Anatomy Unit 2: Back

the vertebral column is located in the __________ portion of the trunk

posterior

what are the four functions of the vertebral column?

1. posture

2. support of weight

3. protection for spinal cord and spinal nerves

4. partial protection for thoracic and abdominal organs

number of cervical vertebrae

7

number of thoracic vertebrae

12

number of lumbar vertebrae

5

fibrocartilaginous structures found between the bodies of adjacent vertebrae

intervertebral discs

number of sacral vertebrae

5 fused vertebrae

number of coccygeal vertebrae

4 fused vertebrae

number of bones in the vertebral column before fusion

33

cause of primary curvature

result of differences in the height between the anterior and the posterior aspects of the vertebral bodies

what direction is the fetal curvature?

concave anteriorly

what direction is the primary curvature?

concave anteriorly

what direction is the secondary curvature?

concave posteriorly

cause of secondary curvature

differences in the heights between the anterior and the posterior aspects of the intervertebral discs

what adult vertebral sections have primary curvature?

thoracic and sacral

what adult vertebral sections have secondary curvature?

cervical and lumbar

large round mass of a vertebra; it forms the anterior aspect of the vertebra

body

Posterior to the body; formed by two pedicles and two laminae

vertebral arch

bridge of bone extending from the posterior aspect of the body

pedicle

flat plate of bone extending from the pedicle; the two laminae fuse with each other in the median plane

lamina

boundaries of the vertebral arch

anterior: body

posterior: laminae

lateral: pedicles

formed by the individual vertebral foramina when the 24 presacral vertebrae are articulated

vertebral canal

single process that projects posteriorly from each vertebral arch at the junction of the two laminae

spinous process

two processes that project laterally from the junction of a lamina and a pedicle

transverse processes

two processes that project superiorly to articulate with the inferior articular process of the supra-jacent vertebra

superior articular processes

two processes that project inferiorly to articulate with the superior articular process of the infra-jacent vertebra

inferior articular processes

found on the superior and inferior surface of the pedicle.

vertebral notches

when two vertebrae articulate, the vertebral notches form a foramen called the...

intervertebral foramen

found in the transverse process of all cervical vertebrae; the vertebral artery ascends through this from CV6-CV1

transverse foramen

divides into two smaller projections; is found on cervical vertebrae CV2-CV6

bifid spinous process

divided into two projections, the anterior and posterior tubercles found on cervical vertebrae CV3-CV6

bifid transverse processes

found on CV1 (atlas), this structure replaces the laminae and spinous processes

posterior arch

superior articular processes of CV1 (atlas) are ________ for articulation with the occipital condyles.

concave

found on CV2 (axis), a prominent superior projection that extends to the atlas

dens

found on CV7; the longest and most prominent spinous process of all the cervical vertebrae, and it does not bifurcate

vertebra prominens

found on the transverse processes of the thoracic vertebra; for articulation with the ribs

transverse costal facets

are there foramina on the transverse processes of thoracic vertebra?

no

head of the rib articulates with the body of the vertebra

costovertebral joint

tubercle of the rib articulates with the transverse process of the vertebra

costotransverse joint

what vertebra are the largest in size?

lumbar

the spinous processes of lumbar vertebra are _______________ in shape

quadrangular

on the sacrum, the intervertebral disc inferior to LV5 articulates with the ...

sacral promontory

the ___ of the sacrum articulates with the ilium of the hip bone

ala

a smooth surface on the lateral portion of the ala; forms the sacro-iliac (SI) joint with the ilium

auricular surface

on the pelvic surface of the sacrum, there are four pairs of openings for the ventral rami of S1 to S4

pelvic sacral foramina

ridge that is remnant of the spinous processes of the superior 3 to 4 sacral vertebrae

median sacral crest

four pairs of foramina for the dorsal rami of S1 to S4

dorsal sacral foramina

an opening due to the absence of laminae on the fifth sacral segment

sacral hiatus

prominent ridge continuous laterally with the acromion on the scapula; its posterior surface is its crest, the edges of which are the upper lip and the lower lip

