Gross Anatomy Day 2 (Back)

Triangle of Auscultation

• lower border of the trap

• latissimus dorsi

• medial border of the scapula

intermediate (middle) layer

Rhomboids

• major

• minor

levator scapulae

upper back and posterior neck

semispinalis and splenius capitus

Deep layer

erector spinae

• iliocostalis

• longissimus

• spinalis

Vertebral Column

consists of 26 bones:

• 24 vertebrae, 1 sacrum, and 1 coccyx

Functions of the vertebral column

• provides a column of support

• bears the weight of the head, neck, and trunk

• transfers weight to the lower limbs

• encloses and protects the spinal cord

• provides a passageway for spinal nerves

• helps maintain the upright position of the body

regions of the vertebral column

from superior to inferior they are,

• cervical (7)

• Thoracic (12)

• lumbar (5)

• sacral (1) composed of 5 fused vertebrae

• coccygeal (1) composed of 3-5 fused vertebrae

cervical vertebrae

7 total- smallest most superior

spinous processes are relatively stumpy and may be split, resulting in bifid process

C7 vertebral prominens

the last cervical vertebrae and therefore resembles the thoracic vertebra in structure

• has a long, slender spinous process

• enlarged transverse processes that may or may not contain a transverse foramen

Nuchal ligment

extends from the spinous process cranially to the occipital crest

limits flexion of the head and neck and provides attachment surface for the dorsal muscles of the neck

Thoracic Vertebrae

12 total vertebrae make up the posterior of the rib cage

the bodies have a heart shape

the spinous process is long and slender and points on a posterocuadal angle

the transverse processes point dorsolateral

the thoracic vertebrae articulate with ribs and contain extra facets

Lumbar vertebrae

the largest vertebrae (5) make up the lower back region- weight bearing

the body is very thick and oval shaped

relatively small vertebral foramina are triangular

the transverse processes point more laterally

the spinous process resembles a tail fin of a fish, stumpy and flattened

The sacrum

• is curved with a convex dorsal surface, consist of the fused components of 5 sacral vertebrae

  • fuse shortly after puberty (25-30)

• protects reproductive, digestive, and excretory organs

• broad surface area provides an extensive area for attachment of muscles

  • especially those involved in thigh movement

• sacral apex: narrow cuadal portion

• broad superior surface forms the base

The coccyx

consists of 3-5 fused coccygeal vertebrae

• being fusing by age 26

provides an attachment site for ligaments and a muscle that constricts the anal opening

in males, the adult coccyx points anteriorly while in females it points inferiorly

in the very elderly the coccyx may fuse with the sacrum

extrinsic (superficial)

• trapezius

• latissimus dorsi

• levator scapulae

• rhomboids

intermediate muscles of the back

• erector spinae

  • costalis

  • longissimus

  • spinalis

intrinsic muscles of the back

splenius capitus

• splenius cervicus ( this is deep)

Trapezius Origin

occipital protruberance

superior nuchal line

nuchal ligament

spinous process of C7, T1-T12

Trapezius Insertion

posterior boarder of the lateral clavicle

medial border of the acromion

spine of the scapula

Trapezius Action

adducts the scapula

upper part elevates

lower part depresses

Trapezius Nerve

spinal accessory nerve

Latissimus dorsi origin

• vertebral spines of T6-L

• medial crest of the sacrum (via the thoracolumbar facia)

• posterior 1/3 of the iliac crest

• lower 4 ribs

• inferior angle of the scapula

Latissimus dorsi insertion

floor or inner lip of the intertubercular groove

latissimus dorsi action

extends, adducts and medially rotates the arm

latissimus dorsi nerve

thoracodorsal (C6, C7, C8)

Rhomboids minor origin

from the nuchal and spine of C7

Rhomboid major origin

from the nuchal spine of T5

rhomboids insertion

medial border of the scapula

rhomboids action

adducts scapula

rhomboids innervation

dorsal scapula

Levator scapulae origin

posterior tubercles of the transverse process C1-C4

Levator scapulae insertion

superior angle of the scapula

levator scapulae action

“I don’t know” elevates the scapula

levator scapulae nerve

dorsal scapula

Semispinalis Capitis origin

transverse process of C7 - T7

articular process of C4-C6

Semispinalis Capitis insertion

occipital bone and inferior nuchal line

Semispinalis Capitis action

extends the head

rotates to the opposite side

Semispinalis Capitis innervation

posterior (dorsal) rami of spinal nerves

Splenius capitus origin

nuchal ligament

spines of C7-T3

Splenius capitus insertion

lateral 1/3 of the nuchal line

mastoid process

Splenius capitus action

extends and laterally flexes head and laterally rotates the head

Splenius capitus nerve

posterior rami of the spinal nerves

splenius cervicus origin

spinous process of T3, T4, T5, T6

splenius cervicus insertion

posterior transverse processes of upper 3 cervical vertebrae

splenius cervicus action

extension of the neck, rotation and lateral flexion to the same side

splenius cervicus nerve

posterior rami of the cervical spinal nerves

erector spine innervation

posterior rami of the spinal nerves

axial skeleton

part of the skeleton that forms the central axis of the body. it supports and protects the brain, spinal cord, and organs in the chest

Parts of the axial skeleton

1. skull - protects the brain

2. vertebral column (spine) : protects the spinal cord and supports the body

3. thoracic cage: includes the ribs and sternum (breastbone) and protects the heart

