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Lecture 8

BLG 700 Lecture Notes - Extensor Digiti Minimi Muscle, External Occipital Protuberance, Acromion

11 Pages
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Department
Biology
Course Code
BLG 700
Professor
Nancy Woodley

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Muscular System
Chap 9 (Section 9.6, 9.7), 10, 11
Skeletal muscles most extend from one bone to another and cross at least on joint
contraction causes movement pulling one bone toward another across a joint
o some attached to bone only on one end and to some other tissue on the other end e.g. to skin of
face allowing for facial expressions
strength related to the total number of myofibers (muscle cells) in the muscle
range of motion related to fascicle arrangement (bundles of muscle cells) (Fig 9.12)
o shape and size greatly influence the degree to which a muscle can contract and the amount of force it
can generate
o parallel muscles fascicules parallel to long axis of muscle and terminate on a flat tendon that spans
the width of the entire muscle
most skeletal muscles = parallel muscles
can be interrupted by transverse segments of connective tissue
may exhibit twisted or spinal arrangement
when activated can be shortened to a maximum of ~30%
o circular arranged in a circle around an opening and act as sphincters to close opening
when muscle contracts diameter of opening decreases
guard entrances and exits of internal passages
o convergent fasciculi arrive at one common attachment
tendon, tendinosus sheet, or raphe - slender band of collagen fibers
fibers spread out in fan-like manner
o pennate fasciculi emerge feather-like from a common tendon that runs the entire length of the
muscle
unipennate = fascicles arise from one side of the tendon only
bipennate = two sides of the tendon
multipennate = arranged in many places around central tendon
muscle terminology
o origin = fixed end of skeletal muscle, usually most stationary and proximal end of muscle
head = name given when muscle has multiple origins that converge to form one muscle
triceps brachii
o insertion = mobile end usually the distal end attached to the bone undergoing the greatest
movement
o belly = part of muscle between origin and insertion
o tendons long cable-like dense regular connective tissue that attach muscle to bone
aponeuroses = broad, sheet-like tendons
o innervation = nerve supply to a particular structure
one or more motor nerves control each muscle
actions = movement produced when muscle contracts
o agonist = muscle that produces a certain desired movement e.g. flexion
synergists = group of muscles working together to produce a movement e.g. hip flexors
prime mover = muscle within a synergistic group that plays the major role in the movement
o antagonist = muscle contraction whose action that counteracts the agonist movement e.g. extension
o fixators = prime movers and antagonists contract simultaneously to hold one bone in place relative to
the body while a usually more distal bone is moved
named according to:
o location (brachialis)
o size (gluteus maximus)
o length longus (long), brevis (short)
o shape (deltoid triangular)
o orientation of fascicles (rectus femoris straight with the axis of the bone)
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o origin and insertion (sternocleidomastoid origin sternum and clavicle, insertion mastoid process of
temporal bone)
o number of heads (biceps two heads)
o Function (abductor femoris)
Divisions of Skeletal Muscle System (Fig 10.1, 10.2)
Axial musculature origins on axial skeleton
o Positions head and vertebral column and assists in breathing by moving rib cage
Appendicular musculature stabilizes or moves components of appendicular skeleton
Axial Muscles
4 groups based on location and/or function
o Head and neck muscles, muscles of vertebral column, muscular walls of thoracic and abdominopelvic
cavities, muscles of the perineum and pelvic diaphragm
Head and Neck Muscles (Fig 10.3-10.9, Table 10.1-10.6)
A lot of these muscles are cutaneous they have origin that is on bone and have intersections on skin
Originate on skull or hyoid bone and not associated with vertebral column
Muscles of facial expression, extra-ocular muscles, muscles of mastication, muscles of the tongue, muscles
of the pharynx, and anterior muscles of the neck
o Responsible for verbal and non-verbal communication, feeding, and movement of eyes
Facial Expression (Fig 10.3, 10.4, Table 10.1)
