JMU BIO 290 Final Review

Somites

Segmental embryonic cells, lie in pairs along the spinal cord

Vertebrates are _________________ animals: we exhibit _________________________ of structures along the longitudinal axis of the body.

segmental/ serial repetition

What are the Somatic Trunk structures?

1. Vertebrae and ribs

2. Axial muscles (back and abs)

3. Urogenital system

4. Skin

also somatic nervous system

Non-segmental trunk structures:

1. Digestive system/ gut tube structures

2. Respiratory system structures

3. Body cavities: celoms

Pharyngeal arches

Embryonic bands of gill tissues that form parts of the head and neck

Somatic Nervous system

Sends and receives signals from somatic structures

Trunk skeleton: Vertebra

Part of axial skeleton

Function of vertebral processes

Provide more area for a muscle to attach

Cervical vertebrae #

7 (C1-C7)

Cervical vertebrae distinctive features

Transverse foramina

C1

Atlas (no vertebral body, articulates with skull)

C2

Axis (DENS - Superior pointing process)

C7

- The largest and most inferior vertebra in the neck region

- Has a large spinous process that protrudes posteriorly toward the skin at the back of the neck

Thoracic vertebrae #

12 (T1-T12)

Thoracic vertebrae distinctive features

Costal facets (superior, inferior, transverse)

Lumbar vertebrae #

5 (L1-L5)

Lumbar vertebrae distinctive features

No costal facets, no transverse foramina, very large

Sacral vertebrae #

5 fused to form sacrum

Sacral vertebrae distinctive features

Sacral foramina

Coccygeal vertebrae #

Usually 3 fused

Coccygeal vertebrae distinctive features

Vestigal tail

Supraspinous ligament

Runs along the posterior surface and in between spinous processes of vertebrae inferior to C7

Nuchal ligament

- Continuation of supraspinous ligament superior to C7

- Runs along the posterior surface and in between spinous processes of vertebrae

Anterior longitudinal ligament

Runs along the anterior surfaces of the vertebral bodies

Posterior longitudinal ligament

Runs along the posterior surfaces of vertebral bodies

Ligamenta Flava

Connects lamina to lamina

Ligaments connect ___________ to ____________.

bone/ bone

Intertransverse ligament

Run in between transverse processes of vertebrae

Interspinous ligament

Runs in between spinous processes of vertebrae

Intervertebral disks are made of

Annulus fibrosus and nucleus pulposus

Function of intervertebral disks

Each acts as a shock absorber for vertebrae

Annulus fibrosus

Outer ring of fibrous tissue

Nucleus pulposus

Soft, gel-like center

Herniated disk

Nucleus pulposus emerges through a tear in the annulus fibrosus

Epaxial muscles are defined as being located ______________________

Dorsal to the transverse process of each vertebra

Bilateral actions of epaxial muscles

- Right and left sides acting together

- Extension of head/vertebral column

Unilateral action of epaxial muscles

- One side acting alone

- Lateral flexion of head/ vertebral column

Innervation of epaxial muscles

Dorsal rami of spinal nerves

What region of the trunk is the epaxial superficial layer located in?

The epaxial superficial layer (splenius muscles) is located in the neck and upper thoracic region of the trunk

What is the epaxial superficial muscle layer and what direction do its fibers run?

- Muscle group: Splenius muscles

- Fiber direction: Superolateral (up and out)→ "V" shape from spine to skull/neck

What region of the trunk is the epaxial intermediate layer located in?

The epaxial intermediate layer (erector spinae group) spans the entire length of the trunk, from the sacrum to the skull.

epaxial intermediate layer (direction of muscle fibers)

up and out (makes a V)

Splenius

O: nuchal ligament, cervical and thoracic spinous processes

I: cervical transverse processes, occipital bone, mastoid process

A: bilateral-extend head and neck

unilateral-laterally flex and rotate head and neck

Innerv: cervical dorsal rami

Epaxial deep layer (region of trunk)

cervical, thoracic, and lumbar

epaxial deep layer (direction of muscle fibers)

up and in (A shaped)

Erector Spinae group includes...

