Osteology- Introduction to the skeletal system

What is osteology?

The study of bones.

Anatomical position

• standing up

• hands at the sides

• palms facing forward

• feet together

Laying down in anatomical position

• supine (face up)

• prone (face down)

What are the two major divisions of the skeleton?

Axial skeleton and appendicular skeleton.

What is the axial skeleton?

The bones along the axis of the body.

What is the appendicular skeleton?

The bones of the appendages (arms and legs) and the girdles (shoulder and pelvic)

What are articulations?

Contacts with other bones.

What are bone landmarks (bone markings)?

Areas of muscle and ligament attachment.

What are foramina?

Openings in bones for nerves and blood vessels.

What are the functions of the axial skeleton?

• Supports and protects organs in body cavities

• Attaches to muscles of the head, neck, and trunk

• Performs respiratory movements

• Stabilizes parts of the appendicular skeleton.

What structures make up the axial skeleton?

Vertebral column, sacrum, coccyx, thoracic cage, ribs, and sternum.

What are the functions of the vertebral column?

Protects the spinal cord and supports the head and body.

How many vertebrae are in the vertebral column?

26

24 vertebrae + (1) Sacrum + (1) Coccyx

What additional bones are associated with the vertebral column?

The sacrum and coccyx.

What structures form the thoracic cage?

24 ribs and the sternum

What are the five regions of the vertebral column?

(7) Cervical (C), (12) Thoracic (T), (5) Lumbar (L), (1) Sacral (S), and (1) Coccygeal (Co).

What is kyphosis?

An abnormal curvature of the spine.

What is scoliosis?

An abnormal curvature of the spine characterized by lateral deviation.

What are the major components of a typical vertebra?

Vertebral body, vertebral arch, and articular processes.

What is the vertebral body (centrum)?

The weight-bearing portion of a vertebra that transfers weight along the spine.

What is the vertebral arch?

The structure forming the posterior margin of the vertebral foramen.

What are articular processes?

Lateral projections located between the laminae and pedicles of a vertebra.

What structures are seen in a posterior view of articulated vertebrae?

Vertebral body, transverse process, spinous process, lamina of vertebral arch, superior and inferior articular processes, superior articular facets, and intervertebral disc.

What are intervertebral discs?

Pads of fibrocartilage that separate vertebral bodies.

What is the function of intervertebral discs?

Absorb shocks between vertebrae.

What structures are seen in a lateral view of articulated vertebrae?

Vertebral body, intervertebral disc, intervertebral foramen, transverse process, spinous process, lamina of vertebral arch, superior articular facets, inferior articular facet, and vertebral canal.

How many cervical vertebrae are there?

Seven cervical vertebrae (C1-C7).

Which vertebra is called the atlas?

C1

Which vertebra is called the axis?

C2

What is the vertebra prominens?

C7

What are characteristic features of typical cervical vertebrae (C3-C6)?

Pedicle, costal process, transverse process, vertebral body, transverse foramen, superior articular facet, superior articular process, spinous process, vertebral arch, and vertebral foramen.

What is the dens (odontoid process)?

A projection of the axis (C2) that articulates with the atlas (C1).

What structures are associated with the atlas (C1)?

Anterior arch, posterior arch, and transverse ligament

How many thoracic vertebrae are there?

Twelve thoracic vertebrae (T1-T12)

What is unique about thoracic vertebrae?

They articulate with ribs

How does C7 compare with T1?

C7 resembles T1 but lacks facets for rib articulation

How does T12 compare with L1?

T12 resembles L1 but has a facet for rib articulation

How many lumbar vertebrae are there?

Five lumbar vertebrae (L1-L5)

Which structures are found inferior to the lumbar vertebrae?

The sacrum and coccyx

What structures are visible on the posterior sacrum?

Sacral cornu, articular process, entrance to sacral canal, sacral tuberosity, lateral sacral crest, median sacral crest, coccygeal cornu, and sacral hiatus

What structures are visible on the anterior sacrum?

Apex, transverse lines, alae, base, sacral foramina, sacral promontory, and coccyx

What is the thoracic cage?

The skeleton of the chest that supports the thoracic cavity

What bones form the rib cage?

The ribs and sternum

What is another name for the sternum?

Breastbone

How many pairs of ribs are there?

12 pairs

What type of bones are ribs?

Long, curved, flat bones

What are true ribs?

Ribs 1-7

What are false ribs?

Ribs 8-12

What is the pectoral girdle also called?

The shoulder girdle

How does the pectoral girdle connect to the axial skeleton?

Only at the manubrium

What bones make up the pectoral girdle?

Two scapulae and two clavicles

What are scapulae commonly called?

Shoulder blades.

What bones do the scapulae articulate with?

The arm and the clavicle.

What is the subscapular fossa?

A depression on the anterior surface of the scapula.

What are clavicles commonly called?

Collarbones.

Where does the clavicle originate medially?

At the manubrium via the sternal end.

Where does the clavicle articulate laterally?

With the scapula via the acromial end.

What landmark is found on the superior view of the clavicle?

Facet for articulation with the acromion.

What landmarks are found on the inferior view of the clavicle?

Conoid tubercle, costal tuberosity, and sternal facet.

What attaches to the conoid tubercle and costal tuberosity?

Stabilizing ligaments.

What are the three borders of the scapular body?

Superior border, medial (vertebral) border, and lateral (axillary) border.

What are the two processes associated with the glenoid cavity?

Coracoid process and acromion.

What is the coracoid process?

The smaller anterior process of the scapula.

What is the acromion?

The larger posterior process of the scapula.

What joint is formed by the acromion and clavicle?

The acromioclavicular joint.

What structures are visible on the anterior view of the right scapula?

Acromion, coracoid process, superior border, superior angle, lateral angle, subscapular fossa, lateral border, body, inferior angle, and medial border.

What is the medial border of the scapula also called?

The vertebral border.

What is the lateral border of the scapula also called?

The axillary border.

What is the lateral angle of the scapula associated with?

The glenoid cavity.

What is the inferior angle of the scapula?

The lower pointed end of the scapula.

What is the superior angle of the scapula?

The upper medial corner of the scapula.