Chapter 10. The Muscular System. AP1-Lecture Goodwin College. Introduction. In this chapter we will cover: 4/27/2015

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1 Chapter 10 The Muscular System AP1-Lecture Goodwin College Introduction In this chapter we will cover: Structural and functional organization of muscles Muscles of the head and neck Muscles of the trunk Muscles acting on the shoulder and upper limb Muscles acting on the hip and lower limb

2 The Functions of Muscles Myology the study of the muscular system About 600 human skeletal muscles Constitute about half of our body weight Three kinds of muscle tissue : Skeletal, cardiac, smooth Functions: Movement Move from place to place, movement of body parts and body contents in breathing, circulation, feeding and digestion, defecation, urination, and childbirth Role in communication: speech, writing, nonverbal communications Stability Maintain posture by preventing unwanted movements Antigravity muscles: resist pull of gravity and prevent us from falling or slumping over Stabilize joints 10-3 The Functions of Muscles Control of openings and passageways Sphincters: internal muscular rings that control the movement of food, bile, blood, and other materials within the body Heat production by skeletal muscles As much as 85% of our body heat Glycemic control Regulation of blood glucose concentrations within its normal range Specialized for one major purpose Converting the chemical energy in ATP into the mechanical energy of motion

3 Connective Tissues of a Muscle Tendon Fascia Skeletal muscle Nerve Blood vessels Epimysium Perimysium Endomysium Figure 10.1a Muscle fascicle Perimysium Muscle fiber (a) 10-5 Connective Tissues and Fascicles Endomysium Thin sleeve of loose connective tissue surrounding each muscle fiber Allows room for capillaries and nerve fibers to reach each muscle fiber Provides extracellular chemical environment for the muscle fiber and its associated nerve ending Perimysium Slightly thicker layer of connective tissue Fascicles: bundles of muscle fibers wrapped in perimysium Carry larger nerves and blood vessels, and stretch receptors Epimysium Fibrous sheath surrounding the entire muscle Outer surface grades into the fascia Inner surface sends projections between fascicles to form perimysium Fascia Sheet of connective tissue that separates neighboring muscles or muscle groups from each other and the subcutaneous tissue

4 Fascicles and Muscle Shapes Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Fusiform Parallel Triangular Unipennate Bipennate Multipennate Tendon Circular Belly Biceps brachii Tendon Rectus abdominis Pectoralis major Palmar interosseous Figure 10.2 Rectus femoris Deltoid Orbicularis oculi Strength of a muscle and the direction of its pull are determined partly by the orientation of its fascicles 10-7 Muscle Compartments Anterior Lateral Medial Posterior Key Anterior compartment Lateral compartment Posterior compartment, deep layer Posterior compartment, superficial layer Tibia Fibula Interosseous membrane Artery, veins, and nerve Intermuscular septa Fasciae Subcutaneous fat Figure 10.3 A group of functionally related muscles enclosed and separated from others by connective tissue fascia Contains nerves, blood vessels that supply the muscle group Thoracic, abdominal walls, pelvic floor, limbs Intermuscular septa separate one compartment from another

5 Muscle Attachments Indirect attachment to bone Tendons bridge the gap between muscle ends and bony attachment Collagen fibers of the endo, peri, and epimysium continue into the tendon From there into the periosteum and the matrix of bone Biceps brachii, Achilles tendon Aponeurosis tendon is a broad, flat sheet (palmar aponeurosis) Retinaculum connective tissue band that tendons from separate muscles pass under Direct (fleshy) attachment to bone Little separation between muscle and bone Muscle seems to immerge directly from bone Margins of brachialis, lateral head of triceps brachii 10-9 Muscle Origins and Insertions Origin Bony attachment at stationary end of muscle Belly Thicker, middle region of muscle between origin and insertion Insertion Bony attachment to mobile end of muscle Origins Scapula Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Extensors: Triceps brachii Long head Lateral head Origins Humerus Bellies Flexors: Biceps brachii Brachialis Exception: Facial muscles Insertion insert in the skin Distal tendon of the biceps brachii inserts on the fascia of Figure 10.4 Insertion Radius Ulna

