Skeletal System: Axial vs Appendicular Skeleton

Axial Skeleton

• The clavicle is not part of the axial skeleton; ribs, vertebral column, and the mandible are.
• The axial skeleton has 80 bones.
• Rib is part of the axial skeleton.
• The sinuses are cavities within a bone.

Appendicular Skeleton

• The parietal bone is not part of the appendicular skeleton; coxal bones, radius, and the clavicle are.
• The appendicular skeleton is composed of 126 bones.
• The scapula is part of the appendicular skeleton.

Skull and Vertebrae

• The lambdoid suture is between the occipital and parietal bones.
• The temporal bone contains a sinus that can become inflamed, causing mastoiditis.
• The occipital bone articulates with the first vertebra.
• The ethmoid bone forms the upper parts of the nasal septum and side walls of the nasal cavity.
• An irregular bone that lies anterior to the sphenoid but posterior to the nasal bones is the ethmoid bone.
• The mandible does not articulate with the maxillae.

Other Skeletal Components

• Damage to the cribriform plate may allow infectious materials to pass from the nose to the brain.
• Fontanels are unossified areas in an infant's skull.
• The manubrium is the upper part of the sternum.
• The skeletal framework of the neck consists of the cervical vertebrae.
• There are 12 thoracic vertebrae.
• All vertebrae, except the sacrum and coccyx, have a central opening called the vertebral foramen.
• The scapula is not part of the thoracic cage.
• The frontal bone is not part of the face.
• The zygomatic bone does not contain paranasal sinuses.
• The occipital bone forms four joints with other bones.
• The largest of the paranasal sinuses is within the maxilla.
• Another name for the zygomatic bone is the malar bone.
• The vertebral column sequence from superior to inferior is: cervical, thoracic, lumbar, sacral, and coccyx.
• The dens is the structure providing the axis for head rotation.
• The average adult skeleton has 206 bones.
• The bones of the middle ear are part of the axial skeleton.
• The mandible and vomer are the two unpaired facial bones.
• The palatine bone makes up part of the hard palate.
• The only bone in the body that does not articulate with another bone is the hyoid.
• The dens is part of the cervical vertebrae.
• The body has 7 true pairs of ribs.
• The maxilla acts as the keystone for the face.
• The dens is associated with the vertebral column.
• Xiphoid process is the blunt cartilaginous lower tip of the sternum.
• The floating ribs articulate with the vertebrae.
• Fossa bone markings are defined as a depression in a bone and often receives an articulating bone?

Bone Markings and Skull Composition

• Ramus is a curved bone and is a bone marking.
• Trochanter is a large bump for muscle attachment
• Foramen is a round hole for vessels and nerves.
• The forehead and the anterior part of the calvaria are made up by the frontal bone.
• The parietal bones make up the bulging top side of the cranium.
• The temporal bones make up the lower side of the cranium and part of the floor.
• The mandible forms the only movable joint in the skull with the temporal bone.
• The lacrimal bone is a thin bone shaped like a fingernail, posterior and lateral to each nasal bone.
• The muscles of the eye are not found in the eye orbit.
• The skull makes up a larger part of the body in the fetus, not in the adult.

Appendicular Skeleton Specifics

• The body of the sternum lies between the manubrium and the xiphoid process.
• Thoracic and sacral curvatures are posteriorly convex.
• A newborn's spine forms a continuous convex curve known as the primary curvature.
• Collarbone is the layman's name for the clavicle.
• The trochlea and capitulum are distal portions of the humerus.
• The human hand has greater dexterity due to the freely movable joint of the thumb.
• The ulna articulates proximally with the humerus.
• Metacarpal bones form the framework of the hand.
• The pisiform bone is in the wrist.
• The false pelvis sits above the pelvic inlet.
• The anterior of the pelvic girdle is formed by the pubis.
• A baby passes through the pelvic outlet during childbirth.
• The femur is the longest and heaviest bone in the body.
• The knee would experience discomfort with a fractured patella.
• The knee is where the patella is located.
• Scaphoid is not a tarsal bone.
• The pelvic cavity is narrower in males compared to females.
• From proximal to distal, the bones of the upper extremity are: humerus, radius, carpals, and metacarpals.
• Sequentially, the bones of the lower extremity are: tarsals, metatarsals, femur, and tibia (proximal to distal).

Bone Properties and Variations

• After the age of 50, the density of bone increases slowly.
• Skeletal variations may result from mechanical stress, age, and inadequate calcium/vitamin D supply.