Axial Skeleton Vocab

• Define acetabulum?

  Located at the lateral end of the pelvis creating a concave structure as a socket to fits the femoral head forming a "ball and socket" hip joint
• Define actinotrichia?

  Any fibers in the finfolds of fish larvae that are threadlike. These fibers will later develop into fin rays.
• Define amphicoelous?

  Vertebrae that have both posterior and anterior centra concave (inward curve) that have the notochord run through the center of the bone. Commonly seen in fish.
• Define anal fin?

  This is found on the ventral side of the fish and is located near the anus. It largely provides stability but also aids in maneuverability, steering, and can help assist with propulsion.
• Define arch centers?

  A cartilaginous structure in the notochord that provides additional support to the vertebrae and helps develop the dorsal and ventral arches
• Define arcualia?

  They are cartilaginous structures from embryonic development that form vertebrae.
• Define aspondyly?

  A medical condition of the vertebre where there is an absense of the centrum.
• Define atlas?

  The uppermost vertebra located at the top of the spine.
• Define axis?

  Is the second vertebrae in the spinal coloum that allows and supports the movement of the head to be able to look around.
• Define carapace?

  Carapace comes in many different styles as it represents a protective covering for an organism.
• Define centra?

  The centra, also known as centrum, is the vertreba's central body. It is the main solid piece that is ventral to the neural arch, which is attached to all other parts within the body.
• Define cervical ribs?

  An extra rib that develops from the seventh cervical vertebra. They are a congenital abnormality that occurs in less than 0.5% of the human population.
• Define chevron bones?

  Chevron bones are small bones that are attached to the lower spine and are used as attachment sites for muscles that helps tails move and protect the blood vessels.
• Define chordacentra?

  Small ring structures that surround the notochord.
• Define cleithrum?

  The major bone in the pectoral girdle that is located at the base of the pectoral fin.
• Define costal ribs?

  "Costal" refers to anything related to the ribs, while "ribs" are the curved bones that form the ribcage. So, together, it could be interpreted as referring to the ribs themselves, particularly within the context of their attachment to the chest or thoracic region.
• Define coccyx?

  The coccyx is the bone located at the very end of the spine. It is ocmmonly referred to as the "tailbone".
• Define diapophysis?

  The diapophysis is the bone growth of the dorsal side of vertebrae where the ribs attach to the spine.
• Define diplospondyly?

  The diplospondyly is the splitting in half of each vertebrae to form twice as many vertebrae.
• Define dorsal fin?

  a fin on the top/back or the fish and some marine mammals meant to help when making sharp turns.
• Define entoplastron?

  This specifies to the order testudines this part of one of the pieces of the shell is located at the underside of the shell and acts as an interclavicle that connects towards the front of the shell inbetween the left and right hyoplastrons.
• Define false rib?

  A set of ribs that lay just below the the sternal rib and or segment that shows articulation with each other but not with the sternum.
• Define floating rib?

  This can include one or two ribs that don’t connect to the breastbone, they remain connected to the back vertebrae.
• Define gastrialia?

  Dermal bones found between the sternum and pelvis that provide support of the abdomen and it's muscles
• Define hemal canal?

  Is a passage on the lower region of the spine usually on the tail. It provided protection for blood vessels and nerves.
• Define hemal spines?

  The spiny projection coming out of the bony arch on the ventral side of a tail.
• Define heterocoelous?

  Means that an articular bone in the vertebrae is saddle-shaped on both ends. This is mainly found in birds.
• Define hypapophysis?

  A small bony projection found in the ventral surface of the vertebrae used for the attachment of muscules and ligaments.
• Define intervertebral ligaments?

  strong bands that connect vertebrae together to stabilize and protect the spin and disc.
• Define intervertebral pads?

  Also known as intervertebrsal discs, are made of fibrocartilage and serve in crucial functions such as maintaining the vertebrate column's sturcture and function. These "pads" reduce the risk of injury, provide mobility, flexibility, support, and spacing between the adjacent vertebrae.
• Define lepospondylous vertebra?

  It is a simple, stool-shaped vertebrae that is grown as bony cylinder around the notochord
• Define lumbar?

  the lower end of the spinal column that consists of five bones
• Define manubrium?

  It is the handle like structure that is located at the top of the sternum.
• Define myosepta?

  Connective tissue sheets that separate the myomeres.
• Define neural arch?

  Part of the spinal column responsible for protecting the nerve cord in chordates. Depending on the taxa, it may or may not have a neural spine
• Define neural spines?

  A neural spine is an extension of the neural arch. It can provide general structure and support, but may also support a large amount of muscle.
• Define nucleus pulposus?

  The nucleus pulposus is what gives the spine the ability to absorb shock during movement.
• Define omosternum?

  A part of the skeleton that sits between the clavicles and the (epi)sternum
• Define parapophysis?

  A transverse process that projects laterally from the centrum in a vertebrae.
• Define parasternalia?

  Situated beside the sternum