Chapter 10 anatomy

internal intercostals

- 11 pairs Lie between ribs; fibers run deep to and at right angles to those of external intercostals (i.e. run downward and posteriorly) 1) O- super border of rib below 2) I- inferior border (costal groove) of rib above 3) A- with 12th ribs fixed by quadrates lumborum and abdominal muscles, the internal intercostals draw ribs together and depress rib cage; aid in forced expiration; antagonists to external intercostals

external intercostals

- 11 pairs lie between ribs; fibers run obliquely from each rib to rib below 1) O- inferior border of rib above 2) I- superior border of rib below 3) A- with first ribs fixed by scalene muscles, pull ribs toward one another to elevate rib cage; aid in inspiration; synergists of diaphragm

external oblique

- Largest of the three layers; most superficial layer; fibers run inferiorly and medially (hands in pocket orientation); its aponeurosis turns under inferiorly, forming the inguinal ligament 1) O- by fleshy strips from outer surfaces of lower eight ribs 2) I- most fibers insert into linea alba via a broad aponeurosis 3) A- compress abdominal wall; trunk rotation and lateral flexion; used in oblique curls

deep muscles of the thorax

- breathing -the thoracic muscles are very short - most run only from one rib to the next - they form three layers in the wall of the thorax Include: - external intercostals - internal intercostals - diaphragm

splenius

- broad bipartite superficial muscle (capitis and crevices parts) extending from upper thoracic vertebrae to skull 1) O- ligamentum niche, spinous process of C7-T6 2) I- mastoid process of temporal bone and occipital bone (capitis), transverse process of c2-c4 vertebrae 3) A- extend or hyperextend head; when spleniua muscles on one side are activated, head is rotated and bent laterally toward same side

diaphragm

- broad muscle pierced by the aorta, inferior vena cava, and esophagus; forms floor of thoracic cavity 1) O- inferior internal surface of rib cage and sternum, costal cartilages of last six ribs, and lumbar vertebrae 2) I- central tendon 3) A- prime mover of inspiration; flattens on contraction, increasing vertical dimensions of thorax, when strongly contracted, dramatically increases intraabdominal pressure

semispinalis

- capitis, cervicis, and thoracis regions - composite muscle forming part of deep layer of intrinsic back muscles 1) O- transverse process C7-T12 2) I- occipital boen (captitis) and spinous processes of cervical (cervicis) and thoracic vertebrae T1-T4 thoracis 3) A- (capitis) together, the two sides extend the neck; alone, each side extends and laterally flexes next and turns head to opposite side; extends vertebral column and rotates toward opposite side

orbicularis oris

- complicated, multilayered muscle of the lips with fibers that run in different directions, mostly circularly 1) O- arises indirectly from maxilla and mandible; fibers blended with fibers of other facial muscles associated with the lips 2) I- encircles mouth; inserts into muscle and skin at angles of mouth 3) A-closes, purses and protrudes lips; kissing and whistling muscle

digastric

- consist of two bellies united by an intermediate tendon, forming a V shaped under the chin 1) O- lower margin of mandible (anterior belly) and mastoid process of the temporal bone (posterior belly) 2) I- by a connective tissue loop to hyoid bone 3) A- open mouth and depress mandible; acting in concert, the digastric muscles elevate the hyoid bone and steady it during swallowing and speech

medial pterygoid

- deep two-headed muscle that runs along internal surface of mandible, and it largely concealed by that bone 1) O- medial surface of lateral pterygoid plate of sphenoid bone, maxilla, and palatine bone 2) I- medial surface of mandible near its angle 3) A- acts with lateral pterygoid muscle to protract mandible an t promote side-to-side (grinding) movements; synergist of temporalis and masseter muscles in elevation of the mandible

transversus abdominus

- deepest (innermost) muscle layer of abdominal wall; fibers run horizontally 1) O- inguinal ligament, lumbar fascia, cartilages of last six ribs; iliac crest 2) I- Linea alba, pubic crest 3) A- compresses abdominal contents

Genioglossus

- fan-shaped muscle; forms bulk of inferior part of tongue; its attachment to mandible prevents tongue from falling backward and obstructing respiration 1) O- internal surface of mandible near symphysis 2) I- inferior aspect of the tongue and body of hyoid bone 3) A- primarily protracts tongue, but can be depress or act in concert with other extrinsic muscles to retract tongue

hypoglossus

- flat, quadrilateral muscle 1) O- body and greater horn of hyoid bone 2) I- inferolateral tongue 3) A- depressed tongue and draws it sides downward

mylohyoid

- flat, triangular muscle just deep to digastric muscle; this muscle pair forms a sling that forms the floor of the anterior mouth 1) O- medial surface of mandible 2) I- hyoid bone and median raphe 3) A- elevates hyoid bone and floor of mouth, enabling tongue to exert backward and upward pressure that forces food bolus into pharynx

