11 Muscles of the Body

Superficial Muscles of the Body—Anterior View Trapezius Shoulder Deltoid Arm Triceps brachii Biceps brachii Brachialis Forearm Pronator teres Brachioradialis Flexor carpi radialis Palmaris longus Pelvis/thigh Iliopsoas Pectineus Thigh Rectus femoris Vastus lateralis Vastus medialis Leg Fibularis longus Extensor digitorum longus Tibialis anterior Head Facial Temporalis Epicranius, frontal belly Orbicularis oculi Zygomaticus Orbicularis oris Neck Sternohyoid Sternocleidomastoid Thorax Pectoralis major Pectoralis minor Serratus anterior Intercostals Abdomen External oblique Rectus abdominis Internal oblique Transversus abdominis Sartorius Tensor fasciae latae Adductor longus Gracilis Gastrocnemius Soleus Masseter Platysma (a) Figure 11.8a

Superficial Muscles of the Body—Posterior View Neck Epicranius, occipital belly Arm Sternocleidomastoid Triceps brachii Trapezius Brachialis Shoulder Deltoid Forearm Infraspinatus Brachioradialis Teres major Extensor carpi radialis longus Rhomboid major Triangle of auscultation Flexor carpi ulnaris Latissimus dorsi Extensor carpi ulnaris Hip Extensor digitorum Gluteus medius Gluteus maximus Iliotibial tract Thigh Adductor magnus Gracilis Hamstrings: Biceps femoris Leg Semitendinosus Gastrocnemius Semimembranosus Soleus Fibularis longus Calcaneal (Achilles) tendon (b) Figure 11.8b

Muscles of the Neck and Vertebral Column Mastoid process Splenius capitis Spinous processes of the vertebrae Splenius cervicis (b) Posterior Figure 11.12b

Muscles of the Neck and Vertebral Column Trunk extension Deep muscles of the back Maintain normal curvatures of the spine Form a column from sacrum to the skull Erector spinae group Largest of the deep back muscles

Muscles of the Neck and Vertebral Column Mastoid process of temporal bone Semispinalis capitis cervicis Multifidus Quadratus lumborum thoracis Longissimus capitis Iliocostalis cervicis Longissimus cervicis Iliocostalis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis lumborum External oblique Iliocostalis Longissimus Erector spinae Spinalis Ligamentum nuchae (c) O = origin I = insertion Intertransversarius Rotatores Multifidus Interspinales PLAY PLAY A&P Flix: Iliocostalis A&P Flix: Spinalis PLAY A&P Flix: Longissimus (d)

Deep Muscles of the Thorax—Breathing Deep muscles provide movements for breathing External intercostal muscles Lift the rib cage Internal intercostal muscles Aid expiration during heavy breathing

Deep Muscles of the Thorax—Breathing Diaphragm Most important muscle of respiration Flattens as it contracts Increases the volume of the thoracic cavity

Deep Muscles of the Thorax—Breathing External intercostal Internal intercostal (a) PLAY PLAY A&P Flix: External intercostal muscles A&P Flix: Internal intercostal muscles Figure 11.13a

Deep Muscles of the Thorax—Breathing Foramen for esophagus Costal cartilage Lumbar vertebra Diaphragm Quadratus lumborum Psoas major Xiphoid process of sternum Foramen for inferior vena cava Central tendon of diaphragm Foramen for aorta 12th rib (b) Figure 11.13b

Muscles of the Abdominal Wall Lateral and anterior abdominal wall Formed from three flat muscle sheets External oblique Internal oblique Transversus abdominis Fourth muscle pair Rectus abdominis Inserts at the linea alba

Muscles of the Abdominal Wall Pectoralis major Serratus anterior Linea alba Tendinous intersection Transversus abdominis Rectus abdominis Internal oblique External oblique Inguinal ligament (formed by free inferior border of the external oblique aponeurosis) Aponeurosis of the external oblique (a) PLAY PLAY A&P Flix: Internal obliques A&P Flix: External obliques Figure 11.14a

Muscles of the Abdominal Wall Rectus abdomini Internal oblique External oblique Transversus abdominis PLAY PLAY A&P Flix: Transverse abdominis A&P Flix: Rectus abdominis Figure 11.14c