6 Functional Groups of Muscles Action The effects produced by a muscle To produce or prevent movement Four categories depending on action A) Prime mover (agonist) : Muscle that produces most of force during a joint action. Ex. In flexing elbow, prime mover is brachialis B) Synergist: Muscle that aids the prime mover, Stabilizes the nearby joint, Modifies the direction of movement Ex. Bicep brachii acts as synergist of brachialis to flex elbow Functional Groups of Muscles C) Antagonist: opposes the prime mover Relaxes to give prime mover control over an action Preventing excessive movement and injury Antagonistic pairs muscles that act on opposite sides of a joint Ex. In flexion of elbow brachialis is prime mover and triceps is the antagonist D) Fixator: muscle that prevents movement of bone Ex. Rombiods muscles attach (fix) the scapula to the vertebral column 6

7 Examples of Functional Groups of Muscles Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Prime mover brachialis Origins Scapula Extensors: Triceps brachii Long head Lateral head Insertion Origins Humerus Bellies Flexors: Biceps brachii Brachialis Insertion Radius Ulna Synergist biceps brachii Antagonist triceps brachii Fixator muscle that holds scapula firmly in place Rhomboids Figure Intrinsic and Extrinsic Muscles Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. (b) Intermediate flexor Flexor digitorum superficialis tendons Flexor digitorum profundus tendons Figure 10.28b Common flexor tendon Flexor digitorum superficialis Flexor pollicis Intrinsic muscles entirely contained within a region, such as the hand Both its origin and insertion there Extrinsic muscles act on a designated region, but has its origin elsewhere Fingers: extrinsic muscles in the forearm Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Tendon sheath First dorsal interosseous Tendon of flexor Adductor digitorum profundus pollicis Tendon of flexor digitorum superficialis Tendon of flexor Lumbricals pollicis Opponens digiti minimi Flexor pollicis brevis Flexor digiti Abductor pollicis brevis Abductor digiti minimi Opponens pollicis Flexor retinaculum Tendons of: Tendons of: Abductor pollicis Flexor carpi ulnaris Flexor carpi Flexor digitorum radialis superficialis Flexor pollicis Palmaris (a) Palmar aspect, superficial Figure 10.31a

8 Muscle Innervation Innervation of a muscle refers to the identity of the nerve that stimulates it Enables the diagnosis of nerve, spinal cord, and brainstem injuries from their effects on muscle function Spinal nerves arise from the spinal cord Emerge through intervertebral foramina Immediately branch into a posterior and anterior ramus Innervate muscles below the neck Plexus: weblike network of spinal nerves adjacent to the vertebral column Cranial nerves arise from the base of the brain Emerge through skull foramina Innervate the muscles of the head and neck Numbered CN I to CN XII Blood Supply Muscular system receives about 1.24 L of blood per minute at rest (one quarter of the blood pumped by the heart) During heavy exercise total cardiac output rises and the muscular system s share is more than threequarters (11.6 L/min) Capillaries branch extensively through the endomysium to reach every muscle fiber

9 The Muscular System Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Superficial Deep Deep Superficial Frontalis Orbicularis oculi Zygomaticus major Platysma Deltoid Pectoralis major Biceps brachii Brachioradialis Flexor carpi radialis External abdominal oblique Tensor fasciae latae Masseter Orbicularis oris Sternocleidomastoid Trapezius Pectoralis minor Coracobrachialis Serratus anterior Brachialis Rectus abdominis Supinator Flexor digitorum profundus Flexor pollicis Transverse abdominal Internal abdominal oblique Pronator quadratus Semispinalis capitis Sternocleidomastoid Splenius capitis Levator scapulae Supraspinatus Rhomboideus minor Rhomboideus major Deltoid (cut) Infraspinatus Serratus anterior Triceps brachii (cut) Serratus posterior inferior External abdominal oblique Internal abdominal oblique Erector spinae Flexor carpi ulnaris Extensor digitorum (cut) Gluteus minimus Occipitalis Trapezius Infraspinatus Teres minor Teres major Triceps brachii Latissimus dorsi Extensor carpi radialis and brevis External abdominal oblique Extensor digitorum Gluteus medius Extensor carpi ulnaris Gluteus maximus Lateral rotators Adductor Sartorius Rectus femoris Vastus lateralis Vastus medialis Adductors Vastus lateralis Vastus intermedius Gracilis Adductor magnus Iliotibial band Semimembranosus Biceps femoris Gracilis Semitendinosus Iliotibial band Biceps femoris Gastrocnemius (cut) Fibularis Gastrocnemius Soleus (cut) Tibialis posterior Gastrocnemius Tibialis anterior Extensor digitorum Soleus Extensor digitorum Flexor digitorum Extensor hallucis Fibularis Calcaneal tendon Soleus Figure 10.5a (a) Anterior view Figure 10.5b (b) Posterior view Muscles of Facial Expression Muscles that insert in the dermis and subcutaneous tissues Tense the skin and produce facial expressions Innervated by facial nerve (CN VII) Paralysis causes face to sag Found in scalp, forehead, around the eyes, nose, and mouth, and in the neck

