biol 2304 chapter 7 2
DESCRIPTION
The Axial skeleton: notesTRANSCRIPT
CHAPTER 7“The Axial Skeleton #2”
Course objectives:
Define and identify the bones of Define and identify the bones of the axial skeletonthe axial skeleton
Vertebral columnVertebral column
composed of composed of 2626 irregularirregular bones. bones.
These bones provide a solid support These bones provide a solid support
structure, but are also remarkably structure, but are also remarkably flexible. flexible.
Regions of the Vertebral Regions of the Vertebral ColumnColumn
– CervicalCervical − neck region 7 vertebrae − neck region 7 vertebrae – ThoracicThoracic – thorax region 12 – thorax region 12
vertebrae vertebrae – LumbarLumbar – lower back 5 vertebrae – lower back 5 vertebrae – SacralSacral – low, low back 1 vertebrae – low, low back 1 vertebrae
(5 fused) (5 fused) – CoccygealCoccygeal – – tail bone 1 vertebrae tail bone 1 vertebrae
(4 fused)(4 fused)
Spinal CurvatureSpinal Curvature
Thoracic and sacral are concaveThoracic and sacral are concave (i.e. (i.e. backward) backward)
Primary curves since they developed first.Primary curves since they developed first.
Cervical and lumbar curves are convexCervical and lumbar curves are convex (i.e. forward) and secondary curves.(i.e. forward) and secondary curves.
Vertebral columnVertebral column
VertebraeVertebrae
Individual vertebrae are found in the Individual vertebrae are found in the cervical, thoracic and lumbar regions cervical, thoracic and lumbar regions of the vertebral column. of the vertebral column.
There are significant differences There are significant differences between the vertebrae in each of between the vertebrae in each of these regions that you should know. these regions that you should know.
Cervical vertebrae – C1- C7Cervical vertebrae – C1- C7 Body is oval; spinous process is short (except C-Body is oval; spinous process is short (except C-
7) and sometimes split; 7) and sometimes split; Large vertebral foramen Large vertebral foramen Transverse foramen for vertebral artery to Transverse foramen for vertebral artery to
brainstem.brainstem. C1 is AtlasC1 is Atlas articulates (atlanto-occipital joint) articulates (atlanto-occipital joint)
with occipital bone of skull with occipital bone of skull
-allows “yes” motion of head-allows “yes” motion of head C2 is AxisC2 is Axis characterized by peg-like process characterized by peg-like process
called “dens” or odontoid process which called “dens” or odontoid process which interlocks with atlas (atlanto-axial joint)interlocks with atlas (atlanto-axial joint)
-allows sideward rotation or “no” motion of head. -allows sideward rotation or “no” motion of head.
Cervical VertebraeCervical Vertebrae
AtlasAtlas
Axis Axis
Atlanto/axial jointAtlanto/axial joint
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Atlas
(C1vertebra)
Transverse ligament
Axis C2 vertebrae)
Articular facet of densDens
(c) Axis and atlas, posterosuperior view
Cervical VertebraeCervical Vertebrae
Thoracic vertebrae T1- T12Thoracic vertebrae T1- T12
Body is roughly heart shapedBody is roughly heart shaped Demifacets for rib articulation Demifacets for rib articulation Vertebral foramen are circularVertebral foramen are circular Spinous process long and points Spinous process long and points
inferiorly inferiorly
The thoracic vertebra look like a The thoracic vertebra look like a giraffe’s head when viewed from the giraffe’s head when viewed from the lateral view!lateral view!
Thoracic vertebrae T1- T12
Lumbar Vertebrae L1-L5Lumbar Vertebrae L1-L5 Pedicles and laminae are short and thickerPedicles and laminae are short and thicker Spinous processes are short, flat and Spinous processes are short, flat and
hatchet shapedhatchet shaped Vertebral foramen is triangularVertebral foramen is triangular Inferior and superior processes lock the Inferior and superior processes lock the
adlacent vertebrae together for strength adlacent vertebrae together for strength and stability.and stability.
The lumbar vertebra look like a Moose’s The lumbar vertebra look like a Moose’s head!head!
Lumbar Vertebrae L1-L5
Sacral Vertebrae S1-S5Sacral Vertebrae S1-S5
Sacral vertebrae consists of 5 fused Sacral vertebrae consists of 5 fused vertebrae fully fused by 30 years of agevertebrae fully fused by 30 years of age
Women sacrum is shorter, wider and more Women sacrum is shorter, wider and more curvedcurved
Connects the spine to the pelvic girdle at Connects the spine to the pelvic girdle at the sacroiliac joint.the sacroiliac joint.
Sacral canal is continuation of vertebral Sacral canal is continuation of vertebral canal. canal.
