Chapter 11 Muscles Muscles of facial expression Muscles of mastication Extrinsic tongue muscles Muscles of the neck and throat Back muscles Deep thorax muscles Abdominal wall muscles Superficial thorax muscles Shoulder muscles Elbow muscles Forearm muscles Hip & knee muscles Leg muscles

Chapter 11 Muscles

You are responsible for muscles described in class– Origin– Insertion– Action– Nerve - innervation (if given)

Be able to recognize muscles in all diagrams of text

Muscles of facial expression

Orbicularis oculi– Sphincter muscle of eyelid– O: frontal & maxillary bones– I: tissue of eyelid– Action: closes eye– Nerve: facial / CN VII

(11.6)

Muscles of facial expression

Zygomaticus – O: zygomatic bone– I: corners of mouth– Action: smiling– Nerve: facial / CN VII

(11.6)

Major and Minor

Muscles of mastication

Masseter – O: zygomatic arch– I: angle & ramus of

mandible– Action: elevate mandible– Nerve: trigeminal nerve /

CN V (foramen ovale)

(11.7a)

Masseter

Muscles of mastication

Temporalis – O: temporal fossa– I: coronoid process of

mandible– Action: elevate and

retract mandible– Nerve: trigeminal n. /

CN V

(11.7a)

Extrinsic tongue muscles

Styloglossus – O: styloid process of

temporal bone– I: tongue– Action: retract & elevate

tongue– Nerve: hypoglossal n. /

CN XII

(11.7c)

Styloglossus

Extrinsic tongue muscles

Hyoglossus – O: hyoid bone– I: tongue– Action: depresses tongue– Nerve: hypoglossal n. /

CN XII

(11.7c)

Hyoid bone

Muscles of neck & throat

Digastric – two muscle bellies with an

intermediate tendon attached to the hyoid bone

– O: inferior margin of mandible (anterior belly); mastoid process of temporal bone (posterior belly)

– I: hyoid bone– Action: elevate hyoid, stabilize

hyoid, depress mandible– Nerve: trigeminal n. / CN V

(anterior belly), facial n. / CN VII (posterior belly)

(11.8a)Anterior belly Posterior belly

Muscles of neck & throat

Stylohyoid – O: styloid process of

temporal bone– I: hyoid bone– Action: elevate & retract

hyoid, swallow– Nerve: facial n. / CN VII

(11.7c)

Stylohyoid

Muscles of neck & throat

Sternohyoid – O: manubrium &

medial end of clavicle– I: hyoid bone– Action: depress hyoid

(11.8a)

Sternohyoid

Muscles of neck & throat

Pharyngeal constrictors – O: mandible, pterygoid

process, hyoid, laryngeal cartilages

– I: posterior medial raphe of pharynx

– Action: peristaltic contraction / swallow

(11.8b)

Superior

Middle

Inferior

Muscles of neck & throat

Sternocleidomastoid – O: manubrium & medial

clavicle– I: mastoid process of

temporal bone– Action: head & neck

flexion, rotate head contralaterally

– Nerve: accessory n. / CN XI

(11.8a)

Muscles of neck & throat

Sternocleidomastoid

Back muscles

Spinalis – O: spines of upper

lumbar and lower thoracic vertebrae

– I: spines of upper thoracic and cervical vertebrae

– Action: extends vertebral column

(11.9d)

Deep thorax muscles

External & internal intercostals – O&I: inferior & superior

border of ribs – Action: inspiration and

expiration

(11.10a)

Internal

Deep thorax muscles

Diaphragm – O: inferior internal

surface of rib cage & sternum, inferior costal cartilages, lumbar vertebrae

– I: central tendon– Action: flattens on

contraction (inspiration)– Nerve: phrenic nerves (11.10b)

Xiphoid process

Abdominal wall muscles

Rectus abdominis – O: pubic crest & symphysis– I: xiphoid process and

costal cartilages of ribs 5-7– Action: flex & rotate lumbar

vertebrae, fix & depress ribs, stabilize pelvis during walking, increase intraabdominal pressure

– Note: 3 tendinous insertions, aponeurosis & linea alba

(11.11ab)

Superficial thorax muscles

Pectoralis minor – O: anterior surface of

ribs 3-5– I: coracoid process of

scapula– Action: with ribs fixed,

pulls scapula anterior & inferior; with scapula fixed, pulls ribs superiorly

– Nerve: Medial and lateral pectoral nerves (C6-C8)

