Head and Neck Muscles Facial muscles Frontalis—raises eyebrows Orbicularis oculi—closes eyes, squints, blinks, winks Orbicularis oris—closes mouth and protrudes the lips Buccinator—flattens the cheek, chews Zygomaticus—raises corners of the mouth

Head and Neck Muscles Chewing muscles Masseter—closes the jaw and elevates mandible Temporalis—synergist of the masseter, closes jaw

Head and Neck Muscles Neck muscles Platysma—pulls the corners of the mouth inferiorly Sternocleidomastoid—flexes the neck, rotates the head

Cranial aponeurosis Frontalis Temporalis Orbicularis oculi Occipitalis Zygomaticus Buccinator Masseter Orbicularis oris Sternocleidomastoid Trapezius Platysma Figure 6.16

Muscles of Trunk, Shoulder, Arm Anterior muscles Pectoralis major—adducts and flexes the humerus Intercostal muscles External intercostals—raise rib cage during inhalation Internal intercostals—depress the rib cage to move air out of the lungs when you exhale forcibly

Clavicle Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachio- radialis (a) Figure 6.17a

Muscles of Trunk, Shoulder, Arm Muscles of the abdominal girdle Rectus abdominis—flexes vertebral column and compresses abdominal contents (defecation, childbirth, forced breathing) External oblique—flex vertebral column; rotate trunk and bend it laterally Internal oblique—flex vertebral column; rotate trunk and bend it laterally Transversus abdominis—compresses abdominal contents

Transversus abdominis Pectoralis major Rectus abdominis Transversus abdominis Internal oblique External oblique Aponeurosis (b) Figure 6.17b

Muscles of Trunk, Shoulder, Arm Posterior muscles Trapezius—elevates, depresses, adducts, and stabilizes the scapula Latissimus dorsi—extends and adducts the humerus Erector spinae—back extension Quadratus lumborum—flexes the spine laterally Deltoid—arm abduction

Muscles of Trunk, Shoulder, Arm Muscles that arise from the shoulder girdle and cross the shoulder joint to insert into the humerus include: Pectoralis major Latissimus dorsi Deltoid

Occipital bone Sternocleidomastoid Spine of scapula Trapezius Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna (deep to tendon) (a) Figure 6.18a

C7 T1 Erector spinae • Iliocostalis • Longissimus • Spinalis Quadratus Iumborum (b) Figure 6.18b

Muscles of the Upper Limb Biceps brachii—supinates forearm, flexes elbow Brachialis—elbow flexion Brachioradialis—weak muscle; elbow flexion Triceps brachii—elbow extension (antagonist to biceps brachii)

Clavicle Deltoid Sternum Pectoralis major Biceps brachii Brachialis Brachio- radialis (a) Figure 6.17a

Occipital bone Sternocleidomastoid Spine of scapula Trapezius Deltoid (cut) Deltoid Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna (deep to tendon) (a) Figure 6.18a

Muscles of the Upper Limb Muscles of the forearm, which insert on the hand bones and cause their movement include: Flexor carpi—wrist flexion Flexor digitorum—finger flexion Extensor carpi—wrist extension Extensor digitorum—finger extension

Muscles of the Lower Limb Muscles causing movement at the hip joint include: Gluteus maximus—hip extension Gluteus medius—hip abduction, steadies pelvis when walking Iliopsoas—hip flexion, keeps the upper body from falling backward when standing erect Adductor muscles—adduct the thighs

Gluteus medius Gluteus maximus Adductor magnus Iliotibial tract Biceps femoris Semitendinosus Hamstring group Semimembranosus Gastrocnemius (a) Figure 6.20a

Posterior superior iliac spine IIiac crest Safe area in gluteus medius Gluteus maximus Sciatic nerve (b) Figure 6.20b

12th thoracic vertebra 12th rib Iliac crest Psoas major lliopsoas lliacus 5th lumbar vertebra Anterior superior iliac spine Sartorius Adductor group Rectus femoris Vastus lateralis Quadriceps Vastus medialis Patella Patellar ligament (c) Figure 6.20c

Muscles of the Lower Limb Muscles causing movement at the knee joint Hamstring group—thigh extension and knee flexion Biceps femoris Semimembranosus Semitendinosus

Gluteus medius Gluteus maximus Adductor magnus Iliotibial tract Biceps femoris Semitendinosus Hamstring group Semimembranosus Gastrocnemius (a) Figure 6.20a

Muscles of the Lower Limb Muscles causing movement at the knee joint Sartorius—flexes the thigh Quadriceps group—extends the knee Rectus femoris Vastus muscles (three)

12th thoracic vertebra 12th rib Iliac crest Psoas major lliopsoas lliacus 5th lumbar vertebra Anterior superior iliac spine Sartorius Adductor group Rectus femoris Vastus lateralis Quadriceps Vastus medialis Patella Patellar ligament (c) Figure 6.20c

Inguinal ligament Adductor muscles Sartorius Vastus lateralis (d) Figure 6.20d

Muscles of the Lower Limb Muscles causing movement at ankle and foot Tibialis anterior—dorsiflexion, foot inversion Extensor digitorum longus—toe extension and dorsiflexion of the foot Fibularis muscles—plantar flexion, foot eversion Soleus—plantar flexion

Fibularis longus Tibia Fibularis brevis Soleus Tibialis anterior Extensor digitorum longus Fibularis tertius (a) Figure 6.21a

Gastrocnemius Soleus Calcaneal (Achilles) tendon Medial malleolus Lateral malleolus (b) Figure 6.21b

Figure 6.22 Facial • Frontalis Facial • Orbicularis oculi • Temporalis • Zygomaticus • Masseter • Orbicularis oris Neck Shoulder • Platysma • Trapezius • Sternocleidomastoid Thorax • Deltoid • Pectoralis minor • Pectoralis major Arm • Serratus anterior • Triceps brachii • Biceps brachii • Intercostals • Brachialis Abdomen • Rectus abdominis Forearm • External oblique • Brachioradialis • Internal oblique • Flexor carpi radialis • Transversus abdominis Pelvis/thigh • lliopsoas Thigh • Sartorius • Adductor muscle Thigh (Quadriceps) • Rectus femoris • Gracilis • Vastus lateralis • Vastus medialis Leg • Fibularis longus • Extensor digitorum longus Leg • Gastrocnemius • Tibialis anterior • Soleus Figure 6.22

Figure 6.23 Neck • Occipitalis • Sternocleidomastoid • Trapezius Shoulder/Back • Deltoid Arm • Triceps brachii • Brachialis • Latissimus dorsi Forearm • Brachioradialis • Extensor carpi radialis longus • Flexor carpi ulnaris • Extensor carpi ulnaris Hip • Extensor digitorum • Gluteus medius • Gluteus maximus Thigh lliotibial tract • Adductor muscle • Hamstrings: Biceps femoris Semitendinosus Semimembranosus Leg • Gastrocnemius • Soleus • Fibularis longus Calcaneal (Achilles) tendon Figure 6.23

Deltoid muscle Humerus Figure 6.19

Posterior superior iliac spine IIiac crest Safe area in gluteus medius Gluteus maximus Sciatic nerve (b) Figure 6.20b

Inguinal ligament Adductor muscles Sartorius Vastus lateralis (d) Figure 6.20d