The Muscular System Part A 10 The Muscular System Part A 10 Hold onto your glutes, this is a big one. 10 Interactions of Skeletal Muscles

▪ Skeletal muscles work together or in opposition ▪ Muscles only pull (never push) ▪ As muscles shorten, the insertion generally moves toward the origin ▪ Whatever a muscle (or group of muscles) does, another muscle (or group) “undoes” Muscle Classification: Functional Groups

▪ Prime movers – provide the major force for producing a specific movement ▪ Antagonists – oppose or reverse a particular movement ▪ Synergists ▪ Add force to a movement ▪ Reduce undesirable or unnecessary movement ▪ Fixators – synergists that immobilize a bone or muscle’s origin Naming Skeletal Muscles

I call this one Betty Naming Skeletal Muscles

▪ Location of muscle – bone or body region Rectus Abdominus associated with the muscle Naming Skeletal Muscles

▪ Shape of muscle – e.g., the deltoid muscle (deltoid = triangle) Naming Skeletal Muscles

▪ Relative size – e.g., maximus (largest), minimus (smallest), longus (long)

Gluteus Maximus Naming Skeletal Muscles

▪ Direction of fibers – e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an imaginary defined axis) Naming Skeletal Muscles

▪ Number of origins – e.g., biceps (two origins) and triceps (three origins)

Triceps Brachii = A long, a lateral and A medial origin Naming Skeletal Muscles ‘Cause this is the occiput

▪ Location of attachments – named according to point of origin or insertion Naming Skeletal Muscles

▪ Action – e.g., flexor or extensor, as in the names of muscles that flex or extend, respectively Major Skeletal Muscles: Anterior View

Facial Levator labii sup/inf Head Levator/depressor anguli oris ▪ The 48 superficial Temporalis Epicranius, frontal belly Masseter Orbicularis oculi Zygomaticus major/minor Shoulder muscles and the Orbicularis oris Trapezius Neck Deltoid Platysma diaphragm here are Arm Sternocleidomastoid Triceps brachii Thorax Biceps brachii Coracobrachialis divided into 11 Brachialis Subscapularis Forearm Pectoralis minor Pronator teres Serratus anterior regional areas of Brachioradialis Pectoralis major Flexor carpi radialis Intercostals and diaphragm Palmaris longus Abdomen the body (definitelyFlexor digit superficialis Pelvis/thigh Rectus abdominis Iliopsoas Internal oblique know all of these + Pectineus Transversus abdominis Thigh External oblique Thigh thenar, hypothenar Rectus femoris Vastus lateralis Tensor fasciae latae Vastus medialis Sartorius and extrinsic eye) Adductor longus Leg Gracilis Fibularis longus Leg Extensor digitorum longus Gastrocnemius Tibialis anterior Soleus Extensor halluces longus Major Skeletal Muscles: Posterior View

Neck ▪ The 28 superficial Epicranius, occipital belly Sternocleidomastoid Arm muscles here are Trapezius Triceps brachii Shoulder Brachialis divided into 7 Deltoid Forearm regional areas of Infra/supraspinatus Brachioradialis Teres major/minor Extensor carpi the body radialis longus/brevis Rhomboid major Latissimus dorsi Flexor carpi ulnaris Hip (definitely know Extensor carpi ulnaris Gluteus medius Gluteus maximus all of these +, Extensor digitorum again, thenar, Iliotibial tract Thigh Adductor magnus hypothenar and Hamstrings: Leg Biceps femoris extrinsic eye) Gastrocnemius Semitendinosus Flexor pollicis Opponens brevis Soleus Semimembranosus digiti minimi Abductor pollicis brevis Flexor digiti Fibularis longus minimi brevis Opponens pollicis Abductor Calcaneal digiti minimi 89 total (Achilles) tendon Only 165 slides to go in this chapter covering almost every muscle in the body from the smallest eye muscle to the largest thigh muscle.