scapular spine

structure on scapula; parallels the vertebral column

medial border

on the humerus; found between the greater tubercle and the lesser tubercle

intertubercular groove

origin of trapezius

occipital bone on posterior skull

spinous processes of all cervical vertebrae via ligamentum nuchae

spinous processes of all thoracic vertebrae

insertion of trapezius

lateral third of the clavicle

acromion

rest of the spine of the scapula, superior lip

action of trapezius

upward rotation of the scapula in which the inferior angle moves laterally

elevation of the scapula and lateral clavicle (upper fibers) depression of the scapula and lateral clavicle

innervation of trapezius

CN XI, accessory nerve

ventral rami of C3 and C4

the insertion of the trapezius embraces the origin of the...

deltoid

origin of latissimus dorsi

lower 3 or 4 ribs

spinous processes of the lower 6 thoracic vertebrae

spinous processes of the lumbar and sacral vertebrae via aponeurosis

iliac crest

insertion of latissimus dorsi

intertubercular groove of the humerus

action of latissimus dorsi

adduction of the arm at the shoulder joint

extension of the arm at the shoulder joint

medial rotation of the arm at the shoulder joint

innervation of latissimus dosri

thoracodorsal nerve

origin of levator scapulae

medial border of the scapula superior to the scapular spine

insertion of levator scapulae

medial border of the scapula superior to the scapular spine

action of levator scapulae

elevation of the scapula

innervation of levator scapulae

ventral rami of C3 and C4

origin of rhomboid minor

spinous processes of CV7 and TV1

insertion of rhomboid minor

medial border of the scapula at the scapular spine

action of rhomboid minor

adduction of the scapula

innervation of rhomboid minor

dorsal scapular nerve

origin of rhomboid major

spinous processes of TV2 to TV5

insertion of rhomboid major

medial border of the scapula inferior to the scapular spine

action of rhomboid major

adduction of the scapula

innervation of rhomboid major

dorsal scapular nerve

consists of a series of three longitudinally coursing muscles and constitutes the largest muscular mass of the back

erector spinae

centimeter-wide muscle along the spinous processes (erector spinae group)

spinalis

intermediate muscle in erector spinae group extending all the way to the skull; it is the longest column

longissimus

most lateral muscle, extending from the ilium to the ribs

iliocostalis

the erector spinae group is an important postural muscle that holds the spine erect by __________ the vertebral column

extending

innervation of erector spinae group

dorsal rami

deep back muscle located in the neck

splenius

what are the two parts of splenius?

splenius capitis and splenius cervicis

the superior part of the splenius that extends from the ligamentum nuchae and CV7-TV4 to the skull

splenius capitis

the inferior part of the splenius courses from TV3-TV6 upward to CV1-CV3

splenius cervicis

the two parts of the splenius are continuous at their _______, separable only at their ________

origin, insertion

when one side of the splenius acts, the head and cervical column _______ toward that same side; when both act together, the head and cervical column ________

rotate, extend

innervation of splenius

dorsal rami

what muscles make up the transversospinal group?

semispinalis, multifidus, and rotatores

how many vertebral segments does semispinalis course?

4-6

deep back muscle that occupies the upper half of the vertebral column in the transversospinal group

semispinalis

what are the three regional parts of semispinalis?

semispinalis capitis (biventer cervicis), semispinalis cervicis, semispinalis thoracis

semispinalis capitis is also called ____________ because of its prominent intervening tendon

biventer cervicis

semispinalis cervicis lies _________ to semispinalis capitis

deep

semispinalis thoracis is __________ to semispinalis capitis in the thoracic region

inferior

action of semispinalis capitis (biventer cervicis)

extend the head and rotate towards the same side

actions of semispinalis cervicis and thoracis

rotate vertebrae toward the opposite side

innervation of semispinalis

dorsal rami

how many vertebral segments does multifudus course?

2-4

deep back muscles that are best developed in the lumbar region deep to the erector spinae

multifudus

action of multifidus

rotate the vertebral column toward the opposite side

innervation of multifudus

dorsal rami

deep back muscles that are best developed in the thoracic region deep to semispinalis thoracis

rotatores