chap 11

Axial muscles

• have both origins & insertions on axial skeleton

• support & move the head & vertebral column

• function in facial expression, breathing, chewing, & swallowing

• support & protect abdominal & pelvic organs

Appendicular muscles

• control movements of upper & lower limbs

• control movements of pectoral & pelvic girdles

• organized into groups based on locations

Muscles on the front vs back

• front: flex & can do other motions

• back: extend & can do other motions

Tendon

• attaches muscle to bone, skin, or another muscle

• aponeurosis: thin, flattened, sheetlike tendon

• dense regular CT

Muscle attachments

• most cross at least one mobile joint

• upon contraction, one bone moves while other is fixed

• axial muscles

  • attachments

    • superior attachment (usually more moveable)

      • is pulled toward the inferior portion when the muscles contract

    • inferior attachment (usually less moveable)

• appendicular muscles

  • attachments

    • proximal attachment (usually less moveable)

      • of biceps brachii are on scapula

      • ex. biceps brachii is on scapula

    • distal attachment (usually more moveable)

      • is moved toward the proximal attachment when muscles contract

      • ex. biceps brachii is on radius

        • contraction pulls radius toward scapula, flexing the blow

previously used

origin = less moveable attachment

insertion = more moveable attachment

Organizational Patterns of Skeletal Muscle Fibers

• varied organization of fascicles (bundles of muscle fibers)

  • circular muscles

    • concentrically arranged fascicles

    • create a sphincter, control material passage through an opening

    • ex. orbicularis oris

  • parallel muscles

    • fascicles run parallel to muscles long axis

    • sometimes have an expanded central belly / body / gaster

    • high endurance & range of motion, not strong

    • ex. rectus abdominis, biceps brachii

  • convergent muscles

    • widespread fascicles merge toward a common attachment site

    • can pull in varying directions, but not as hard as parallel muscles

    • generates more powerful contractions

    • ex. pectoralis major

  • pennate muscles (anchor points)

    • fascicles organized as if part of large feather

    • fibers pull at an angle to the tendon

      • fascicles that attach obliquely to the tendon

      • 1 or more tendons extending through their body

    • generate more tension/force but don’t pull their tendons as far as parallel muscles

    • 3 subtypes “anchors”

      • unipennate: fascicles on same side of tendon

        • ex. extensor digitorum

      • bipennate: fascicles on both side of tendon, most common

        • ex. rectus femorus, interosseous muscles

      • multipennate: branches of tendon within muscle & fascicles arranged around both sides of each tendon branch

        • generates more powerful contractions

        • ex. deltoid

Actions of skeletal muscles

• agonist

  • prime mover, muscle that contracts to produce a movement

  • ex. triceps brachii is agonist for forearm extension

• antagonist

  • muscle whose contraction opposes that of the agonist

  • allows for smooth movement of controlled speed

  • ex. biceps brachii is antagonist for forearm extension

• synergist

  • muscle that assists agonist by contributing tension or stabilizing point of origin / bones involved (acting as fixators, preventing movement)

    • most useful at start of a movement when the agonist is lengthened & cannot exert much power

  • ex. biceps brachii of the arm is a syngerist to the brachialis muscle (agonist), when both work synergistically to flex elbow joint

Skeletal Muscle Naming

• named according to several criteria

• muscle action

  • indicates muscles primary action

  • ex. flexor digitorum longus flexes digits

• specific body regions

  • indicates muscle location

  • ex. rectus femoris is near the femur

• muscle attachments

  • indicates origins and/or insertions

  • ex. sternocleidomastoid originates on the sternum & clavicle & inserts on the mastoid process

• orientation of muscle fibers

  • indicates organization of muscle fascicles

  • ex. rectus abdominis is composed of fibers running in vertically straight (“rectus”) orientation

• muscle shape

  • ex. deltoid is shaped like a triangular delta symbol

  • ex. abductor pollicis longus is a long muscle

• muscle size

  • gluteus maximus is the largest of the buttocks muscles

    • magnus (big) → major (bigger) → maximus (biggest)

• number of muscle heads at an attachment site

  • indicates # of muscle bellies or heads each contains at the superior or proximal attachment site

  • biceps = 2 heads / triceps = 3 heads / quadriceps = 4 heads

  • ex. triceps brachii has 3 heads,

Muscle naming: Muscle action

• adductor: adducts body part

  • ex. adductor magnus

• abductor: abducts body part

  • ex. abductor pollicis longus

• flexor: flexes a joint

  • ex. flexor carpi radialis

• extensor: extends a joint

  • ex. extensor hallucis longus

Muscle naming: Specific body regions

• oris (mouth)

  • orbicularis oris

• cervis (neck)

  • semispinalis cervicis

• brachial (arm)

  • biceps brachii

• carpi (wrist)

  • flexor carpi ulnaris

• pollicis (thumb)

  • opponens pollicis

• gluteal (buttocks)

  • gluteal medius

• femoris (thigh)

  • quadratus femoris

• hallucis (great toe)

  • extensor hallucis longus

• anterior (front of body)

  • tibialis anterior

• posterior or dorsal/dorsi (back of body)

  • tibialis posterior

  • latissimus dorsi

• superior (closer to the head)

  • serratus posterior superior

• inferior (closer to the feet)

  • serratus posterior inferior

• superficialis (superficial)

  • flexor digitorum super ficialis

• profundus (deep)

  • flexor digitorum produndus

rectus

• straight

deltoid

• triangular

quadratus

• rectangular

trapezius

• trapezoidal

brevis

• short

Clinical: Intramuscular injections

• one route of medication administration

• may be inserted into muscle w a syringe

• medication to cardiovascular system thru muscles blood vessels

• allows large amount of medication given at once

• ensures slower, & more uniform delivery than orally or intravenously

• ex. vaccines, some contraceptive medications, some antibiotics

• common sites: deltoid, gluteal, quadriceps

muscle belly

• the thick, fleshy, and contractile middle part of a skeletal muscle located between its origin and insertion tendons

• forearm larger near elbow than it is near the wrist bc the bellies of the forearm muscles that move the wrist are located near the elbow & the tendons of these muscles extend toward the wrist

palpebrae

• eyelids

Muscles of facial expression

• general characteristics

  • arise from skull & attach to skin

  • generally attach to subcutaneous layer, deep to skin

  • cause skin to move (facial expression) during contraction

  • most are innervated by facial nerve (CN VII)

• muscles of forehead, scalp, & eyebrows

  • occipitofrontalis muscle

    • connects w epicranial aponeurosis (galea aponeurotica) to form epicranius

    • frontal belly raises eyebrows, wrinkles forehead

    • occipital belly retracts scalp slightly

  • corrugator supercilii muscle (deep)