4. hyoid bone: supports the tounge and helps with swollowing

Body (vertebral body)

large, thick anterior portion of the vertebral

bears weight and supports the vertebral column

Vertebral arch

posterior portion surrounding the vertebral foramen

helps protect the spinal cord

vertebral foramen

opening between the body and vertebral arch

the openings line up to form the vertebral canal, which contains the spinal cord

spinous process

single projection extending posteriorly

provides attachment for muscles and ligaments; acts as a level for spinal movement

transverse processes

two projections extending laterally

provide muscle/ligament attachment and act as levers for movement

superior articular processes

processes that project upward

form facet joints with the vertebra above; help guide and limit movement

inferior articular processes

processes that project downward

form facet joints with the vertebra below; help guide and limit movement

intervertebral foramen

opening between adjacent vertebrae

allows spinal nerves and blood vessels to exit/enter the vertebral canal

Cervical Vertebral body

small and wider from side to side than anteroposterior; superior surface concave with uncus of body (uncinate process); inferior surface convex

Cervical vertebral foramen

large and triangular

cervical transverse processes

foramina transversarii and anterior and posterior tubercles; vertebral arteries and accompanying venous and sympathetic plexuses pass through foramina transversarii of all cervical vertebrae except C7, which transmits only small accessory vertebral veins

cervical articular processes

superior facets directed superoposteriorly; inferior facets directed inferoanteriorly; obliquely placed facets are most nearly horizontal in this region

cervical spinous processes

short (C3-C5) and bifid (C3-C6); process of C6 long, that of C7 is longer

thoracic vertebral body

heart-shaped; two or four costal facets for articulation with heads of the ribs

thoracic vertebral foramen

circular and smaller than those of cervical and lumbar vertebrae (admits the distal part of a medium-size index finger)

thoracic transverse process

long and strong and extend posterolaterally; length diminishes from T1 to T12

thoracic articular processes

nearly vertical articular facets; superior facets directed posterity and slightly laterally; inferior facets directed anteriorly and slightly medially; planes of facets lie on an arc centered in the vertebral body

thoracic spinous processes

long, slope posteroinferiorly; tips extend to level of vertebral body below

Lumbar vertebral body

massive; kidney shaped when viewed superiorly

lumbar vertebral foramen

triangular; larger than in thoracic vertebrae and smaller than in cervical vertebrae

lumbar transverse processes

long and slender; accessory process on posterior surface of the base of each process

lumbar articular process

nearly vertical facets, superior facets directed posteromedially; inferior facets directed anterolaterally; mammillary process on posteror surface of each superior articular process

Lumbar spinous processes

short and sturdy; thick, broad, and hatchet shaped

transverse foramina

found in cervical vertebrae

Bifid spinous processes

typically C2-C6

C1

atlas, has no body and no typical spinous process

C2

axis, has the dens (odontoid process)

C7

has a long, prominent spinous process called the vertebra prominens

costal facets/demifacets

allow attachment of the ribs

T1

has a complete superior costal facet for rib 1

T11 and T12

have a single complete costal facet on each side and lack transverse costal facets

mammillary processes

found on lumbar vertebrae

accessory process

found on lumbar vertebrae

Transverse and spinous process (action)

provide attachment for deep back muscles and serve as levers, facilitating the muscles that fix or change the position of the vertebrae

vertebral body

small and wider from side to side than anteroposteriorly; superior surface concave with uncus of body

foramen transversarium

the most distinctive feature of each cervical vertebra is the oval foramen transversarium in the transverse process. the vertebral arteries and their acompanying veins pass through the foramina, except those in C7, which transmit only small accessory veins

vertebral foramen

the vertebral arch and the posterior surface of the vertebral body form the walls of this

pedicule

short, stout cylindrical processes that project posteriorly from the vertebral body to meet two broad, flat plates of bone, called laminae which unite in the midline

which vertebrae articulates with the skull?

atlas-cervical-C1

what is the role of the transverse ligament

this ligament extends from one lateral mass of the atlas to the other, passing between the dens and spinal cord, forming the posterior wall of the “socket” that receives the dens. it prevents posterior displacement of the dens and anterior displacement of the atlas

what is the main function of the sacrum?

the sacrum provides strength and stability to the pelvis and transmits the weight of the body to the pelvic girdle, the bony ring formed by the hip bones and sacrum, to which the lower limbs are attached

usually composed of 5 fused sacral vertebrae in adults. it its located between the hip bones and forms the roof and posterosuperior wall of the posterior half of the pelvic cavity

anterior longitudinal ligament (ALL) location

runs along the anterior/front surfaces of the vertebrae bodies

anterior longitudinal ligament (ALL) how it increases spinal stability

prevents excessive extension (backward bending) and helps prevent the vertebrae from separating anteriorly

posterior longitudinal ligament (PLL) location

runs along the posterior surfaces of the vertebral bodies inside the vertebral canal

posterior longitudinal ligament (PLL) how it increases spinal stability

limits excessive flexion (forward bending) and helps stabilize the vertebral bodies

ligamentum flavum location

connects the laminae of adjacent vertebrae

ligamentum flavum how it increases spinal stability

helps resist excessive flexion and assist the spine in returning to its normal position after flexion, its elastic fibers also help protect the spinal cord

interspinous ligaments location

between adjacent spinous processes

interspinous ligaments how it increases spinal stability

limit excessive flexion and help keep the spinous processes aligned

supraspinous ligament location

runs along the tips of the spinous processes

supraspinous ligament- how it increases spinal stability

helps limit flexion and provides additional support between the vertebrae