Study Guide: The Axial and Appendicular Skeleton

The Axial Skeleton

Overview

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

• Major Components:

  • Skull (cranial and facial bones)

  • Vertebral column (spine)

  • Thoracic cage (ribs and sternum)

  • Hyoid bone

Skull Bones

The skull is composed of cranial and facial bones, each with distinct features and processes.

• Frontal Bone:

  • Supraorbital foramen

  • Supraorbital margin

• Parietal Bones

• Occipital Bone:

  • Foramen magnum

  • Occipital condyles

• Temporal Bones:

  • Zygomatic process

  • Mandibular fossa

  • Mastoid process

  • External auditory meatus

  • Styloid process

  • Jugular foramen

  • Carotid canal

• Ethmoid Bone:

  • Perpendicular plate

  • Cribriform plate

  • Olfactory foramina

• Sphenoid Bone:

  • Sella turcica

  • Foramina ovale

  • Foramina rotundum

  • Greater and lesser wings

  • Optic canal

• Other Facial Bones:

  • Vomer

  • Nasal

  • Palatine

  • Maxilla (alveoli)

  • Lacrimal

  • Zygomatic (temporal process)

• Mandible:

  • Condylar process

  • Coronoid process

  • Ramus

  • Mental foramen

  • Alveoli

Skull Sutures

Skull sutures are immovable joints connecting the bones of the skull.

• Coronal

• Sagittal

• Squamous

• Lambdoid

Hyoid Bone

The hyoid bone is a U-shaped bone in the neck that supports the tongue and is not directly attached to any other bone.

Vertebrae

The vertebral column consists of individual vertebrae, each with characteristic features.

• Key Features to Identify:

  • Spinous process

  • Vertebral foramen

  • Body

  • Transverse process

  • Articular processes/facets (for attachment)

  • Intervertebral foramen (between vertebrae)

  • Vertebral arch

• Special Vertebrae:

  • Atlas (C1) and Axis (C2): allow head movement

  • Transverse foramen (cervical vertebrae)

  • Thoracic vertebrae: rib attachment facets

  • Know coccyx and sacrum

• Classification:

  • Cervical (neck)

  • Thoracic (chest)

  • Lumbar (lower back)

• Orientation: Distinguish vertebrae by superior (top) and inferior (bottom) sides.

Sternum and Ribs

The thoracic cage protects vital organs and supports respiration.

• Sternum:

  • Manubrium

  • Body

  • Xiphoid process

  • Clavicular notch

  • Jugular/suprasternal notch

• Ribs:

  • True ribs (attach directly to sternum)

  • False ribs (attach indirectly or not at all)

  • Floating ribs (no anterior attachment)

  • Head

  • Tubercle

The Appendicular Skeleton

Overview

The appendicular skeleton includes the bones of the limbs and girdles that attach them to the axial skeleton. It is essential for movement and manipulation of the environment.

Pectoral Girdle

• Clavicle:

  • Sternal end

  • Acromial end

• Scapula:

  • Acromion

  • Coracoid process

  • Glenoid cavity

  • Supraspinous fossa

  • Infraspinous fossa

  • Subscapular fossa

Upper Limb

• Humerus:

  • Head

  • Greater tubercle

  • Lesser tubercle

  • Deltoid tuberosity

  • Olecranon fossa

  • Coronoid fossa

  • Capitulum

  • Medial epicondyle

  • Lateral epicondyle

• Radius:

  • Head

  • Radial tuberosity

  • Styloid process

• Ulna:

  • Trochlear notch

  • Olecranon process

  • Radial notch

  • Coronoid process

  • Styloid process

• Carpals (Wrist Bones):

  • Scaphoid

  • Lunate

  • Triquetrum

  • Pisiform

  • Trapezium

  • Trapezoid

  • Capitate

  • Hamate

• Metacarpals

• Phalanges

Pelvic Girdle

• Hip Bone (Coxal):

  • Ilium

  • Ischium

  • Pubis

  • Iliac crest

  • Anterior superior iliac spine

  • Anterior inferior iliac spine

  • Posterior superior iliac spine

  • Posterior inferior iliac spine

  • Greater and lesser sciatic notches

  • Ischial tuberosity

  • Obturator foramen

  • Acetabulum

Lower Limb

• Femur:

  • Head

  • Neck

  • Greater trochanter

  • Lesser trochanter

  • Lateral and medial condyles

  • Lateral and medial epicondyles

  • Linea aspera

• Patella

• Tibia:

  • Medial condyle

  • Lateral condyle

  • Medial malleolus

• Fibula:

  • Head

  • Lateral malleolus

• Tarsals (Ankle Bones):

  • Calcaneus

  • Talus

  • Navicular

  • Cuboid

  • Intermediate, lateral, and medial cuneiform

• Metatarsals

• Phalanges

Key Definitions and Concepts

• Foramen: An opening or hole in a bone for the passage of nerves and blood vessels.

• Process: A projection or outgrowth of bone for muscle attachment or articulation.

• Condyle: A rounded articular projection.

• Epicondyle: A raised area on or above a condyle.

• Fossa: A shallow depression in a bone.

• Trochanter: Large, blunt, irregularly shaped process (found only on the femur).

• Tuberosity: Large rounded projection; may be roughened.

• Facet: Smooth, nearly flat articular surface.

Table: Comparison of Vertebrae Types

Type	Location	Key Features
Cervical	Neck	Transverse foramen, small body, bifid spinous process (C2-C6)
Thoracic	Chest	Facets for rib articulation, heart-shaped body, long spinous process
Lumbar	Lower back	Large body, short and thick spinous process

Additional info:

• Students should be able to identify bones and features on both articulated (connected) and disarticulated (separate) specimens.

• Right vs. left identification is required for bones marked with an asterisk in the original notes.