o Cutaneous muscles origins on surface of skull and insertions via collagenous fibers of epimysium
(connective tissue wrapping skeletal muscles) woven into dermis of skin
Allow skin to twitch to remove irritants (e.g. insects)
Important in non-verbal communication
o Largest group associated with movement of mouth
Closing and puckering lips:
Orbicularis oris closes lips constricts opening while other muscles move lips or corners of
mouth
o Origin = nasal septum, maxilla, and mandible
Buccinator flattens cheek allows suckling and puckering
o Origin = mandible and maxilla
Smiling:
zygmaticus major and minor elevate and abduct upper lip; origin = zygomatic bone
levator anguli oris elevates angle of mouth; origin = maxilla
risoris abducts angle of mouth: origin = fascia of masseter
Sneering:
levator labii superioris elevates upper lip; origin = maxilla
Pouting or frowning:
Depressor annuli oris depresses angle of mouth; origin = mandible
Depressor labii inferioris depresses lower lip; origin = mandible
Mentalis- protrudes lower lip; origin = mandible
Name one or 2 anagonist that smile, antagonist are those that causes you to frown
A synergist is the same thing; ex name a synergist of zygmaticus major the synergist will be zygmaticus
minor
o Smaller group controls movement of eyebrows, eyelids, scalp, nose and external ear
occipitofrontalis raises eyebrows and furrows skin of forehead; origin = occipital bone; insertion =
skin of eyebrow and nose
Orbicularis oculi closes eyelids and auses o’s feet; origin = maxilla and frontal bones
levator palpebrae superior (Fig 10.5) raises upper lids; origin = lesser wing of sphenoid bone
Ptosis = droopy eyelid on one side usually indicates nerve damage leading to the muscle
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Corrugator supercilii draws eyebrows inferiorly and medially producing vertical corrugations
between eyes origin = nasal bridge
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find more resources at oneclass.com Muscular System Chap 9 (Section 9.6, 9.7), 10, 11 Skeletal muscles – most extend from one bone to another and cross at least on joint  contraction – causes movement – pulling one bone toward another across a joint o some attached to bone only on one end and to some other tissue on the other end – e.g. to skin of face allowing for facial expressions  strength related to the total number of myofibers (muscle cells) in the muscle  range of motion related to fascicle arrangement (bundles of muscle cells) (Fig 9.12) o shape and size greatly influence the degree to which a muscle can contract and the amount of force it can generate o parallel muscles – fascicules parallel to long axis of muscle and terminate on a flat tendon that spans the width of the entire muscle  most skeletal muscles = parallel muscles  can be interrupted by transverse segments of connective tissue  may exhibit twisted or spinal arrangement  when activated can be shortened to a maximum of ~30% o circular – arranged in a circle around an opening and act as sphincters to close opening  when muscle contracts diameter of opening decreases  guard entrances and exits of internal passages o convergent – fasciculi arrive at one common attachment  tendon, tendinosus sheet, or raphe - slender band of collagen fibers  fibers spread out in fan-like manner o pennate – fasciculi emerge feather-like from a common tendon that runs the entire length of the muscle  unipennate = fascicles arise from one side of the tendon only  bipennate = two sides of the tendon  multipennate = arranged in many places around central tendon  muscle terminology o origin = fixed end of skeletal muscle, usually most stationary and proximal end of muscle  head = name given when muscle has multiple origins that converge to form one muscle  triceps brachii o insertion = mobile end – usually the distal end attached to the bone undergoing the greatest movement o belly = part of muscle between origin and insertion o tendons – long cable-like dense regular connective tissue that attach muscle to bone  aponeuroses = broad, sheet-like tendons o innervation = nerve supply to a particular structure  one or more motor nerves control each muscle  actions = movement produced when muscle contracts o agonist = muscle that produces a certain desired movement – e.g. flexion  synergists = group of muscles working together to produce a movement – e.g. hip flexors  prime mover = muscle within a synergistic group that plays the major role in the movement o antagonist = muscle contraction whose action