Overview
This lecture explains the human locomotor system, covering the structure and function of bones, muscles, and joints, and how they enable movement.
The Human Locomotor System
- The locomotor system enables body movement, such as walking, writing, or jumping.
- Bones form the skeleton and serve as passive support for movement.
- Muscles attach to bones and actively produce movement.
Structure of the Human Skeleton
- The skeleton consists of the skull, body, and limbs.
- The skull is composed of cranial and facial bones, protecting the brain and shaping the face.
- The body skeleton includes the shoulder girdle, spine, ribs, sternum, and pelvis.
- The spine supports the head and body posture.
- The sternum and ribs protect the heart and lungs and aid breathing.
- The pelvis is made of fused iliac, pubic, and sit bones, supporting body weight and protecting pelvic organs.
- Limbs include bones of the hands (upper arm, lever and cubit, wrist, palm, fingers) and legs (femur, kneecap, shin, calf, ankle, sole, toes).
Types of Muscles
- There are three muscle types: smooth, cardiac, and skeletal.
- Smooth muscle (involuntary) is found in respiratory and digestive organs.
- Cardiac muscle (involuntary) is found only in the heart.
- Skeletal muscle (voluntary) attaches to bones and moves the skeleton.
- Skeletal muscles contract to move bones and relax when not active.
- Some muscles work antagonistically (e.g., biceps/triceps) or synergistically (e.g., pronator muscle).
Joints and Movement
- Joints connect bones and enable movement.
- Hinge joints (e.g., knee, elbow) allow movement in one direction.
- Saddle joints (e.g., thumb) allow movement in two directions.
- Swivel joints (e.g., neck, forearm) enable rotation.
- Ball joints (e.g., shoulder, hip) allow movement in all directions.
Bone and Joint Care
- Good posture prevents skeletal deformities.
- Bones can fracture from strong impact.
- Maintain healthy bones and muscles through proper posture, regular exercise, and nutrition with calcium and vitamin D.
Key Terms & Definitions
- Locomotor system â body system enabling movement
- Skeleton â body framework made of bones
- Muscle â tissue that contracts to move bones
- Joint â structure connecting bones and allowing movement
- Antagonistic muscles â muscles that perform opposite actions (e.g., biceps/triceps)
- Synergistic muscles â muscles that work together for the same movement
Action Items / Next Steps
- Reflect: Which bone is the largest and which is the smallest in the human body?
- Maintain good posture, exercise regularly, and consume calcium and vitamin D for bone health.