Superficial Muscles of the Anterior Thorax Movements of the scapula Pectoralis major Pectoralis minor Serratus anterior Subclavius PLAY PLAY A&P Flix: Pectoralis major A&P Flix: Serratus anterior PLAY A&P Flix: Pectoralis minor

Superficial Muscles of the Anterior Thorax Sternocleidomastoid Deltoid Pectoralis major Sternum Biceps brachii (a) Subclavius Clavicle Subscapularis minor Coracobrachialis Serratus anterior Humerus Figure 11.16a

Superficial Muscles of the Posterior Thorax Movements of the scapula Trapezius Levator scapulae Rhomboid major Rhomboid minor PLAY PLAY A&P Flix: Trapezius A&P Flix: Levator scapulae PLAY PLAY A&P Flix: Rhomboid major A&P Flix: Rhomboid minor

Superficial Muscles of the Posterior Thorax Trapezius (c) Levator scapulae Supraspinatus Clavicle Spine of scapula Infraspinatus Teres minor Humerus Deltoid Teres major Latissimus dorsi Rhomboid minor Figure 11.16c

Superficial Muscles of the Posterior Thorax Levator scapulae (d) Rhomboid minor major Infraspinatus Teres major Teres minor Latissimus dorsi Trapezius Deltoid Triceps brachii Triangle of auscultation Figure 11.16d

Muscles Crossing the Shoulder Joint Movements of the arm Deltoid Pectoralis major Clavicle Deltoid Sternum Pectoralis major Lateral head Long head Medial head Coracobrachialis Triceps brachii Biceps brachii Brachialis Brachio- radialis (a) Anterior view PLAY A&P Flix: Deltoid Figure 11.17a

Muscles Crossing the Shoulder Joint Movements of the arm A&P Flix: Latissimus dorsi A&P Flix: Supraspinatus A&P Flix: Infraspinatus Supraspinatus Spine of scapula (b) Posterior view Deltoid (cut) Greater tubercle of humerus Infraspinatus Teres minor Teres major Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna Lateral head Long head Anconeus PLAY PLAY PLAY Figure 11.17b

Muscles Crossing the Shoulder Joint Movements of the arm A&P Flix: Teres minor A&P Flix: Teres major A&P Flix: Subscapularis Supraspinatus Spine of scapula (b) Posterior view Deltoid (cut) Greater tubercle of humerus Infraspinatus Teres minor Teres major Triceps brachii Latissimus dorsi Humerus Olecranon process of ulna Lateral head Long head Anconeus PLAY PLAY PLAY Figure 11.17b

Muscles Crossing the Elbow Joint Clavicle Deltoid Sternum Pectoralis major Coracobrachialis Triceps brachii Lateral head Long head Medial head PLAY Biceps brachii A&P Flix: Biceps brachii Brachialis PLAY A&P Flix: Brachialis Brachio- radialis PLAY A&P Flix: Brachioradialis (a) Anterior view Figure 11.17a

Muscles Crossing the Elbow Joint Posterior muscles—extensors of the forearm Triceps brachii Anconeus Anterior muscles—flexors of the forearm Biceps brachii—also supinates the forearm Brachialis Brachioradialis PLAY A&P Flix: Triceps brachii

Movements of the wrist, hand, and fingers Muscles of the Forearm Movements of the wrist, hand, and fingers Tendons are anchored by Flexor and extensor retinacula Most forearm muscles arise from the distal humerus Movements at the wrist include Flexion, extension, abduction, and adduction Wrist and fingers are “operated” by muscles in the forearm

Originate from a common tendon Muscles of the Forearm Flexors Anterior flexor compartment Innervated by median and ulnar nerves Originate from a common tendon Medial epicondyle of the humerus

Superficial Anterior Muscles of the Forearm Biceps brachii Medial head of triceps brachii Tendon of biceps brachii Pronator teres Brachioradialis Extensor carpi radialis longus Flexor pollicis longus Pronator quadratus Flexor retinaculum (a) Medial epicondyle of humerus Flexor carpi radialis Palmar aponeurosis Superficial transverse ligament of palm Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis Pronator teres Flexor carpi radialis Palmaris longus Flexor carpi ulnaris Flexor digitorum superficialis PLAY A&P Flix: Flexor carpi radialis PLAY A&P Flix: Flexor carpi ulnaris PLAY A&P Flix: Flexor digitorum superficialis Figure 11.18a

