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# Skeletal System: Axial and Appendicular Skeleton ## Learning Objective Define the terms for common bone markings. ### Distinctive Bone Markings Distinctive bone markings are the surface features that characterize each bone in the body. * **Articulating surfaces** between adjacent bones tend...

# Skeletal System: Axial and Appendicular Skeleton ## Learning Objective Define the terms for common bone markings. ### Distinctive Bone Markings Distinctive bone markings are the surface features that characterize each bone in the body. * **Articulating surfaces** between adjacent bones tend to be smooth areas. * **Depressions** on a bone provide space for a bony articulation, muscular structure, or other body component, for example, lobes of a brain. * **Projections** from the bone surface mark the points where muscles, tendons, and ligaments attach. * **Openings and spaces** through bones indicate sites for passageways for blood vessels and nerves. Anatomists use specific terms to describe these characteristics. ### General Structure and Surfaces | Anatomic Term | Description | |---|---| | Condyle | Large, smooth, rounded, oval structure | | Facet | Small, flat, shallow surface | | Head | Prominent, rounded epiphysis | | Trochlea | Smooth, grooved, pulleylike process | | Alveolus (pl. alveoli) | Deep pit or socket in the maxilla or mandible | | Fossa (pl., fossae) | Flattened or shallow depression | | Sulcus | Narrow groove | ### Depressions ### Projections | Anatomic Term | Description | |---|---| | Crest | Narrow, prominent, ridgelike projection | | Epicondyle | Projection adjacent to a condyle | | Line | Low ridge | | Process | Any marked bony prominence | | Ramus (pl. rami) | Angular extension of a bone relative to the rest of the structure | | Spine | Pointed, slender process | | Trochanter | Massive, rough projection found only on the femur | | Tubercle | Small, round projection | | Tuberosity | Large, rough projection | ### Openings and Spaces | Anatomic Term | Description | |---|---| | Canal | Passageway through a bone | | Fissure | Narrow, slitlike opening through a bone | | Foramen (pl., foramina) | Rounded passageway through a bone | | Meatus | Passageway through a bone | | Sinus | Cavity or hollow space in a bone | ### Illustrations #### Skull, Anterior View * **Fissure** * **Ramus** #### Skull, Sagittal View * **Sinus** * **Process** * **Foramen** * **Alveolus** #### Humerus * **Tubercle** * **Sulcus** * **Head** * **Tuberosity** * **Fossa** * **Trochlea** * **Epicondyle**