that counteracts the agonist movement – e.g. extension o fixators = prime movers and antagonists contract simultaneously to hold one bone in place relative to the body while a usually more distal bone is moved  named according to: o location (brachialis) o size (gluteus maximus) o length – longus (long), brevis (short) o shape (deltoid – triangular) o orientation of fascicles (rectus femoris – straight with the axis of the bone) 1 find more resources at oneclass.com find more resources at oneclass.com o origin and insertion (sternocleidomastoid – origin sternum and clavicle, insertion mastoid process of temporal bone) o number of heads (biceps – two heads) o Function (abductor femoris) Divisions of Skeletal Muscle System (Fig 10.1, 10.2)  Axial musculature – origins on axial skeleton o Positions head and vertebral column and assists in breathing by moving rib cage  Appendicular musculature – stabilizes or moves components of appendicular skeleton Axial Muscles  4 groups based on location and/or function o Head and neck muscles, muscles of vertebral column, muscular walls of thoracic and abdominopelvic cavities, muscles of the perineum and pelvic diaphragm Head and Neck Muscles (Fig 10.3-10.9, Table 10.1-10.6)  A lot of these muscles are cutaneous – they have origin that is on bone and have intersections on skin  Originate on skull or hyoid bone and not associated with vertebral column  Muscles of facial expression, extra-ocular muscles, muscles of mastication, muscles of the tongue, muscles of the pharynx, and anterior muscles of the neck o Responsible for verbal and non-verbal communication, feeding, and movement of eyes Facial Expression (Fig 10.3, 10.4, Table 10.1) o Cutaneous muscles – origins on surface of skull and insertions via collagenous fibers of epimysium (connective tissue wrapping skeletal muscles) woven into dermis of skin  Allow skin to twitch to remove irritants (e.g. insects)  Important in non-verbal communication o Largest group associated with movement of mouth  Closing and puckering lips:  Orbicularis oris – closes lips – constricts opening while other muscles move lips or corners of mouth o Origin = nasal septum, maxilla, and mandible  Buccinator – flattens cheek – allows suckling and puckering o Origin = mandible and maxilla  Smiling:  zygmaticus major and minor – elevate and abduct upper lip; origin = zygomatic bone  levator anguli oris – elevates angle of mouth; origin = maxilla  risoris – abducts angle of mouth: origin = fascia of masseter  Sneering:  levator labii superioris – elevates upper lip; origin = maxilla  Pouting or frowning:  Depressor annuli oris – depresses angle of mouth; origin = mandible  Depressor labii inferioris – depresses lower lip; origin = mandible  Mentalis- protrudes lower lip; origin = mandible Name one or 2 anagonist that smile, antagonist are those that causes you to frown A synergist is the same thing; ex name a synergist of zygmaticus major the synergist will be zygmaticus minor o Smaller group controls movement of eyebrows, eyelids, scalp, nose and external ear  occipitofrontalis – raises eyebrows and furrows skin of forehead; origin = occipital bone; insertion = skin of eyebrow and nose  Orbicularis oculi – closes eyelids and ▯auses ▯▯▯o▯’s feet▯; origin = maxilla and frontal bones  levator palpebrae superior (Fig 10.5)– raises upper lids; origin = lesser wing of sphenoid bone  Ptosis = droopy eyelid on one side – usually indicates nerve damage leading to the muscle 2 find more resources at oneclass.com find more resources at oneclass.com  Corrugator supercilii – draws eyebrows inferiorly and medially producing vertical corrugations between eyes – origin = nasal bridge 3 find more resources at oneclass.com find more resources at oneclass.com Extra-Ocular Muscles (Fig 10.5, Table 10.2) o 6 extra-ocular (extrinsic eye) muscles rotate eyeball within orbit to allow vision in a wider range of directions o origins = surface of orbit, insertions = sclera (thick fibrous outer layer of wall of eye) o rectus muscles = nearly straight with axis of eye and rotate eye in direction of their attachment  superior rectus – ▯look up▯  inferior rectus – ▯look do▯▯▯  superior and inferior are slightly offset so also bring eye medially  lateral rectus – abdu▯ts e▯e ▯look to the side▯  medial rectus – addu▯ts e▯e ▯look to the ▯ose▯ o oblique muscles = oriented at an oblique axis of the eye inserting into posterior lateral margin  superior oblique – ▯o▯es e▯e ▯do▯▯ a▯d out▯  inferior oblique – ▯o▯es e▯e ▯up