Anat 338 Lab 2: Spinal Cord | Vertebral Column | Trunk Wall Part I

Cervical region

7 vertebrae

neck portion of spine that supports the head

Thoracic region

12 vertebrae

middle part of trunk extending from neck to diaphragm

supported by rib cage and thoracic spine

Lumbar region

5 vertebrae (largest)

lower back segment and bear most body weight

Sacral region

triangular shaped bone at base of spine between L5 and coccyx

formed by fusion of 5 sacral vertebrae during early adulthood

Cervical enlargement

Widened portion of the spinal cord spanning roughly C3–T2 (commonly C4–T1 or peaking at C5)

Extra motor and sensory neurons supply the upper limbs

Lumbar enlargement

Widened area of the spinal cord that supplies nerves to the lower limbs, located between the T11 and L2 vertebrae

Higher density of motor neurons in the ventral horns, which are responsible for innervating the lower limbs

Conus medularis

tapered, end of spinal cord (L1-L2)

coordinates motor, sensory, autonomic functions of the lower body

Cauda equina

bundle of spinal nerves after conus medullaris essential for leg movement and bladder, bowel, and pelvic organ function

Meninges

3 protective membranes that cover and support the brain and spinal cord

Dura mater

outermost, thick, durable layer of meninges

attaches to inside of skull and vertebrae

Arachnoid mater

middle, thin, transparent layer of meninges

lies above pia mater

forms subarachnoid space which contains CSF and fine filaments that connect to pia mater

Pia mater

innermost layer, delicate membrane that closely adheres to surface of the brain and spinal cord

highly vascularized and allows blood vessels to pass through to supply CNS

Denticulate ligament

Horizontal anchors to provide support and stability to spinal cord

Triangular-shaped extensions of the spinal pia mater, extending sideways from the spinal cord.

Filum terminale

Anchors spinal cord to coccyx and stabilizes within vertebral column

Thread-like structure extending from the apex of the conus medullaris (the tapered end of the spinal cord) down to the coccyx

White matter

Connects different brain regions to transmit signals efficiently

Dorsal column

Location: Dorsal/posterior horns

Function: Sensory input

• Receives fine touch, vibration, and proprioception of spinal cord

Ventral column

Location: ventral/anterior horns

Function: motor output

• contains lower motor neurons → skeletal muscles

• contains lateral neurons → visceral muscle control

Lateral column

Houses sympathetic preganglionic neurons

In white matter between anterior and posterior columns

Contains myelinated axons that transmit information up and down CNS so sensory and motor neurons can communicate

Gray matter

Processes information and controls thinking and movement

Posterior horn

processes somatosensory information i.e. fine touch, vibration, proprioception, pain, temperature

in gray matter - butterfly-like shape with 3 columns

contains second-order sensory neurons (receiving input from first-order neurons in dorsal root ganglia)

Lateral horn

projection of gray matter in thoracic spinal cord that contains preganglionic sympathetic neuron

Anterior horn

contains lower motor neurons that send axons via anterior nerve to innervate skeletal muscles

Central canal

Cerebrospinal fluid-filled space that runs through spinal cord

Located with gray commissure

Dorsal root ganglion

Cluster of sensory neuron cell bodies located near spinal cord that transmit sensory information from PNS → CNS

Dorsal root and rootlets

Dorsal rootlets are small nerve fibers that carry sensory info from body to spinal cord and converge to form dorsal root

Ventral root and rootlets

Ventral rootlets converge to form ventral root which carries motor (efferent) signals from spinal cord → muscles & glands

Spinal nerves

Mixed periphery nerves that connect spinal cord to body carrying sensory, motor, and autonomic signals

