Overview of Major Bones and Bone Features

This study guide summarizes the principal bones of the human skeleton and highlights their most important anatomical features. Understanding these structures is essential for students of Anatomy & Physiology, particularly in the study of the skeletal system (Ch. 7) and bones and bone tissue (Ch. 6).

Cranial and Facial Bones

• Frontal Bone: Forms the forehead and the superior part of the eye sockets (orbits).

• Parietal Bones: Paired bones forming the superior and lateral aspects of the skull.

• Temporal Bones: Located on the sides of the skull; notable feature: zygomatic arch (formed with the zygomatic bone).

• Occipital Bone: Forms the posterior and base of the skull; features include the external occipital protuberance and foramen magnum (large opening for the spinal cord).

• Sphenoid Bone: Central bone of the skull base; key feature: sella turcica (houses the pituitary gland).

• Ethmoid Bone: Located between the eyes; notable for the cribriform plate (contains olfactory foramina).

• Nasal Bones: Form the bridge of the nose.

• Lacrimal Bones: Small bones forming part of the medial wall of each orbit.

• Palatine Bones: Form the posterior part of the hard palate.

• Maxilla: Upper jaw; features the alveolar process (holds upper teeth) and palatine process (anterior hard palate).

• Zygomatic Bones: Cheekbones; contribute to the zygomatic arch.

• Mandible: Lower jaw; features include the alveolar process (holds lower teeth), condylar process (articulates with temporal bone), and coronoid process (muscle attachment).

• Orbit: The bony socket housing the eye, formed by several bones.

• Hyoid Bone: U-shaped bone in the neck, not directly articulated with other bones; supports the tongue.

Vertebral Column

• Vertebrae: 33 bones divided into regions:

  • Cervical (7): Neck region; includes atlas (C1) and axis (C2).

  • Thoracic (12): Upper back; articulate with ribs.

  • Lumbar (5): Lower back; largest vertebrae.

  • Sacral (5, fused): Form the sacrum.

  • Coccyx (4, fused): Tailbone.

• Key Features: Body (weight-bearing), spinous process (posterior projection), transverse process (lateral projections), vertebral foramen (spinal cord passage), vertebral prominens (C7), atlas (no body, supports skull), axis (dens/odontoid process).

Thoracic Cage

• Sternum: Breastbone; consists of manubrium (superior), body (middle), and xiphoid process (inferior tip). Sternal angle and sternal notch are important landmarks.

• Ribs: 12 pairs; features include costal cartilage (connects ribs to sternum). True ribs (1-7) attach directly to sternum; false ribs (8-12) do not.

Pectoral Girdle and Upper Limb

• Clavicle: Collarbone; acromial end (lateral, articulates with scapula), sternal end (medial, articulates with sternum).

• Scapula: Shoulder blade; features include spine, acromion, coracoid process, glenoid fossa (articulates with humerus), and fossae (supraspinous, infraspinous, subscapular).

• Humerus: Upper arm bone; features: head (articulates with scapula), greater tubercle, lateral/medial epicondyles, olecranon fossa, trochlea, capitulum.

• Radius: Lateral forearm bone; head (proximal), radial tuberosity, styloid process.

• Ulna: Medial forearm bone; olecranon process (elbow), coronoid process, trochlear notch, styloid process.

• Carpals: 8 wrist bones (as a group).

• Metacarpals: 5 hand bones, numbered I-V from thumb to little finger.

• Phalanges: Finger bones; each finger has proximal, middle, and distal phalanges (thumb lacks middle).

Pelvic Girdle and Lower Limb

• Hip (Coxal) Bone: Composed of ilium (with iliac crest), ischium (with ischial tuberosity), and pubis. Features include acetabulum (hip socket), greater sciatic notch, and pubic symphysis (cartilaginous joint).

• Femur: Thigh bone; features: head (articulates with acetabulum), neck, greater trochanter, medial/lateral condyles, medial/lateral epicondyles.

• Patella: Kneecap; sesamoid bone in the quadriceps tendon.

• Tibia: Medial lower leg bone; medial malleolus (ankle), tibial tuberosity, medial/lateral condyles.

• Fibula: Lateral lower leg bone; head (proximal), lateral malleolus (ankle).

• Tarsals: 7 ankle bones (as a group); key bones: calcaneus (heel), talus (articulates with tibia).

• Metatarsals: 5 foot bones, numbered I-V from big toe to little toe.

• Phalanges: Toe bones; similar structure to fingers.

Selected Bone Features and Processes

Many bones have specific features important for articulation, muscle attachment, or passage of nerves and blood vessels. Below is a summary of key features:

Classification of Bones by Region

• Axial Skeleton: Skull, vertebral column, thoracic cage, hyoid bone.

• Appendicular Skeleton: Pectoral girdle, upper limbs, pelvic girdle, lower limbs.

Examples and Applications

• Clinical Example: The foramen magnum is a critical landmark in neurosurgery and trauma assessment, as it is the passage for the brainstem and spinal cord.

• Functional Example: The glenoid fossa of the scapula forms the socket of the shoulder joint, allowing for a wide range of arm movement.

Additional info:

• Some features (e.g., "by number") refer to the convention of numbering metacarpals and metatarsals from the thumb/big toe (I) to the little finger/toe (V).

• "True" vs. "false" ribs: True ribs attach directly to the sternum via their own costal cartilage; false ribs either attach indirectly or not at all.

• "Fossa" refers to a depression or hollow in a bone, often for articulation or muscle attachment.