10 Main Muscles of Facial Expression Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Superficial Deep Frontalis Galea aponeurotica Orbicularis oculi Levator labii superioris Zygomaticus minor Zygomaticus major Risorius Modiolus Depressor anguli oris Depressor labii inferioris Platysma (a) Anterior view Nasalis Levator anguli oris Masseter Buccinator Orbicularis oris Mentalis (cut) Figure 10.8a Muscles of Facial Expression Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Galea aponeurotica Temporalis Occipitalis Masseter Sternocleidomastoid Levator scapulae Thyrohyoid Sternothyroid Omohyoid Sternohyoid (b) Lateral view Frontalis (cut) Orbicularis oculi Nasalis Levator labii superioris Zygomaticus minor Zygomaticus major Orbicularis oris Mentalis Depressor labii inferioris Buccinator Figure 10.8b

11 Muscles of Chewing and Swallowing Four pairs of muscles produce the biting and chewing movements of the mandible Depression: to open mouth Elevation: biting and grinding Protraction: incisors can cut Retraction: make rear teeth meet Lateral and medial excursion: grind food Temporalis, masseter, medial pterygoid, and lateral pterygoid Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Temporalis Orbicularis oris Buccinator Masseter (cut) (a) Lateral view Lateral pterygoid plate Medial pterygoid plate Lateral pterygoid muscle Innervated by mandibular nerve, a branch of the trigeminal (CN V) Medial pterygoid muscle Interior of oral cavity (b) Posterior view Figure 10.10a,b Muscles of Chewing and Swallowing Hyoid muscles suprahyoid group Aspects of chewing, swallowing, and vocalizing Eight pairs of hyoid muscles associated with hyoid bone Digastric opens mouth widely Geniohyoid depresses mandible Mylohyoid elevates floor of mouth at beginning of swallowing Stylohyoid elevates hyoid Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Superficial Deep Suprahyoid group Levator scapulae Digastric: Anterior belly Posterior belly Stylohyoid Mylohyoid Hyoid bone Common carotid artery Internal jugular vein Infrahyoid group Sternohyoid Omohyoid: Superior belly Inferior belly Thyrohyoid Sternothyroid Infrahyoid group Sternocleidomastoid Clavicle (a) Anterior view Figure 10.11a

12 Muscles of Chewing and Swallowing Hyoid muscles infrahyoid group Fix hyoid bone from below, allowing suprahyoid muscles to open mouth Omohyoid depresses hyoid after elevation Sternohyoid depresses hyoid after elevation Thyrohyoid depresses hyoid and elevates larynx Sternothyroid depresses larynx after elevation Stylohyoid Hyoglossus Mylohyoid Digastric (anterior belly) Hyoid bone Thyrohyoid Omohyoid (superior belly) Sternothyroid Sternohyoid (b) Lateral view Digastric (posterior belly) Splenius capitis Inferior pharyngeal constrictor Sternocleidomastoid Trapezius Levator scapulae Scalenes Omohyoid (inferior belly) Figure 10.11b Muscles of Chewing and Swallowing Copyright The McGraw Hill Companies, Inc. Permission required for reproduction or display. Styloid process Palatoglossus Styloglossus Mastoid process Posterior belly of digastric (cut) Superior pharyngeal constrictor (cut) Inferior longitudinal muscle of tongue Genioglossus Stylohyoid Middle pharyngeal constrictor Hyoglossus Mylohyoid (cut) Hyoid bone Geniohyoid Larynx Figure 10.9 Trachea Inferior pharyngeal constrictor Esophagus Pharynx: three pairs pharyngeal constrictors Encircle pharynx forming a muscular funnel During swallowing, drive food into the esophagus

13 Muscles Acting on the Head Originate on the vertebral column, thoracic cage, and pectoral girdle Insert on the cranial bones Actions Flexion (tipping head forward) Extension (holding the head erect) Lateral flexion (tipping head to one side) Rotation (turning the head to the left and right) Muscles Acting on the Head Neck flexors Sternocleidom astoid (whip lash) Neck extensors Trapezius May cause contralateral movement: movement of the head toward the opposite side Superior nuchal line Semispinalis capitis Sternocleidomastoid Longissimus capitis Longissimus cervicis Trapezius May cause ipsilateral movement: movement of the head toward the same side Figure