    • draws eyebrows together

    • forms vertical wrinkle lines around the nose

• muscles of the eyelid

  • orbicularis oculi

    • circular muscle fibers surround orbit

    • closes eye (squint, blink, wink)

  • levator palpebrae superioris

    • elevates upper eyelid (open eyes)

• muscles associated w the nose

  • nasalis

    • elevates corners of the nostrils for “flared” nostrils

  • procerus

    • transverse wrinkles nose in distaste

    • continuous w frontal belly of occipitofrontalis muscle

    • above nasalis

• muscles associated w the mouth

  • orbicularis oris

    • closes mouth, puckers lips

  • depressor labii inferioris

    • pulls lower lip inferiorly

  • depressor anguli oris

    • pulls corners of the mouth inferiorly to frown

  • levator labii superioris

    • pulls upper lip superiorly

  • levator anguli oris

    • pulls corners of mouth superiorly & laterally

    • works w zygomaticus major & minor in smiling

  • risorius

    • pulls corner of the lips laterally

    • “why so serious” joker

  • mentalis

    • protrudes lower lip (pouting)

  • platysma (superficial)

    • tenses skin of neck & pulls lower lip inferiorly (pout)

  • buccinator

    • compresses cheek against the teeth when chewing

    • covered by masseter

  • zygomaticus major & minor

    • “smile” elevates the corner of the mouth

What cranial nerve mainly controls muscles in face

• cranial nerve VII (7)

• except levator palpebrae (CN III)

Clinical: Idiopathic Facial Nerve Paralysis (Bell palsy)

• may be without known cause (idiopathic)

• facial nerve inflamed & compressed

• muscles on same side paralyzed

• prednisone often used to reduce swelling

• level & timing of recovery varies

Extrinsic Eye Muscles

• are extraocular

  • insert onto outer / external surface (white/sclera) of the eye & move it

    • outside the eye, not inside

  • 6 extrinsic muscles: 4 rectus & 2 oblique

• rectus eye muscles originate from common tendinous ring

  • medial rectus

    • pulls eye medially (adducts)

  • lateral rectus

    • pulls eye laterally (abducts)

  • inferior rectus

    • pulls eye inferiorly & medially

  • superior rectus

    • pulls eye superiorly & medially

• oblique eye muscles (arise from orbit)

  • inferior oblique

    • elevates & turns eye laterally

  • superior oblique

    • depresses & turns the eye laterally

    • passes through pulleylike loop, trochlea

Muscles of the Oral Cavity & Pharynx: Mastication

• muscles of mastication

  • 4 paired muscles move mandible at temporomandibular joint (TMJ)

  • all 4 are innervated by CN V (trigeminal)

  • temporalis

    • elevates & pulls the mandible posteriorly (retracts)

    • broad, fan shaped

    • when u bite u can feel it

  • masseter

    • elevates & pulls the mandible anteriorly (protracts)

    • most powerful & important masticatory muscle

  • medial & lateral pterygoid

    • protraction & side to side movement of mandible

    • medial also helps w elevation of mandible

• + buccinator is considered an accessory mastication muscle

• menonmic

  • Must Taste Like My Burger

Muscles of the Oral Cavity & Pharynx: Tongue

• intrinsic muscles

  • compose the tongue itself

  • change shape during chewing & speaking

• extrinsic muscles

  • arise from other head & neck structures, attach to tongue

  • names end in -glossus (tongue)

  • produce movements for manipulating food (chewing/swallowing) & speaking

  • most are innervated by CN XII, hypoglossal nerve

    • except palatoglossus, CN X

  • are paired, & include

    • genioglossus: protract tongue

      • genie pops out of a lamp

      • geni = chin

    • styloglossus: elevate & retract tongue

      • imagine pulling string from styloid process

    • hyoglossus: depress & retract tongue

      • imagine pulling string from hyoid bone

    • palatoglossus: elevate posterior part of tongue

      • palate roof of mouth

Muscles of the Oral Cavity & Pharynx: Pharynx

• pharynx muscles

  • the pharynx is a funnel shaped tube (throat) located posterior to and connects oral & nasal cavities

  • includes several muscles that aid in swallowing (constrictors), including superior, middle, & inferior pharyngeal constrictor muscles

    • innervated by CN X (vagus)

    • contract sequentially to push food into esophagus

palato-

• relating to the palate

  • roof of the mouth

Muscles of the Anterior Neck: The Hyoid Muscles

• suprahyoid muscles (MGSD My Gut Seems Damaged / My Gosh Suc D)

  • superior to hyoid bone (floor of the mouth)

  • elevate hyoid bone during swallowing or speaking

  • digastric

    • has 2 bellies, anterior & posterior

    • helps depress mandible

      • starts digestion (by opening mouth)

    • elevates hyoid bone

  • geniohyoid

    • elevates the hyoid bone

    • genio = chin

  • mylohyoid

    • provides muscular floor of mouth, also raises both floor & hyoid up

    • mylo = molar

  • stylohyoid

    • attached to styloid process of temporal bone

    • elevates hyoid bone, elongates oral cavity floor during swallowing

• infrahyoid muscles (TOSS)

  • inferior to hyoid bone

  • depress hyoid bone or thyroid cartilage of larynx as swallowing finishes / speaking

  • Omohyoid

    • depresses hyoid by pulling it toward scapula

  • Sternohyoid

    • depresses hyoid by pulling it toward sternum

  • Sternothyroid

    • depresses thyroid cartilage by pulling it toward sternum

      • to return it to its og position after swallowing

    • deep

  • Thyrohyoid

    • extends from thyroid cartilage to hyoid

    • depresses hyoid bone & elevates thyroid cartilage

      • closes off larynx during swallowing

Muscles of the Anterolateral neck

• generally act to flex neck & head

• sternocleidomastoid (deep)

  • extends from sternum & clavicle to mastoid process

  • bilateral (both sides): flexes neck

  • unilateral (one side): lateral flexion of neck, rotates head to opposite side

    • if left sternocleidomastoid muscle contracts, it rotates the head to the right side of the body

• anterior, middle, & posterior scalene muscles

  • work w sternocleidomastoid to flex neck

  • pull cervical vertebrae toward 1st & 2nd ribs (lateral flexion of neck)

  • elevate 1st & 2nd ribs during forced inhalation

  • “scale” the neck

Muscles of the Posterior neck

• move the head & neck

• generally act to extend the neck & head

• trapezius

  • primary function is to help move pectoral girdle but also helps extend neck

  • medial attachment: occipital bone (superior nuchal line), ligamentum nuchae, spinous processes of C7-T12

  • lateral attachment: clavicle, acromion process & spine of scapula

• splenius capitis, longissimus capitis

  • “bandage”

  • bilateral contraction: extend neck/head

  • unilateral contraction: turn / rotate head to same side (lateral flexion)

