Body and Light Elements

Across

1. Inner lining of digestive tract

4. Colorful arc after a rainstorm

5. Bright light on a clear day

6. Central open area in a building

10. Courage needed to face a challenge

11. Middle part of the torso

12. Muscle that bends a joint

13. Unit measuring light output

Down

2. Face or facial expression seen clearly

3. Transparent front part of the eye

7. Upper leg section below the hip

8. Morning light appearing over the horizon

9. Back of the neck or untidy appearance