If you haven’t started studying yet, tonight would be a very good time. Muscles: Name, O/I, Action, and Innervation

▪ Name and description of the muscle – be alert to information given in the name (ie, temporalis) ▪ Origin and insertion – there is always a joint between the origin and insertion ▪ Action – best learned by acting out a muscle’s movement on one’s own body (OK, everyone test the fibularis longus right now) ▪ Nerve supply – name of major nerve that innervates the muscle Muscles of the Scalp

Here’s the first one. Let’s see if you can wrap your head around this one. Muscles of the Scalp

▪ Epicranius (occipitofrontalis) – bipartite muscle consisting of the: ▪ Frontalis & ▪ Occipitalis & ▪ Galea aponeurotica – cranial aponeurosis connecting above muscles ▪ These two muscles have alternate actions of pulling the scalp forward and backward Muscles of the Scalp

Facial nerve Muscles of the Scalp

Epicranius

Galea aponeurotica Frontal belly

Occipital belly Facial nerve

Muscles of the Face

▪ 11 muscles are involved in lifting the eyebrows, flaring the nostrils, opening and closing the eyes and mouth, and smiling Pretty Face ▪ All are innervated by cranial nerve Japanese author Yasuhiro Kano VII (facial nerve) ▪ Usually insert in skin (rather than bone), and adjacent muscles often fuse Muscles of the Face

Corrugator supercilii Orbicularis oculi Levator labii superioris Zygomaticus minor and major Buccinator Risorius Orbicularis oris Mentalis Depressor labii inferioris Depressor anguli oris Platysma Yes, sorry, you just have to commit them to memory. Here’s a sample question from the test

The muscles of facial expression are innervated by… a) cranial nerve III b) cranial nerve XII c) cranial nerve VII d) cranial nerve V

Muscles of Mastication

▪ There are four pairs of muscles involved in mastication (chewing your food) ▪ Prime movers – temporalis and masseter ▪ Grinding movements – 2 pterygoids ▪ All are innervated by cranial nerve V (trigeminal nerve) Muscles of Mastication All four are Trigeminal nerve, CN V

Temporalis

Masseter

Under masseter Muscles of Mastication

Lateral pterygoid Medial pterygoid

Masseter pulled away These are Trigeminal nerve, CN V Extrinsic Tongue Muscles

▪ Three major muscles that anchor and move the tongue ▪ All are innervated by cranial nerve XII (hypoglossal nerve) Extrinsic Tongue Muscles

Cranial nerve XII (hypo-glossal nerve) For all the –glossus muscles

Tongue Styloid process Styloglossus Genioglossus Hyoglossus Mandibular Stylohyoid symphysis Hyoid bone Geniohyoid Thyrohyoid Thyroid cartilage

But, that’s it for the easy innervations: The next bunch have 7 different innervations Muscles of the Anterior Neck and Throat: Suprahyoid

▪ Four deep throat muscles ▪ Form the floor of the oral cavity ▪ Anchor the tongue ▪ Elevate the hyoid (suprahyoid, they only pull, so, these must elevate) ▪ Move the larynx superiorly during swallowing Muscles of the Anterior Neck and Throat: Suprahyoid

Anterior Mylohyoid Digastric belly Stylohyoid Posterior Hyoid bone belly

And, a geniohyoid which is deep to the mylohyoid Muscles of the Anterior Neck and Throat: Suprahyoid

Mylohyoid Hyoid bone (cut) Geniohyoid But,,,,,,,,

Muscles of the Anterior Neck and Throat: Infrahyoid

▪ Straplike muscles that depress the hyoid and larynx during swallowing and speaking Muscles of the Anterior Neck and Throat: Infrahyoid

Omohyoid (superior belly) Thyrohyoid Sternohyoid

Sternothyroid Omohyoid (inferior belly) But, again

Muscles of the Neck: Head Movements Muscles of the Neck: Head Movements

▪ Major head flexor is the sternocleidomastoid ▪ Lateral head movements are accomplished by the sternocleidomastoid and scalene muscles ▪ Head extension is accomplished by the deep splenius muscles and aided by the superficial trapezius Muscles of the Neck: Head Movements

Base of 1st cervical occipital bone vertebra Mastoid process Middle Sternocleido- scalene mastoid Anterior scalene Posterior scalene

