Anatomy 1 - Axial Muscles
Terms
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Masseter -
Origin: zygomatic arch
Insertion: mandible
Action: elevates mandible, closes jaw -
Temporalis -
Origin: temporal lines of parietal
Insertion: coronoid process of mandible
Action: elevates mandible, closes jaw -
Digastric: Anterior Belly -
Origin: from inferior surface of mandible at chin
Insertion: hyoid
Action: depresses mandible, opening mouth,and/or elevates larynx -
Digastric: Posterior Belly -
Origin: from mastoid region of temporal bone
Insertion: hyoid
Action: depresses mandible, opening mouth,and/or elevates larynx -
Mylohyoid -
Origin: mylohyoid line of mandible
Insertion: median connective tissue band (raphe) that runs to hyoid bone
Action: elevates floor of mouth, elevates hyoid bone,and/or depresses mandible -
Sternohyoid -
Origin: clavicle & manubrium
Insertion: hyoid bone
Action: depresses hyoid bone and larynx -
Sternocleidomastoid: Clavicular Head -
Origin: attaches to sternal end of clavicle
Insertion: mastoid region of skull, lateral portion of superior nuchal line
Action: together flex neck, alone bend side to side -
Sternocleidomastoid: Sternal Head -
Origin: attaches to manubrium
Insertion: mastoid region of skull, lateral portion of superior nuchal line
Action: together flex neck, alone bend side to side -
Splenius capitis -
Origin: cervical & thoracic vertebrae
Insertion: mastoid process,occipital bone, superior cervical vertebrae
Action: together extend neck, alone rotates & flexes side to side -
Spinalis Thoracis -
Origin: thoracic & lumbar vertebrae
Insertion: spinous process of thoracic vertebrae
Action: extends vertebral column -
Scalenes (anterior, middle & posterior) -
Origin: transverse & costal processes of cervical vertebrae C2-C7
Insertion: superior surface of ribs 1-2
Action: elevates ribs, flexes neck, rotates and bends neck -
External Intercostals -
Origin: inferior border of each rib
Insertion: superior border of more inferior rib
Action: elevates ribs -
Internal Intercostals -
Origin: superior border of each rib
Insertion: inferior border of the more superior rib
Action: depresses ribs -
Diaphragm -
Origin: xiphoid process, ribs 7-12 & anterior surfaces of lumbar vertebrae
Insertion: central tendinous sheet
Action: contraction expands thoracic cavity, compresses abdominopelvic cavity -
External Oblique -
Origin: ribs 5-12
Insertion: extend to linea alba & iliac crest
Action: compresses abdomen; depresses ribs; laterally flexes or rotates vertebral column -
Internal Oblique -
Origin: lumbodorsal fascia & iliac crest
Insertion: inferior surfaces of ribs 9-12, costal cartilages 8-10, linea alba & pubis
Action: compresses abdomen; depresses ribs; laterally flexes or rotates vertebral column -
Transverse Abdominis -
Origin: cartilages of ribs 6-12, iliac crest, lumbodorsal fascia
Insertion: linea alba, pubis
Action: compresses abdomen -
Rectus Abdominis -
Origin: superior surface of pubis, around symphysis
Insertion: inferior surfaces of cartilages (ribs 5-7) & xiphoid process
Action: depresses ribs, flexes vertebral column, compresses abdomen