Bones, Bone Markings, and Articulations: Study Guide for ANP College Students

Bones and Bone Tissue

Axial Skeleton

The axial skeleton forms the central axis of the body and consists of the skull, vertebral column, and thoracic cage. It provides support and protection for the brain, spinal cord, and organs in the thorax.

• Cranial Bones (8 bones): Protect the brain and provide attachment sites for head and neck muscles.

  • Frontal (1): Supraorbital foramen, Frontal sinus

  • Parietal (2): Sagittal suture, Coronal suture, Squamous suture

  • Temporal (2): Zygomatic process, External auditory meatus, Styloid process, Mandibular fossa, Mastoid process

  • Occipital (1): Lambdoid suture, Foramen magnum, Occipital condyles

  • Sphenoid (1): Sella turcica, Sphenoid sinus

  • Ethmoid (1): Perpendicular plate, Crista galli, Superior and middle nasal conchae, Cribriform plate, Ethmoid sinuses

• Facial Bones (14 bones): Form the framework of the face, contain cavities for the sense organs, and provide openings for air and food.

  • Maxilla (2): Alveoli, Palatine process, Maxillary sinus, Infraorbital foramen

  • Zygomatic (2): Temporal process

  • Lacrimal (2): Lacrimal fossa

  • Mandible (1): Alveoli, Mandibular ramus, Mandibular condyle, Coronoid process, Mandibular notch, Mental foramen, Mandibular foramen, Mandibular body

• Middle Ear Bones (6 bones): Malleus (hammer), Incus (anvil), Stapes (stirrup) – transmit sound vibrations.

• Hyoid Bone (1 bone): Not attached directly to any other bone; supports the tongue and aids in swallowing.

• Fetal Skull: Contains fontanels (soft spots) such as anterior, posterior, sphenoid (anterolateral), and mastoid (posterolateral) fontanels, which allow for growth and flexibility during birth.

• Vertebral Column (26 bones): Protects the spinal cord and supports the head and body.

  • Cervical (C1–C7): Transverse foramen, Atlas (nod "yes"), Axis (rotate "no"), Odontoid process (dens)

  • Thoracic (T1–T12): Body, Vertebral foramen, Vertebral arch, Transverse process, Spinous process, Pedicle, Lamina, Intervertebral foramen, Vertebral notches, Superior and inferior articular processes

  • Lumbar (L1–L5): Similar markings as thoracic vertebrae

  • Sacrum (1): Median sacral crest, Sacral canal, Sacral hiatus (fusion of five sacral vertebrae)

  • Coccyx (1): Formed by fusion of three to five coccygeal vertebrae

• Ribs (24 bones): Protect thoracic organs; classified as true (vertebrosternal, 7 pairs), false (vertebrochondral, 3 pairs), and floating (2 pairs).

  • Head, Neck, Tubercle, Body

• Sternum (1 bone): Manubrium, Body, Xiphoid process

Appendicular Skeleton

The appendicular skeleton includes the limbs and girdles, facilitating movement and interaction with the environment.

• Shoulder (Pectoral) Girdle (4 bones):

  • Scapula (2): Spine, Acromion, Glenoid cavity, Coracoid process

  • Clavicle (2): Sternal end, Acromial end

• Bones of Upper Limbs (60 bones):

  • Humerus (2): Head, Anatomical neck, Surgical neck, Greater and lesser tubercle, Deltoid tuberosity, Capitulum, Trochlea, Lateral and medial epicondyle, Olecranon fossa, Coronoid fossa

  • Radius (2): Radial head, Radial tuberosity, Styloid process

  • Ulna (2): Trochlear notch, Coronoid process, Olecranon process, Radial notch, Styloid process

  • Carpals (16): Scaphoid, Lunate, Triquetrum, Pisiform, Trapezium, Trapezoid, Capitate, Hamate

