vertebral column

Examples of vertebral column in the following topics:

• Human Axial Skeleton

  • The axial skeleton forms the central axis of the human body and consists of the skull, vertebral column, and thoracic cage.
  • The vertebral column, or spinal column, surrounds and protects the spinal cord, supports the head, and acts as an attachment point for the ribs and muscles of the back and neck.
  • The adult vertebral column is comprised of 26 bones: the 24 vertebrae, the sacrum, and the coccyx bones.
  • The arched curvature of the vertebral column increases its strength and flexibility, allowing it to absorb shocks like a spring.
  • The axial skeleton consists of the bones of the skull, ossicles of the middle ear, hyoid bone, vertebral column, and rib cage.

• The Evolution of Craniata and Vertebrata

  • Hagfish are the only known living animals that have a skull, but not a vertebral column .
  • Vertebrates are members of the subphylum Vertebrata, the clade Craniata, and the phylum Chordata.
  • Vertebrates display the four characteristic features of chordates, but they are named for the vertebral column composed of a series of bony vertebrae joined together as a backbone .
  • In adult vertebrates, the vertebral column replaces the embryonic notochord.
  • All vertebrates are in the Craniata clade and have a cranium.

• Characteristics of Vertebrates

  • More than 64,000 species of vertebrates have been described, but the extant vertebrate species represent only a small portion of all the vertebrates that have existed.
  • All vertebrates are built along the basic chordate body plan: a stiff rod running through the length of the animal (vertebral column), with a hollow tube of nervous tissue (the spinal cord) above it and the gastrointestinal tract below.
  • Vertebrates are defined by the presence of the vertebral column.
  • In vertebrates, the notochord develops into the vertebral column or spine: a series of bony vertebrae each separated by mobile discs .
  • Vertebrates are differentiated by having a vertebral column.

• Limitations of Phylogenetic Trees

  • For example, the tree in the diagram shows that the oldest trait is the vertebral column, followed by hinged jaws, and so forth.
  • So, simply because a vertebral column evolved does not mean that invertebrate evolution ceased.
  • This ladder-like phylogenetic tree of vertebrates is rooted by an organism that lacked a vertebral column.

• Agnathans: Jawless Fishes

  • Jawless fishes or agnathans are craniates that represent an ancient vertebrate lineage that arose over one half-billion years ago.
  • Unlike true vertebrates, hagfishes do not replace the notochord with a vertebral column during development.
  • However, lampreys develop some vertebral elements as an adult.
  • Their notochord is surrounded by a cartilaginous structure called an arcualia, which may resemble an evolutionarily-early form of the vertebral column.
  • These agnathans are classified as Myxini and do not have a vertebral column.

• Characteristics of Chordata

  • In vertebrates, the notochord is present during embryonic development, at which time it induces the development of the neural tube which serves as a support for the developing embryonic body.
  • The notochord, however, is replaced by the vertebral column (spine) in most adult vertebrates.
  • In vertebrate fishes, the pharyngeal slits develop into gill arches, the bony or cartilaginous gill supports.
  • In some terrestrial vertebrates, the tail also helps with balance, courting, and signaling when danger is near.

• Animal Body Planes and Cavities

  • Vertebrates can be divided along different planes in order to reference the locations of defined cavities.
  • Vertebrate animals have a number of defined body cavities .
  • In the posterior cavity, the cranial cavity houses the brain and the spinal cavity (or vertebral cavity) encloses the spinal cord.
  • The brain and spinal cord are protected by the bones of the skull and vertebral column and by cerebrospinal fluid, a colorless fluid produced by the brain, which cushions the brain and spinal cord within the posterior (dorsal) cavity.
  • Vertebrate animals have two major body cavities.

• Types of Skeletal Systems

  • As with vertebrates, muscles must cross a joint inside the exoskeleton.
  • The bones of vertebrates are composed of tissues, whereas sponges have no true tissues.
  • The skeletal system in vertebrates is divided into the axial skeleton (which consists of the skull, vertebral column, and rib cage), and the appendicular skeleton (which consists of the shoulders, limb bones, the pectoral girdle, and the pelvic girdle).

• Phylum Chordata

  • In most vertebrates, it is replaced developmentally by the vertebral column.
  • In many of the invertebrate chordates, these function as suspension feeding devices; in vertebrates, they have been modified for gas exchange, jaw support, hearing, and other functions.
  • In addition to containing vertebrate classes, the phylum Chordata contains two clades of invertebrates: Urochordata (tunicates) and Cephalochordata (lancelets).

• Spinal Cord

  • Connecting to the brainstem and extending down the body through the spinal column is the spinal cord: a thick bundle of nerve tissue that carries information about the body to the brain and from the brain to the body.
  • The spinal cord is contained within the bones of the vertebral column, but is able to communicate signals to and from the body through its connections with spinal nerves (part of the peripheral nervous system).
  • While a reflex may only require the involvement of one or two synapses, synapses with interneurons in the spinal column transmit information to the brain to convey what happened (the knee jerked, or the hand was hot).
  • For example, if the spinal cord is damaged at the level of the neck, it can cause paralysis from the neck down, whereas damage to the spinal column further down may limit paralysis to the legs.