• except for semispinalis capitis

  • bilateral contraction: extends neck/head

  • unilateral contraction: rotates head to opposite side

• suboccipital muscles

  • obliquus capitis superior & inferior

    • turn / rotate head to same side (unilateral contraction)

  • rectus capitis posterior major & minor

    • extend neck

Clinical: Congenital Muscular Torticollis

• newborn with shortened sternocleidomastoid

• may persist into childhood

• from birth trauma or prenatal position

• head tilts to affected side & chin to unaffected side

• treatments include

  • physical therapy

  • botulinum toxin, which impairs contraction of affected muscle

Muscles of the Vertebral Column: Erector spinae

• maintain upright posture

  • bilaterally contracted: vertebral column extends

  • unilaterally contracted: lateral flexion toward that side

• 3 groups (listed lateral to medial) (ILS SLI = I Love Sushi) (all deep & paired)

  • iliocostalis group

    • comes from illiac crest to ribs

  • longissimus group

  • spinalis group

Muscles of the Vertebral Column: Other muscles

• transversospinalis muscles

  • connect & stabilize the vertebrae (at an angle)

  • even deeper to erector spinae

  • extend vertebral column & neck

• quadratus lumborum muscles

  • bilaterally contracted: extends vertebral column

  • unilaterally contracted: laterally flexes column

  • located primarily in lumbar region

Inspiration vs Expiration

• inspiration (inhalation)

  • several muscles contract to increase the size of the thoracic cavity, allowing lungs to fill w air

  • diaphragm goes down, larger chest area, lungs fill/get bigger

• expiration (exhalation)

  • some respiratory muscles contract & others relax, decreasing the size of the thoracic cavity & forcing air out of lungs

  • diaphragm goes up, smaller chest area, lungs empty/get smaller

Muscles of Respiration

• found on posterior & anterior thorax

• serratus posterior superior

  • elevates ribs during forced inspiration

  • increases lateral dimensions of thorax (width)

• serratus posterior inferior

  • depresses ribs during forced expiration

• scalene muscles

  • anterior, middle, posterior

  • help elevate 1st and 2nd ribs during forced inspiration

• external intercostals

  • elevate ribs during forced & relaxed inspiration, expanding cavity

  • extend inferomedially (bottom to right)

• internal intercostals

  • deep to external intercostals

  • fibers at right angles to external intercostals

    • & next to sternum (bottom to left)

  • depress ribs during forced expiration / pulls in

    • normal exhalation takes no active muscular effort

• transversus thoracis

  • depresses ribs during forced expiration

• diaphragm

  • internally placed dome shaped muscle that partitions thoracic & abdominal cavities

  • most important muscle associated with breathing

    • quiet, normal breathing

  • muscle fibers converge toward fibrous central tendon

  • contracts during inspiration

    • central tendon pulled inferiorly, increasing dimension of thoracic cavity

      • flattens & moves downwards

    • decreases pressure in the thoracic cavity & increases pressure in abdominopelvic cavity

Muscles of the abdominal wall

• all 4 compress (abdominal wall) & hold abdominal organs in place

  • involved in forced expiration

• flex vertebral column (except for transversus abdominis, at least by itself)

• external oblique

  • located superficially, lateral abdominal wall

  • fibers directed inferomedially

    • fibers go up & right

  • forms aponeurosis anteriorly, that becomes inguinal ligament inferiorly

  • capable of rotating / flexing (+ laterally) vertebral column

• internal oblique

  • located deep to external oblique, fibers project superomedially

    • fibers go down & right

  • forms aponeurosis anteriorly

  • capable of rotating / flexing (+ laterally) vertebral column

• transversus abdominis

  • deepest abdominal muscle, fibers project transversely

  • forms aponeurosis anteriorly

  • “belt” goes straight across

  • provides support & stabilization

• rectus abdominis

  • anteromedial location, fibers run vertically

  • partitioned into 4 segments by 3 fibrous tendinous intersections

    • make “six pack”

  • enclosed within fibrous sleeve, rectus sheath

    • formed from aponeuroses of external & internal oblique, & transversus abdominis

    • rectus sheaths of 2 sides connected by fibrous strip, linea alba

  • flexes vertebral column

• unilateral contraction of oblique muscles & transversus abdominis helps laterally flex the vertebral column & rotate it toward the side opposite the contraction

  • ex. if they contracted the left side it would laterally flex to the left but also twist right

  • also contribute to flexion of the vertebral column when both sides contract simultaneously

Contralateral vs Ipsilateral rotator muscles

• Contralateral: a muscle contracting on one side rotates the head or trunk toward the opposite side

  • ex.

    • external oblique (left contracts → rotates spine to the right)

    • transversospinalis (rotates vertebral column to opposite side)

    • sternocleidomastoid (right contract → rotates the head to the left)

    • semispinalis capitis

• Ipsilateral: a muscle contracting on one side rotates the head or trunk toward the same side

  • ex.

    • internal oblique (left contracts → rotates spine to left)

    • splenius capitis, splenius cervicis, longissimus capitis (right contracts → rotates head to right)

    • obliquus capitis superior & inferior

*the left external oblique and right internal oblique work together to rotate your trunk to the right

Angle of fibers (might be wrong)

• if its external imagine V

• if its internal imagine upside down V

• the point is the medial of body

Muscle Actions on Axial Skeleton

• extend the neck and/or vertebral column

  • splenius muscles

  • erector spinae (ILS: illiocostals, longissimus, spinalis)

  • quadratus lumborum

  • transversospinalis group

  • rectus capitis posterior major & minor

• flex the neck and/or vertebral column

  • sternocleidomastoid

  • scalene muscles

  • external oblique

  • internal oblique

  • rectus abdominis

• laterally flex the vertebral column

  • quadratus lumborum

  • external oblique

  • internal oblique

• rotate head to one side

  • sternocleidomastoid

  • splenius muscles

  • longissimus capitis

  • obliquus capitis inferior

  • obliquus capitis superior

• elevate the ribs

  • serratus posterior superior

  • external intercostals

  • scalene muscles (1st & 2nd ribs only)

• depress the ribs

  • serratus posterior inferior

  • internal intercostals

  • transversus thoracis

Clinical: Hernias

• portion of viscera protrudes through weak point of abdominal wall

• inguinal hernia

  • loop of small intestine protrudes through superficial inguinal ring

  • more likely to occur in males since their inguinal canals are larger to accommodate spermatic cord

  • high abdominal pressure (ex. straining to lift smthin heavy) can push intestine into canal

  • physicians test for it by palpating inguinal ring while patient coughs (cough raises abdominal pressure)

Muscles of the Pelvic floor

• pelvic diaphragm

  • pelvic floor formed by 3 layers of muscles & fasciae

  • supports pelvic viscera (organs)

  • extends from the ischium & pubis of the ossa coxae across the pelvic outlet to the sacrum & coccyx