Deep Anterior Muscles of the Forearm Flexor pollicis longus Flexor digitorum profundus Pronator quadratus

Deep Anterior Muscles of the Forearm Tendon of flexor digitorum profundus Tendon of flexor digitorum superficialis Tendon of flexor digitorum superficialis (cut) Lumbricals Tendon of flexor pollicis longus Tendon of brachioradialis (cut) Thenar muscles of thumb Tendon of flexor carpi ulnaris (cut) Tendon of flexor carpi ulnaris (cut) Pronator quadratus Pronator quadratus Tendon of flexor carpi radialis (cut) Flexor pollicis longus Flexor pollicis longus Flexor digitorum superficialis Extensor carpi radialis longus Flexor digitorum profundus Supinator Supinator Tendon of biceps brachii (cut) (b) (c) Figure 11.18b, c

Muscles of the Forearm Extensors Posterior compartment of the forearm Innervated by the radial nerve Originate at a common tendon Lateral epicondyle of the humerus

Superficial Posterior Muscles of the Forearm Insertion of triceps brachii Anconeus Flexor carpi ulnaris Extensor carpi ulnaris Extensor digiti minimi Extensor indicis Tendons of extensor carpi radialis brevis and longus Extensor expansion (a) Extensor pollicis longus brevis Abductor pollicis longus Extensor digitorum radialis brevis radialis longus Brachioradialis Tendons of extensor digitorum Brachioradialis— flexes forearm Extensor carpi radialis longus Extensor carpi radialis brevis Extensor digitorum Extensor carpi ulnaris PLAY PLAY A&P Flix: Extensor carpi radialis longus A&P Flix: Extensor digitorum PLAY PLAY A&P Flix: Extensor carpi radialis brevis A&P Flix: Extensor carpi ulnaris Figure 11.19a

Deep Posterior Muscles of the Forearm Supinator Abductor pollicis longus Extensor pollicis brevis and longus Extensor indicus Interossei Extensor indicis Extensor pollicis brevis Extensor pollicis longus Abductor pollicis longus Supinator Anconeus PLAY A&P Flix: Supinator Olecranon process of ulna (b) Figure 11.19b

Intrinsic Muscles of the Hand Fine movement of the fingers All located in the palm Control precise movements Include muscles of Adduction, abduction, and opposition

Intrinsic Muscles of the Hand Flexor digitorum profundus Tendons of superficialis Third lumbrical Fourth Opponens digiti minimi Flexor digiti minimi brevis Abductor Pisiform bone Flexor carpi ulnaris tendon tendons Flexor pollicis longus Flexor carpi radialis Palmaris longus Flexor retinaculum Abductor pollicis longus pollicis brevis Flexor pollicis Adductor pollicis Dorsal interossei First lumbrical Second lumbrical Fibrous sheath (a) Superficial layer Figure 11.21a

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Anterior muscles Flex the thigh and extend the leg at the knee Posterior muscles Extend the thigh and flex the leg

Muscles Crossing the Hip and Knee Joints Thigh and leg movements Adductor muscles—on medial aspect of thigh Adduct the thigh only Deep fascia of the thigh Surrounds and encloses all three groups

Muscles Crossing the Hip and Knee Joints Movements at the hip joint Muscles that flex the thigh Originate on vertebral column or pelvis Muscles that extend the thigh Arise posterior to the hip joint Adductors originate medial to the hip joint Abductors originate lateral to the hip joint

Anterior and Medial Muscles Origin on pelvis or vertebral column Iliacus Psoas major Sartorius Muscles of the medial compartment Adductor longus Adductor brevis Adductor magnus Pectineus Gracilis PLAY A&P Flix: Iliopsoas PLAY A&P Flix: Sartorius

Anterior and Medial Muscles 12th rib Quadratus lumborum 12th thoracic vertebra 5th lumbar vertebra Adductor longus Gracilis Adductor magnus Patella Patellar ligament Psoas minor Iliac crest Psoas major Iliacus Anterior superior iliac spine Tensor fasciae latae Pectineus Sartorius Tendon of quadriceps femoris Quadriceps femoris Rectus femoris Vastus lateralis Vastus medialis Iliopsoas (a) Figure 11.22a