(a) Anterior Muscles of the Neck: Head Movements

Mastoid process

Splenius capitis Spinous processes of the vertebrae Splenius cervicis

(b) Posterior Muscles of the Neck: Head Movements

Trapezius Muscles of the Neck: Head Movements

Flexion and lateral flexion Trunk Movements: Deep Back Muscles Trunk Movements: Deep Back Muscles

▪ The prime mover of back extension is the erector spinae ▪ Erector spinae, or sacrospinalis, muscles consist of three columns on each side of the vertebrae – iliocostalis, longissimus, and spinalis ▪ Lateral bending of the back is accomplished by unilateral contraction of these muscles ▪ Other deep back extensors include the semispinalis muscles and the quadratus lumborum Trunk Movements: Deep Back Muscles

Mastoid process of temporal bone Semispinalis Longissimus capitis capitis Iliocostalis cervicis Semispinalis Longissimus cervicis cervicis Iliocostalis Semispinalis thoracis thoracis Longissimus thoracis Spinalis thoracis Iliocostalis Erector Longissimus spinae Spinalis Multifidus Iliocostalis lumborum Quadratus lumborum External oblique

(d) Trunk Movements: Deep Back Muscles Trunk Movements: Deep Back Muscles Trunk Movements: Short Muscles

▪ Four short muscles Nor this extend from one vertebra to another O = origin I = insertion

▪ These muscles are Intertransversarius synergists in Rotatores extension and Multifidus rotation of the Interspinales spine (e) ▪ Not in the table Muscles of Respiration - Ribs

The only thing I could think of was the BBQ ribs and I already did that. Muscles of Respiration External ▪ The primary function intercostal of deep thoracic muscles is to promote movement for breathing ▪ External intercostals – more superficial layer that lifts the rib cage and increases thoracic volume to allow inspiration (a) Muscles of Respiration - Intercostals

▪ Internal intercostals – deeper layer that aids in forced expiration

Internal intercostal Muscles of Respiration - Intercostals

▪ Diaphragm – most important muscle in inspiration Muscles of Respiration: The Diaphragm

Xiphoid process of sternum Foramen for inferior vena cava Foramen for esophagus Costal cartilage Central tendon of diaphragm Diaphragm

Foramen for aorta Lumbar vertebra

12th rib Quadratus lumborum Psoas major Muscles of Respiration: The Diaphragm

Central tendon of diaphragm

Body of thoracic vertebra Aorta Diaphragm (muscular part) Inferior vena cava Esophagus Pericardial sac

Pericardium (cut) Muscles of Respiration:

Table 10.5.1 Muscles of the Abdominal Wall Muscles of the Abdominal Wall Muscles of the Abdominal Wall

▪ The abdominal wall is composed of four paired muscles (internal and external obliques, transversus abdominis, and rectus abdominis), their fasciae, and their aponeuroses ▪ Fascicles of these muscles run at right and oblique angles to one another, giving the abdominal wall added strength Muscles of the Abdominal Wall - continue

▪ In addition to forming the abdominal wall, these muscles: ▪ Are involved with lateral flexion and rotation of the trunk ▪ Help promote urination, defecation, childbirth, vomiting, coughing, and screaming(sneezing, spitting, tackling, hitting a baseball, throwing, running, driving, getting out of bed, getting into bed………) Muscles of the Abdominal Wall

Tendinous Transversus abdominis intersection

Internal oblique Rectus abdominis External oblique

Aponeurosis of the Inguinal ligament external oblique (formed by free inferior border of the external oblique aponeurosis) (a) Muscles of the Abdominal Wall

LineaLinea alba alba

Not to be confused with…….

