Human Skeletal Classification

Human Skeletal Classification will be covered in this blog. The human skeleton is the internal framework of the human body, composed of around 206 bones in adulthood. It can be divided into the axial skeleton and the appendicular skeleton. Human Skeleton Classification include: regional, developmental and morphological. The human skeleton performs several functions. Additionally, the skeleton is not as sexually dimorphic as that of many other primate species, but subtle differences between sexes in the morphology of the skull, dentition, long bones, and pelvis are exhibited across human populations

Classification of human skeleton

Human Skeleton are classified as:

1. REGIONAL CLASSIFICATION
2. DEVELOPMENTAL CLASSIFICATION
3. MORPHOLOGICAL CLASSIFICATION

REGIONAL CLASSIFICATION

i. Axial skeleton

The axial skeleton, which consists of 80 bones including the skull, vertebral column, and thoracic cage, forms the central core of the human body. Its functions include support, protection, and also providing a surface for muscle attachment. 

Skull consists of 29 bones comprising of Cranium, Face, Auditary ossicles and Hyoid bone:

1. Cranium and face included 22 bones, involving

CRANIUM BONES:

• Two (2) Parietal bone
• Two(2) Temporal bones
• One (1) Frontal bone
• One (1) Occipital bone
• One (1) Ethmoid bone
• One (1) Sphenoid bone
  • FACE BONES:
• Two (2) Maxilla
• Two (2) Zygomatic
• One (1) Mandible
• Two (2) Nasal bones
• Two (2) Palatine bones
• Two (2) Inferior Nasal Choncha
• Two (2) Lacrimal bones
• One (1) Vomer

2. Auditory Ossicles consists of 6 (six) bones, 3 in each ear.

ii. Appendicular skeleton

The appendicular skeleton is composed of the bones of the upper and lower limbs, along with the pectoral (shoulder) girdle and the pelvic (hip) girdle. It consists of 126 bones. The primary functions of the appendicular skeleton are to facilitate movement and provide shape to the arms and legs. The upper limbs are comprised of the arms and the pectoral girdle, which attaches the arms to the rib cage, while, The lower limbs consist of the legs and the pelvic girdle, which not only protects the organs of the reproductive and urinary systems but also provides a surface for muscle attachment.

DEVELOPMENTAL SKELETAL CLASSIFICATION

Membranous, cartilaginous, and membranous-cartilaginous bones are the three kinds of bones that form throughout the process of bone growth.

1. Membranous Bones: Membranous ossification involves the direct conversion of mesenchymal tissue to bone. It forms flat bones, such as certain bones of the skull and some irregular bones. Osteoblasts migrate to the connective tissue membranes and deposit bony matrix around themselves, then forming membranous bones.
2. Cartilaginous Bones: Cartilaginous ossification, involves the replacement of hyaline cartilage with bone. It begins when mesenchymal cells differentiate into chondrocytes, which form a cartilage bone model.
3. Membranous-Cartilaginous Bones: Some bones, such as those in the vertebral column, pelvis, and limbs, are first formed as cartilage and later become bone.

MORPHOLOGICAL SKELETAL CLASSIFICATION

The human skeleton can be morphologically classified into five categories based on their shapes: long bones, short bones, flat bones, irregular bones, and sesamoid bones in addition to pneumatic bones and supernummary bones.