Muscles of the Anterior Compartment of the Thigh Quadriceps femoris Has four separate heads Has a common insertion at the quadriceps tendon Powerful knee extensors Rectus femoris Vastus lateralis Vastus medialis Vastus intermedius Tensor fasciae latae PLAY A&P Flix: Rectus femoris PLAY A&P Flix: Vastus lateralis PLAY A&P Flix: Vastus medialis PLAY A&P Flix: Vastus intermedius

Muscles of the Anterior Compartment of the Thigh (b) Patella Tensor fasciae latae Iliopsoas Sartorius Rectus femoris Vastus lateralis medialis Pectineus Adductor magnus Gracilis longus 12th rib Quadratus lumborum 12th thoracic vertebra 5th lumbar vertebra Adductor longus Gracilis Adductor magnus Patella Patellar ligament Psoas minor Iliac crest Psoas major Iliacus Anterior superior iliac spine Tensor fasciae latae Pectineus Sartorius Tendon of quadriceps femoris Quadriceps femoris Rectus femoris Vastus lateralis Vastus medialis Iliopsoas (a) Figure 11.22a, b

Posterior Muscles Origin on pelvis or sacrum Gluteus maximus Gluteus medius Gluteus minimus Lateral rotators Piriformis Obturator externus Obturator internus Superior and inferior gemellus Quadratus femoris PLAY A&P Flix: Gluteus maximus PLAY A&P Flix: Gluteus medius

Posterior Muscles Gluteus medius Gluteus maximus Adductor magnus Gracilis Iliotibial tract Long head Semitendinosus Semimembranosus Short head Biceps femoris (c) Figure 11.23c

Muscles of the Posterior Compartment of the Thigh Hamstrings Biceps femoris Semitendinosus Semimembranosus Gluteus medius (cut) Gluteus minimus Superior gemellus PLAY A&P Flix: Biceps femoris Piriformis Obturator internus Obturator externus PLAY A&P Flix: Semimembranosus Inferior gemellus Quadratus femoris PLAY A&P Flix: Semitendinosus Gluteus maximus (cut) (a) Figure 11.23a

Fascia lata of the leg surrounds muscles Muscles of the Leg Fascia lata of the leg surrounds muscles Tightly binds muscles Prevents swelling during exercise Aids venous return Divides leg into three compartments Tendons are held in place by Extensor, fibular, and flexor retinacula Muscle movement at ankle and intertarsal joints

Muscles of the Anterior Compartment Fibularis longus Gastrocnemius Tibia Tibialis anterior Extensor digitorum longus Soleus Extensor hallucis longus Fibularis tertius Extensor hallucis brevis Extensor digitorum Superior and inferior extensor retinacula (a) Tibialis anterior Extensor digitorum longus Fibularis tertius Extensor hallucis longus PLAY A&P Flix: Tibialis anterior PLAY A&P Flix: Extensor digitorum longus PLAY A&P Flix: Extensor hallucis longus Figure 11.25a

Muscles of the Lateral Compartment Fibularis longus Fibularis brevis Flexor hallucis longus Extensor hallucis longus Fibularis tertius Patella Head of fibula Gastrocnemius Soleus Fibularis longus Extensor digitorum longus Tibialis anterior Extensor hallucis longus Fibularis tertius Fibularis brevis Flexor hallucis longus Fibular retinaculum Lateral malleolus Superior and inferior extensor retinacula Extensor digitorum brevis 5th metatarsal Extensor hallucis brevis (a) PLAY A&P Flix: Fibularis longus PLAY A&P Flix: Flexor hallucis longus Figure 11.26a

Muscles of the Lateral Compartment Tendon of fibularis longus O = origin I = insertion (b) Fibularis longus Fibularis brevis (c) Figure 11.26b, c

Muscles of the Posterior Compartment Superficial muscles Triceps surae Gastrocnemius Soleus Plantaris PLAY A&P Flix: Gastrocnemius PLAY A&P Flix: Soleus