  • forms muscular wall that covers inferior pelvic opening

• perineum

  • diamond shaped region between lower appendages

  • bound by pubic symphysis, coccyx, ischial tuberosities

  • contains 2 triangles divided by transverse line between ischial tuberosities

    • urogenital triangle contains external genitalia & urethra, more anterior

    • anal triangle contains anus, more posterior

• anal triangle muscles

  • coccygeus

    • forms pelvic floor & supports pelvic viscera

    • right next to sacrum

  • external anal sphincter

    • constricts anal opening, must voluntarily relax to defecate

  • levator ani

    • group of muscles that form the anterior & lateral parts of pelvic diaphragm

  • iliococcygeus

    • forms pelvic floor & supports pelvic viscera

    • above coccygeus

  • pubococcygeus

    • forms pelvic floor & supports pelvic viscera

    • above iliococcygeus

  • puborectalis

    • supports anorectal junction, must relax to defecate

    • above pubococcygeus

• urogenital triangle muscles

  • superficial layer

    • bulbospongiosus (female)

      • narrows vaginal opening, compresses & stiffens clitoris

    • bulbospongiosus (male)

      • ejects urine or semen, compresses base of penis & stiffens penis

    • ischiocavernosus

      • assists w erection of penis or clitoris

    • superficial transverse perineal muscle

      • supports pelvic organs

  • deep layer

    • deep transverse perineal muscle

      • supports pelvic organs

    • external urethral sphincter

      • constricts urethra, must voluntarily relax in order to urinate

serratus

• saw

levator

• raises

rhomboid

• diamond shaped

trapezion

• irregular 4 sided figure

-cep

• head

Movements of the scapula

Elevation & Depression (Up and Down)

• Elevation: Lifting the shoulder blade upward. An example of this is shrugging your shoulders.

  • muscle would have to be above scapula

• Depression: Pulling the shoulder blade downward. An example is pushing down into your chair to lift your hips up.

  • muscle would have to be below scapula

Protraction & Retraction (Forward and Backward)

• Protraction (Abduction): Moving the shoulder blade forward and away from the spine. This happens when you reach forward or push open a heavy door.

  • muscle would have to be

• Retraction (Adduction): Pinching the shoulder blades backward toward the spine. This occurs when you squeeze your shoulder blades together or pull your elbows back during a row exercise.

  • muscle would have to be between scapula

Upward & Downward Rotation (Tilting)

• Upward Rotation: Rotating the lower point (inferior angle) of the scapula outward and upward. This movement is essential for allowing you to lift your arm over your head.

  • imagine abducting

• Downward Rotation: Rotating the scapula back down to its resting position. This happens when you pull your arms down from a high position or put your hands in your pockets

  • imagine adducting

Thoracic Muscles that Move the Pectoral Girdle

• muscles of the pectoral girdle originate on the axial skeleton & insert on the clavicle & scapula

• anterior thoracic muscles: tend to depress / protract (abduct) scapula or clavicle

• all anterior muscles that move the pectoral girdle are deep to other thoracic muscles

  • pectoralis minor

    • deep to pectoralis major

    • helps depress & protract (abducts) scapula

    • hunches shoulder

    • superior attachment: coracoid process of scapula

    • inferior attachment: ribs 3-5

  • serratus anterior

    • fan shaped muscle between anterior ribs & anterior scapula

    • abducts / protracts (agonist) scapula, stabilizes scapula (against the posterior side of the rib cage)

    • superior rotator

      • rotates scapula superiorly so glenoid cavity moves superiorly (imagine abducting limb)

    • superior attachment: medial border of scapula

    • inferior attachment: ribs 1-8 (anterior & superior margins)

  • subclavius

    • extends from clavicle to first rib

    • stabilizes & depresses clavicle

• posterior thoracic muscles: tend to elevate / retract (adduct) scapula

  • levator scapulae

    • attaches to cervical vertebrae & scapula

    • elevates & inferiorly rotates the scapula

      • moves glenoid cavity inferiorly

    • superior attachment: transverse processes of C1-C4

    • inferior attachment: superior part of medial border of scapula (superior angle of scapula)

  • rhomboid major & rhomboid minor

    • runs inferolaterally from vertebrae to scapula, deep to trapezius

    • helps elevate, retract (adduct), inferiorly rotate the scapula

    • major

      • medial attachment: spinous processes of T2-T5

      • lateral attachment: medial border of scapula from spine to inferior angle

    • minor

      • medial attachment: spinous processes of C7-T1

      • lateral attachment: medial border of scapula superior to spine

  • trapezius

    • diamond shaped muscle extending from skull & vertebral column to pectoral girdle

    • superior fibers: elevate scapula, rotate scapula superiorly

    • middle fibers: retract (adducts) scapula

    • inferior fibers: depress scapula

    • medial attachment: occipital bone (superior nuchal line), ligamentum nuchae, spinous processes of C7-T12

    • lateral attachment: clavicle, acromion process & spine of scapula

• in general all posterior thoracic muscles either adduct or extend the arm at the glenohumeral (shoulder) joint

Retraction (adductors) & Protraction (abductors) of the Scapula

• Protractors (anteriorly located)

  • pectoralis minor

  • serratus anterior

• Retractors (posteriorly located)

  • trapezius

  • rhomboids

Elevation, Depression, & Rotation of the Scapula

• Elevators

  • rhomboid major

  • rhomboid minor

  • levator scapulae

  • trapezius (superior part)

• Depressors

  • trapezius (inferior part)

  • pectoralis minor

• Superior rotators

  • serratus anterior

  • trapezius (superior part)

• Inferior rotators

  • rhomboid major

  • rhomboid minor

  • levator scapulae

latissimus

• widest

dorsi

• back

delta

• triangular

teres

• round

Muscles that move the arm at the glenohumeral joint

• 11 muscles cross the glenohumeral joint & move the humerus

• agonists (prime movers) of the glenohumeral joint: latissimus dorsi & pectoralis major (handcuffs)

  • latissimus dorsi

    • broad triangular muscle on back inferiorly

    • agonist of arm extension

    • adducts & medially rotates arm

    • “swimmers muscle”

    • proximal attachment: spinous processes of T7 - T12, ribs 8-12, iliac crest

    • distal attachment: intertubercular sulcus of humerus

  • pectoralis major

    • thick fan shaped muscle on superior, anterior thorax

    • agonist of arm flexion

    • adducts & medially rotates arm

    • proximal attachment / origin: medial clavicle, costal cartilages of ribs 2-6, body of sternum

    • distal attachment / insertion: humerus (lateral part of intertubercular sulcus)

    • “the nae-nae”

  • triceps brachii

    • long head originates on scapula, spans shoulder joint

    • helps extend & adduct the arm

    • proximal attachment:

