REGIONAL COMPONENTS OF SKELETON

• Regional components of skeleton

  MAJOR COMPONENTS:

  • Vertebral column
  • Skull
  • Ribs
  • Sternum

  A) SKULL

  B) STERNUM

  C) VERTEBRAL COLUMN

  D) RIBS

  
• VERTEBRAL COLUMN

  VERTEBRAL COLUMN

  • Vertebrae: metameric series of essentially

  similar skeletal systems.

  • Segmented, flexible, arch rod flanked by axial musculature.

  ▪ The head is attached.

  ▪ The rest of the body is suspended in fishes.

  ▪ The trunk is suspended between anterior and posterior limbs in most tetrapods.

  
• FUNCTION OF VERTEBRAL COLUMN

  VERTEBRAL COLUMN:

  a.Encloses and protects spinal cord with spinal

  canal.

  b. Allows vertebrates to maintain upright posture.

  c. Flexibility and movement

  d. Attachment of pectoral and pelvic girdles
• Structure of vertebral column

  ● Centrum

  ● Arches

  ● Apophyses

  A) centrum

  B) notochord

  C) transverse processes

  D) neural arch

  E) centrum

  F) notochord

  G) hemal arch

  H) vertebral canal

  I) neural arch

  
• CENTRUM

  • Occupy the position of notochord.
  • pierced by the remnants of the latter, particularly in lower vertebrates.

  Classification of vertebrae according to the shape and orientation of the centrum:

  ● Amphicoelous vertebrae

  ● Heterocoelous vertebrae

  ● Amphiplatyan (acoelous) vertebrae

  ● Procoelous vertebrae

  ● Ophistocoelous vertebrae

  A) amphicoelus

  B) procoelus#

  C) opisthocoelus

  D) acoelus

  
• NEURAL ARCH:

  ● Perched upon the centrum.

  ● Composed of left and right neural plates.

  ● successive arches and ligaments enclose a

  long vertebral canal (neural canal).

  HEMAL ARCH:

  • composed of hemal plates.

  Chevron bones: similar structure to hemal

  arch that occurs among most amniotes.

  ● Hemal arches and chevron bones enclose the

  caudal artery and vein within a hemal canal.

  A) notochord

  B) CENTRUM

  C) HEMAL ARCH

  D) neural arch

  E) NEURAL SPINE

  
• APOPHYSES

  APOPHYSES

  ● Vertebral processes are projections from the

  arches and centrum.

  Some vertebral processes:

  ● Zygapophyses

  ● Diapophyses

  ● Parapophyses

  ● Basapophyses

  ● Hypapophyses

  ● Pleurapophyses

  A) ZYAGOPHYSIS

  B) DIAPOPHYSIS

  C) PARAPOPHYSES

  D) PLEURAPOPHYSES

  
• BUILDING STONES OF THE VERTEBRA

  -Arcualia - consists of four cartilages on each

  side at each intermyotomal interval.

  ▪ Basidorsal

  ▪ Basiventral

  ▪ Interdorsal

  ▪ Interventral

  A) BASIDORSAL

  B) INTERDORSAL

  C) INTERVENTRAL

  D) BASIVENTRAL

  
• BUILDING STONES OF THE VERTEBRA

  • Perichordal Mesenchymal Concentrations - a cylinder of perichordal mesenchyme forms around the notochord.

  ● Notochord Sheath - membranous structure

  that surrounds and protects the notochord.

  A) SPINAL CORD

  B) NOTOCORD

  C) CAUDAL ARTERY

  D) CAUDAL VEIN

  E) INTERCALATARY PLATE

  F) DORSAL PLATE

  G) PERICHORDIAL CARTILAGE

  H) CHORDAL CARTILAGE

  
• DEVELOPMENT OF THE VERTEBRAL COLUMN

  PARAXIAL MESODERM

  ● Divides into segments called 'somites'

  ● Each somite divides into 3 parts:

  ▪ Dermatome: future skin

  ▪ Myotome: future muscles

  ▪ Sclerotome: future bones

  A) DERMATOME

  B) SCLEROTOME

  C) MYOTOME

  
• DEVELOPMENT OF THE VERTEBRAL COLUMN

  Sclerotome around neural tube: forms vertebral

  (neural) arch.

  ● Sclerotome around notochord: forms body of

  vertebra.

  ● Sclerotome in body wall near to neural tube and

  notochord: forms costal process

  A) SCLEROTOME

  B) SCLEROTOME

  
• DEVELOPMENT OF THE VERTEBRAL COLUMN

  Each sclerotome becomes subdivided in 2 parts:

  ▪ Cranial

  ▪ Caudal

  ● The caudal part of each somite fuses with the

  cranial part of the consecutive somite, around the notochord to form the body of the vertebra, called: Centrum.
• Vertebral columns of different vertebrates’

  group

  Vertebral columns of different vertebrates’

  group

  A) shark

  B) teleost

  C) python

  D) porpoise

  E) bird

  
• Vertebral columns of different vertebrates’

  group

  FISHES

  Composed of two morphological varieties of

  vertebrae:

  ● Abdominal (trunk)

  ● Caudal (tail)

  A) trunk

  B) tail

  C) vertebral canal

  D) neural arch

  E) notochord

  F) centrum

  G) notochord

  H) centrum

  I) neural arch

  J) hemal arch

  K) notochord

  L) neural spine

  M) neural arch

  N) centrum

  O) hemal arch

  P) hemal spine

  
• Vertebral columns of different vertebrates’

  group

  AMPHIBIANS:

  ● notochord is usually within the vertebral column.

  ● Amphibians, with little independent movement of the head, exhibit a single cervical vertebra.

  
• Vertebral columns of different vertebrates’group

  REPTILESa:

  ● Exhibit well-ossified cervicals, dorsals, sacrals, and caudals.

  ● All types of centra occur in the class.

  (Procoelus - most typical)

  ● the usual Apophyses occurs in lizards and snakes.

  ● Notochord is persistent in many PRIMITIVE reptiles.

  A) hypapophysis

  B) transverse processes

  C) prezygapophysis

  D) zygosphene

  E) neural spine

  F) centrum

  G) chevron bone

  H) postzygapophysis

  
• Vertebral columns of different vertebrates’ group

  AVES:

  ● specializations: rigidity, brought about by extensive ankylosis between the vertebrae.

  ● synsacrum provides a rigid framework valuable in flight.

  ● The vertebrae of many birds have pneumatic foramina.

  ● The notochord is obliterated.

  A) prezygapophysis

  B) neural spine

  C) postzygapophysis

  D) vertebral canal

  E) heterocoelus centrum

  F) transverse foramen

  G) transverse process

  
• Vertebral columns of different vertebrates’ group

  MAMMALIA:

  ● vertebral columns of mammals are uniform to number of neck and trunk vertebrae.

  ● Between successive vertebrae lie intervertebral discs, each disc consists of fibrocartilage with a soft center, the nucleus pulposus, a remnant of the notochord.

  A) neural spine

  B) neural arch

  C) centrum

  D) transverse process