Dorsal rami

Posterior branch of spinal nerve

motor innervation → deep back muscles

sensory innervation → skin of posterior head, neck, back

Ventral rami

larger, anterior branch of spinal nerve

Sensory + motor fibers → front & sides of trunk & limbs

Rectus abdominis

6-pack muscle

Trunk flexion, stability, posture

Internal oblique

Deep to external obliques

Trunk rotation, lateral flexion

External oblique

largest, most superficial of the flat muscles

trunk rotation, lateral flexion

Tranversus abdominis

deepest abdominal muscle

stabilizes core, wrapped around abdomen like corset, keeps organs in

Erector spinae

Group of 3 main muscles in the back

ilicostalis (I in I Love Sports)

most lateral of the erector spinae muscles. runs from the iliac crest of pelvis to the ribs

when contracted bilaterally: extend spine and help to maintain upright posture against gravity

when unilaterally contracted: lateral flexion

Longissimus (L in I Love Sports)

longest of the erector spinae muscles

when contracted bilaterally: extend spine and help to maintain upright posture against gravity

when unilaterally contracted: lateral flexion

Spinalis (S in I Love Sports)

thin and medial - closest to the spine

when contracted bilaterally: extend spine and help to maintain upright posture against gravity

when unilaterally contracted: lateral flexion

False ribs

don’t directly articulate with sternum (3 of them)

True ribs

directly articulate with sternum through costal cartilage (7 of them)

Floating ribs

only attach to the spine and not to the breast bone - they protect kidneys (2 of them) Found on the anterior (front) part of the chest wall, acting as an extension of the ribs.

Costal cartilage

Flexible band of hyaline cartilage that connects the front of the ribs to the breastbone, or sternum.

head of the ribs

wedge-shaped posterior end that connects the rib to the spine through costovertebral joints

Manubrium - sternum

wide, triangular shaped, upper segment of the sternum (breastbone) located at the level of the T3 and T4 vertebrae

Body of the sternum

longest, flat middle portion of the sternum (breastbone) located in the center of the chest

Xiphoid process - sternum

the small, lowest pointed end of your sternum (breastbone) located in the center of your chest

Sternal angle

the visible and palpable ridge on the chest where the manubrium meets the body (top meeds middle)

Suprasternal notch

the visible dip or hollow at the base of the neck, located right above the top of the breastbone (manubrium) and between the collarbones

Clavicular notch

small, oval depression located on the top corner of the manubrium (upper part of sternum)

Spinous process

the bony bump that sticks out from the back of each vertebra along your spine

Transverse process

small, bony projections pointing out from the left and right sides of each vertebra in the spine

Superior articular process

bony projection pointing upward on each side of a vertebra that locks with the vertebra above it to form a spinal joint

Superior articular facet

a smooth bone surface on the upper part of a vertebra that faces upward and connects with the inferior articular facet of the vertebra directly above it

Inferior articular process

bony projection that extends downward from the articular process of a vertebra to lock with the vertebra directly below it

Inferior articular facet

smooth, bone-surfaced area on the bottom of a vertebra's lower process that links with the superior articular facet of the vertebra directly below it

Body of vertebral column

thick, cylindrical front part of a spinal bone that bears weight and supports the upper body

Transverse foramen

opening found on each side of the transverse processes in the cervical (neck) vertebrae

Atlas: anterior arch

C1 - supports skull and allows head to nod

anterior arch articulates with dens of axis

Atlas: posterior arch

C1 - larger than anterior arch - attachment site for muscles/ligaments and a groove for vertebral artery

Axis: dens

Dens/odontoid process - prominent projection of C2 that serves as pivot for head rotation & stabilized by ligaments connecting it to the atlas and occipital bone

Superior costal demifacet

the top half-facet depression surfaces on the sides of typical thoracic vertebral bodies (T2–T9) that join with adjacent parts to form complete sockets for rib heads

Inferior costal demifacet

the bottom half-facet depression surfaces on the sides of typical thoracic vertebral bodies (T2–T9) that join with adjacent parts to form complete sockets for rib heads

Costal facet of the transverse process

a smooth, oval spot on the transverse process of a thoracic vertebra that connects to a rib

Intervertabrael discs

Cushion of cartilage

Location: Between adjacent vertebrae in the spine

Function: Acts as a shock absorber and allows the back to bend and twist

Posterior longitudinal ligament

strong band of fibrous tissue that runs down the back of the vertebral bodies inside the spinal canal, stretching from the neck (axis) to the sacrum

Anterior longitudinal ligament

strong, fibrous band running down the front surface of the vertebral column from the base of the skull (occiput/atlas) to the sacrum