14 Muscles of the Trunk/ Functional Groups Three functional groups Muscles of respiration Muscles that support abdominal wall and pelvic floor Movement of vertebral column Breathing requires the use of muscles enclosing thoracic cavity Diaphragm, external intercostal, internal intercostal, and innermost intercostal muscles Other muscles of chest and abdomen that contribute to breathing Sternocleidomastoid, scalenes of neck Pectoralis major and serratus anterior of chest Latissimus dorsi of back Abdominal muscles: internal and external obliques, and transverse abdominis Some anal muscles Muscles of Respiration External intercostals Elevate ribs Expand thoracic cavity Create partial vacuum causing inflow of air Internal intercostals Depresses and retracts ribs Compresses thoracic cavity Expelling air Internal intercostals External intercostals Diaphragm muscular dome between thoracic and abdominal cavities (a) Lateral view of intercostal muscles Figure 10.13a

15 Muscles of the Anterior Abdominal Wall Internal abdominal oblique Intermediate layer of lateral abdominal muscles Unilateral contraction causes ipsilateral rotation of waist Aponeurosis Tendons of oblique and transverse muscles Broad, fibrous sheets Subclavius Pectoralis minor (cut) Pectoralis minor Internal intercostals Serratus anterior External intercostals Rectus abdominis (cut) Rectus sheath External abdominal oblique (cut) Internal abdominal oblique Inguinal ligament Internal abdominal oblique (cut) Posterior wall of rectus sheath (rectus abdominis removed) Transverse abdominal (cut) (b) Deep Figure 10.15b Muscles of the Anterior Abdominal Wall Transverse abdominal Deepest of lateral abdominal muscles Horizontal fibers Contributes to movements of vertebral column Subclavius Pectoralis minor (cut) Pectoralis minor Internal intercostals Serratus anterior External intercostals Rectus abdominis (cut) Rectus sheath External abdominal oblique (cut) Internal abdominal oblique Inguinal ligament Internal abdominal oblique (cut) Posterior wall of rectus sheath (rectus abdominis removed) Transverse abdominal (cut) (b) Deep Figure 10.15b

16 Muscles of the Anterior Abdominal Wall Rectus abdominis Flexes lumbar region of vertebral column Produces forward bending at the waist Three transverse tendinous intersections divide rectus abdominis into segments, sometimes called a six pack Pectoralis major Latissimus dorsi Serratus anterior Tendinous intersections Rectus sheath (cut edges) Rectus sheath Umbilicus Linea semilunaris Linea alba Aponeurosis of external abdominal oblique (a) Superficial Transverse abdominal Internal abdominal oblique (cut) External abdominal oblique (cut) Rectus abdominis Inguinal ligament Figure 10.15a Sternocleidomastoid Trapezius Deltoid Erector spinae Latissimus dorsi Major Muscles of Back Superficial Deep Semispinalis capitis Splenius capitis Levator scapulae Rhomboideus minor Rhomboideus major Supraspinatus Infraspinatus Teres minor Teres major Serratus anterior Serratus posterior inferior External abdominal oblique Superficial muscles Extend, rotate, and laterally flex vertebral column Most prominent: Latissimus dorsi and Trapezius External abdominal oblique Thoracolumbar fascia Gluteus medius Internal abdominal oblique Gluteus minimus Gluteus maximus Lateral rotators Figure

17 Muscles of the Pelvic Floor Three layers of muscles and fasciae that span pelvic outlet Penetrated by anal canal, urethra, and vagina Perineum diamond shaped region between the thighs Bordered by four bony landmarks Pubic symphysis anteriorly Coccyx posteriorly Ischial tuberosities laterally Urogenital triangle: anterior half of perineum Anal triangle: posterior half of perineum Hernias Hernia any condition in which the viscera protrudes through a weak point in the muscular wall of the abdominopelvic cavity Inguinal hernia Most common type of hernia (rare in women) Viscera enter inguinal canal or even the scrotum Aponeurosis of external abdominal oblique muscle Inguinal canal External inguinal ring Herniated loop of small intestine Upper scrotum Hiatal hernia Stomach protrudes through diaphragm into thorax Overweight people over 40 Figure Umbilical hernia Viscera protrude through the navel