(11.13a)

Superficial thorax muscles

Superificial thorax muscles

Serratus anterior – O: ribs 1-8– I: vertebral border of

scapula– Action: hold scapula

against chest wall, moves inferior angle of scapula lateral & superior (abduction, pushing, punching)

– Nerve: long thoracic nerve (11.13a,8.1a reversed)

Superificial thorax muscles

Trapezius – O: occipital bone,

ligamentum nuchae, C7-T12 spinous processes

– I: acromion, spine of scapula, lateral third of clavicle

– Action: stabilize, elevate, adduct, depress scapula, extend head

– Nerve: Accessory (CNXI), C3 and C4 (11.13b)

Shoulder muscles

Pectoralis major – O: medial clavicle,

sternum, cartilage of ribs 1-6, aponeurosis of external oblique

– I: greater tubercle of humerus

– Action: arm-flexion, medial rotation, adduction, elevation of rib cage

(11.13a)

-Nerve: Medial and lateral pectoral nerves (C6-C8)

Shoulder muscles

Deltoid – O: lateral clavicle,

acromion & spine of scapula (compare to insertion of trapezius)

– I: deltoid tuberosity of humerus

– Action: arm-abduction, flexion, extension, medial & lateral rotation

– Nerve: Axillary nerve(C5-C-6)

(11.13ab)

Shoulder muscles

Subscapularis – O: subscapular fossa– I: lesser tubercle of

humerus– Action: medial rotate

arm, stabilize shoulder joint

– Nerve: Subscapular nerves (C5-C7)

(11.14d)

Shoulder muscles

Infraspinatus – O: infraspinous fossa– I: greater tubercle of

humerus– Action: lateral rotate

humerus, stabilized shoulder joint

– Nerve: Suprascapular nerve

(11.14b)

Rotator cuff muscles

Act to stabilize head of humerus in glenoid cavity and prevent dislocation

Supraspinatous (Suprascapular nerve) Infraspinatus (Suprascapular nerve) Subscapularis (Subscapular nerve) Teres minor (Axillary nerve)

Elbow muscles

Triceps brachii – O: long head-

infraglenoid tubercle, lat. & med. heads-posterior shaft of humerus

– I: olecranon process of ulna

– Action: extend forearm, assist adduction of arm

– Nerve: Radial nerve (11.14b)

Elbow muscles

Biceps brachii – O: short head-coracoid

process, long head-tubercle above glenoid cavity and lip of glenoid cavity (intertubercular groove)

– I: radial tuberosity– Action: flex elbow, supinate

forearm, weak arm flexor– Nerve: Musculocutaneous

nerve (C5 & C6)

(11.14c)

Forearm muscles

Flexor carpi (radialis & ulnaris) – O: medial epicondyle

of humerus, ulna– I: metacarpals and

carpals– Action: wrist flexion,

abduct & adduct hand– Carpal tunnel (Median

nerve) syndrome p. 184

(11.15a)Anterior view

radialis

ulnaris

Forearm muscles

Extensor carpi– O: lateral epicondyle of

humerus– I: base of metacarpals – Action: extend, abduct,

and adducts wrist– Palpate forearm muscles

Hip & knee muscles

Quadriceps femoris – O: anterior inferior iliac

spine, superior margin of acetabulum, greater trochanter, shaft of femur

– I: patella and tibial tuberosity via patellar tendon

– Action: extend knee, flex thigh

Hip & knee muscles

Gluteus muscles– O: ilium, sacrum, coccyx– I: shaft & greater

trochanter of femur– Action: extend thigh (climb

stairs, running), lateral & medial rotate thigh, abduct thigh, steadies pelvis

Hip & knee muscles

Hamstrings– O: ischial tuberosity, shaft

of femur– I: lateral & medial

condyles and shaft of tibia, head of fibula, lateral condyle femur

– Action: extend thigh, flex knee

– Makes touching toes hard

Leg muscles

Tibialis anterior – O: lateral condyle and

shaft of tibia– I: tarsal and first

metatarsal bones– Action: dorsiflexion

Leg muscles

Gastrocnemius – O: medial & lateral

condyles of femur– I: calcaneus via Achilles

tendon– Action: plantar flexion, flex

knee