GROSS ANATOMY OF THE MUSCULAR SYSTEM Figure 6.21 Figure 6.22

Naming Skeletal Muscles (I) 1. By location of muscle Ex: Temporalis (temporal bone), Oris (mouth) 2. By number of origins Ex: Triceps (three heads) 3. By direction of muscle fibers Ex: Rectus (straight) 4. By relative size of muscle Ex: Maximus (largest)

Naming Skeletal Muscles (II) 5. By location of muscle’s origin & insertion Ex: Sterno (on sternum), Cleido (clavicle) 6. By shape of muscle Ex: Deltoid (triangular), Trapezius (diamond) 7. By action of muscle Ex: Flexor & extensor (flexes or extends bone)

I. Head & Neck Muscles Figure 6.15

A. Facial Muscles Frontalis—raises eyebrows Orbicularis oculi—closes eyes, squints, blinks, winks Orbicularis oris—closes mouth & protrudes lips Buccinator—flattens cheek, chews Zygomaticus—raises corners of the mouth

B. Chewing Muscles Masseter—closes jaw & elevates mandible Temporalis—closes jaw

C. Neck Muscles Platysma—pulls corners of mouth inferiorly Sternocleidomastoid—flexes neck, rotates head

Know these! Table 6.3 (1 of 3)

II. Muscles of Trunk, Shoulder, Arm Figure 6.16a

A. Chest Muscles Pectoralis major—adducts & flexes humerus

B. Abdominal Muscles Rectus abdominis—flexes vertebral column External & internal obliques—flex vertebral column; rotate trunk and bend it laterally Transversus abdominis—compresses abdomen

Table 6.3 (2 of 3)

C. Shoulder & Back Muscles Trapezius—elevates, depresses, & adducts scapula Latissimus dorsi—extends & adducts humerus Deltoid—arm abduction Figure 6.17a

Table 6.4 (1 of 3)

D. Arm Muscles Biceps brachii—supinates forearm, flexes elbow Brachialis—elbow flexion Triceps brachii—elbow extension Figure 6.17a

Table 6.4 (2 of 3)

III. Muscles of Lower Limb

A. Muscles of the Pelvis (Hips) Gluteus maximus—hip extension Gluteus medius—hip abduction, steadies pelvis in walking Iliopsoas—hip flexion, keeps the upper body from falling backward when standing erect

B. Muscles of the Thigh (Anterior) Sartorius—flexes the thigh; “Tailor’s Muscle” Quadriceps group—extends the knee Rectus femoris Vastus muscles – medialis, intermedius, lateralis

Table 6.3 (3 of 3)

C. Muscles of the Thigh (Posterior) Hamstring group—thigh extension & knee flexion Biceps femoris Semimembranosus Semitendinosus

D. Muscles of the Lower Leg Tibialis anterior—dorsiflexion of foot Gastrocnemius & Soleus—plantar flexion Figure 6.20a Figure 6.20b

Table 6.4 (3 of 3)

Intramuscular Injection Sites Figure 6.18, 6.19b, d