Sacrum and CoccyxSacrum and Coccyx
Ant. ViewAnt. View
Post view Post view
Coccyx Vertebrae Co1-Co4Coccyx Vertebrae Co1-Co4
Coccyx is Greek for “cuckoo”Coccyx is Greek for “cuckoo” Consists of 4 fused vertebraeConsists of 4 fused vertebrae Fuse between 20 and 30 yearsFuse between 20 and 30 years Tailbone is vestige of tailTailbone is vestige of tail
- Men it points anteriorly- Men it points anteriorly
- Women it points inferiorly - Women it points inferiorly
Cervical and Thoracic Cervical and Thoracic vertebraevertebrae
Lumbar vertebraeLumbar vertebrae
Additional structures of the vertebral Additional structures of the vertebral
columncolumn Intervertebral discsIntervertebral discs
Present between all vertebrae C2- L5/S1;Present between all vertebrae C2- L5/S1; Composed of fibro cartilageComposed of fibro cartilage Two regions of disc:Two regions of disc:
- nucleus pulposis- nucleus pulposis – central core of – central core of discdisc
- annulus fibrosis- annulus fibrosis - outer covering of - outer covering of fibro cartilagefibro cartilage
Function: Function: -discs permit various movements -discs permit various movements
-provide shock absorbing functions for -provide shock absorbing functions for vertebral columnvertebral column
Vertebra and vertebral discVertebra and vertebral disc
Herniated Intervertebral Herniated Intervertebral discsdiscs
Dorsal root ganglion
Spinal cord
Vertebral LigamentsVertebral Ligaments
(1). Anterior and posterior longitudinal (1). Anterior and posterior longitudinal ligaments hold vertebral column together ligaments hold vertebral column together along with trunk skeletal musclesalong with trunk skeletal muscles
-prevent hyper-extension and hyper--prevent hyper-extension and hyper-flexion of the vertebral column. flexion of the vertebral column.
(2). Shorter ligaments connect adjoining (2). Shorter ligaments connect adjoining vertebrae together. vertebrae together.
-There are 3 of these ligaments the -There are 3 of these ligaments the ligamentum flavumligamentum flavum, the supraspinous , the supraspinous ligaments and the interspinous ligaments.ligaments and the interspinous ligaments.
Vertebral LigamentsVertebral Ligaments
Bony ThoraxBony Thorax Consists of ribs attached to the vertebral Consists of ribs attached to the vertebral
column and sternumcolumn and sternum True ribs R1-R7 attach directly to True ribs R1-R7 attach directly to
sternumsternum False ribs R8-R10 attach indirectlyFalse ribs R8-R10 attach indirectly Two floating ribs R11 & R12Two floating ribs R11 & R12 The Sternum consisting of:The Sternum consisting of:
- manubrium- manubrium
- body- body
- Xiphoid process- Xiphoid process
Bony ThoraxBony Thorax
RibsRibs1.1. true ribstrue ribs – – the first (superiormost) seven pairs of the first (superiormost) seven pairs of
ribs R1-R7 are directly connected to the sternum ribs R1-R7 are directly connected to the sternum via costal cartilage.via costal cartilage.
- are called - are called vertebrosternal ribsvertebrosternal ribs..
2.2. false ribsfalse ribs – – the remaining five pairs of ribs.the remaining five pairs of ribs.
There are two types of false ribsThere are two types of false ribs.. vertebrochondral ribsvertebrochondral ribs -- rib pairs #8, #9, and -- rib pairs #8, #9, and
#10 are connected by a single band of costal #10 are connected by a single band of costal cartilage to the inferior portion of the sternum. cartilage to the inferior portion of the sternum. Unlike the first seven pairs of ribs they do Unlike the first seven pairs of ribs they do notnot have their own individual attachments.have their own individual attachments.
floating or vertebral ribsfloating or vertebral ribs – rib pairs #11 and – rib pairs #11 and #12 are connected only to the vertebral #12 are connected only to the vertebral column, they have no anterior connection to column, they have no anterior connection to the skeleton.the skeleton.
All ribs articulate with vertebral column. The head All ribs articulate with vertebral column. The head of the rib articulates at a demifacet on the body of the rib articulates at a demifacet on the body of the vertebrae, while the tubercle of the rib of the vertebrae, while the tubercle of the rib articulates at a facet on the transverse process. articulates at a facet on the transverse process.
Sternum “breast plate”Sternum “breast plate”
Anterior central portion of thoraxAnterior central portion of thorax Only bony attachment of axial Only bony attachment of axial
skeleton to appendicular skeleton via skeleton to appendicular skeleton via clavicle.clavicle.
Consists of Manubrium, Body and Consists of Manubrium, Body and Xiphoid processXiphoid process
Key landmarks: calvicular notches, Key landmarks: calvicular notches, jugular notch “suprasternal notch”, jugular notch “suprasternal notch”, sternal angle.sternal angle.
SternumSternum
The sternal foramen is an anomaly and occurs in ~ 4-10% of the population. It can The sternal foramen is an anomaly and occurs in ~ 4-10% of the population. It can be mistaken for a bullet puncture in cases of traumatic death. be mistaken for a bullet puncture in cases of traumatic death.
Hyoid boneHyoid bone Lies inferior to the mandibleLies inferior to the mandible Is not attached to skeleton by bony meansIs not attached to skeleton by bony means Helps movement of base of tongueHelps movement of base of tongue
Hyoid boneHyoid bone