quadrates lumborum

- fleshy muscle forming part of posterior abdominal wall 1) O- iliac crest and lumbar fascia 2) I- transverse processes of upper lumbar vertebrae/ lower margin of 12th rib 3) A- together, they depress the ribs; flexes vertebral column laterally; fixes floating ribs 11-12 during forced exhalation; assisting in forced inhilation

erector spinae

- intrinsic muscles of the back - prime mover of back extension; these muscles, on each side, consist of three columns of muscles, whose subset muscles are named according to their location on the vertebral column Includes: - iliocostalis - longissimus - spinalis

sternothyroid

- lateral and deep to sternohyoid 1) O- posterior surface of manubrium 2) I- thyroid cartilage 3) A- pulls larynx and hyoid bone inferiorly

rectus abdominis

- medial muscle pair of anterior wall, whose fibers extend vertically from pubis to rib cage - ensheathed by aponeuroses (rectal sheath) of the lateral muscles of the abdominal wall - segmented by 3 tendinous inscriptions (band of fibrous tissue) - extend medially to unseat on the linea alba (white lines), which is a tendinous raphe/seam that extends from sternum to pubic symphysis

internal oblique

- most fibers run superiorly and medially (opposite that of external oblique muscles) 1) O- lumbar fascia, iliac crest, and inguinal ligament 2) I- linea alba, pubic crest, last three or four ribs and costal margin 3) A- same as for external oblique

sternohyoid

- most medial muscle of the neck; thin; superficial except inferiorly, where it is covered by the sternocleidomastoid muscle 1) O- manubrium and medial end of clavicle 2) I- lower margin of hyoid bone 3) A- depresses larynx and hyoid bone if mandible is fixed; may also flex skull

zygomaticus

- muscle pair extending diagonally from cheekbone to corner of mouth 1) A- zygomatic bone 2) I- skin and muscle at corner of mouth 3) A- raises lateral corners of mouth upward (smiling muscle)

supra hyoid muscles

- muscles that help form floor of oral cavity, anchor tongue, elevate hyoid, and move larynx superiorly during swallowing; lie superior to hyoid bone Include: - digastric - stylohyoid -mylohyoid -geniohyoid

geniohyoid

- narrow muscle in contact with it partner medially; runs from chin to hyoid bone deep to mylohyoid 1) O- inner surface of mandibular symphysis 2) I- hyoid bone 3) A- pulls hyoid boen superiorly and anteriorly, shortening floor of mouth and widening pharynx for receiving food during swallowing

mentalis

- one of the muscle pair forming a V-shaped muscle mass on chin 1) O- Mandible below incisors 2) I- skin of chin 3) A- protrudes lower lip; wrinkles chin

epicranius

- or occipitofrontalis - bipartite muscle consisting of two muscles connected by a cranial aponeurosis, called the galea aponeurotic; the alternate actions of the two muscles pull the scalp forward and backward Includes - frontalis muscle (or frontal belly) - occipitals muscle ( or occipital belly)

occipitals muscle ( or occipital belly)

- overlies the posterior occipital 1) O- occipital and temporal (mastoid) bones 2) I- galea aponeurotica 3) A- fixes aponeurosis and pulls the scalp posteriorly

masseter

- powerful muscle that covers the lateral aspect of the mandibular ramus 1) O- zygomatic arch and zygomatic bone 2) I- angle and ramus of mandible 3) A- prime mover of jaw closure; elevates mandible

multifidus

- relatively short muscle 1) O- sacrum ad transverse process of each vertebra 2) I- spinous processes of 3rd or 4th more superior vertebra 3) A- extends vertebral vertebral column and rotates toward opposite side

stylohyoid

- slender muscle below angle of jaw; parallels posterior belly of digastric muscle 1) O- styloid process of temporal bone 2) I- hyoid bone 3) A- elevates and retracts hyoid, thereby elongating floor of mouth during swallowing

styloglossus

- slender muscle running superiorly to and at right angles to hypoglossus 1) O- styloid process of temporal bone 2) I- lateral inferior aspect of tongue 3) A- retracts and elevates tongue

depressor labii inferioris

- small muscle running from mandible to lower lip 1) O- body of mandible lateral to its midline 2) I- skin and muscle of lower lip 3) A- draws lower lip inferiorly (as in a pout)

corrugator supercilii

- small muscle; activity associated with hat of orbiculares oculi 1) o-arch of frontal bone above nasal bone 2) I- skin of eyebrow 3) A- draws eyebrows together and inferiorly wrinkles skin of forehead vertically (as in frowning)

omohyoid

- strap like muscle with two bellies united by an intermediate tendon; lateral to sternohyoid 1) O- superior surface of scapula 2) I- hyoid bone, lower border 3) A- depresses and retracts hyoid bone

levator labii superioris

- thin muscle between orbicularis oris and inferior eye margin 1) O- zygomatic bone and infraorbital margin of maxilla 2) I- skin and muscle of upper lift 3) A- opens lips; raises and furrows the upper lip