Muscles of the Posterior Compartment Plantaris Tendon of gastrocnemius Calcaneal tendon Medial malleolus Medial head Gastroc- nemius Lateral head Lateral Calcaneus (a) Soleus Tendon of tibialis posterior Tendon of plantaris Fibularis brevis Head of fibula Popliteus Plantaris Gastroc- nemius Lateral head (cut) Medial head Fibularis longus (b) Figure 11.27a, b

Muscles of the Posterior Compartment Deep muscles Popliteus Flexor digitorum longus Flexor hallucis longus Tibialis posterior Plantaris (cut) Gastrocnemius lateral head (cut) Gastrocnemius medial head (cut) Popliteus Soleus (cut) Tibialis posterior Fibula Fibularis longus Flexor digitorum longus Flexor hallucis longus PLAY A&P Flix: Tibialis posterior Tendon of tibialis posterior Fibularis brevis PLAY A&P Flix: Flexor digitorum longus Medial malleolus Calcaneal tendon (cut) PLAY A&P Flix: Flexor hallucis longus Calcaneus (c) Figure 11.27c

Muscles of the Foot Plantar interossei Adductor hallucis (d) Fourth layer: plantar Adductor hallucis (transverse head) (oblique head) Interosseous muscles Flexor hallucis brevis Flexor digiti minimi brevis Fibularis longus (tendon) Flexor accessorius Flexor digitorum longus (tendon) (c) Third layer Figure 11.28c, d

Palpation—feeling internal structures through the skin Surface Anatomy Palpation—feeling internal structures through the skin “Living anatomy”—provides information about Palpation of arterial pulses Skeleton, muscles, and blood vessels Sounds of the heart and lungs Where to give injections

The Anterior Thorax and Abdomen Jugular notch Clavicle Sternal angle Infrasternal angle Costal margin Linea semilunaris Iliac crest Pubic symphysis Pubic crest Pectoralis major Midaxillary line Midclavicular line Xiphoid process Serratus anterior Tendinous intersections in the rectus abdominis Linea alba External oblique Anterior superior iliac spine Inguinal ligament Figure 11.31

Structures felt through the skin The Abdomen Structures felt through the skin Iliac crest Anterior superior iliac spine Inguinal ligament Runs medially from anterior superior iliac spine to the pubic tubercle Pubic crest

Surface Anatomy of the Back Acromion Spine of scapula Medial border of scapula Teres major Inferior angle Triangle of auscultation Latissimus dorsi (superior border) Trapezius (lateral border) Spinous processes Superior part Inferior part Deltoid muscle Posterior median furrow Erector spinae Supracristal line at L4 Iliac crest, superior point Figure 11.32

Muscles of the Back Trapezius Latissimus dorsi Erector spinae

Surface Anatomy of the Back Acromion Spine of scapula Medial border of scapula Teres major Inferior angle Triangle of auscultation Latissimus dorsi (superior border) Trapezius (lateral border) Spinous processes Superior part Inferior part Deltoid muscle Posterior median furrow Erector spinae Supracristal line at L4 Iliac crest, superior point Figure 11.32

Shoulder and Arm Acromioclavicular joint Clavicle Greater tubercle of the humerus Intermediate part Anterior part Deltoid Posterior part Teres major (a) (b) Biceps brachii Median bicipital furrow Base of the axilla Anterior axillary fold Posterior axillary Trapezius Olecranon process of ulna Triceps brachii Figure 11.33

Acromion—lateral end of the spine of the scapula The Shoulder Deltoid muscle Humerus Acromion—lateral end of the spine of the scapula Acromioclavicular joint Deltoid muscle Covers the greater tubercle of the humerus Figure 11.34

The region between the shoulder and elbow Humerus Biceps brachii The Arm The region between the shoulder and elbow Humerus Palpated through skin along its entire length Biceps brachii Medial bicipital groove The medial boundary of the biceps brachii Triceps brachii

The Arm Acromioclavicular joint Clavicle Greater tubercle of the humerus Intermediate part Anterior part Deltoid Posterior part Teres major (a) (b) Biceps brachii Median bicipital furrow Base of the axilla Anterior axillary fold Posterior axillary Trapezius Olecranon process of ulna Triceps brachii Figure 11.33

