Human Anatomy_ Musculoskeletal System

Mandible

forms the lower jaw

ramus of mandible

two upward-going projections

coronoid process of the mandible

Anterior projection in mandible that provides attachment for one of the biting muscles

Mandibular condyles

Posterior rounded projection in the mandibular bone

Angle of the mandible

Where the body and ramus come together

Mandibular notch

U-shaped curve located between the coronoid and condylar processes

The Orbit

Composed of frontal,zygomatic, maxilla & palatine bone, Ethmoid & lacrimal, sphenoid

Optic Canal

It is an opening at the posterior apex of the orbit; Allows for passage of the optic nerve from the retina to the brain

Superior orbital fissure

Provides passage for the artery that supples the eyeball, sensory nerves, and the nerves that supply the muscles involved in eye movements

Hyoid Bone

a U-shaped bone in the neck that supports the tongue, attached to the larynx below and the pharynx posteriorly.

vertebral column

Cervical (7), Thoracic (12), Lumbar (5), One Sacrum (Fused S1-S5), Coccyx (Cx)

C1 Vertebra

Articulates superiorly with the occipital condyles of the skull; Articulates inferiorly with the C2 vertebra

Primary Curvature

Retained from the original fetal; Retained as thoracic & Sacrococcygeal curve

Secondary Curvature

Develops after birth; concave posteriorly; cervical & lumbar curve

Components of a typical vertebra

Body; vertebral arch; Seven processes((2)Transverse process, (1)spinous, (2)Superior articular, (2)Inferior articular)

typical cervical vertebrae

Small body;Bifid(Y-shaped spinous process);Sharply curved(U-shaped) transverse processes; Superior & Inferior articular Process are flattened & either upward or downward.

Atypical cervical vertebrae(Atlas)

Lacks body or spinous process(formed by ant. arch & post. arch); Transverse processes are longer compared to other cervical vertebrae; Superior articular proc. are deeply curved for articulation with the occipital condyles on the base of the skull; Inferior arti. joins with superior articular process of C2

Axis(C2)

It has a bony prominence(The dens/odontoid process) that fits into the ring of the atlas. It permits the *head to rotate side to side*; Dens join with the inner aspect of the anterior arch of the atlas then held in place by transverse ligament

Typical Thoracic Vertebrae

Larger bodies, long spinous process but pronounced downward; Superior anti. proc faces anteriorly & Inferior anti. proc. faces superiorly; Costal facet is located on transverse process for articulation with tubercle of a rib

Lumbar Vertebrae

Thickest & largest vertebral body; short transverse process & short blunt spinous process that projects posteriorly; Articular processe are large with superior process facing backward & inferior facing forward

Sacrum

5 fused vertebrae(Median sacral crest,Lateral sacral crest; Sacral promontory; sacral foramina; Superior articular process of the sacrum); Inverted triangular shaped where it tapers down to a non-weight bearing apex

Coccyx

4 fused vertebrae; Articulates with the inferior tip of the sacrum;

intervertebral discs

fibrocartilage pads that separate and cushion the vertebrae; Consists of anulus fibrosus tough fibrous outerlayer of the disc; nucleus pulposus is softer,gel-like material in inner layer of disc

Ribs(Total 12; 7 true;3 False;2 floating)

Articulates posteriorly T1-T12; Most attach anteriorly via costal cartilages to the sternum

Composition of Rib

Head of Rib(Posterior end), articulates with costal facet in T. vertebrae; Costal groove is passage for blood vessels & nerves on the inferior margin of each rib

Clavicle

S-shaped bone on the anterior side of the shoulder; Attached medially to the sternum of the thoracic cage; lateral end articulates with the scapula; Anchored to the axial skeleton by the sternoclavicular joint; allows extensive mobility of the entire pectoral girdle

Scapula

Lies on the posterior aspect of the shoulder; articulates with the humerus to form shoulder joint; Flat, triangular-shaped bone with a prominent ridge running across its posterior surface(Spine of the scapula)

borders of scapula

superior, medial (vertebral), lateral (axillary)

glenoid cavity

Located between the superior and lateral borders; shallow depression that articulates with the humerus to form the glenohumeral join(shoulder joint)