Figure 10.11a Muscles of the Abdominal Wall

Jessica Alba Muscles of the Abdominal Wall - continue

Rectus abdominis External Internal oblique oblique Lumbar IIiac crest Pubic fascia tubercle

Transversus Lumbar abdominis fascia Inguinal ligament

(b) Muscles of the Abdominal Wall - continue

Peritoneum Transversus abdominis Rectus abdominis Linea alba External oblique Internal oblique Aponeuroses Skin (c) Again, not…. Table 10.6.1 Extrinsic Shoulder Muscles Extrinsic Shoulder Muscles Extrinsic Shoulder Muscles

▪ Muscles of the thorax ▪ Anterior: pectoralis major, pectoralis minor, serratus anterior, and subclavius ▪ Posterior: latissimus dorsi, trapezius muscles, levator scapulae, and rhomboids ▪ These muscles are involved with the movements of the scapula including elevation, depression, rotation, and lateral and medial movements ▪ Prime movers of shoulder elevation are the trapezius and levator scapulae Extrinsic Shoulder Muscles

Subclavius Clavicle Subscapularis Deltoid Pectoralis minor Pectoralis major Coracobrachialis Sternum Serratus anterior

Humerus

Extrinsic Shoulder Muscles

▪ Muscles of the thorax ▪ Posterior: latissimus dorsi, trapezius muscles, levator scapulae, and rhomboids ▪ These muscles are involved with the movements of the scapula including elevation, depression, rotation, and lateral and medial movements ▪ Prime movers of shoulder elevation are the trapezius and levator scapulae Extrinsic Shoulder Muscles

Levator scapulae Trapezius Supraspinatus Clavicle Deltoid Spine of scapula Rhomboid minor Infraspinatus Rhomboid Teres minor major Teres major

Humerus

Latissimus dorsi

(c)

Muscles Crossing the Shoulder

▪ Nine muscles cross the shoulder joint and insert into the humerus ▪ Prime movers include: ▪ Pectoralis major – arm flexion ▪ Latissimus dorsi and posterior fibers of the deltoid – arm extension ▪ Middle fibers of the deltoid – arm abduction Muscles Crossing the Shoulder

Clavicle

Deltoid Sternum Pectoralis major

Latissimus dorsi

(a) Anterior view (b) Posterior view

Muscles Crossing the Shoulder

▪ Rotator cuff muscles – supraspinatus, infraspinatus, teres minor, and subscapularis SITS ▪ Function mainly to reinforce the capsule of the shoulder ▪ Secondarily act as synergists and fixators Muscles Crossing the Shoulder Supraspinatus

Infraspinatus Teres minor

Subscapularis

Muscles Crossing the Shoulder

▪ The teres major: ▪ Act as a synergist ▪ Does not contribute to reinforcement of the shoulder joint, not a rotator cuff SITS muscle Muscles Crossing the Shoulder

Teres major

Muscles Crossing the Elbow Muscles Crossing the Elbow

▪ Forearm extension ▪ The triceps brachii is the prime mover of forearm extension Muscles Crossing the Elbow

Triceps brachii: Lateral head Long head

Muscles Crossing the Elbow

▪ Forearm flexion ▪ Brachialis and biceps brachii are the chief forearm flexors Muscles Crossing the Shoulder

Biceps Long head brachii Short head

Biceps brachii Brachialis

Brachialis

Muscles of the Forearm

There are a lot of them. Yes, you have to know them. Muscles of the Forearm

▪ The two functional forearm muscle groups are: those that cause wrist movement, and those that move the fingers and the thumb ▪ These muscles insert via strong ligaments which pass under the flexor and extensor retinacula ▪ Most anterior muscles are flexors, and posterior muscles are extensors ▪ The pronator teres and pronator quadratus are not flexors, but pronate the forearm ▪ The supinator muscle is a synergist with the biceps brachii in supinating the forearm Muscles of the Forearm: Anterior Compartment ▪ These muscles are primarily flexors of the wrist and fingers

Palmar aponeurosis

Flexor retinaculum

Flexor digitorum superficialis Flexor carpi ulnaris Palmaris longus Flexor carpi radialis Brachioradialis Medial epicondyle Pronator teres of humerus Table 10.11.1 There are some unspecified, as yet unidentified muscles Flexible Politicus Longus Flexible Politicus Longus Mudwater Quadratus Mudwater Quadratus Muscles of the Forearm: Posterior Compartment These muscles are primarily extensors of the wrist and fingers

Extensor indicis Extensor digiti minimi Extensor carpi ulnaris Extensor digitorum Flexor carpi ulnaris Extensor carpi radialis brevis Extensor carpi radialis longus

(a)

More undiscovered muscles

Extensor Carp Radials Longus and Brevis

Not this one, but the…

Extensor digitorum unos

Not the supinator but the…….