      • long head: infraglenoid tubercle of scapula

      • lateral head: posterior humerus superior to radial groove

      • short head: posterior humerus inferior to radial groove

    • distal attachment: olecranon of ulna

  • biceps brachii

    • both heads originate on scapula & span shoulder joint

    • assists in flexing the arm (weakly)

    • proximal attachment: supraglenoid tubercle & coracoid process of scapula

    • distal attachment: radial tuberosity & bicipital aponeurosis

  • deltoid

    • forms rounded contour of shoulder

    • agonist / prime abductor of the arm

    • anterior fibers: flex & medially rotate arm

    • lateral / middle fibers: abduct the arm (agonist)

    • posterior fibers: extend & laterally rotate arm

    • canNOT adduct

    • proximal attachment: acromial end of clavicle, acromion & spine of scapula

    • distal attachment: deltoid tuberosity of humerus

  • coracobrachialis

    • flexes & adducts the arm (+ medial rotation)

    • synergist to the pectoralis major

    • proximal attachment: coracoid process of scapula

    • distal attachment: middle medial shaft of humerus

  • teres major

    • extends, adducts, medially rotates arm

    • synergist to the latissimus dorsi

  • rotator cuff muscles (on scapula but move humerus)

    • subscapularis

    • supraspinatus

    • infraspinatus & teres minor

      • teres minor is below infraspinatus

• mnemonic

• “2 Majors and a Mis get cuffed Groove”

• All 3 attach to intertubercular groove of humerus

• all adduct & medially rotate the humerus

  • arm movements when your in handcuffs

  • if handcuffed infront: pec major

  • if handcuffed in back: teres major, latismiss dorsi

• Pec Major

  • + flexes

• Teres Major

  • + extends

• latisMISS dorsi

  • + extends

mnemonic

• Deltoid is Dumb

• he cant add (no adduction)

• but he can flex, extend, med & lat rotation, abduction

Rotator cuff muscles

• (on scapula but move humerus, not scapula)

• reinforce the glenohumeral joint & secure the head of humerus in the glenoid cavity (provide strength + stability)

  • subscapularis

    • medially rotates arm (agonist)

    • ex. when u wind up for a pitch

    • connects scapula to lesser tubercle

    • proximal attachment: subscapular fossa of scapula

    • distal attachment: lesser tubercle of humerus

  • supraspinatus

    • abducts the arm

    • ex. when you start to execute the pitch

    • proximal attachment: supraspinous fossa of scapula

    • distal attachment: greater tubercle of humerus

  • infraspinatus & teres minor

    • laterally rotate arm (agonist) & adducts

    • teres minor is below infraspinatus

    • ex. help slow down the pitching arm upon completion of the pitch

    • connect scapula to greater tubercle

    • proximal attachment: infraspinous fossa of scapula

    • distal attachment: greater tubercle of humerus

• mnemonic

• SITS

  • SIT goes to great tubercle

  • S goes to lesser tubercle

• S: Supraspinatus

  • abducts

• I: Infraspinatus

  • lateral / external rotation

• T: Teres minor

  • lateral / external rotation

• S: Subscapularis

  • medial / internal rotation

Clinical: Rotator Cuff Injuries

• result of trauma or disease

• can be caused by repetitive use

• can be caused by falling on the shoulder or lifting too heavy of an object

• supraspinatus most commonly involved

  • most superficial

• symptoms are swelling, tenderness, & pain w movement

• especially common in baseball players

• may require physical therapy or surgical repair

septa / septum

• a dividing wall, fence, or partition in the body

• intermuscular septa is dense CT and subdivides deep fascia

Arm & Forearm Muscles (that move the forearm at elbow joint)

• limbs are organized into compartments surrounded by deep fascia & subdivided by intermuscular septa

• a compartment houses functionally related muscles

• anterior compartment of the arm has flexor muscles (elbow flexors)

  • supplied blood by deep brachial artery

  • innervated by musculocutaneous nerve

  • ex. biceps brachii, brachialis

• posterior compartment of the arm has extensor muscles (elbow extensors)

  • supplied blood by deep brachial artery

  • innervated by radial nerve

  • ex. triceps brachii

Muscles of the arms anterior compartment

• biceps brachii

  • proximal attachment: supraglenoid tubercle & coracoid process of scapula

  • distal attachment: radial tuberosity & bicipital aponeurosis

  • 2 headed muscle on anterior humerus

    • short / medial head

    • long / lateral head, wraps around

  • flexes (shoulder & elbow)

    • weak flexor of humerus

    • long head only

  • supinates forearm

    • when elbow flexed (agonist)

• brachialis

  • deep to biceps brachii

  • most powerful elbow flexor of forearm

  • proximal attachment: distal anterior surface of humerus

  • distal attachment: tuberosity & coronoid process of ulna

  • u can see it lateral view

• brachioradialis

  • located on anterolateral forearm

    • actually in posterior

  • involved in elbow flexion

  • synergist to the biceps brachii

mnemonic

• bicep brachii 2 heads, 3 actions

• flex shoulder, flex elbow, supination

Muscles of the arms posterior compartment

• triceps brachii

  • large 3 headed muscle on posterior arm

    • lateral head, long head, medial head

      • long head extends & adducts arm

  • major elbow extensor of forearm (agonist) + helps extend humerus

    • extend shoulder, elbow

  • proximal attachment:

    • long head: infraglenoid tubercle of scapula

    • lateral head: posterior humerus superior to radial groove

    • short head: posterior humerus inferior to radial groove

  • distal attachment: olecranon of ulna

• anconeus

  • weak elbow (forearm) extensor

  • crosses posterolateral region of elbow

mnemonic

• triceps brachii 3 heads, 2 actions

• extend shoulder, extend elbow

General rules (can be changed/revised)

• LOTS of muscles end in -alis

• minor above major muscle

• posterior (back)

  • extends

  • laterally rotate

  • adducts (?)

• anterior (front)

  • flexes

  • medially rotate (except latissimus dorsi & teres major)

  • abducts (?)

• abduction

  • radius / lateral side

• adduction

  • ulna / medial side

• for arm

  • biceps brachii (anterior)

    • long head is lateral

    • short head is medial

  • triceps brachii (posterior)

    • lateral head is lateral

    • long head is medial

• for leg

  • biceps femoris (posterior)

    • short head is lateral

    • long head is more medial

• key note: a group’s functions aren’t necessarily shared by every individual muscle!

  • distinguish what the group accomplishes together from what each individual muscle contributes

  • being active during a movement doesn’t necessarily mean a muscle directly produces that movement.

• muscles are like ropes

• pull one attachment toward another attachment

• only move areas they attach to

• muscles moving straight up & down spine (spinalis) only extend

• muscles running at angles to spine (iliocostalis, SCM, QL) move the spine at angles (rotates or laterally flexes)

• origin is the more stable or fixed bone, while the insertion is attached to the bone that moves

• as the muscle shortens, it pulls on its insertion bone, moving it relative to the origin bone.

