Comprehensive Study Guide: Bones and Bone Markings of the Human Skeleton

Bones and Bone Markings of the Human Skeleton

Overview

The human skeleton is divided into two main regions: the axial skeleton and the appendicular skeleton. Each region contains specific bones and bone markings that are essential for identification and understanding of anatomical structure and function. This guide provides detailed descriptions and key facts for each bone and bone marking listed, organized by region and subregion.

Axial Skeleton

Skull

The skull protects the brain and supports facial structures. It consists of cranial and facial bones, each with distinct markings.

• Alveolar processes: Ridges on the maxilla and mandible that contain the teeth.

• Ethmoid: A delicate bone forming part of the nasal cavity and the medial wall of the orbit.

• Foramen magnum: Large opening in the occipital bone for the spinal cord.

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

• Glabella: Smooth area between the eyebrows, above the nose.

• Hyoid: U-shaped bone in the neck, not directly attached to other bones; supports the tongue.

• Infraorbital foramen: Opening below the orbit for nerves and blood vessels.

• Lacrimal: Small bone forming part of the medial wall of the orbit.

• Mandible: Lower jawbone; only movable bone of the skull.

• Mastoid process: Rounded projection on the temporal bone, behind the ear.

• Maxilla: Upper jawbone; forms part of the orbit, nose, and mouth.

• Mental foramen: Opening on the anterior surface of the mandible for nerves and vessels.

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

• Occipital: Forms the posterior part of the skull and base.

• Occipital condyle: Articulates with the atlas (C1) vertebra.

• Palatine: Forms part of the hard palate and nasal cavity.

• Parietal: Forms the sides and roof of the cranium.

• Sphenoid: Butterfly-shaped bone at the base of the skull.

• Supraorbital foramen: Opening above the orbit for nerves and vessels.

• Temporal: Forms part of the sides and base of the skull.

• Vomer: Forms part of the nasal septum.

• Zygomatic bone: Cheekbone; forms part of the orbit.

• Zygomatic process: Projection of the temporal bone that forms part of the zygomatic arch.

Vertebral Column

The vertebral column supports the body and protects the spinal cord. It is divided into regions with unique vertebrae.

• Atlas (C1): First cervical vertebra; supports the skull.

• Axis (C2): Second cervical vertebra; has the dens for rotation of the head.

• Cervical vertebra: Seven vertebrae (C1–C7); small, with transverse foramina.

• Thoracic vertebra: Twelve vertebrae (T1–T12); articulate with ribs, have heart-shaped bodies.

• Lumbar vertebra: Five vertebrae (L1–L5); large, kidney-shaped bodies.

• Sacrum: Five fused vertebrae; forms the posterior wall of the pelvis.

• Coccyx: Four fused vertebrae; forms the tailbone.

• Vertebra: General features include:

  • Body: Main weight-bearing portion.

  • Lamina: Part of the vertebral arch.

  • Spinous process: Posterior projection for muscle attachment.

  • Transverse process: Lateral projections for muscle and ligament attachment.

  • Vertebral foramen: Opening for the spinal cord.

Thoracic Cage

The thoracic cage protects vital organs and supports the upper body.

• Ribs: 12 pairs; classified as:

  • True ribs (1–7): Directly attached to the sternum.

  • False ribs (8–12): Indirectly attached or not attached to the sternum.

• Sternum: Flat bone in the center of the chest; consists of:

  • Clavicular notch: Articulation point for the clavicle.

  • Jugular notch: Central indentation at the superior border.

  • Manubrium: Upper portion.

  • Body: Central portion.

  • Xiphoid process: Inferior, small cartilaginous extension.

Appendicular Skeleton

Upper Limb

The upper limb includes the shoulder girdle, arm, forearm, and hand. Each bone has specific markings for muscle attachment and articulation.

Scapula (Shoulder Blade)

• Acromion: Lateral projection; articulates with the clavicle.

• Coracoid process: Anterior projection for muscle attachment.

• Glenoid cavity: Articulates with the head of the humerus.

• Inferior angle: Lowest point of the scapula.

• Infraspinous fossa: Depression below the spine.

• Lateral border: Edge closest to the arm.

• Medial border: Edge closest to the vertebral column.

• Spine: Prominent ridge on the posterior surface.

• Superior angle: Uppermost point.

• Superior border: Upper edge.

• Supraspinous fossa: Depression above the spine.

Humerus (Upper Arm Bone)

• Capitulum: Lateral condyle; articulates with the radius.

• Coronoid fossa: Depression for the ulna during flexion.

• Deltoid tuberosity: Rough area for deltoid muscle attachment.