18 Muscles Acting on the Shoulder and Upper Limb Compartments spaces in which muscles are organized and are separated by fibrous connective tissue sheets (fasciae) Each compartment contains one or more functionally related muscles along with their nerve and blood supplies Muscles of upper limbs divided into anterior and posterior compartments Muscles of lower limbs divided into anterior, posterior, medial, and lateral compartments Intermuscular septa (thick fascia) separates compartments Compartment syndrome one of the muscles or blood vessels in a compartment is injured Compartment Syndrome Fasciae of arms and legs enclose muscle compartments very snugly If a blood vessel in a compartment is damaged, blood and tissue fluid accumulate in the compartment Fasciae prevent compartment from expanding with increasing pressure Compartment syndrome mounting pressure on the muscles, nerves, and blood vessels triggers a sequence of degenerative events Blood flow to compartment is obstructed by pressure If ischemia (poor blood flow) persists for more than 2 to 4 hours, nerves begin to die After 6 hours, muscles begin to die Nerves can regenerate after pressure relieved, but muscle damage is permanent Myoglobin in urine indicates compartment syndrome Treatment: immobilization of limb and fasciotomy (incision to relieve compartment pressure)

19 Muscles Acting on the Shoulder and Upper Limb Upper limb is used for a broad range of powerful and subtle actions Climbing, grasping, throwing, writing, playing musical instruments, and manipulating small objects Muscles that act on the scapula Muscles that act on the humerus and shoulder joint Muscles that act on the forearm and elbow joint Intrinsic forearm Extrinsic hand Muscles Acting on the Scapula Lateral rotation Trapezius (superior part) Serratus anterior Elevation Levator scapulae Trapezius (superior part) Rhomboideus major Rhomboideus minor Medial rotation Levator scapulae Rhomboideus major Rhomboideus minor Depression Trapezius (inferior part) Serratus anterior Retraction Rhomboideus major Rhomboideus minor Trapezius Protraction Pectoralis minor Serratus anterior Figure

20 Pectoralis minor Muscles Acting on the Shoulder Anterior group of muscles of pectoral girdle Ribs 3 5 to coracoid process of scapula Draws scapula laterally Serratus anterior Rbs 1 9 to medial border of scapula Abducts and rotates or depresses scapula Subclavius Pectoralis minor (cut) Pectoralis minor Internal intercostals Serratus anterior External intercostals Rectus abdominis (cut) Rectus sheath External abdominal oblique (cut) Internal abdominal oblique Inguinal ligament Internal abdominal oblique (cut) Posterior wall of rectus sheath (rectus abdominis removed) Transverse abdominal (cut) (b) Deep Figure 10.15b Muscles Acting on the Shoulder Posterior group of muscles of pectoral girdle Four muscles of posterior group Trapezius: superficial Levator scapulae, rhomboideus minor, and rhomboideus major: deep Sternocleidomastoid Trapezius Deltoid Superficial Deep Semispinalis capitis Splenius capitis Levator scapulae Rhomboideus minor Rhomboideus major Supraspinatus Infraspinatus Teres minor Teres major Erector spinae Serratus anterior Trapezius Stabilizes scapula and shoulder Elevates and depresses shoulder apex Latissimus dorsi External abdominal oblique Thoracolumbar fascia Gluteus medius Gluteus maximus Figure Serratus posterior inferior External abdominal oblique Internal abdominal oblique Gluteus minimus Lateral rotators

21 Muscles Acting on the Shoulder Levator scapulae Elevates scapula Flexes neck laterally Rhomboideus minor Retracts scapula and braces shoulder Rhomboideus major Same as rhomboideus minor Muscles Acting on the Arm Nine muscles cross the shoulder joint and insert on humerus Two are axial muscles because they originate on axial skeleton Pectoralis major: flexes, adducts, and medially rotates humerus Latissimus dorsi: adducts and medially rotates humerus Deltoid Clavicle Sternum Pectoralis major Supraspinatus Spine of scapula Greater tubercle of humerus Infraspinatus Humerus Teres minor Teres major Triceps brachii: Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis Coracobrachialis Triceps brachii: Lateral head Long head Latissimus dorsi (a) Anterior view (b) Posterior view Figure 10.23a Figure 10.23b