• muscles that run in diff directions (angled) can do diff things

• pay attention to orgin, thats not gonna move. also direction of fibers indicate how insertion will be pulled toward orgin

Muscles in opposite compartments tend to be

• antagonists

• ex. anterior forearm muscles are primarily flexors & pronators / posterior forearm muscles are primarily extensors & supinators

• ex. muscles in the anterior compartment of the thigh are knee extensors / muscles in the posterior compartment of the thigh are knee flexors

• ex. muscles in medial compartment of thigh are hip adductors / muscle in lateral side of thigh is hip abductor

Muscles that Pronate or Supinate the Forearm

• pronator teres & pronator quadratus

  • rotate the radius across the ulna to pronate forearm

  • located in anterior compartment of forearm

    • teres closer to elbow (rounded)

    • quadratus closer to wrist (rectangle like)

  • more distal

• supinator

  • supinates forearm

  • located in posterior compartment of forearm

  • more proximal

• + biceps brachii when elbow flexed (agonist)

  • anterior, upper arm

Clinical: Lateral Epicondylitis

• also known as tennis elbow

• from trauma or overuse of common extensor tendon of posterior forearm muscles

• pain at lateral epicondyle of humerus, tendons attachment site

• often results from repeated forceful contraction of forearm extensors

Extrinsic Forearm Muscles that move the Wrist Joint, Hand, & Fingers

• forearm muscles are extrinsic to wrist & hand

• intermuscular septa partition muscles into anterior & posterior compartments

• anterior forearm compartment muscles (flexors of wrist)

  • generally flex the wrist, MP, some flex IP joint

  • most arise from medial epicondyle of humerus

• posterior forearm compartment muscles (extensors of wrist)

  • generally extend the wrist, some MP & IP

  • most arise from lateral epicondyle of humerus

• retinacula of the forearm

  • fibrous bands at the wrist formed from deep fascia (made of dense regular CT)

  • hold tendons close to bone

  • flexor retinaculum

    • covers palmar (anterior) surface of carpal bones

    • carpal tunnel: tight space between carpal bones & flexor retinaculum through which flexor tendons pass

  • extensor retinaculum

    • superficial to dorsal (posterior) surface of carpal bones

    • extensor tendons of wrist & digits pass between the bones & extensor retinaculum

Clinical: Carpal Tunnel Syndrome

• space between carpal bones & flexor retinaculum

• flexor tendons extending through through tunnel

• median nerve extending through tunnel

• syndrome caused by compression of nerve

• characterized by pain and “pins and needles” (paresthesia)

Extrinsic Anterior Forearm Muscles (wrist flexors)

anterior compartment muscles

• generally flex the wrist (some flex interphalangeal (IP) joint)

• most arise from medial epicondyle of humerus (proximal attachment)

  • F ME (F for flexors, ME for medial epicondyle)

  • except for flexor pollicis longus & flexor digitorum profundus

superficial layer

• flexor carpi radialis

  • prominent muscle on lateral forearm

  • flexes wrist & abducts hand

• palmaris longus

  • narrow muscle on anterior forearm (between flexor carpi radialis & ulnaris)

  • weakly assists in wrist flexion

  • creates palmar aponeurosis (spiderweb on hand)

• flexor carpi ulnaris

  • flexes wrist & adducts hand

intermediate layer

• flexor digitorum superficialis

  • 4 tendons attach distally to middle phalanges of fingers 2 to 5

  • flexes wrist, MP joints, & proximal interphalangeal (PIP) joints of fingers 2 to 5

deep layer

• flexor pollicis longus

  • lateral side, attaches to distal phalanx of thumb

    • pollex = thumb

  • flexes MP & IP joints of the thumb, weak flexor of wrist

  • proximal attachment: anterior shaft of radius, interosseous membrane

• flexor digitorum profundus

  • medial side, lies deep to flexor digitorum superficialis (intermediate)

  • its 4 tendons attach distally to distal phalanges of finger 2-5

  • flexes wrist, MP joints, proximal interphalangeal (PIP) joints, & distal interphalangeal (DIP) joints of fingers 2 to 5

  • proximal attachment: anteromedial surface of ulna, interosseous membrane

mnemonic (medial → lateral)

• “Pass Fail Pass Fail”

• superficial layer (from lateral to medial)

  • pronator teres → flexor carpi radialis → palmaris longus → flexor carpi ulnaris

• deep layer (from lateral to medial)

  • flexor pollicis longus, flexor digitorum profundus

    • pronator quadratus is deep

Extrinsic Posterior Forearm Muscles (wrist extensors)

• posterior compartment muscles

  • generally extend the wrist (some extend metacarpophalangeal (MP) & interphalangeal (IP) joints)

  • most arise from lateral epicondyle of humerus (proximal attachment)

superficial layer

• extensor carpi radialis longus

  • extends & abducts hand at wrist

• extensor carpi radialis brevis

  • extends & abducts hand at wrist

  • works synergistically w longus

• extensor digitorum

  • inserts on distal phalanges of fingers 2-5

  • extends hand at wrist, extends MP joints, PIP joints, & DIP joints of finger 2-5

• extensor digit minimi

  • attaches to distal phalanx of finger 5 (pinky)

    • extends MP, PIP, DIP joints

    • weakly extends wrist

• extensor carpi ulnaris

  • distal attachment on 5th metacarpal bone (below pinky)

  • extends & adducts hand at wrist

deep layer

• extensor pollicis brevis

  • helps extend MP joint of the thumb

  • weakly extends wrist

• extensor pollicis longus

  • extends MP & IP joints of the thumb

  • weakly extends wrist

• extensor indicis

  • extends MP, PIP, & DIP joints of index finger (2)

  • weakly extends wrist

• abductor pollicis longus (not in slides)

  • abducts the thumb

  • weakly extends hand at wrist

• superficial layer (lateral to medial)

  • brachioradialis → extensor carpi radialis longus → extensor carpi radialis brevis → extensor digitorum → extensor digit minimi → extensor carpi ulnaris

indicis

• of the index finger / pointer

eminence

• circumscribed area raised above the general level of the surrounding surface

Intrinsic Muscles of the Hand

• both proximal & distal attachments are in hand

thenar group: form fleshy mass at base of thumb (thenar eminence)

• flexor pollicis brevis

  • flexes thumb

  • superficial / anterior

• abductor pollicis brevis

  • abducts thumb

  • superficial / anterior

• opponens pollicis

  • assists in opposition of thumb

  • deep / anterior

hypothenar group: fleshy mass at base of little finger (pinky) (hypothenar eminence)