Coracoid process

Hook-like projection located on the lateral end of the superior border; Anchored to the clavicle by ligament, serves as attachment site for muscles of the anterior chest and arm

Acromion (acromial process)

Flattened region extending laterally from the spine; Forms boy tip of the superior shoulder region and articulates with the lateral end of the clavicle

supraspinous fossa, infraspinous fossa and subscapular fossa

Supraspinous fossa(Narrow depression located superior to the spine);Infra(Broader depression located inferior to the spine); Subscapular fossa(Broad depression on the anterior surface of the scapula)

Bones of the Upper Limb

30 Bones in total(Humerus(1),Ulna & Radius(paired bones), 8 carpal, 5 metacarpal, 14 phalanges)

Humerus

upper arm bone

medial epicondyle & Lateral epicondyle

prominent bony projection o the medial and lateral side of the distal humerus

Elbow joint

Trochlea-More medial,pulley-shaped region that articulates ulna bone;Capitulum looks knob-like on humerus that articulates with radius bone

Olecranon Fossa

Large depression at the posterior humerus that receives the olecranon process of the ulna when the forearm is fully extended

Ulna

Trochlear notch;Radial notch of the ulna; Olecranon process; Interosseous Membrane of the forearm; Head of the Ulna; Styloid process of the ulna

Radius

Head of Radius, Radial tuberosity; Radiocarpal joint(Wrist joint); Styloid process of the radius

Wrist Bones

Proximal row(Lateral-medial) Scaphoid, lunate, triquetrum & Pisiform; Distal(lateral-Medial)Trapezium, Trapezoid, Capitate & Harnate

carpometacarpal joint

The proximal end of each bone articulates with one of the distal carpal bones

Metacarpophalangeal joint

The distal end of each bone articulates with the proximal phalanx bone; Forms the knuckles of the hand

phalanx bones

14 Bones;Thumb(Pollex);Dgits1-5(3 bones;Proximal,middle,distal); Interphalangeal join is articulation between adjacent phalanges of the digits

pelvic girdle

hip bones; 2 Hip bones which serves as the attachment point for lower limb

Pelvis

Two hip bones + sacrum and coccyx of the axial skeleton; Forms largely immobile, weight-bearing structure

Pubic symphysis

Where the right and left hip bones converge anteriorly to attach to each other

Adult Hip Bone

Ilium- Fan-like, superior region that forms the largest part,Firmly united to the sacrum at the sacroiliac joint; Ischium-Forms the posteroinferior region, supports the body when sitting; Pubis- forms anterior portion, it curves medially where it joins to the pubis of the apposite hip bone at the pubic symphysis

Acetabulum

Where the 3 hip bone converge centrally to form a deep, cup-shaped cavity; Located on the lateral side of the hip bone; Part of the hip joint

Obturator foramen

Large opening in the anteroinferior hip bone between the ischium and pubis; For the attachment of muscles on both its internal external surfaces

greater pelvis (false pelvis)

Broad, superior region defined laterally by the large upper hip bone; Occupied by parts of the small and large intestines

Lesser pelvis (true pelvis)

More inferior, narrow, rounded space that contains the bladder and other pelvic organs

pelvic brim

Forms the superior margin of the lesser pelvis; Defined by a line formed by the upper margin of the pubic symphysis, iliopectineal line, and the sacral promontory

Pelvic Outlet

Inferior limit of the lesser pelvic; Defined by the inferior margin of the pubic symphysis, ischial tuberosity, and the inferior tip of the coccyx

Buccinator

Origin: maxilla and mandible
Insertion: orbicularis oris/Lips
Action: compresses cheeks & lips against teeth

depressor anguli oris

origin: mandible
insertion: angle of mouth, lower lip
action: depresses angle of mouth

levator labii superioris

Origin: Maxilla
Insertion: upper lip, nose
Action: elevates upper lip

Occipitofrontalis

Origin: occipital
Insertion: skin of eyebrow, nose
Action: elevates brows; moves scalp

