Overview of the Skeletal System

Overview of the Skeletal System

• The skeleton provides structure and allows for upright posture and mobility.
• Key functions include protection of vital organs and hematopoiesis (blood production).

Division of the Skeleton

• Divided into two main sections:
  • Axial Skeleton
  • Appendicular Skeleton

Axial Skeleton

• Comprises the main trunk of the body:
  • Skull (made of eight bones)
  • Spinal Column (26 vertebrae, protected by intervertebral discs)
  • Ribs (24 total: 12 pairs; 7 true ribs, 5 false ribs, 2 floating ribs)
• Ribs serve to protect the heart, major blood vessels, and lungs.

Vertebral Column

• Function: Protects the spinal cord and serves as a shock absorber.

Appendicular Skeleton

• Forms the extremities of the body:
  • Shoulder girdle
  • Arm bones
  • Pelvic girdle
  • Leg bones

Shoulder Girdle

• Comprised of four bones:
  • Two clavicles (collar bones)
  • Two scapulas (shoulder blades)

Arm Structure

• Upper arm: humerus (long bone).
• Lower arm: radius and ulna.
• Wrist: composed of eight carpals.
• Hand: consists of five metacarpals (palm) and 14 phalanges (fingers and thumbs).

Pelvic Girdle

• Attaches leg bones; made of two os coxae (hip bones).
• Each hip bone consists of three sections: ilium, ischium, pubis.

Leg Structure

• Each leg contains:
  • Femur (thigh bone, long bone)
  • Patella (kneecap)
  • Tibia (shin bone)
  • Fibula (runs parallel to tibia)
• Ankle: composed of seven tarsals.
• Foot: includes five metatarsals and 14 phalanges (toes) along with the calcaneus (heel).

Characteristics of Long Bones

• Hard, dense, and provide strength and mobility.
• Structurally include:
  • Diaphysis (shaft)
  • Proximal and distal epiphysis (ends)
  • Medullary canal (filled with yellow marrow)
  • Endosteum (membrane lining the canal)
  • Periosteum (outer tough membrane covering the bone)

Joint Classification

• Joints categorized by mobility:
  • Diarthrosis (freely movable, e.g., shoulder)
  • Amphiarthrosis (slightly movable, e.g., vertebrae)
  • Synarthrosis (immovable, e.g., sutures of the cranium)
• Ligaments and cartilage provide support for the joints.

Overview of the Skeletal System

• The skeleton supports bodily structure, maintaining upright posture and enabling movement.
• Essential functions include protecting vital organs and facilitating hematopoiesis, the process of blood cell production.

Division of the Skeleton

• The skeleton is categorized into two sections:
  • Axial Skeleton: central framework of the body.
  • Appendicular Skeleton: includes limbs and their attachments.

Axial Skeleton

• Composed of the main body trunk, featuring:
  • Skull: consists of eight bones.
  • Spinal Column: contains 26 vertebrae with intervertebral discs for protection and shock absorption.
  • Ribs: a total of 24, arranged as 12 pairs; includes 7 true ribs, 5 false ribs, and 2 floating ribs, protecting organs like the heart and lungs.

Vertebral Column

• Protects the spinal cord, acts as a shock absorber during movement.

Appendicular Skeleton

• Forms and supports the body's extremities, comprising:
  • Shoulder girdle: connects the arms.
  • Arm bones: including the humerus, radius, and ulna.
  • Pelvic girdle: connects the legs.
  • Leg bones: including femur, patella, tibia, and fibula.

Shoulder Girdle

• Made up of four bones:
  • Two clavicles (collar bones) support shoulder stability.
  • Two scapulas (shoulder blades) allow arm movement.

Arm Structure

• Upper arm features the humerus, a long bone.
• The lower arm consists of radius and ulna.
• Wrist bones number eight carpals.
• Hand structure includes five metacarpals (form the palm) and 14 phalanges (fingers and thumbs).

Pelvic Girdle

• Connects the leg bones; formed by two os coxae (hip bones).
• Each hip bone is structured in three parts: ilium, ischium, and pubis.

Leg Structure

• Each leg contains:
  • Femur: the longest bone, known as the thigh bone.
  • Patella: the kneecap.
  • Tibia: the shin bone; larger and weight-bearing.
  • Fibula: parallels the tibia, providing stability.
• Ankle composed of seven tarsal bones.
• Foot includes five metatarsals and 14 phalanges (toes), as well as the calcaneus (heel).

Characteristics of Long Bones

• Long bones are hard, dense, and provide strength and mobility.
• Structure includes:
  • Diaphysis: the long shaft.
  • Proximal and distal epiphysis: ends of the bone.
  • Medullary canal: filled with yellow marrow for fat storage.
  • Endosteum: a membrane lining the medullary canal.
  • Periosteum: a tough outer membrane covering the bone.

Joint Classification

• Joints are categorized based on mobility:
  • Diarthrosis: freely movable joints (e.g., shoulder).
  • Amphiarthrosis: slightly movable joints (e.g., between vertebrae).
  • Synarthrosis: immovable joints (e.g., skull sutures).
• Ligaments and cartilage provide structural support and stability to joints.

This quiz covers the essential functions and divisions of the skeletal system, including the axial and appendicular skeletons. You'll learn about the structure of the skull, spinal column, and ribs, as well as the shoulder girdle and arm bones. Test your knowledge on how these components contribute to mobility and protection of vital organs.