Skeletal Muscles: Functional Groups Agonist = Prime mover - Provides the major force for producing a specific movement Antagonist - Opposes or reverses a particular movement Synergist – Works together with a prime mover to add force or control Fixator – Synergist that immobilizes a bone that is a muscle’s origin

Naming Skeletal Muscles Location of attachments—named according to the bones to which they attach Location—bone or body region close to the muscle Action—e.g., flexor or extensor, muscles that flex or extend, respectively

Naming Skeletal Muscles Shape—e.g., deltoid muscle (deltoid = triangle) Relative size—e.g., maximus (largest), minimus (smallest), longus (long) Number of origins—e.g., biceps (2 origins) and triceps (3 origins) Direction of fibers or fascicles—e.g., rectus (fibers run straight), transversus, and oblique (fibers run at angles to an defined axis)

Figure 10.1 Patterns of fascicle arrangement in muscles. (b) (f) Circular (orbicularis oris) (b) Convergent (pectoralis major) (c) (e) (c) Parallel (sartorius) (d) Unipennate (extensor digitorum longus) (d) (e) Bipennate (rectus femoris) (f) Fusiform (biceps brachii) (g) Multipennate (deltoid)

Figure 6.2 Major skeletal muscle groups and their functions. (1 of 2)

Figure 6.2 Major skeletal muscle groups and their functions. (2 of 2)

Figure 10.5 Posterior view of superficial muscles of the body. Arm Forearm Hip Gluteus medius Gluteus maximus Thigh Leg

Figure 10.6 Lateral view of muscles of the scalp, face, and neck. Epicranius Aponeurosis Frontal belly Orbicularis oculi Occipital belly Zygomaticus minor and major Temporalis Buccinator Masseter Sternocleidomastoid Orbicularis oris Trapezius Platysma

Anterior belly Digastric Posterior Hyoid bone belly Sternocleido- Figure 10.8a Muscles of the anterior neck and throat that promote swallowing. Anterior belly Digastric Posterior belly Hyoid bone Sternocleido- mastoid Thyroid gland (a)

Base of occipital bone 1st cervical vertebra Mastoid process Middle Figure 10.9a Muscles of the neck and vertebral column causing movements of the head and trunk. Base of occipital bone 1st cervical vertebra Mastoid process Middle scalene Sternocleido- mastoid Anterior scalene Posterior scalene (a) Anterior

Figure 10.10a Muscles of respiration. External intercostal (a) Internal intercostal

Figure 10.10b Muscles of respiration. Xiphoid process of sternum Foramen for inferior vena cava Foramen for esophagus Costal cartilage Central tendon of diaphragm Diaphragm Foramen for aorta Lumbar vertebra 12th rib (b) Psoas major

Figure 10.11a Muscles of the abdominal wall. Pectoralis major Serratus anterior Transversus abdominis Internal oblique Rectus abdominis External oblique aponeurosis (a)

Figure 10.11b Muscles of the abdominal wall. Rectus abdominis External oblique Internal oblique Lumbar fascia IIiac crest Pubic tubercle Lumbar fascia Transversus abdominis (b)

Sternocleido- mastoid Clavicle Deltoid Pectoralis major Sternum Figure 10.13a Superficial muscles of the thorax and shoulder acting on the scapula and arm. Sternocleido- mastoid Clavicle Deltoid Pectoralis major Sternum Serratus anterior Biceps brachii Humerus (a)

Trapezius Clavicle Deltoid Spine of scapula Humerus Latissimus dorsi Figure 10.13c Superficial muscles of the thorax and shoulder acting on the scapula and arm. Trapezius Clavicle Deltoid Spine of scapula Humerus Latissimus dorsi (c)

Spine of scapula Deltoid (cut) Greater tubercle of humerus Figure 10.14b Muscles crossing the shoulder and elbow joint, causing movements of the arm and forearm, respectively. Spine of scapula Deltoid (cut) Greater tubercle of humerus Triceps brachii: Lateral head Long head Latissimus dorsi Humerus Olecranon process of ulna (b) Posterior view

