Question

Examine the principal axial muscles of the body and distinguish their origins, insertions, actions, and innervations.​

A) Frontalis - Origin: Frontal bone; Insertion: Skin of eyebrows; Action: Raises eyebrows; Innervation: Facial nerve (VII).

B) Pectoralis Major - Origin: Clavicle, sternum, ribs; Insertion: Humerus; Action: Adducts and medially rotates arm; Innervation: Medial and lateral pectoral nerves.

C) Quadriceps Femoris - Origin: Femur; Insertion: Patella and tibial tuberosity; Action: Extends knee; Innervation: Femoral nerve.

D) Gastrocnemius - Origin: Femur; Insertion: Calcaneus via Achilles tendon; Action: Plantarflexes foot; Innervation: Tibial nerve.

Answer 1

The principal axial muscles of the body include the Frontalis, Pectoralis Major, Quadriceps Femoris, and Gastrocnemius. Each muscle has a specific origin, insertion, action, and innervation. For example, the Frontalis muscle raises the eyebrows and is innervated by the Facial nerve (VII).

Step-by-step explanation:

Axial Muscles of the Body

The principal axial muscles of the body include the Frontalis, Pectoralis Major, Quadriceps Femoris, and Gastrocnemius.

The Frontalis muscle originates from the frontal bone and inserts into the skin of the eyebrows. It raises the eyebrows and is innervated by the Facial nerve (VII).

The Pectoralis Major muscle originates from the clavicle, sternum, and ribs, and inserts into the humerus. It adducts and medially rotates the arm, and is innervated by the Medial and Lateral pectoral nerves.

The Quadriceps Femoris muscle originates from the femur and inserts into the patella and tibial tuberosity. It extends the knee and is innervated by the Femoral nerve.

The Gastrocnemius muscle originates from the femur and inserts into the calcaneus via the Achilles tendon. It plantarflexes the foot and is innervated by the Tibial nerve.