Lateral and medial epicondyles of the humerus The Elbow Lateral and medial epicondyles of the humerus Ulnar nerve—“funny bone” runs across medial epicondyle Olecranon process of the ulna Cubital fossa—(antecubital fossa) Forms anterior surface of forearm

The Anterior Surface of the Forearm and Fist (a) Posterior view of left arm and forearm (b) Anterior view of left arm and forearm Medial head Head of radius Tendon Long head Lateral head Triceps brachii Extensor muscles Ulna Head of ulna Olecranon process of ulna Cubital fossa Brachioradialis Medial and lateral epicondyles of humerus Pronator teres Flexor muscles Tendon of flexor carpi radialis Tendon of palmaris longus carpi ulnaris Figure 11.35

Forearm Bones Ulna—palpate entire length Styloid process and head—distal end Radius—partly covered in muscle Head of the radius—proximal end Styloid process—distal end

Flexor muscles—anterior forearm Muscles of the Forearm Flexor muscles—anterior forearm Flexor carpi radialis Palmaris longus This muscle is absent in about 30% of people Extensor muscles—posterior forearm

Muscles of the Forearm Figure 11.36 (a) Anterior view of distal forearm (b) Dorsal surface of the hand Flexor carpi ulnaris Flexor digitorum superficialis Pisiform bone radialis Palmaris longus Anatomical snuff box Tendon of extensor pollicis brevis Tendons of digitorum pollicis longus Figure 11.36

Other Structures of the Forearm Anatomical snuff box bordered by Extensor pollicis brevis Extensor pollicis longus

The Hand Dorsum of hand Dorsal venous network Tendons of extensor digitorum

Posterior superior iliac spine Sacroiliac joint Gluteal Region Iliac crests Posterior superior iliac spine Sacroiliac joint Prominences of the buttocks “Cheeks” of the buttocks Formed from subcutaneous fat and the gluteal muscles

The Gluteal Region Most superior point of iliac crest Gluteus medius maximus Gluteal fold Dimple for posterior superior iliac spine Most superior point of iliac crest Natal cleft Ischial tuberosity Greater trochanter Hollow posterior to the greater trochanter Figure 11.37

Medial and lateral condyles of the femur Patella Thigh Medial and lateral condyles of the femur Patella Three groups of muscles Quadriceps femoris—anterior thigh Vastus lateralis—injection site Adductors—medial thigh Hamstrings—posterior thigh

Thigh Inguinal ligament The femoral Adductor triangle longus Sartorius Vastus lateralis The femoral triangle (within dashed outline) (b) Lateral thigh site Figure 11.38b

The Thigh The femoral triangle Popliteal fossa Superior border—inguinal ligament Inferior borders Sartorius Adductor longus Popliteal fossa Diamond-shaped hollow on posterior knee Defined by borders of “hamstring” tendons and gastrocnemius

Palpate patella to find the patellar ligament Leg and Foot Palpate patella to find the patellar ligament Structures of the proximal leg Tibial tuberosity Lateral and medial condyles of the tibia Head of the fibula Structures of the distal leg Medial malleolus Lateral malleolus

Leg and Foot Figure 11.39 Femoral triangle Adductor longus Sartorius Quadriceps femoris Rectus femoris Vastus lateralis Vastus medialis Patella (a) Anterior thigh Lateral condyle of femur of tibia Head of fibula Anterior muscle compartment Anterior border Medial condyle Patella Patellar ligament Tibial tuberosity Medial surface (b) Anterior knee and leg Patella Head of the fibula Fibularis muscles Lateral malleolus Medial malleolus (c) Lateral leg and foot Tibialis anterior in anterior muscle compartment Lateral malleolus Tendons of extensor digitorum Anterior border of tibia Medial surface Medial malleolus Tendon of extensor hallucis longus (d) Anterior leg and foot Figure 11.39

Muscle Groups of the Leg Posterior calf muscles Gastrocnemius and soleus Calcaneal tendon—inferior end of the soleus and gastrocnemius Anterior compartment muscles Tibialis anterior Extensor digitorum Fibularis

Muscle Groups of the Leg Semitendinosus Semimembranosus Biceps femoris Hamstring muscles: Medial head Popliteal fossa Soleus Lateral head Calcaneal tendon Lateral malleolus Calcaneus Gastrocnemius: Figure 11.40