  • Metacarpals (10): Numbered 1–5 from thumb to little finger

  • Phalanges (28): Numbered 1–5; fingers have proximal, middle, distal; thumb has proximal, distal

• Pelvic Girdle (2 bones):

  • Coxal (hip) (2): Ilium, Ischium, Pubis, Pubic symphysis, Acetabulum, Greater sciatic notch, Obturator foramen, Male vs. Female pelvis structure

• Bones of Lower Limbs (60 bones):

  • Femur (2): Head, Fovea capitis, Neck, Greater and lesser trochanter, Medial and lateral condyle, Patellar surface, Medial and lateral epicondyle

  • Patella (2): Sesamoid bone in the knee

  • Tibia (2): Medial and lateral condyle, Tibial tuberosity, Medial malleolus

  • Fibula (2): Head, Lateral malleolus

  • Tarsals (14): Talus, Calcaneus, Navicular, Medial, intermediate, lateral cuneiform, Cuboid

  • Metatarsals (10): Numbered 1–5 from great toe to little toe

  • Phalanges (28): Numbered 1–5; toes have proximal, middle, distal; great toe has proximal, distal

Articulations

Types of Joints

Joints, or articulations, are sites where two or more bones meet. They are classified by their structure and function. Diarthroses are freely movable synovial joints, characterized by a joint cavity, articular cartilage, and a capsule.

• Synovial Joint Features:

  • Joint cavity

  • Articular (hyaline) cartilage

  • Articular capsule (outer dense fibrous connective tissue, ligaments)

  • Articular disks (sometimes)

  • Bursae (fluid-filled sacs reducing friction)

• Types of Diarthroses:

  • Ball-and-Socket: Shoulder, hip; allows flexion/extension, abduction/adduction, rotation

  • Hinge: Knee, elbow, ankle, interphalangeal joints; angular motion like a door

  • Planer (Gliding): Intercarpal, intertarsal, sternoclavicular, acromioclavicular joints; flexion/extension, hyperextension; rotation prevented by ligaments

  • Pivot: Atlantoaxial joint; atlas rotates around axis, allows head to turn side to side

  • Condyloid: Wrist, metacarpophalangeal joints (digits 2–5); flexion/extension, abduction/adduction

  • Saddle: Thumb (metacarpal and trapezium); opposition, rotation in all 3 anatomical planes

Knee Joint

The knee is a complex synovial joint, allowing flexion and extension. It is stabilized by ligaments and menisci.

• Parts to Know:

  • Anterior cruciate ligament (ACL)

  • Posterior cruciate ligament (PCL)

  • Medial meniscus

  • Lateral meniscus

  • Tibial collateral ligament

  • Fibular collateral ligament

  • Quadriceps tendon

  • Patellar ligament

  • Transverse ligament

Summary Table: Major Bone Groups and Markings

Bone Group	Number of Bones	Key Markings/Structures
Cranial Bones	8	Supraorbital foramen, sella turcica, foramen magnum, etc.
Facial Bones	14	Alveoli, palatine process, temporal process, etc.
Vertebral Column	26	Atlas, axis, body, spinous process, etc.
Ribs	24	Head, neck, tubercle, body
Sternum	1	Manubrium, body, xiphoid process
Shoulder Girdle	4	Spine, acromion, sternal end, acromial end
Upper Limbs	60	Head, tubercle, epicondyle, fossa, etc.
Pelvic Girdle	2	Ilium, ischium, pubis, acetabulum
Lower Limbs	60	Head, trochanter, condyle, malleolus, etc.

Example: Ball-and-Socket Joint

The shoulder joint is a classic example of a ball-and-socket joint, allowing a wide range of motion including rotation, abduction, and flexion. The head of the humerus fits into the glenoid cavity of the scapula.

Additional info:

• Fontanels in the fetal skull allow for rapid brain growth and passage through the birth canal.

• Male and female pelvises differ in structure to accommodate childbirth in females.

• Ligaments and menisci in the knee joint are critical for stability and movement.