TBL 2 Flashcards
What does the axial skeleton consist of?
The axial skeleton includes the skull, vertebrale column, ribs and sternum.
What are the parts of the vertebrae that make up the posterior vertebral arches?
The vertebral arches are made up of the pedicle and lamina. At the junction of these two, the transverse process projects laterally. The spinous process projects posteriorly from the junction of the laminae.
What is the importance of the transverse and spinous processes of the vertebrae?
The transverse and spinous processes proved attachment sites for deep back muscles that fix or change positions of the vertebrae.
How are the vertebrae aligned?
The superior and inferior articular processes are medial to the transferse processes, and they fit together like puzzle pieces with adjacent vertebrae.
What is spondylolysis? What are the consequences of spondylolysis at L5?
Spondylolysis is fracture of a vertebra between its superior and inferior articular processes (pars interarticularis). Dislocation between adjacent vertebrae, known as spondylolisthesis, may occur.
Spondylolysis of L5 especially may result in spondylolisthesis of L5 vertebral body relative to the sacrum due to the downward tilt of the LF/S1 IV joint. This may result in pressure on the spinal nerves of the cauda equina, causing lower back and lower limb pain.
What do the IV discs consist of? What is their function?
The nucleus pulposus, a gelatinous central mass that is surrounded by concentric layers of Type I collagen fibers forming the annulus fibrosis.
The discs strongly attach adjacent vertebral bodies and their resilient deformability provides shock absorbers for the spine.
What emerges from the intervertebral foramina?
The spinal nerves emerge from the vertebral canal via the intervertebral foramina.
Which clinical conditions might require a laminectomy and how is a laminectomy surgically performed?
The surgical excision of one or more spinous processes and adjacent supporting vertebral laminae in a prticular region of the vertebral column is called a laminectomy. It can also denote removal of most of the vertebral arch by transecting the pedicles.
It is often performed to relieve pressure on the spinal cord or nerve roots caused by **tumor, herniated IV disc, **or bony hypertrophy.
How does stenosis affect the lumbar portion of the vertebral canal and lumbar spinal nerves?
Lumbar spinal nerves increase in size as the vertebral column descends, but the IV foramina decrease in size. Stenosis of lumbar vertebral foramen alone may cause compression of one or more spinal nerve roots occupying the inferior vertebral canal.
What are the ligamenta flava?
The ligamenta flava vertically interconnect the laminae of adjacent vertebrae, thus contributing to the posterior wall of the vertebral canal.
What covers the anterior surfaces of the vertabral bodies and IV discs? What resides on the posterior surfaces of the vertebral bodies?
The anterior longitudinal ligament covers anterior surfaces of the vertebral canal.
The narrower posterior longitudinal ligament attaches mainly to the IV discs within the vertebral canal.
What are the functions of the anterior and posterior longitudinal ligament?
The anterior longitudinal ligament is a strong, broud fibrous band that prevents hyperextension of the vertebral column, maintaining the stability of the joints between vertebral bodies. It is the only ligament that limits extension.
The posterior longitudinal ligament is a much narrower, somewhat weaker band that weakly resists hyperflexion of the vertebral column and helps prevent or redirect posterior herniation of the nucleus pulposus.
Which sections of the spine have secondary curvatures? When are these curvatures formed?
The cervical and lumbar sections of the spine have secondary curvatures. Theses curvatures form after an infant can lift his head and begins to walk.
Why do herniations of the nucleus pulposus usually protrude posterolaterally?
The anulus fibrosis is relatively thin posterolaterally, and does not receive support from either the posterior or he anterior longitudinal ligaments.
What are primary causes of excessive kyphosis and lordosis? How does scoliosis differ in appearance from excessive kyphosis?
Excessive kyphosis is characterized by an abnormal increase in the thoracic curvature. This can result from erosion of the anterior part of one or more vertebrae.
Excessive lumbar lordosis is characterized by anterior tilting of the pelvis, with increased extension of the lumbar vertebrae. This can be caused by weak abdominal muscles, obesity, and pregnancy.
Scoliosis is characterized by abnormal lateral curvature that is accompanied by rotation of the vertebrae. This is caused by deformities of the vertebral column.
What is the notochord derived from?
Some migrating mesodermal cells that initially invade the developing endoderm detach and formthe notochord, a rigid rod of supporting mesoderm that induces formation of the axial skeleton and neural tube.
What is the annulus fibrosis of the IV discs derived from? What else is formed by these cells?
The mesenchymal cells of the somites differentiate into fibroblasts that form the annulus fibrosis and the dermis mainly associated with the vertebral column and thoracic wall.
What are skeletal muscles associated with the spine and thoracic wall derived from?
Mesenchymal cell-derived myoblasts form the skeletal muscles associated with the spine and thoracic wall.
What are chondroblasts and osteoblasts derived from? What do they produce?
Mesenchymal cells generate chondroblasts and osteoblasts that produce cartilage and bone, respectively.
What causes spina bifida occulta, the most common congenital anomaly of the vertebral column?
**Spina bifida occulta: **the neural arches of L5 and/or S1 fail to develop normally and fuse posterior to the vertebral canal
Name the steps in the formation of compact bone.
- Primary osteons (oval profiles of trabecular bone lined by endosteum, in which the space between bone and capillary is filled by interstitial fluid)
- Osteoblasts of the endosteum produce bony matrix that grows progressively inward.
- Secondary (mature) osteons are formed by enclosement of the capillaries by bone. The space around the capillaries is called the central canal.
What connects the central canal to the innermost row of lacunae and interconnects concentric rows of lacunae in each osteon? What is its importance?
Bony canaliculi (tiny canals)
This way, lacunae throughout the osteon have access to capillary filtrates in the central canal.
What are Volkmann canals and what are their purpose?
Where are interstitial lamellae found? How do they differ from concentric lamellae?
Central canals are joined at right angles by Volkmann canals, thereby enabling capillaries of the periosteum to extend into the central canals.
Interstitial lamellae reside between clustered osteons. Concentric lamellae are inside of osteons, and are the layers of lacunae.
Cite the respective number of cervical, thoracic, lumbar, and sacral spinal nerves.
8 cervical nerves
12 thoracic nerves
5 lumbar nerves
5 sacral nerves
What are the dura and arachnoid composed of? What fills the subarachnoid space?
The dura and arachnoid of the spinal meninges are composed of dense and loose connective tissue, respectively.
Cerebral spinal fluid (CSF) fills the subarachnoid space, and presses the arachnoid against the inner surface of the dura.
