Bio 162 - Chapter 9 Musculoskeletal System

Axial Skeleton

skull, vertebral column, sacrum, ribs, and sternum

Cervical Curvature

Lumbar Curvature

known as “the small of the back”

Thoracic Curvature

Pelvic Curvature

Intervertebral Disc

• made of connective tissue

• separate the bodies every vertebra and reduce friction as the vertebrae move

• help to absorb shock

Sacrum

Coccyx

Tailbone

Cervical Vertebrae in Neck

7

Atlas

• first of the cervical vertebrae

• articulates with the skull superiorly and the axis inferiorly

• Supports skull

Axis

• second cervical vertebrae

• allows you to shake your head back in forth

  • allows you head to move along an axis

Body

• On all vertebrae except the atlas

• Transmits weight down the bodies of the vertebrae

Superior Articular Process

bony projections that point superiorly to articulate with vertebra above

Superior Articular Facet

surface where two bones physically articulate

Inferior Articular Process

bony projections that point inferiorly to articulate with vertebra below

Inferior Articular Facet

surfaces where two bones physically articulate

Transverse Process

bony region that extends laterally from the body

Spinous Process

somewhat sharp projection that extends posteriorly, opposite from the body of the vertebra

Vertebral Arch

transverse and spinous processes arise from this bony arch

Vertebral Foramen

opening formed by the vertebral body and arch

Vertebral (Spinal) Canal

All of the vertebral foramina will line up together and form this long tube. Nerves of spinal cord run though this canal

Thoracic Vertebrae

12

• body

• superior articular processes with facets

• inferior articular processes with facets

• transverse process

• spinous process

• vertebral arch

• vertebral foramen

Rib (Costal) Facets

found on the body and on the transverse processes. covered with articular cartlage and appear smooth in real bone

Lumbar Vertebrae

5

• body

• superior articular processes with facets

• inferior articular processes with facets

• transverse process

• spinous process

• vertebral arch

• vertebral foramen

articular processes are curved/cupped

Sacrum Body

main thick medial region of the sacrum

Median Sacral Crest

formed from the spinous processes of the fused vertebrae

Sacral Canal

passageway which corresponds with vertebral canal

Auricular Surface

on the lateral faces of the sacrum. forms the joint between the sacrum and the ilium

Ribs (total #?)

12 pairs of ribs that articulate with the thoracic vertebrae

True Ribs

• ribs 1-7

• articulate directly with the sternum via costal cartilage

False Ribs

• ribs 8-12

• articulate with the sternum indirectly (8-10)

• don’t articulate at all (11-12)

Floating Ribs

• ribs 11 and 12

• don’t articulate with the sternum

Head of the rib

articular facet on the head of each rib articulates medially with the rib facets of the tracic vertebra

Tubercle of the rib

small bumpy ridge found distal to the head of the rib

Body of the rib

main part where rib is distal to the neck

Angle of the rib

distal to the tubercle. makes a sharp bend

Sternum

• sometimes called the “breast bone”

• articulates with the true ribs

  • together they protect the heart and the lungs

Body of the sternum

large middle portion

Facets of the sternum

where costal cartilage associated with the ribs articulate

Manubrium of the sternum

upper part of the sternum

Xiphoid Process of the sternum

inferior to the body of the sternum

Abdominal Muscles

• responsible for moving the spine, abdomen, and ribs

• rectus abdominis, external oblique, internal oblique, transversus abdominis

Rectus Abdominis

• “6-pack”

• connected by a strong column of connective tissue - linea alba

  • connects xiphoid process to the pubic bone

External Oblique

• lateral to the rectus abdominis muscles

• forms most superficial part of the abdominal wall

Internal Oblique

• lateral to the rectus abdominis and hidden underneath the external oblique muscles

• form the middle layer of much of the abdominal wall

Transverse Abdominis

• deepest muscle layer of the lateral abdominal wall

• lies below the internal oblique muscle

• fibers run side to side

Intercostal Muscles

• three layers of muscles

• inter(between)costal(ribs)

• forms a continuous wall over thorax and helps stabilize and move rib cage

• external, internal, and innermost intercostal muscles

External Intercostal Muscles

• fibers run on either side of your chest from superior-lateral to inferior-medial

  • forms a v shape, mirrors striations of the external oblique muscles

• may assists with inhalation by pulling ribs upward

Internal Intercostal Muscles

• fibers run on either side of you chest like an A shape from superior-medial to inferior-lateral

• may assist with exhalation by pulling ribs downwards

Innermost Intercostal Muscles

• fibers line the inside of your chest and run superior-inferior

• may assist with exhalation by pulling ribs downwards

Diaphragm

• dome shaped muscle responsible for increasing the volume of your thoracic cavity to help you inhale

• forms division between the thoracic cavity above and the abdominal cavity below

• Skeletal Muscle

Thoracic Cavity

Abdominal Cavity

Erector Spinae (Deep Back Muscles)

Sternocleidomastoid

• moves head and neck

• muscle extends from mastoid process to medial clavicle (collar bone) and manubrium of the sternum

• name indicates attachment points:

  • sterno (sternum)

  • cleido (clavicle)

  • mastoid (mastoid process)

Clavicle

collar bone