Chapter 7: The Skeleton Study Guide

A comprehensive vocabulary review of the human skeletal system, covering axial and appendicular divisions, bone landmarks, and clinical conditions.

Skeletal system body mass percentage

The skeletal system makes up about $20\%$ of total body mass.

Axial skeleton

The division of the skeleton that supports the body axis, protects the brain, spinal cord, and thoracic organs, and supports the head, neck, and trunk.

Appendicular skeleton

The division of the skeleton that allows movement and connects the limbs to the axial skeleton via the pectoral and pelvic girdles.

Cranial bones

A group of $8$ bones (frontal, $2$ parietal, $2$ temporal, occipital, sphenoid, ethmoid) that enclose and protect the brain.

Facial bones

A group of $14$ bones that form the framework of the face, protect sense organs, provide openings for air and food, and secure the teeth.

Sutures

Immovable, interlocking joints that unite the bones of the skull.

Occipital bone landmarks

Includes the foramen magnum (opening for the spinal cord) and occipital condyles (articulate with the $C1$ vertebra).

Sphenoid bone

Known as the “keystone” bone because it articulates with all other cranial bones; contains the sella turcica and optic canals.

Ethmoid bone

Forms part of the nasal cavity and medial orbit wall; contains the crista galli, cribriform plates, and perpendicular plate.

Mandible

The largest and strongest facial bone and the only freely movable bone of the skull.

Maxillae

The keystone bones of the face; they form part of the hard palate, orbits, and nasal cavity.

Hyoid bone

A unique bone that does not articulate directly with any other bone; serves as a base for the tongue and attachment for swallowing muscles.

Vertebral column region counts

Consists of $26$ irregular bones: $7$ cervical, $12$ thoracic, $5$ lumbar, $1$ sacrum ($5$ fused), and $1$ coccyx ($3-5$ fused).

Scoliosis

An abnormal lateral curvature of the vertebral column.

Kyphosis

An exaggerated thoracic curvature, commonly known as hunchback.

Lordosis

An exaggerated lumbar curvature, commonly known as swayback.

Nucleus pulposus

The inner gelatinous core of an intervertebral disc.

Anulus fibrosus

The outer fibrocartilage collar of an intervertebral disc.

Atlas (C1)

The first cervical vertebra which has no body or spinous process; it supports the skull and allows the “yes” motion.

Axis (C2)

The second cervical vertebra which contains the dens, acting as a pivot for the “no” motion.

Vertebra prominens (C7)

A cervical vertebra with a prominent spinous process that can be felt through the skin.

True ribs

Rib pairs $1-7$ that attach directly to the sternum via costal cartilage.

False ribs

Rib pairs $8-10$ that attach indirectly to the sternum.

Floating ribs

Rib pairs $11-12$ that do not attach to the sternum.

Pectoral girdle

Consists of the clavicles and scapulae; it emphasizes mobility and attaches the upper limbs to the axial skeleton.

Humerus

The only bone of the arm; its surgical neck is a common fracture site.

Ulna

The medial bone of the forearm.

Radius

The lateral bone of the forearm.

Hand bone counts

Includes $8$ carpals, $5$ metacarpals, and $14$ phalanges.

Pelvic girdle

Formed by two coxal bones (fusion of ilium, ischium, and pubis) meeting at the acetabulum; emphasizes stability and weight bearing.

Femur

The largest and strongest bone in the body, located in the thigh.

Tibia

The medial, weight-bearing bone of the leg; its medial malleolus forms the inner ankle.

Fibula

The lateral, non-weight-bearing bone of the leg; its lateral malleolus forms the outer ankle.

Hallux

The anatomical term for the great toe.

Pollex

The anatomical term for the thumb.

Colles’ fracture

A fracture of the distal radius often caused by catching a fall with an outstretched hand.

Carpal tunnel syndrome

Compression of the median nerve due to tendon inflammation within the carpal tunnel.