orbicularis oculi

- thin, flat sphincter muscle of eyelid; surrounds the rim of the orbit 1) O- frontal and maxillary bones and ligaments around orbit 2) I- tissue of eyelid 3) A- closes the eye; protects from intense light and injury; produces blinking squinting, and draws eyebrows inferiorly

infra hyoid muscles

- traplike muscles that depress the hyoid bone and larynx during swallowing and speaking Includes: - sternohyoid - sternothyroid - omohyoid - thyrohyoid

sternocleidomastoid

- two-headed muscle located deep to platysma; key muscular landmark in neck 1) O- manubrium and medial portion of clavicle 2) I- mastoid process of temporal bone and superior nuchal line of occipital bone 3) A- flexes and laterally rotates the head; simultaneous contraction of bone muscles causes neck flexion, generally against resistance as when one raises head when lying on back; acting alone, each muscle rotates head toward shoulder on opposite side and tilts or laterally flexes head to its own side

platysma

- unpaired, thin, sheet-like superficial neck muscle 1) O- fascia of chest (over pectoral muscles and deltoid) 2) I- lower margin of mandible; and skin and muscle at corner of mouth 3) A- helps depress mandible; pulls lower lip back and down, i.e., produces downward sag of mouth; tenses skin of neck (e.g. during shaving)

spinalis group

-cervicis and thoracis -most medial muscle group; cervicis usually rudimentary and poorly defined 1) O- spines of upper lumbar and lower thoracic vertebrae 2) I- spines of upper thoracic and cervical vertebrae 3) A- extends vertebral column

iliocostalis group

-cervicis, thoracis, lumborum - most lateral muscle group of erector spinae, extending from pelvis to neck 1) O- iliac crests (lumborum); inferior 6 ribs (thoracic); ribs 3-6 (crevices) 2) I- angles of ribs (lumborum and thoracic); transverse processes of C6-C4 3) A- extend and laterally flex the vertebral column; acting on one side, causes lateral flexion; (capitis) extends head and turns the face toward same side

lateral pterygoid

-deep two-headed muscle; lies superior to medial pterygoid muscle 1) O- greater wing and lateral pterygoind plate of sphenoid bone 2) I- condyle of mandible and capsule of temporomandibular joint 3) A- proves forward sliding and side-to-side grinding movements of the lower teeth; protracts mandible (pulls it anteriorly)

interspinales

-relatively short muscle 1) O- spinous process of each vertebra 2) I- spinous processes of more superior vertebra 3) A- extends vertebral column

deep muscles of the spine (transversospinalis)

-semispinalis -multifidus - interspinales - intertransversarii - quadratus lumborum

Risorius

-slender muscle inferior and lateral to zygomaticus 1) O- lateral fascia associated with masseter muscle 2) I- skin at angle of mouth 3) A- draws corner of lip laterally; tenses lips; synergist of zygomaticus

linea alba

-white line between rectus abdominis - goes through belly button

rectus abdominis (OIA)

1) O- pubic crest and symphysis 2) I- xiphoid process and costal cartilages of ribs 5-7 3) A-flex and rotate lumbar region of vertebral column; fix and depress ribs, stabilize pelvis during walking, increase intra-abdominal pressure; used in sit-ups/ curls

intertransversarii

1) O- transverse process of each vertebra 2) I- transverse process f more superior vertebra 3) A- lateral flexion of vertebral column

buccinator

Thin, horizontal (principle) cheek muscle; deep to masseter 1) O- molar region of maxilla an mandible 2) I- orbicularis oris 3) A- draws corner of mouth laterally; compresses cheek (as in whistling and sucking); holds food between teeth during chewing; well developed in nursing infants

temporalis

a fan-shaped muscle that covers parts of the temporal, frontal, and parietal bones 1) O- temporal fossa 2) I- coronoid process of mandible via a tendon that passes deep to zygomatic arch 3) A- closes jaw; elevates ad retracts mandible; maintains position of the mandible at rest; deep anterior part may help protract mandible

thyrohyoid

appears as a superior continuation of sternothyroid muscle 1) O- thyroid cartilage 2) I- hyoid bone 3) A- depresses hyoid bone or elevates larynx if hyoid bone is fixed

frontalis muscle

covers the forehead and dome of skull; no bony attachments 1) O- galea aponeurotica 2) I- skin of eyebrows and root of nose 3) A- with aponeurosis fixed, it raises the eyebrows (as in surprise); wrinkles forehead skin horizontally

anterolateral neck muscles

includes: - sternocleidomastoid - scalenes

scalenes

located more laterally than anteriorly on neck; deep to platysma and sternocleidomastoid 1) O- transverse processes of cervical vertebrae 2) I- anterolaterally on first two ribs 3) A- elevate first two ribs (aid in inspiration); flex and rotate neck

masseter, temporalis, and buccinator are what?

mastication muscles