and out▯ o diplopia = double-vision - each eye not focused on same image and get two separate images  can result from paralysis or weakness of certain extrinsic muscles or neurological diseases o strabismus = ▯o▯ge▯ital ▯eak▯ess of e▯te▯▯al e▯e ▯us▯les i▯ ▯hi▯h e▯e ▯otates ▯ediall▯ ▯▯▯oss-e▯ed▯ o▯ late▯all▯ ▯▯all-e▯ed▯  to compensate eyes may alternate focusing on objects, or only the controllable eye may be used and the brain ignores the input from the other eye making it functionally blind (amblyopia) Mastication (Fig 10.6, Table 10.3) = chewing o move mandible at temporomandibular joint o elevators of mandible – brings mandibular teeth forcefully against maxillary teeth to crush food  masseter – elevates and protracts mandible; origin = zygomatic arch, insertion = mandibular ramus  most powerful and important muscle  temporalis – elevates and retracts mandible; origin = temporal fossa of parietal bone, insertion = mandibular ramus and coronoid process of mandible  medial pterygoid – elevates and protracts mandible; origin = pterygoid plate of sphenoid bone  lateral pterygoid – protracts and depresses mandible; origin = pterygoid plate of sphenoid bone o slight mandibular depression due to relaxation of the elevators and pull of gravity – ▯sla▯k ja▯▯ o grinding food between teeth = medial and lateral excursion of mandible – and all muscles of mastication Muscles of the Tongue (Fig 10.7) o Important in mastication and speech  Moves food around mouth  Holds food in place  Pushes food up to palate and back toward pharynx to initiate swallowing  Changes shape to modify sound during speech o intrinsic muscles = within the tongue itself – change shape of tongue o extrinsic muscles = outside of tongue but attach to it  names end in glossus – meaning tongue  most origins = bone (mandible, styloid process of temporal bone, hyoid)  change shape of tongue, and move it – up, down, out, back Muscles of the Pharynx (Fig. 10.10, 10.11) o Important for swallowing - involves muscles of the hyoid, soft palate, pharynx and larynx o Pharyngeal constrictors (superior, middle and inferior) – initiation of swallowing  Move food bolus (mass of food) into esophagus  Closes larynx to prevent food and water from getting into your respiratory passage o Laryngeal elevators – ▯-pharyngeous▯ muscle insert onto thyroid cartilage and elevate the larynx o salpingopharyngeus – together with palatal muscles opens auditory tube – equalizes pressure between middle ear and atmosphere o Palatal muscles – ▯-palatini▯ – elevate the soft palate 4 find more resources at oneclass.com find more resources at oneclass.com  Close the posterior opening to the nasal cavity during swallowing Anterior Muscles of the Neck (Fig 10.9, Table 10.6) o control position of larynx, depress mandible, tense the floor of the mouth o extrinsic muscles of the larynx – position the larynx  narrow or close laryngeal opening so food does not enter larynx o intrinsic muscles of the larynx – contraction affects the vocal cords  shortening vocal cords lowers the pitch of the voice  lengthening raises the pitch of the voice o suprahyoid muscles – depress mandible, opening mouth and/or elevates mandible;  digastric, geniohyoid, mylohyoid, stylohyoid - insertion = hyoid bone o infrahyoid group – depress the larynx  omohyoid, sternohyoid, sternothyroid - insertion = hyoid bone o sternocleidomastoid  one contracting laterally flexes head to shoulder on same side or rotates head and neck to opposite side  both contracting together flex neck  origin = manubrium and medial clavicle; insertion = mastoid process and superior nuchal line o laryngospasm = tetanic contraction of the muscles that narrow the opening of the larynx  o▯▯u▯s ▯he▯ food o▯ li▯uid ▯goes do▯▯ the ▯▯o▯g ▯a▯▯  can result from severe allergic reactions, tetanus infections or hypocalcemia  typical episode lasts 30-60 seconds  severe cases opening is closed completely and air cannot pass through the larynx to the lungs  botulinum toxin – injection can relax muscles  tracheotomy Muscles of Vertebral Column (Fig 10.10-10.12, Table 10.7, 10.8)  has many extensors but few flexors o many of the large trunk muscles flex the vertebral column when they contract o most of the body weight lies anterior to the vertebral column and gravity tends to flex spine o longus capitis – transverse processes of C4-C6 to base of occipital bone  together - flex neck; one side – rotates neck to that side o longus colli - anterior margins of the cervical vertebrae to transverse