22 Muscles Acting on the Shoulder Posterior scapular muscles Superficial Deep Sternocleidomastoid Trapezius Deltoid Latissimus dorsi Erector spinae External abdominal oblique Gluteus medius Gluteus maximus Semispinalis capitis Splenius capitis Levator scapulae Rhomboideus minor Rhomboideus major Supraspinatus Infraspinatus Teres minor Teres major Serratus anterior Serratus posterior inferior External abdominal oblique Internal abdominal oblique Gluteus minimus Lateral rotators Figure Muscles Acting on the Arm Seven scapular muscles Originate on scapula Deltoid Rotates and abducts arm Intramuscular injection site Teres major Extension and medial rotation of humerus Coracobrachialis Flexes and medially rotates arm Remaining four form the rotator cuff that reinforce the shoulder joint Figure 10.23a Figure 10.23b Clavicle Sternum Deltoid Pectoralis major Triceps brachii: Coracobrachialis Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis (a) Anterior view Supraspinatus Spine of scapula Greater tubercle of humerus Infraspinatus Humerus Teres minor Teres major Triceps brachii: Lateral head Long head Latissimus dorsi (b) Posterior view

23 Anterior View of Cadaver Chest Deltoid Pectoralis major Biceps brachii: Long head Short head Serratus anterior External abdominal oblique (a) Anterior view The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/don Kincaid, dissections Figure 10.24a Back Muscles of Cadaver Levator scapulae Rhomboideus minor Rhomboideus major Deltoid Infraspinatus Teres minor Teres major Triceps brachii: Latissimus dorsi (b) Posterior view The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/don Kincaid, dissections Figure 10.24b

24 Muscles Acting on the Arm Rotator cuff muscles Tendons of the remaining four scapular muscles form the rotator cuff Acronym SITS muscles Supraspinatus Infraspinatus Teres minor Subscapularis Holds head of humerus into glenoid cavity Supraspinatus tendon most easily damaged Rotator Cuff Muscles Anterior Posterior Rotator cuff (SITS) muscles: Supraspinatus Infraspinatus Teres minor Subscapularis Clavicle Acromion Coracoid process Glenoid cavity Inferior angle Figure

25 Muscles Acting on the Forearm Elbow and forearm capable of flexion, extension, pronation, and supination Carried out by muscles in both brachium (arm) and antebrachium (forearm) Muscles with bellies in the arm (brachium) Principal elbow flexors: anterior compartment Brachialis and biceps brachii Brachialis produces 50% more power than biceps brachii Brachialis is prime mover of elbow flexion Principal elbow extensor: posterior compartment Triceps brachii Prime mover of elbow extension Muscles Acting on the Forearm Muscles with bellies in the forearm (antebrachium) Most forearm muscles act on the hand and wrist Brachioradialis: flexes elbow Anconeus: extends elbow Pronator quadratus: prime mover in forearm pronation Pronator teres: assists pronator quadratus in pronation Supinator: supinates the forearm

26 Muscles Acting on the Forearm Principal flexor Brachialis Figure 10.23c Biceps brachii: Long head Short head Synergistic flexors Biceps brachii Brachioradialis Deltoid Triceps brachii: Lateral head Long head Medial head Biceps brachii Brachialis Brachioradialis Clavicle Sternum Pectoralis major Coracobrachialis (c) Anterior view Supraspinatus Principal extensor Triceps brachii (a) Anterior view Figure 10.23a Spine of scapula Greater tubercle of humerus Infraspinatus Humerus Teres minor Teres major Triceps brachii: Lateral head Long head Figure 10.23b Latissimus dorsi (b) Posterior view Muscles Acting on the Forearm Lateral epicondyle Medial epicondyle Supinator Pronator teres Lateral epicondyle Medial epicondyle Supinator Pronator teres Ulna Radius Pronator quadratus Biceps brachii Ulna Radius Pronator quadratus Biceps brachii Radius Supinator Bursa Ulna Radius Supinator Bursa Ulna (b) Muscle actions in supination (b) Muscle actions in supination (a) Supination Figure 10.26a Figure 10.26c Supination Supinator muscle Palm facing anteriorly or superiorly (c) Pronation Pronation Pronator quadratus and pronator teres Palm faces posteriorly or inferiorly