• Greater tubercle: Lateral prominence for muscle attachment.

• Head: Articulates with the glenoid cavity.

• Lateral epicondyle: Lateral projection for muscle attachment.

• Lesser tubercle: Anterior prominence for muscle attachment.

• Medial epicondyle: Medial projection for muscle attachment.

• Neck: Narrow region below the head.

• Olecranon fossa: Posterior depression for the ulna.

• Trochlea: Medial condyle; articulates with the ulna.

Lower Arm

• Radius: Lateral bone of the forearm.

  • Head of the radius: Disc-shaped; articulates with the capitulum.

  • Neck of the radius: Narrow region below the head.

  • Radial styloid process: Lateral projection at the distal end.

  • Radial tuberosity: Rough area for muscle attachment.

  • Ulnar notch of the radius: Articulates with the ulna.

• Ulna: Medial bone of the forearm.

  • Coronoid process: Anterior projection for articulation with the humerus.

  • Head of the ulna: Distal end; articulates with the radius.

  • Olecranon: Posterior projection; forms the elbow.

  • Radial notch of the ulna: Articulates with the radius.

  • Trochlear notch: Articulates with the trochlea of the humerus.

  • Ulnar styloid process: Medial projection at the distal end.

Hand and Wrist

• Carpal bones: Eight bones forming the wrist:

  • Scaphoid

  • Lunate

  • Triquetrum

  • Pisiform

  • Trapezium

  • Trapezoid

  • Capitate

  • Hamate

• Metacarpals: Five bones forming the palm.

• Phalanges: Proximal, middle, and distal bones of the fingers.

Lower Limb

The lower limb includes the pelvic girdle, thigh, leg, and foot. These bones support body weight and enable movement.

Pelvis

• Acetabulum: Socket for the head of the femur.

• Anterior inferior iliac spine: Projection on the ilium.

• Anterior superior iliac spine: Upper projection on the ilium.

• Greater sciatic notch: Large notch for the sciatic nerve.

• Iliac crest: Superior border of the ilium.

• Inferior pubic ramus: Lower branch of the pubis.

• Ischial ramus: Branch of the ischium.

• Ischial spine: Pointed projection on the ischium.

• Ischial tuberosity: Rough area for muscle attachment.

• Obturator foramen: Large opening for nerves and vessels.

• Posterior inferior iliac spine: Lower projection on the posterior ilium.

• Posterior superior iliac spine: Upper projection on the posterior ilium.

• Superior pubic ramus: Upper branch of the pubis.

Femur (Thigh Bone)

• Fovea capitis: Small pit on the head for ligament attachment.

• Greater trochanter: Large lateral projection for muscle attachment.

• Head: Articulates with the acetabulum.

• Lateral condyle: Lateral distal projection for articulation with the tibia.

• Lateral epicondyle: Lateral projection above the condyle.

• Lesser trochanter: Medial projection for muscle attachment.

• Medial condyle: Medial distal projection for articulation with the tibia.

• Medial epicondyle: Medial projection above the condyle.

• Femoral neck: Narrow region below the head.

• Patellar surface: Anterior area for articulation with the patella.

Lower Leg

• Tibia: Medial bone of the leg.

  • Intercondylar eminence: Raised area between the condyles.

  • Lateral condyle: Lateral proximal projection.

  • Medial condyle: Medial proximal projection.

  • Medial malleolus: Medial distal projection; forms the ankle.

  • Shaft of the tibia: Main body.

  • Tibial tuberosity: Rough area for muscle attachment.

• Fibula: Lateral bone of the leg.

  • Head of the fibula: Proximal end.

  • Lateral malleolus: Lateral distal projection; forms the ankle.

  • Shaft of the fibula: Main body.

Foot

• Tarsal bones: Seven bones forming the ankle:

  • Calcaneus: Heel bone.

  • Talus: Articulates with the tibia and fibula.

  • Navicular

  • Cuboid

  • Medial, intermediate, and lateral cuneiforms

• Metatarsals: Five bones forming the foot.

• Phalanges: Proximal, middle, and distal bones of the toes.

Example: Identifying Right vs. Left Bones

• Many bones (scapula, humerus, radius, ulna, pelvis, femur, tibia, fibula, hand, and foot) have distinguishing features that allow identification of right versus left. For example, the glenoid cavity of the scapula faces laterally, and the medial malleolus of the tibia is always on the medial side of the leg.

Additional info:

• Bone markings are important for muscle attachment, articulation, and passage of nerves and blood vessels.

• Understanding the location and function of each bone and marking is essential for anatomical orientation and clinical application.