processes of superior cervical vertebrae insertion = occipital bone  flexes neck  muscle of back arranged into 3 layers: superficial, intermediate, deep o superficial layer (Fig 10.10):  splenius muscles (splenius capitus and splenius cervicis) – origin: ligamentum nuchae and spines of vertebrae (C7-T6), insertion: mastoid process, occipital bone, superior cervical vertebrae  together - extend neck; one side – rotates and laterally flexes neck to that side  trapezius, latissimus dorsi, levator scapulae, and rhomboids  position pectoral girdle and upper limb (see appendicular muscle section below) o intermediate layer (Fig 10.10):  erector spinae – group of muscles on either side of spine that extend the head, neck and vertebral column  3 subgroups (superior to inferior) o spinalis –origin: C6-C7, T11-T12 o longissimus – accounts for most of the muscle mass in the lower back; origins: cervical and thoracic vertebrae o iloiocostalis – origin: sacrum, illium and lumbar spines  each subgroup has muscles that insert on the skull – capitus; upper cervical vertebrae – cervicis; and lower cervical and upper thoracic vertebrae – thoracis 5 find more resources at oneclass.com find more resources at oneclass.com o capitus and cervicis groups: together - extend neck; one side – rotates and laterally flexes neck to that side o thoracis groups: extend vertebral column; one side – lateral flexion to that side  serratus posterior muscles - assist in rib movement during inspiration o deep layer = intrinsic back muscles  transversopinalis muscles - interconnect and stabilize vertebrae  semispinalis group, mulitidus, rotatores, interspinales, intertrranversarii muscles  short muscles that work in combinations to produce slight extension or rotation of vertebral column Oblique and Rectus Muscles (Fig 10.11, 10.12, Table 10.8)  lie between vertebral column and ventral midline  have cervical, thoracic and abdominal groups  oblique muscles – compress underlying structures or rotate vertebral column o cervical region  scalenes – origin = cervical vertebrae; insertion = first and second ribs  elevates ribs and/or flex neck; one side bends neck and rotates to same side o thoracic region  external intercostals – elevates ribs during quiet inspiration  origin: inferior margin of each rib, insertion: superior border of next rib below  superficial to internal intercostals  internal intercostals – depresses ribs during forced expiration; origin: superior margin of each rib, insertion: inferior border of next rib above o abdominal region – muscles compress abdomen; depress ribs; flexes, laterally flexes and rotates vertebral column  crossing pattern of abdominal muscles creates strong anterior wall  external obliques – superficial lateral abdominal muscle; origin: 5 to 12 ribs, insertion: iliac crest, rectus sheath  internal obliques – middle lateral abdominal muscle; origin: iliac crest, lumbar fascia, insertion: 10 to 12 ribs and rectus sheath  transversus abdominis – deepest abdominal muscle; origin: 7 to 12 costal cartilages, lumbar fascia, insertion: xiphoid process, linea alba, pubis  rectus muscles – oppose erector spinae – flex vertebral column o diaphragm (Fig 10.12) = main muscle of inspiration – flattens to depress floor of thorax; origin: interior of lower ribs, sternum and lumbar vertebrae, insertion: central tendon of diaphragm o rectus abdominus – on either side of linea alba and covered by rectus sheath  linea alba = located in the midline from the xiphoid process to the pubis = dense connective tissue  origin: pubic crest and symphysis pubis, insertion: xiphoid process and inferior ribs  depress ribs, flexes vertebral column, compresses abdomen  te▯di▯ous i▯s▯▯iptio▯s = ▯a▯ds of fi▯▯ous tissue that di▯ide ▯us▯le i▯to ▯epeated seg▯e▯ts ▯si▯- pa▯k▯  hernia (Clinical note, p.283) = when visceral organ or part of an organ protrudes abnormally through an opening in a surrounding muscular wall or partition o inguinal hernia – protrusion of portion of greater omentum or small intestine through inguinal canal  more common in males o diaphragmatic hernia – abdominal organs slide into thoracic cavity  hiatal hernia – if entry is through the esophageal hiatus (opening)  very common and most go unnoticed  increase severity of gastric acid entry in esophagus (gastroesophageal reflux, GERD) Muscles of the Perineum and Pelvic Diaphragm (Fig 10.12, 10.13, Table 10.9, 10.11)  extend from sacrum and coccyx to ischium and pubis
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