Muscle actions and movements

what happens during inspiration?

Diaphragm contracts/flattens downward; External Intercostals elevate ribs; Scalenes pull ribs 1–2; SCM assists forceful breathing.

what happens during passive expiration?

Passive recoil of lung tissue and diaphragm relaxation; ribs depress passively to decrease volume.

what happens during forced breathing?

Internal Intercostals depress ribs downward/inward; Abdominals (Rectus, Obliques, Transversus) compress viscera and elevate diaphragm.

which group elevates ribs 1 and 2?

scalenes

what muscles are used in lumbar flexion?

rectus abdominis + internal/external obliques

what muscles are used in lumbar extension?

erector spinae; QL assists

what muscles are used in cervical lateral flexion?

SCM, splenii, erector spinae (not QL)

what muscles are used in cervical rotation?

SCM (opposite), splenii (same), portions of erector spinae

how many vertebrae are in the cervical spine

7

how many vertebrae are in the thoracic spine

12

how many vertebrae are in the lumbar spine?

5