Intrinsic Muscles of the Hand Intrinsic Muscles of the Hand

▪ These small muscles: ▪ Lie in the palm of the hand (none on the dorsal side) ▪ Move the metacarpals and fingers ▪ Control precise movements (e.g., threading a needle) ▪ Are the main abductors and adductors of the fingers ▪ Produce opposition – move the thumb toward the little finger Intrinsic Muscles of the Hand

Tendons of: Flexor digitorum profundus Fibrous sheath Flexor digitorum superficialis Second lumbrical Dorsal interossei Third lumbrical First lumbrical

Fourth Adductor pollicis lumbrical Flexor pollicis Opponens brevis digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Flexor retinaculum

Pisiform bone Abductor pollicis longus Flexor carpi ulnaris tendon Tendons of: Palmaris longus Flexor digitorum superficialis Flexor carpi radialis tendons Flexor pollicis longus (a) First superficial layer Intrinsic Muscles of the Hand

Flexor digitorum profundus tendon Flexor digitorum superficialis tendon

Dorsal interossei Palmar interossei Adductor pollicis Opponens digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis (cut) Abductor pollicis brevis Abductor digiti minimi (cut) Opponens pollicis

Flexor pollicis longus tendon (b) Second layer But…….

Tendons of: Flexor digitorum profundus Fibrous sheath Flexor digitorum superficialis Second lumbrical Dorsal interossei Third lumbrical First lumbrical

Fourth Adductor pollicis lumbrical Flexor pollicis Opponens brevis digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Flexor retinaculum

Pisiform bone Abductor pollicis longus Flexor carpi ulnaris tendon Tendons of: Palmaris longus Flexor digitorum superficialis Flexor carpi radialis tendons Flexor pollicis longus (a) First superficial layer And……

Flexor digitorum profundus tendon Flexor digitorum superficialis tendon

Dorsal interossei Palmar interossei Adductor pollicis Opponens digiti minimi Flexor pollicis brevis Flexor digiti minimi brevis (cut) Abductor pollicis brevis Abductor digiti minimi (cut) Opponens pollicis

Flexor pollicis longus tendon (b) Second layer Except for these…….know these, for this class, can’t guarantee you won’t need to know the others later in life………

Flexor pollicis Opponens brevis digiti minimi Abductor pollicis brevis Flexor digiti minimi brevis Opponens pollicis Abductor digiti minimi Intrinsic Muscles of the Hand: Groups

▪ There are three groups of intrinsic hand muscles ▪ Thenar eminence (ball of the thumb) and ▪ Hypothenar eminence (ball of the little finger) – each have a flexor, an abductor, and an opponens muscle ▪ Midpalm muscles, the lumbricals and interossei, extend the fingers ▪ The interossei also abduct and adduct the fingers

Lower Extremity

Eadweard Muybridge

Edward James Muggeridge April 9, 1830(1830-04-09) Born Kingston upon Thames, England May 8, 1904 (aged 74) Died Kingston upon Thames Resting place Woking Occupation Photographer Muscles Crossing Hip and Knee Joints

▪ Most anterior compartment muscles of the hip and thigh flex the femur at the hip and extend the leg at the knee ▪ Posterior compartment muscles of the hip and thigh extend the thigh and flex the leg ▪ The medial compartment muscles all adduct the thigh ▪ These three groups are enclosed by the fascia lata Fascia Lata (latae) not fascia latte Movements of the Thigh at the Hip: Flexion

▪ The most important thigh flexors are the iliopsoas (prime mover), tensor fasciae lata, and rectus femoris Movements of the Thigh at the Hip: Flexion

Iliac crest Psoas major Iliopsoas Iliacus Anterior superior iliac spine Tensor fasciae latae

• Rectus femoris Movements of the Thigh at the Hip: Flexion Movements of the Thigh at the Hip: Flexion ▪ The medially located adductor muscles and sartorius assist in thigh flexion

