Bones of the Human Skeleton

Bones of the Skull

The human skull is composed of several bones that protect the brain and form the structure of the face. These bones are joined by immovable joints called sutures.

• Frontal: Forms the forehead and the upper part of the eye sockets.

• Parietal: Paired bones forming the sides and roof of the cranium.

• Occipital: Forms the back and base of the skull.

• Temporal: Paired bones located at the sides and base of the skull.

• Maxilla: Upper jaw bone, holds upper teeth.

• Mandible: Lower jaw bone, only movable bone of the skull.

• Zygomatic: Cheekbones.

• Vomer: Forms part of the nasal septum.

• Sphenoid: Forms part of the base of the skull and the sides of the orbits.

• Ethmoid: Located between the eyes, forms part of the nasal cavity.

• Nasal: Small bones forming the bridge of the nose.

• Palatine: Forms part of the hard palate of the mouth.

• Lacrimal: Small bones forming part of the eye socket.

Sutures of the Skull

Sutures are fibrous joints that connect the bones of the skull. They allow for growth during childhood and fuse in adulthood.

• Coronal: Between the frontal and parietal bones.

• Sagittal: Between the two parietal bones.

• Squamous: Between the parietal and temporal bones.

• Lambdoid: Between the parietal and occipital bones.

Bones of the Thorax

The thorax, or chest, contains bones that protect vital organs such as the heart and lungs.

• Sternum: Flat bone at the center of the chest.

• True ribs: First seven pairs, directly attached to the sternum.

• False ribs: Ribs 8-10, attached to the sternum via cartilage.

• Floating ribs: Ribs 11-12, not attached to the sternum.

• Cervical vertebrae (C1 and C2): First two vertebrae of the neck (atlas and axis).

• Thoracic vertebrae: Twelve vertebrae forming the upper and mid-back.

• Lumbar vertebrae: Five vertebrae forming the lower back.

• Sacrum: Triangular bone at the base of the spine.

• Coccyx: Tailbone, small bone at the end of the vertebral column.

• Hyoid: U-shaped bone in the neck, supports the tongue.

Bones of the Upper Limb

The upper limb consists of bones that allow for a wide range of motion and dexterity.

• Scapula: Shoulder blade.

• Clavicle: Collarbone.

• Humerus: Upper arm bone.

• Radius: Lateral bone of the forearm (thumb side).

• Ulna: Medial bone of the forearm (pinky side).

• Carpals: Eight wrist bones.

• Metacarpals (1-5): Five bones forming the palm.

• Phalanges: Finger bones, divided into:

  • Proximal phalanges (1-5): Closest to the palm.

  • Middle phalanges (2-5): Middle segment (thumb does not have a middle phalanx).

  • Distal phalanges (1-5): Farthest from the palm.

Bones of the Lower Limb

The lower limb supports body weight and enables locomotion.

• Coxal (hip bone): Composed of three fused bones:

  • Ilium

  • Ischium

  • Pubis

• Femur: Thigh bone, longest bone in the body.

• Tibia: Shin bone, larger and medial bone of the lower leg.

• Fibula: Smaller, lateral bone of the lower leg.

• Tarsals: Seven ankle bones, including:

  • Calcaneus: Heel bone.

  • Talus: Articulates with tibia and fibula.

• Metatarsals (1-5): Five bones forming the arch of the foot.

• Phalanges: Toe bones, divided into:

  • Proximal phalanges (1-5): Closest to the foot.

  • Middle phalanges (2-5): Middle segment (big toe does not have a middle phalanx).

  • Distal phalanges (1-5): Farthest from the foot.

Example: Classification of Phalanges

Phalanges are classified based on their location in the digits. Each finger and toe (except the thumb and big toe) has three phalanges: proximal, middle, and distal. The thumb and big toe have only proximal and distal phalanges.

Additional info:

• The atlas (C1) and axis (C2) are specialized cervical vertebrae that allow for nodding and rotation of the head.

• The hyoid bone is unique because it does not articulate directly with any other bone.