1. iliocostalis

2. longissimus

3. spinalis

common origin of erector spinae

posterior sacrum, iliac crest, sacrospinous ligament, spinous processes of lumbar and sacral vertebrae

iliocostalis

O: posterior sacrum, iliac crest, sacrospinous ligament, spinous processes of lumbar and sacral vertebrae

I: cervical transverse processes, angles of ribs

A: bilateral- extend vertebral column

unilateral- laterally flex vertebral column

Innerv: dorsal rami (all levels)

longissimus

O: posterior sacrum, iliac crest, sacrospinous ligament, spinous processes of lumbar and sacral vertebra

I: cervical and thoracic transverse processes, mastoid process

A: bilateral- extend vertebral column and head

unilateral- laterally flex vertebral column and head

Innerv: dorsal rami (all levels)

common innervation for erector spinae (intermediate epaxial mm)

dorsal rami (all levels)

spinalis

O: posterior sacrum, iliac crest, sacrospinous ligament, spinous processes of lumbar and sacral vertebrae

I: cervical and thoracic spinous processes

A: bilateral- extend vertebral column

unilateral- laterally flex vertebral column

Innerv: dorsal rami (all levels)

hypaxial muscles

line body wall

hypaxial muscles are defined as being located...

ventral/anterior to the transverse process of each vertebra

hypaxial muscles are found in the......

abdominal body wall and thoracic body wall

hypaxial abdominal wall mm bilateral actions

flex and sometimes rotate trunk; compress and support abdominal viscera

hypaxial thoracic wall mm bilateral actions

elevate/depress ribcage; stabilize thorax

hypaxial abdominal wall mm unilateral actions

laterally flex/ rotate trunk

hypaxial thoracic wall mm unilateral actions

N/A

hypaxial mm of abdominal body wall innervation

inferior thoracic (T7-T12)

2 have L1 ventral rami of spinal nn

hypaxial mm of thoracic body wall innervation

intercostal nn (thoracic ventral rami)

pelvic diaphragm

forms the muscular floor of the pelvis

what muscles compose the pelvic diaphragm?

1. coccygeus

2. levator ani

coccygeus

small in humans, located in the same position as the sacrospinous ligament

levator ani

U-shaped muscular sling that spans the medial surface of the pelvis from the pubis to the ischial spine

functions of pelvic diaphragm

1. support pelvic viscera-both

2. raise pelvic floor (for coughing, puking)- levator ani

coccygeus also flexes coccyx

innervation of hypaxial muscles of the pelvis

sacral ventral rami

structural components of CNS

brain, spinal cord

functional components of CNS

receive and interpret sensory information

generate motor commands

structural components of peripheral NS

cranial nn (in head and neck)

spinal nn in trunk

functional components of peripheral NS

transmits sensory information to CNS

transmits motor commands away from CNS to effectors

nerve cell

neuron

nerve

bundle of axons, which we also call nerve fibers

sensory neuron

afferent

carries impulse toward CNS from receptors

motor neuron

efferent

carries impulse away from CNS to effectors (mm and glands)

3 facts about neurons

1. long-lived cells

2. require continuous supply of glucose and oxygen

3. most lose ability to undergo mitosis and can't make daughter cells

spinal cord runs through the _____________________

vertebral canal

vertebral canal is formed by......

all of the separate vertebra stacked atop one another

white matter

myelinated axons, axons with sheaths of whitish, fatty proteins

central canal

space containing cerebrospinal fluid

gray matter

cell bodies of neurons and un-myelinated axons (no sheaths)

makes up dorsal, lateral and ventral horns

lateral horns are found...

in the visceral region (T1-L2)

ventral horns are made of

cell bodies of general somatic efferent neurons

dorsal horns are made of

cell bodies of interneurons

lateral horns are made of

cell bodies of general visceral efferent neurons

epidural space

outside of spinal cord meninges, contains cerebral spinal fluid

dura mater

"tough mother", outermost covering of spinal cord

arachnoid mater

spider mother, middle covering of spinal cord, connected to subarachnoid space

subarachnoid space

contains cerebrospinal fluid, looks like cobwebs

pia mater

innermost covering os spinal cord, fused with spinal cord

afferent pathways receive signals from

somatic or visceral structures

efferent pathways receive signals from

CNS

afferent pathways carry signals to

CNS

efferent pathways carry signals to

somatic or visceral effectors

how many types of pathways do roots carry?

1

dorsal root contains

afferent neurons only

dorsal root ganglion contains

cell bodies of afferent neurons

ventral root contains

efferent neurons only

spinal nerve contains

both efferent and afferent neurons

rami carry

both afferent and efferent signals

rami travel to

skin and muscle