Vertebral Column and bony thorax

Formed from bones in the different adult animals Formed from bones in the different adult animals Extends from skull to pelvis Extends from skull to pelvis Transmits weight of trunk to the lower limbs Transmits weight of trunk to the lower limbs Surrounds and protects the spinal cord Surrounds and protects the spinal cord

Vertebral Column 1- Cervical Vertebrae 2- Thoracic V 2- Thoracic Vertebrae Lumbar Vertebrae 4- Sacrum 5- Coccyx (Caudal)

Typical Vertebrae: Consists of: 1- Body (1) 2- A vertebral arch - right and left Pedicles and Lamiae 3- Transverse process (7) 4- Spinous process (9) 5- Articular process (5)

Cervical Vertebrae Seven cervical vertebrae (C 1 – C 7 ) – smallest and lightest vertebrae Seven cervical vertebrae (C 1 – C 7 ) – smallest and lightest vertebrae C 3 – C 7 are typical cervical vertebrae C 3 – C 7 are typical cervical vertebrae Body is small, wider side to side Body is small, wider side to side Spinous processes - short and bifid (except C 7 ) Spinous processes - short and bifid (except C 7 ) Vertebral foramen - large and triangular Vertebral foramen - large and triangular Transverse processes- contain transverse foramina Transverse processes- contain transverse foramina

Atlas – C 1 Lacks a body and spinous process Lacks a body and spinous process No intervertebral disc between C1 and C2 No intervertebral disc between C1 and C2 Supports the skull Supports the skull – Cranial articular facets receive the occipital condyles (Atlanto-occipital Joint)

The Axis - C 2 -The most prominent feature is ridge like spinous process - Cranially the body project peg like eminence (the dens)

Vertebrae (T 1 – T 13 ) All articulate with ribs All articulate with ribs Spinous process- long, sharp, projects caudally Spinous process- long, sharp, projects caudally The spine of 11 th vertebrae is perpendicular (anticlinal). The spine of 11 th vertebrae is perpendicular (anticlinal). 12 th and 13 th process project cranially 12 th and 13 th process project cranially Vertebral Foramen - circular Vertebral Foramen - circular Each side of the body bears demifacets for articulation with ribs Each side of the body bears demifacets for articulation with ribs

Lumbar Vertebrae (L 1 – L 5 ) Body– large, kidney shaped Body– large, kidney shaped Transverse processes are thin and tapered Transverse processes are thin and tapered Spinous processes are short, thick, blunt, and point caudally Spinous processes are short, thick, blunt, and point caudally

Sacrum (S 1 – S 3 ) Formed from 3 fused vertebrae Formed from 3 fused vertebrae

Coccyx (Caudal): Is the "tailbone" Is the "tailbone" Small, triangular bone Small, triangular bone Formed from vertebrae Formed from vertebrae Offers only slight support to pelvic organs Offers only slight support to pelvic organs

Intervertebral Discs Cushion-like pads between vertebrae Cushion-like pads between vertebrae Nucleus pulposus – gives the disc its elasticity and compressibility Nucleus pulposus – gives the disc its elasticity and compressibility Annulus fibrosis – strong outer ring of fibrocartilage which surrounds the nucleus pulposus and limits its expansion Annulus fibrosis – strong outer ring of fibrocartilage which surrounds the nucleus pulposus and limits its expansion

Bony Thorax Forms the framework of the chest Forms the framework of the chest Components of the bony thorax Components of the bony thorax Thoracic vertebrae – dorsally Thoracic vertebrae – dorsally Ribs – laterally Ribs – laterally Sternum and costal cartilage – ventrally Sternum and costal cartilage – ventrally Functions Functions Protects thoracic organs Protects thoracic organs Supports shoulder girdle and upper limbs Supports shoulder girdle and upper limbs Provides attachment sites for muscles Provides attachment sites for muscles

Sternum Composed form eight unpaired segments, the sternbrae. Composed form eight unpaired segments, the sternbrae. Joined by intersternebral cartilages Joined by intersternebral cartilages – Manubrium – 1 st sternbra – Xiphoid process – last sternbra

Ribs 13 pairs, form the sides of the thoracic cage 13 pairs, form the sides of the thoracic cage All ribs attach to vertebral column dorsally All ribs attach to vertebral column dorsally True ribs - superior nine pairs of ribs which attach directly to sternum by costal cartilage True ribs - superior nine pairs of ribs which attach directly to sternum by costal cartilage False ribs – remaining 3 pairs of ribs which attach indirectly to the sternum False ribs – remaining 3 pairs of ribs which attach indirectly to the sternum Float ribs-rib#13 Float ribs-rib#13

- Structure Shaft –bulk of the rib Shaft –bulk of the rib Head – dorsally most end Head – dorsally most end Neck – constricted portion of head beyond head Neck – constricted portion of head beyond head Tubercle – articulates with transverse process of the thoracic vertebrae Tubercle – articulates with transverse process of the thoracic vertebrae