Orbicularis oculi

Origin: Maxilla, frontal
Insertion: Encircles eye
Action: Closes eyelids

orbicularis oris

Origin: Maxilla and mandible
Insertion: Lips
Action: Compresses, purses lips

Risorius

origin: fascia of masseter muscle
insertion: angle of mouth
action: draws corner of lip laterally

zygomaticus major

Origin: zygomatic bone
Insertion: Angle of the mouth
Action: Elevates & abducts the upper lip

Zygomaticus Minor

Origin: zygomatic bone
Insertion: orbicularis oris of upper lip
Action: elevates & abducts upper lip

(Muscles of Mastication)Temporalis

origin: temporal fossa
insertion: coronoid process of mandible
action: Elevates & Retracts Mandible

(Muscles of Mastication)Masseter

Origin: Zygomatic arch
Insertion: Mandible
Action: Elevates & Protracts mandible

lateral pterygoid

Origin: Sphenoid bone
Insertion: Mandible
Action: Depresses and retracts mandible

medial pterygoid

origin: Sphenoid, Maxilla
insertion: Mandible
Action:Protracts & Elevates mandible

Sternocleidomastoid

origin: sternum and clavicle
insertion: mastoid process
Action: Individually rotates the head, together flexes the neck and extends the head

Trapezius

Origin: Skull, upper vertebral column
Insertion: Scapula
Action: Extends the head and the neck

Platysma

Origin:
Fascia on superior pectoralis major & deltoid
Insertion:
Edge of Mandible, lower face
Action:
Depresses mandible, depresses
lower lip,
tightens skin of chest

Muscles of the Anterior Neck

Suprahyoid muscles(Geniohyoid,Stylohyoid;Mylohyoid & Digastric);Infrahyoid muscles(Sternohyoid, Sternothyroid, Thyrohyoid & Omohyoid)

Types of Muscles

skeletal, smooth, cardiac

Characteristic of Muscles

excitability:stimuli, contractility:shortens, extensibility: stretch, elasticity: recoil

Skeletal Muscle function

Contract & cause movement, Maintain posture, Prevent excess movement of bones & joints, Opening of internal tracts, Protects internal organs & Maintenance of homeostasis

skeletal muscle Structure

3 layers of connective tissue that compartmentalize the muscle fibers within the muscle

Epimysium

a sheath of dense irregular connective tissue surrounding a muscle; allows contractibility & maintains structural integrity; Separates muscle from other tissues and organs in the area

Perimysium

Middle layer of connective tissue covering each fascicles(muscle fibers organized into bundles); fascicular organization allows the nervous system to trigger a specific movement of a muscle by activating a subset of muscle tissue

Endomysium

Thin connective tissue layer of collagen and reticular fibers covering each muscle fiber; Plays a role in transferring force produced by muscle fibers to the tendons

Sarcomere

the smallest contractile unit of muscle; extends from one Z disc to the next; defined as the region of a myofibril contained between two cytoskeletal structures called Z-discs

A Band

Composed of myosin which span the center of the sarcomere extending toward the Z-discs. Dark due to the thicker myosin filaments overlapping with actin filaments

M-Line

Where the thick filaments are anchored at the middle of the sarcomere

I-Band

Light region contain the thin actin filaments anchored at the Z-discs

H-zone

in the middle of the A band is a little lighter, because the thin filaments do not extend into this region

Myofilament component: Thin filament

Composed of 2 filamentous actin chains; Each globular actin monumer(G-actin) contains a myosin binding site; associated with the regulatory proteins, troponin and tropomyosin

Myofilament component: Thick Filaments

Composed of myosin protein complexes; Its globular head contains an actin-binding site for ATP

Titin

Large protein anchored at the M-line; Helps align the thick filament and adds an elastic element to the sarcomere

Insertion

Moveable end of the muscle that attaches to the bone being pulled

Origin

End of the muscle attached dto a fixed(stabilized) bone

prime mover (agonist)

Principal muscle involved among a number of muscles in an action

Synergist

A muscle that assists the prime mover; can also be the fixator that stabilizes the muscles origin

Antagonist

A muscle with opposite action of the prime mover

Ad

to;toward

ab

away from

sub

under

ductor

something that moves

anti

against, opposite

epi

above

apo

to the side of

longissimus

longest

Longus

long

brevis

short