(1) Intro & Back

anatomical position

standing erect, upper limbs at sides, palms, nose, & toes facing forward

median (midsagittal) plane

Cuts the body into equal left and right planes

sagittal (paramedian) plane

cuts body into any infinite number of left and right sections

frontal (coronal) plane

Cuts the body into any infinite number of front and back planes

transverse (horizontal) plane

cuts body into into any infinite number of top and bottom planes

Medial

toward the midline (median sagittal plane)

Lateral

away from the midline (median sagittal plane)

Ventral

toward the front

Dorsal

toward the back

Anterior

toward the front

Posterior

toward the back

Superior

toward the head

Inferior

towards the feet

Cranial

toward the head; usually used in reference to the trunk

Caudal

toward the tail; usually used in reference to the trunk

Proximal

toward the point of attachment; usually used in reference to limbs

Distal

away from the point of attachment; usually used in reference to limbs

cervical vertebrae

C1-C7. Independently mobile. Smallest vertebral bodies, largest vertebral foramina, articular facets oriented in horizontal plane.

thoracic vertebrae

T1-T12. Independently mobile. Articulate with ribs. Articular facets oriented in coronal plane.

lumbar vertebrae

L1-L5. Independently mobile. Largest vertebral bodies with most prominent processes, articular facets oriented in sagittal plane.

sacral vertebrae

S1-S5. Fused to support weight of pelvis.

coccygeal vertebrae

Co1-Co4. Fused.

lordosis

dorsal concavity of the cervical & lumbar spine

kyphosis

ventral concavity of the thoracic & sacral spine

vertebral body

main anterior portion of the vertebra that bears weight

centrum

vertebral body in a developing vertebrae. essentially equivalent.

vertebral foramen

Opening for spinal cord & spinal nerve roots in vertebrae.

articular process (zygapophysis)

paired process which articulates with process of adjacent vertebrae. project superiorly and inferiorly.

transverse process

paired bony processes that project laterally from the vertebral arch of a vertebra

spinous process (neural spine)

unpaired bony process that projects posteriorly from the vertebral arch of a vertebra

Pedicle

bony region between body and transverse process of a vertebra

lamina

bony region between the transverse process and the spinous process of a vertebra

vertebral arch

composed of pedicle & lamina. extends posteriorly to surround vertebral foramen.

neural arch

essentially the vertebral arch in a developing vertebra

superior articular process

bony process that extends upward from the vertebral arch of a vertebra

superior articular facet

articulates with inferior articular facet of vertebra above it

inferior articular process

bony process that extends downward from the vertebral arch of a vertebra

inferior articular facet

articulates with the superior articular facet of vertebra above it

interarticular joints/zygapophyseal joints/facet joints

Formed by inferior articular processes of one vertebra articulating with superior articular process of the vertebrae below

intervertebral discs

fibrocartilaginous cushions between vertebral bodies that allow bending of the spine and function as shock absorbers. can prolapse or herniate & compress spinal nerves/cord due to close proximity to ivf. composed of a nucleus pulposus and anulus fibrosus.

nucleus pulposus

central gelatinous core of intervertebral discs

anulus pulposus

outer rings of fibrocartilage in intervertebral discs. Restrains spread of nucleus pulposus, which enables a disc to bear weight.

anterior longitudinal ligament

ligament that runs the length of the vertebral column, connecting the anterior aspects of the vertebral bodies. Limits vertebral extension. Commonly injured in whiplash injuries.

posterior longitudinal ligament

ligament that runs the length of the vertebral column, connecting the posterior sides of the vertebral bodies. Limits vertebral flexion.

supraspinous ligament

ligament that connects the posterior tips of the spinous processes together. Limits vertebral flexion.

interspinous ligament

Ligament between adjacent spinous processes. Limits vertebral flexion.

ligamentum flavum

ligament that connects the laminae of adjacent vertebrae. 80% elastin (makes it look yellow). Limits vertebral flexion (most important ligament for this).

Superficial back muscles

trapezius, latissimus dorsi, levator scapulae, rhomboid major, rhomboid minor. During development, start as upper limb muscles that migrate to positions superficial to intrinsic muscles of back.

Trapezius

superficial triangular muscle of upper back.

-Innervated by cranial nerve XI.

-Medial attachments: superior nuchal line, external occipital protuberance, nuchal ligament, spinous processes of C7-T12

-Lateral attachments: lateral ⅓ of clavicle, acromium & spine of scapula.

levator scapulae

superficial back muscle

-innervated by dorsal scapular nerve. Attaches to vertebral border of scapula.