• flexor digiti minimi brevis

  • flexes little finger

  • superficial / anterior

• abductor digiti minimi

  • abducts little finger

  • superficial / anterior

• opponens digiti minimi

  • assists in opposition of little finger

  • deep / anterior

midpalmar group: moves fingers 2-5

• occupies space between thenar & hypothenar groups

  • lumbricals (worm shaped)

    • originate anteriorly but pass posteriorly

    • flex the MP joints

    • extend PIP & DIP joints of fingers 2-5

  • dorsal interossei (between metacarpals)

    • posterior

    • flex MP joints

    • extend PIP & DIP joints of fingers 2-5

    • abducts finger 2-5

  • palmar interossei (between metacarpals)

    • anterior

    • flex the MP joints

    • extend the PIP & DIP joints of fingers 2-5

    • adducts the fingers

  • adductor pollicis

    • anterior

    • adducts thumb

    • tranverse + oblique head

mnenomic for palmar / dorsal interossei

• PAD DAB

• Palmar ADuct

• Dorsal ABduct

Summary of Muscle Actions at the Wrist & Hand

iliotibial tract

• a thick, strong band of fibrous connective tissue (fascia lata) that runs along the outside of the thigh, from the hip down to the shinbone

latae

• wide / broad

tensor

• any muscle that stretches a part of the body or makes it tense

• “to stretch”

Muscles that move the thigh at the hip joint

organization of thigh muscles (muscles that move the thigh at the hip joint)

• bound by the fascia lata

  • deep fascia (of thigh) that partitions them into compartments

  • encircles the thigh muscles like a supportive stocking & tightly binds them

• anterior compartment muscles

  • extend the knee / flex thigh

• medial compartment muscles

  • adduct the thigh

• posterior compartment muscles

  • most flex knee & extend thigh

  • some abduct

• in addition to the compartments

  • gluteal group & deep muscles of the gluteal region

    • gluteus medius + minimus + tensor fascia latae (lateral)

      • abduct the thigh

Muscle of lateral thigh

• tensor fasciae latae

  • attaches to iliotibial tract (lateral thickening of fascia lata)

  • abducts & medially rotates the thigh

Muscles of the medial compartment of thigh

• most adduct & flex thigh (still kinda face anteriorly)

• adductor longus, adductor brevis, gracilis, pectineus

  • adduct & flex the thigh (at hip joint)

    • gracilis: + flexes leg at knee joints

• adductor magnus

  • adducts thigh, flexes thigh (adductor part), extends thigh (hamstring part) & laterally rotates the thigh (hip joint)

• obturator externus

  • laterally rotates the thigh (hip joint)

mnemonic

• “PAAGAm” (for all muscles) or “PAG” for more superficial deep ones

• Pectineus, Adductor brevis, Adductor longus, Gracilis, Adductor magnus

  • help u do pee pee dance (except adductor magnus, that also helps extend & laterally rotate)

Muscles of anterior compartment of thigh

• psoas major & iliacus (collectively iliopsoas)

  • run from lumbar vertebrae & illum to femur

  • flex thigh (hip joint)

• quadriceps femoris

  • composite muscle w 4 heads

  • consists of: rectus femoris, vastus lateralis, vastus medialis, vastus intermedius

    • if it has a V it only extends knee

    • rectus femoris

      • goes up to pelvis (ASIS) / crosses hip joint, so it also flexes hip

      • proximal attachment: anterior inferior iliac spine

      • distal attachment: quadriceps tendon to patella & then patellar ligament to tibial tuberosity

    • vastus intermedius

      • underneath rectus femoris

      • proximal attachment: anterolateral surface of femur

      • distal attachment: quadriceps tendon to patella & then patellar ligament to tibial tuberosity

    • vastus lateralis

      • proximal attachment: greater trochanter & linea aspera

      • distal attachment: quadriceps tendon to patella & then patellar ligament to tibial tuberosity

    • vastus medialis

      • proximal attachment: intertrochanteric line & linea aspera of femur

      • distal attachment: quadriceps tendon to patella & then patellar ligament to tibial tuberosity

  • agonist of knee extension

    • imagine kicking soccer ball, knee extended (vastus) & hip flexed (rectus femoris)

  • pulls on quadriceps tendon, which becomes patellar ligament to tibia

• sartorius

  • acts on both hip & knee joints

    • longest in the body

  • flexes & laterally rotates thigh

  • flexes & medially rotates leg

  • “seatbelt”

Muscles of posterior compartment of thigh

• contraction of gluteal muscle results in extension of the thigh

• contraction of deep muscles of gluteal region results in lateral rotation of the thigh

• superficial muscles in gluteal region

  • gluteus maximus

    • agonist of thigh extension

    • laterally rotates the thigh

  • gluteus medius & gluteus minimus

    • deep to gluteus maximus

    • abduct & medially rotate the thigh

• hamstrings (group of 3 muscles)

  • (lateral → medial) biceps femoris short → long head, semitendinosus, semimembranosus

    • bicep femoris: by itself laterally

      • has 2 heads

      • long head: extends thigh

      • long & short: flexes leg

      • laterally rotates leg when leg is flexed

      • proximal attachment:

        • long head: ischial tuberosity

        • short head: linea aspera of femur

      • distal attachment: head of fibula

    • semitendinosus:

      • medially rotate leg

      • proximal attachment: ischial tuberosity

      • distal attachment: proximal medial surface of tibia

    • semimembranosus:

      • medially rotate leg

      • beneath & more medial to semitendinosus

      • proximal attachment: ischial tuberosity

      • distal attachment: posterior surface of medial condyle of tibia

  • extend thigh (hip joint)

  • flex leg (knee joint)

    • mnemonic: imagine kicking leg up kawaii / getting ready to kick

• group of muscles deep to gluteal muscles

  • piriformis, superior gemellus, obturator internus, inferior gemellus, & quadratus femoris (small muscle that rotates hips outward)

  • laterally rotate the thigh

Clinical: Thigh Muscle Injuries

groin strain (groin pull, pulled groin)

• Tearing, stretching, straining proximal attachments of medial muscles

of thigh (for example, adductor muscles, gracilis)

• Typically occurs if muscles contract too suddenly, forcefully

• ex. jumping, kicking, change direction while running

Strained or pulled hamstring

• Hamstring tendons avulsed (torn away) during quick starts/stops, fast

running, sudden lateral/medial stress to knee joint

Prevention by doing dynamic warm-up prior to exercise, static

stretching after exercise

Leg Muscles that move the Ankle, Foot, Toes

• crural muscles

  • muscles located in leg that move ankle, foot, toes

  • partitioned into anterior, lateral, & posterior compartments

  • evert = lateral / fibula

  • invert = medial / tibia

  • anterior

    • dorsiflex (extends toes up)

    • extend

    • tibialis anterior inverts

  • posterior

    • plantarflex (tippy toes)