▪ If they assist that would make them?????? ▪ A) agonists ▪ B) synergists ▪ C) fixators ▪ D) protagonists ▪ E) assistorius Movements of the Thigh at the Hip: Flexion

Psoas major Iliopsoas Iliacus Anterior superior iliac spine Tensor fasciae latae Pectineus

Sartorius Adductor longus

Adductor magnus • Rectus femoris Movements of the Thigh at the Hip: Flexion

Adductor brevis Adductor magnus Adductor longus

Femur Movements of the Thigh at the Hip: Flexion Movements of the Thigh at the Hip: Extension

▪ Thigh extension is primarily effected by the hamstring muscles (biceps femoris, semitendinosus, and semimembranosus) ▪ Forceful extension is aided by the gluteus maximus Movements of the Thigh at the Hip: Extension

Gluteus maximus

Long head Biceps Short head femoris Hamstrings Semitendinosus Semimembranosus Movements of the Thigh at the Hip: Extension Movements of the Thigh at the Hip: Extension Movements of the Thigh at the Hip: Medial Rotation

▪ ABduction and medial rotation are effected by the gluteus medius and gluteus minimus, and are antagonized by the lateral rotators Movements of the Thigh at the Hip: Medial Rotation

Gluteus medius (cut)

Gluteus minimus Movements of the Thigh at the Hip: Medial Rotation Movements of the Thigh at the Hip: Lateral Rotation Movements of the Thigh at the Hip: Lateral Rotation

Superior gemellus Piriformis Obturator Obturator internus externus Inferior Quadratus gemellus femoris Movements of the Thigh at the Hip: Lateral Rotation Movements of the Thigh at the Hip: Adduction

▪ Thigh adduction is the role of five adductor muscles (adductor magnus, adductor longus, adductor brevis, pectineus, and gracilis) Movements of the Thigh at the Hip: Adduction

Pectineus (cut)

Adductor Adductor magnus longus

Femur Movements of the Thigh at the Hip: Flexion Movements of the Knee Joint Movements of the Knee Joint

▪ The sole extensor of the knee is the quadriceps femoris

Vastus lateralis Vastus ▪ The hamstring intermedius muscles flex the Vastus Rectus femoris medialis tendon (cut) knee, and are Patella antagonists to the Patellar quadriceps femoris ligament Movements of the Knee Joint Muscles of the Leg: Movements

▪ Various leg muscles produce the following movements at the: ▪ Ankle – dorsiflexion and plantar flexion ▪ Intertarsal joints – inversion and eversion of the foot ▪ Toes – flexion and extension Muscles of the Anterior Compartment

▪ These muscles are the primary toe extensors and ankle dorsiflexors

Tibia ▪ They include the Tibialis anterior tibialis anterior, Extensor digitorum longus

extensor digitorum Extensor hallucis longus longus, extensor Superior and inferior hallucis longus, and extensor retinacula fibularis tertius Muscles of the Anterior Compartment

Tibialis anterior

Extensor hallucis longus

Extensor digitorum longus Muscles of the Anterior Compartment Muscles of the Lateral Compartment

▪ These muscles plantar flex and evert the foot

Fibularis longus ▪ They include the fibularis longus and fibularis brevis muscles Fibularis brevis Muscles of the Lateral Compartment

Fibularis longus Fibularis brevis

Tendon of fibularis longus Muscles of the Lateral Compartment Muscles of the Posterior Compartment

▪ These muscles primarily flex the foot and the toes

Gastrocnemius Medial head ▪ They include the Lateral head gastrocnemius, soleus, tibialis posterior, flexor Tendon of digitorum longus, and gastrocnemius flexor hallucis longus Calcaneal tendon Medial malleolus Muscles of the Posterior Compartment

Soleus Tibialis posterior Tendon of plantaris Fibula Flexor digitorum longus Flexor hallucis longus Muscles of the Posterior Compartment I know that you know that there is no need to know and no time to know everything there is to know, so, no need to know the intrinsic foot muscles.

Muscles, end