood supply following a break.

Pelvic brim

A continuous oval ridge that divides the pelvis into the true pelvis (inferiorly) and the false pelvis (superiorly).

Pelvic outlet

The inferiorly placed opening of the pelvis bounded by the coccyx, ischial tuberosities, and the inferior border of the symphysial surface.

Subpubic angle

The angle formed by the alignment of the pubic bones; it is typically wider and more convex in female-like pelves compared to male-like pelves.

Medial longitudinal arch

The highest of the three foot arches, extending from the calcaneus to the great toe ($metatarsals\,I-III$).

Talipes equinovarus

A congenital condition also known as clubfoot, where the feet are permanently inverted and the ankles are plantar flexed.

Amelia

A limb malformation characterized by the complete absence of a limb.

Phocomelia

A condition resulting in a short, poorly formed limb, which was famously caused by the drug thalidomide if taken during weeks $4\,\text{to}\,8$ prenatally.

Syndactyly

A limb malformation commonly referred to as "webbing," characterized by the abnormal fusion of digits.