27 Anterior group Muscles Acting on the Wrist and Hand Extrinsic muscles of the forearm Intrinsic muscles in the hand itself Extrinsic muscle actions Flexion and extension of wrist and digits Radial and ulnar flexion Finger abduction and adduction Thumb opposition Figure 10.28a,b,c Anterior view Flexor retinaculum Palmar aponeurosis Biceps brachii Triceps brachii Brachialis Common flexor tendon Pronator teres Aponeurosis of biceps brachii Brachioradialis Flexor carpi radialis Palmaris Flexor carpi ulnaris Extensor carpi radialis and brevis Flexor digitorum superficialis Flexor digitorum superficialis tendons Flexor digitorum superficialis Flexor pollicis Common flexor tendon Flexor digitorum superficialis tendons Supinator Interosseous membrane Flexor digitorum profundus Flexor pollicis (a) Superficial flexors Flexor digitorum profundus tendons (b) Intermediate flexor (c) Deep flexors Flexor digitorum profundus tendons Muscles Acting on the Wrist and Hand Anterior (flexor) compartment superficial layer Flexor carpi radialis Flexor carpi ulnaris Flexor digitorum superficialis Palmaris Anterior (flexor) compartment deep layer Flexor digitorum profundus Flexor pollicis

28 Muscles Acting on the Wrist and Hand Posterior group Extension of wrist and fingers, adduct/abduct wrist Extension and abduction of thumb (pollicis) Brevis means short, ulnaris indicates on ulna side of forearm Triceps brachii Brachioradialis Olecranon Extensor carpi Anconeus Anconeus radialis Supinator Posterior view Flexor carpi ulnaris Extensor carpi Extensor carpi radialis brevis Extensor digitorum Abductor pollicis ulnaris Extensor digiti minimi Abductor pollicis Extensor pollicis Extensor pollicis brevis Extensor pollicis brevis Extensor indicis Tendon of extensor indicis Extensor pollicis Tendons of extensor carpi radialis Tendons of extensor and brevis digitorum Figure 10.29a,b (a) Superficial extensors (b) Deep extensors Muscles Acting on the Wrist and Hand Posterior (extensor) compartment superficial layer Extensor carpi radialis Extensor carpi radialis brevis Extensor digitorum Extensor carpi ulnaris Posterior (extensor) compartment deep layer Abductor pollicis Extensor pollicis brevis Extensor pollicis Extensor indicis

29 Carpal Tunnel Syndrome Prolonged, repetitive motions of wrist and fingers can cause tissues in the carpal tunnel to become inflamed, swollen, or fibrotic Puts pressure on the median nerve of the wrist that passes through the carpal tunnel along with the flexor tendons Tingling and muscular weakness in the palm and medial side of the hand Pain may radiate to arm and shoulder Treatment: anti inflammatory drugs, immobilization of the wrist, and sometimes surgery to remove part or all of flexor retinaculum Carpal Tunnel Syndrome Tendon of flexor digitorum superficialis Lumbrical Opponens digiti minimi Repetitive motions cause inflammation and pressure on median nerve Flexor digiti minimi brevis Abductor digiti minimi Adductor pollicis Flexor pollicis brevis Abductor pollicis brevis Tendon sheath Tendon of flexor digitorum profundus Tendon of flexor digitorum superficialis Lumbricals First dorsal interosseous Adductor pollicis Tendon of flexor pollicis Pisiform bone Flexor digitorum superficialis Tendon of extensor pollicis brevis Tendon of flexor carpi radialis Opponens digiti minimi Flexor digiti minimi brevis Abductor digiti minimi Flexor pollicis brevis Abductor pollicis brevis Opponens pollicis (b) Palmar dissection, superficial Flexor retinaculum Tendons of: Tendons of: Abductor pollicis Flexor carpi ulnaris Figure 10.31b Flexor digitorum superficialis Palmaris Flexor carpi radialis Flexor pollicis (a) Palmar aspect, superficial Figure 10.31a

30 Muscles Acting on the Hip and Femur Lateral and posterior muscles of the hip Tensor fasciae latae Extends knee, laterally rotates knee Gluteus maximus Forms mass of the buttock Prime hip extensor Provides most of lift when you climb stairs Gluteus medius and minimus Abduct and medially rotate thigh Iliac crest Gluteus medius Sacrum Gluteus maximus Coccyx Ischial tuberosity Superficial Deep Figure Gluteus minimus Lateral rotators: Piriformis Gemellus superior Obturator internus Obturator externus Gemellus inferior Quadratus femoris Muscles Acting on the Hip and Femur Medial (adductor) compartment of thigh Five muscles act as primary adductors of the thigh Adductor brevis Adductor Adductor magnus Gracilis Pectineus Iliopsoas: Iliacus Psoas major Pectineus Adductor magnus Adductor brevis Adductor Gracilis Insertion of gracilis on tibia Figure Piriformis Obturator externus

