Muscular system

1. 10-1
Muscular System II:
Head, Neck and Trunk Muscles
Lecture 10

2. 10-2
Muscles of the Neck
Fig. 11.8
Anterolateral Neck Muscles
• Sternocleidomastoid
• One or both may contract
Posterior Neck Muscles
• Semispinalis capitis, Splenius
capitis, Trapezius
Fig. 11.10
Mylohyoid
Digastric
Anterior belly
Posterior belly
Sternocleidomastoid
Trapezius
Geniohyoid
Hyoid bone
Clavicle
Superficial Deep
Semispinalis capitis (cut)
Splenius capitis (cut)
Semispinalis capitis
Sternocleidomastoid
Splenius capitis
Levator scapulae
Deep Deeper

3. 10-3
Muscles of Facial Expression
Fig. 11.2
Elevators
• Levator labii superioris,
Occipitofrontalis, Zygomaticus
Depressors
• Depressor labii inferioris,
Platysma
Other actions
• Buccinator, Orbicularis oculi,
Orbicularis oris
Superficial Deep
Frontal belly of
occipitofrontalis
Orbicularis oculi
Levator labii
superioris
Zygomaticus
Depressor labii inferioris
Platysma
Platysma
Depressor labii inferioris
Orbicularis oris
Zygomaticus
Levator labii superioris
Orbicularis oculi
Temporalis
Masseter
Orbicularis oris
Buccinator

4. 10-4
Muscles of Facial Expression
Elevators
• Levator labii superioris,
Occipitofrontalis, Zygomaticus
Depressors
• Depressor labii inferioris,
Platysma
Other actions
• Buccinator, Orbicularis oculi,
Orbicularis oris

5. 10-5
Muscles of Facial Expression
Fig. 11.3

6. 10-6
Muscles of Mastication
Major Muscles
• Temporalis and Masseter
Temporalis:
Origin - temporal lines of parietal
Insertion - coronoid process
Masseter:
Origin - zygomatic arch
Insertion - lateral side of mandible
Fig. 11.5

7. 10-7
Hyoid Muscles
Actions of hyoid muscles
• move mandible and hyoid
Fig. 11.8
Mylohyoid
Digastric
Anterior belly
Posterior belly
Geniohyoid
Hyoid bone
Clavicle
Superficial Deep Mylohyoid
Digastric
Anterior belly
Posterior belly

8. 10-8
Trunk Muscles - Muscles of
Vertebral Column
Fig. 11.11
Superficial:
• Erector spinae (Iliocostalis, Longissimus, Spinalis), Semispinalis, and Multifidus
Deep:
• Interspinalis
Actions:
• Extension, rotation, lateral flexion of the back
Multifidus
Iliocostalis
Longissimus
Spinalis
Erector spinae
Deep Deeper
Semispinalis

9. 10-9
Muscles of Respiration
Fig. 11.13
Inspiration:
• Diaphragm is
primary muscle of
inspiration (depresses
floor of thoracic
cavity)
• External intercostals
elevate ribs
Expiration:
• Internal intercostals
depress ribs

10. 10-10
Review Question
Axial muscles of the spine control the position of the
(a) Head, neck, and pectoral girdle
(b)Head, neck, and vertebral column
(c) Vertebral column only
(d)Vertebral column and pectoral and pelvic girdles

11. 10-11
Points to Remember
• Muscles of the face move the skin rather than a
joint allowing a vast range of facial expressions
• Muscles that move the mandible are also known as
muscles of mastication because they provide the
chewing action
• Complexity of muscles of the vertebral column
required for flexibility and maintaining posture

12. 10-12
Questions?