-Medial attachments: transverse processes of C1-C4

-Lateral attachments: medial border of scapula above its spine

rhomboideus minor

superficial back muscle

-innervated by dorsal scapular nerve

-Medial attachments: Nuchal ligament, spinous processes of C7 and T1

-Lateral attachments: Medial border of scapula at its spine

rhomboideus major

superficial back muscle

-innervated by dorsal scapular nerve

-Medial attachments: spinous processes of T2-T5

-Lateral attachments: Medial border of scapula below its spine

latissimus dorsi

superficial back muscle that is the widest muscle of back.

-innervated by thoracodorsal nerve

-Medial attachment: Spinous process of T7-T12 vertebrae, iliac crest, ribs 10-12, inferior angle of scapula

-Lateral attachment: Intertubercular sulcus of humerus

Intermediate back muscles

splenius and erector spinae

spelnius capitis

intermediate back muscle

-innervated by dorsal rami

-Medial attachment: nuchal ligament, C7-T4

-Lateral attachment: mastoid process of temporal bone

erector spinae

intermediate back muscle innervated by dorsal rami that consists of the iliocostalis, longissimus, and spinalis. Extends the spine.

Iliocostalis

most lateral portion of erector spinae

-Medial attachment: iliac crest

-Lateral attachment: ribs

Longissimus

Middle portion of erector spinae. Longest muscle in the back.

-Medial attachment: C4-T4

-Lateral attachment: mastoid process

Spinalis

most medial portion of erector spinae

-Medial attachment: occipital protuberance

-Lateral attachment: C7, T1

innervated by dorsal rami nerve

Deep back muscles

transversospinalis group

Transversospinalis muscles

Group of deep back muscles consisting of the semispinalis, rotatores, and multifidus. Innervated by dorsal rami.

Semispinalis

longest of the transversospinalis muscles, spanning 5-6 vertebral segments.

-Medial attachment: C4-C7 articulate processes, T1-T6 transverse processes

-Lateral attachment: occipital bone

rotatores

smallest of the transversospinalis muscles, spanning 1-2 vertebral segments.

Multifidus

Transversospinalis muscle spanning 3-4 vertebral segments.

-Medial attachment: C4-7, T1-12, L1-L6

-Lateral attachment: C2-C5

spinal nerves split into

dorsal and ventral rami

ventral ramus

the anterior division of spinal nerves that communicate with the muscle and skin of the anterior and lateral trunk and all limbs

dorsal ramus

the division of posterior spinal nerves that transmit motor impulses to the posterior trunk muscles and relay sensory impulses from the skin of the back

origin (when referring to limb muscles)

more proximal attachment site, or that which remains immobile during contraction

Insertion (when referring to limb muscles)

more distal attachment site, or that which moves more during contraction

origin (when referring to intrinsic back muscles)

more inferior/caudal attachment site

insertion (when referring to intrinsic back muscles)

more superior/cranial attachment site

extension of trunk

bending backwards within the sagittal plane. Requires bilateral contraction of intrinsic back muscles (especially erector spinae)

flexion of trunk

bending forward within the sagittal plane. Requires abdominal muscles and gravity.

lateral flexion of trunk

Bending of the spine from side to side within the frontal plane. requires unilateral contraction of laterally-placed intrinsic back muscles (especially iliocostalis), with help from lateral abdominal muscles.

rotation of trunk

twisting motion along axis of spine towards or away from the midline. Requires unilateral contraction of obliquely-oriented intrinsic back muscles (especially rotatores), with help from oblique abdominal muscles

Function of Splenius Capitis and semispinalis capitis

extend head when contracting bilaterally, rotate & laterally flex the head when contracting unilaterally

contralateral rotation for semispinalis

function of all intrinsic back muscles

extend the spine when contracting bilaterally (most important is erector spinae group)

function of laterally-placed intrinsic back muscles

laterally flex the spine when contracting unilaterally (most important is iliocostalis)

function of transversospinalis muscles

rotate the spine toward the contralateral side when contracting unilaterally

Contralateral rotation

Rotation towards the opposite side.

posterior cutaneous branches of dorsal rami

innervate a patch of skin extending approx 1 hand's breadth lateral to the dorsal midline

Greater occipital nerve

dorsal ramus of C2. provides cutaneous innervation to posterior scalp.

occipital artery

Branch of the external carotid artery that supplies blood to the skin and muscles of the scalp and back of the head