    • flex

    • tibialis posterior inverts

  • lateral

    • evert foot

    • weakly plantar flex

• extensor retinaculum

  • thickening of fascia at ankle that holds tendons of the muscles within the anterior compartment close to bones

Legs anterior compartment

• mainly dorsiflexors (foot) & extensors (toes)

  • imagine after toes grab marble it trying to let go of it

• extensor digitorum longus

  • dorsiflexes the foot & extends toes 2-5

• extensor hallucis longus

  • dorsiflexes the foot & extends the great toe

• fibularis tertius

  • dorsiflexes & weakly everts foot

• tibialis anterior

  • primary dorsiflexor & inverts foot

  • proximal attachment: lateral condyle & proximal shaft of tibia, interosseous membrane

  • distal attachment: metatarsal I & 1st cuneiform

Legs lateral compartment

• 2 synergistic muscles, both are powerful foot evertors, weak plantar flexors (foot)

• fibularis longus

  • attaches to plantar side of foot

• fibularis brevis

  • lies deep to fibularis longus

  • attaches to base of 5th metatarsal (below pinky)

Legs posterior compartment

• mainly plantarflexors & flexors (leg & toes)

  • imagine toes trying to grab marble / dig into ground

superficial layer

• gastrocnemius

  • 2 bellies (lat & medial head), forms calf

  • crosses knee & ankle joint

    • “more gas so it crosses 2 joints”

  • flexes the leg (knee joint) & plantar flexes the foot

  • proximal attachment: superior & posterior surfaces of lateral & medial condyles of femur

  • distal attachment: calcaneus

• soleus

  • broad muscle deep to gastrocnemius

  • “so low” only covers 1 ankle joint

  • plantar flexes the foot

  • proximal attachment: head & proximal shaft of fibula, medial border of tibia

  • distal attachment: calcaneus

• triceps surae

  • gastrocnemius + soleus

  • attach to heel (calcaneus) w calcaneal tendon

• plantaris

  • weak leg flexor & plantar flexor of the foot

deep layer

• flexor digitorum longus

  • plantar / flexes foot & MP, PIP, DIP joints of toes 2-5

  • medial side

• flexor hallucis longus

  • plantar / flexes foot & great toe (MP & IP)

  • lateral but crosses over to medial

• tibialis posterior

  • plantar flexes & inverts foot (agonist)

  • in the middle kinda hidden behind

• popliteus

  • flexes leg & medially rotates tibia (to unlock knee)

  • no action at ankle or foot

Clinical: Shin Splints & Compartment Syndrome

• shin splints

  • soreness along length of tibia

  • often occur in new poorly conditioned runners

  • may be considered a type of compartment syndrome

• compartment syndrome

  • compression of blood vessels within a limb compartment

  • due to inflammation & swelling secondary to strain or trauma

  • increased pressure in compartment since deep fascia cannot stretch

  • in severe cases, fascia cut to relieve pressure

Muscles that extend or flex the leg at the knee joint

Intrinsic Muscles of Foot

• have both proximal & distal attachments within foot

• support arches, flex/extend toes, abduct/adduct toes

• rarely perform all the precise movements their names suggest

dorsal group (top of foot): extends

• extensor hallucis brevis

  • extends the MP joint of the great toe (1)

• extensor digitorum brevis

  • extends the MP & PIP joints of toes 2-4

plantar group (bottom of foot): potentially flex, extend, abduct, adduct

• supported by plantar aponeurosis formed by deep fascia

  • extends between phalanges of toes & calcaneus, encloses plantar muscles

• muscles grouped into 4 layers from superficial → deep

1. flexor digitorum brevis, abductor hallucis, abductor digiti minimi

• flexor digitorum brevis: flexes MP & PIP joints of toes 2-5

• abductor hallucis: abducts great toe (1)

• abductor minimi: abducts little toe (5)

2. quadratus plantae, lumbricals

• quadratus plantae: pulls on flexor digitorum longus tendon to flex toes 2-5

• lumbricals: flexes MP joints & extends PIP & DIP joints of toes 2-5

3. adductor hallucis, flexor hallucis brevis, flexor digiti minimi brevis

• adductor hallucis: adducts great toe (1)

• flexor hallucis brevis: flexes MP joint of great toe (1)

• flexor digiti minimi brevis: flexes MP joint of little toe (5)

4. dorsal interossei, plantar interossei

• dorsal interossei: abducts toes

• plantar interossei: adducts toes

Clinical: Plantar Fasciitis

• inflammation of the plantar aponeurosis

• associated with overexertion that stresses the fascia

• ex. weight bearing activities, excessive body weight, poor shoes, poor biomechanics

brachii

• of the arm

Multifidus

• a group of deep, short muscles that run along both sides of the spinal column from the base of the skull down to the sacrum,

• largest role in lower lumbar back

• extends and rotates the vertebral column toward the opposite side of the body. Its origin is on the sacrum and transverse processes of each vertebra and its insertion is the spinous processes of more superior vertebrae

What correctly describe compartments of the thigh

• are anatomically defined by the fascia latae

• include muscles w similar actions

• include blood vessels & nerves for a single compartment

fasciae latae

• deep fascia (of thigh) that partitions them into compartments

• encircles the thigh muscles like a supportive stocking & tightly binds them

The anatomical & functional criteria for defining compartments of muscles that move the hip & knee joints are identical

• true

  • bc compartments are defined anatomically by partitions of deep fascia, muscles within each compartment create similar movements at each joint

Innervation of Muscles of the Head & Neck

• muscles of facial expression: CN VII (facial nerve)

  • except

    • levator palpebrae superioris: CN III (oculomotor nerve)

• extrinsic eye muscles: CN III (occulomotor nerve)

  • except

    • lateral rectus: CN VI (abducens nerve)

    • superior oblique: CN IV (trochlear nerve)

• muscles of mastication: CN V3

• muscles that move the tongue: CN XII

  • except

    • palatoglossus: CN X (vagus nerve)

• muscles of the pharynx: mostly CN X

• muscles of the anterior neck:

• muscles of the posterior neck: either cervical spinal nerves or suboccipital nerve

  • except sternocleidomastoid: CN XI (accessory nerve)

Innervation of Vertebral Column

• either cervical, thoracic, & lumbar spinal nerves (or a combination of them)

Innervation of Muscles of Respiration / thoracic

• thoracic spinal nerves

  • except

    • diaphragm: phrenic nerves (C3-C5)

Innervation of Muscles of the Abdominal Wall

• spinal nerves T8-T-12

  • except

    • rectus abdominis: spinal nerves T7-T12

Innervation of

Innervation of Muscles of the Pelvic Floor

• pudendal nerve (S2-S4)

  • except

    • coccygeus: spinal nerves S4-S5

Innervation of Thoracic Muscles that Move the Pectoral Girdle

•