Study Guide: Bones and Bone Markings of the Human Skeleton

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Bones and Bone Markings of the Human Skeleton

Overview of the Human Skeleton

The human skeleton is divided into two main regions: the axial skeleton and the appendicular skeleton. Each region contains specific bones and markings essential for structure, movement, and protection.

Axial Skeleton: Includes the skull, vertebral column, and thoracic cage. Provides support and protection for the brain, spinal cord, and thoracic organs.
Appendicular Skeleton: Comprises the limbs and girdles, facilitating movement and interaction with the environment.

Diagram of axial and appendicular skeleton

Axial Skeleton

Skull

The skull consists of cranial and facial bones, which protect the brain and form the structure of the face.

Cranial Bones: Frontal (unpaired), parietal (paired), sphenoid (unpaired), ethmoid (unpaired), temporal (paired), occipital (unpaired).
Sutures: Immovable joints connecting cranial bones.
Key Markings:
- Cribriform plate (ethmoid): Contains foramina for olfactory nerves.
- Mastoid process (temporal): Attachment for neck muscles.
- Foramen magnum (occipital): Passage for spinal cord.

Cranial bones labeled Cribriform plate and olfactory fibers

Facial Bones

Facial bones form the structure of the face and support sensory organs.

Nasal, lacrimal, zygomatic, inferior nasal conchae, vomer, maxilla, mandible
Key Markings:
- Alveolar processes (maxilla): Hold teeth.
- Condylar process (mandible): Forms the temporomandibular joint (TMJ).

Facial bones labeled

Vertebral Column

The vertebral column supports the body and protects the spinal cord.

Cervical vertebrae (7): C1 (Atlas), C2 (Axis, with dens).
Thoracic vertebrae (12)
Lumbar vertebrae (5): Body, vertebral foramen, intervertebral foramina.
Sacrum: 3-4 fused vertebrae.
Coccyx: Terminal portion.

Vertebral column regions

Thoracic Cage

The thoracic cage protects vital organs and supports respiration.

Ribs (12):
- True ribs (1-7): Directly attached to sternum.
- False ribs (8-12): Indirectly or not attached to sternum.
- Floating ribs (11-12): No anterior attachment.
Sternum: Manubrium, body, xiphoid process; jugular and clavicular notches.
Costal cartilage: Connects ribs to sternum.

Thoracic cage and rib classification

Appendicular Skeleton

Pectoral Girdle and Upper Limb

The pectoral girdle anchors the upper limbs to the axial skeleton.

Clavicle: Acromial and sternal ends.
Scapula: Acromial clavicular joint, glenoid cavity.
Humerus: Head, tubercles, trochlea, capitulum.
Radius: Head, styloid process.
Ulna: Olecranon, styloid process.
Carpals (8), metacarpals, phalanges (proximal, intermediate, distal; pollex lacks intermediate).

Shoulder girdle and clavicle Upper limb bones labeled

Pelvic Girdle and Lower Limb

The pelvic girdle supports the lower limbs and protects pelvic organs.

Coxal bones: Ilium, pubis, ischium; sacroiliac joints, pubic symphysis, pubic brim & arch (male vs. female).
Femur: Head, medial and lateral condyles.
Patella: Kneecap.
Tibia: Medial and lateral condylar surfaces (tibial plateau & meniscus).
Fibula: Lateral bone of the leg.
Tarsals (7): Includes calcaneus (heel bone).
Metatarsals, phalanges (proximal, intermediate, distal; hallux lacks intermediate).

Male vs. female pelvic brim Pelvic girdle and lower limb bones Hip bones: ilium, pubis, ischium

Calcaneus Bone

The calcaneus is the largest tarsal bone and forms the heel.

Function: Supports body weight and provides attachment for the Achilles tendon.
Location: Posterior part of the foot, articulates with the talus and cuboid bones.

Calcaneus bone in the foot

Summary Table: Major Bones of the Human Skeleton

Region	Main Bones	Key Markings/Features
Skull	Frontal, parietal, sphenoid, ethmoid, temporal, occipital, nasal, lacrimal, zygomatic, maxilla, mandible	Sutures, cribriform plate, mastoid process, foramen magnum, alveolar processes, condylar process
Vertebral Column	Cervical (C1, C2), thoracic, lumbar, sacrum, coccyx	Dens, vertebral foramen, intervertebral foramina
Thoracic Cage	Ribs, sternum, costal cartilage	True/false/floating ribs, manubrium, jugular notch
Pectoral Girdle	Clavicle, scapula	Acromial/sterna ends, glenoid cavity
Upper Limb	Humerus, radius, ulna, carpals, metacarpals, phalanges	Tubercles, trochlea, capitulum, olecranon, styloid process
Pelvic Girdle	Ilium, pubis, ischium, sacrum, coccyx	Sacroiliac joint, pubic symphysis, pubic brim/arch
Lower Limb	Femur, patella, tibia, fibula, tarsals, metatarsals, phalanges	Condyles, tibial plateau, meniscus, calcaneus

Additional info:

The pollex (thumb) and hallux (big toe) lack intermediate phalanges.
Male and female pelvic brims differ in shape and subpubic angle, affecting childbirth.