31 Muscles Acting on the Knee and Leg Anterior (extensor) compartment of the thigh Contains large quadriceps femoris muscle Prime mover of knee extension Most powerful muscle in the body Has four heads rectus femoris, vastus lateralis, vastus medialis, and vastus intermedius All converge on single quadriceps (patellar) tendon Extends to patella Then continues as patellar ligament Inserts on tibial tuberosity Sartorius: longest muscle in the body Tailor s muscle Anterior Thigh Cadaver Muscles Lateral Medial Tensor fasciae latae Iliopsoas Sartorius Femoral vein Femoral artery Pectineus Iliotibial band Quadriceps femoris: Rectus femoris Vastus lateralis Vastus medialis Adductor Gracilis Quadriceps tendon Patella The McGraw-Hill Companies, Inc./Rebecca Gray, photographer/don Kincaid, dissections Figure

32 Muscles Acting on the Knee and Leg Iliac crest Iliopsoas: Iliacus Psoas major L5 Anterior superior iliac spine Tensor fasciae latae Iliotibial band Medial compartment: Adductor magnus Pectineus Adductor brevis Adductor Gracilis Anterior compartment: Sartorius Quadriceps femoris: Vastus intermedius Rectus femoris Vastus lateralis Vastus medialis Quadriceps femoris tendont Patella Patellar ligament (a) Superficial (b) Deep Figure 10.35a,b Muscles Acting on the Knee and Leg Posterior (flexor) compartment of the thigh Contains hamstring muscles From lateral to medial: Biceps femoris Semitendinosus Semimembranosus Gluteus medius Gluteus maximus Gracilis Adductor magnus Iliotibial band Vastus lateralis Hamstring group: Biceps femoris Long head Short head Semitendinosus Semimembranosus Figure

33 Muscles Acting on the Foot Plantaris Popliteus Heads of gastrocnemius (cut) Fibularis Gastrocnemius: Medial head Lateral head Soleus Tendon of plantaris Tendon of gastrocnemius Flexor digitorum Gastrocnemius (cut) Fibularis Fibularis brevis Flexor hallucis Figure 10.39a,b Calcaneal tendon (a) Calcaneus (b) Posterior compartment three muscles of the superficial group Gastrocnemius: plantar flexes foot, flexes knee Soleus: plantar flexes foot Triceps surae collective name for gastrocnemius and soleus Inserts on calcaneus by way of the calcaneal (Achilles) tendon Strongest tendon in the body Muscles Acting on the Foot Plantaris (cut) Tibialis posterior Flexor digitorum Popliteus Gastrocne -mius (cut) Soleus (cut) Fibula (b) (c) Flexor digitorum Tibialis posterior Fibularis Flexor hallucis Popliteus Calcaneal tendon (cut) (a) Fibularis brevis Calcaneus Flexor hallucis Plantar surface of the foot (d) Figure Posterior compartment four muscles in the deep group Flexor digitorum : flexes phalanges Flexor hallucis : flexes great toe Tibialis posterior: inverts foot Popliteus: acts on knee

34 Intrinsic Muscles of Foot Four ventral muscle layers Support for arches Abduct and adduct the toes Flex the toes One dorsal muscle Extensor digitorum brevis extends toes Flexor digiti minimi brevis Abductor digiti minimi (a) Layer 1, plantar view Flexor digiti minimi brevis Quadratus plantae (cut) Lumbricals Flexor hallucis tendon Flexor digitorum Abductor hallucis tendon Abductor hallucis Flexor digitorum (cut) Quadratus plantae brevis Plantar aponeurosis Flexor digitorum (cut) brevis (cut) Calcaneus (b) Layer 2, plantar view Adductor hallucis Plantar Flexor hallucis brevis interosseous Dorsal Flexor hallucis interosseous tendon (cut) Abductor hallucis (cut) Flexor digitorum tendon (cut) Figure 10.42a e Dorsal view (c) Layer 3, plantar view (d) Layer 4, plantar view (e) Layer 4, dorsal view Common Athletic Injuries Muscles and tendons are vulnerable to sudden and intense stress Proper conditioning and warm up needed Common injuries include: Compartment syndrome Shinsplints Pulled hamstrings Tennis elbow Pulled groin Rotator cuff injury Treat with rest, ice, compression, and elevation