Long head Biceps brachii Short head O = origin I = insertion (c) Figure 10.14c Muscles crossing the shoulder and elbow joint, causing movements of the arm and forearm, respectively. Long head Biceps brachii Short head O = origin I = insertion (c)

Flexor digitorum s.. Flexor p.. l.. Flexor c.. u.. Figure 10.15a Muscles of the anterior fascial compartment of the forearm acting on the right wrist and fingers. Flexor digitorum s.. Flexor p.. l.. Flexor c.. u.. Extensor c.. r... l.. Flexor c.. r.. Medial epicondyle of humerus (a)

Extensor p.. l.. Extensor i.. Extensor p.. b.. Extensor d.. m.. Figure 10.16a Muscles of the posterior fascial compartment of the right forearm acting on the wrist and fingers. Extensor p.. l.. Extensor i.. Extensor p.. b.. Extensor d.. m.. Extensor c.. u.. Extensor digitorum Flexor c.. u.. Extensor c.. r.. b.. Extensor c.. r.. l.. (a)

Figure 10.17a Summary of actions of muscles of the arm and forearm. Lateral head Long head Triceps brachii Posterior compartment of arm (extends elbow) Medial head Humerus Extensors Flexors {Brachialis} Others Short head Biceps brachii Long head (a) (a) Muscles of the arm Anterior compartment of arm (flexes elbow)

Figure 10.17b Summary of actions of muscles of the arm and forearm. Posterior compartment of forearm (extends wrist and fingers) Extensors Radius Ulna Others Flexors (b) Muscles of the forearm (b) Extensors Flexors Anterior compartment of forearm (flexes wrist and fingers) Others

Anterior superior iliac spine Figure 10.19a Anterior and medial muscles promoting movements of the thigh and leg. 12th rib 12th thoracic vertebra Iliac crest Psoas major Iliopsoas Iliacus 5th lumbar vertebra Anterior superior iliac spine Adductor longus Sartorius Quadriceps femoris • Rectus femoris • Vastus lateralis • Vastus medialis Patella (a)

Adductor longus Femur O = origin I = insertion (b) Figure 10.19b Anterior and medial muscles promoting movements of the thigh and leg. Adductor longus Femur O = origin I = insertion (b)

muscles of Quadriceps group O = origin I = insertion Vastus lateralis Figure 10.19c Anterior and medial muscles promoting movements of the thigh and leg. muscles of Quadriceps group O = origin I = insertion Vastus lateralis Vastus intermedius Vastus medialis Rectus femoris (tendon cut) Patella Patellar ligament (c)

Figure 10.20a Posterior muscles of the right hip and thigh. Gluteus medius Gluteus maximus Long head Biceps femoris Short head Hamstrings Semitendinosus Semimembranosus (a)

Figure 10.21b Muscles of the anterior compartment of the right leg. Tibialis anterior O = origin I = insertion (b)

Figure 10.22a Muscles of the lateral compartment of the right leg. Patella Head of fibula Gastrocnemius Soleus Fibularis longus Tibialis anterior Lateral malleolus (a)

Figure 10.22b Muscles of the lateral compartment of the right leg. O = origin I = insertion Fibularis longus (b) Tendon of fibularis longus

Figure 10.23a Muscles of the posterior compartment of the right leg. Medial head Gastrocnemius Lateral head Tendon of gastrocnemius Calcaneal tendon (Achilles) Calcaneus (a) Superficial view of the posterior leg.

Figure 10.25a Summary of actions of muscles of the thigh and leg. Adductors Hamstrings Vastus lateralis Femur Posterior compartment of thigh (flexes leg and extends thigh) Vastus intermedius Rectus femoris (a) Vastus medialis Posterior compartment muscles Anterior compartment muscle Medial compartment muscles of thigh and lateral muscles of leg Medial compartment (adducts thigh) Anterior compartment (extends leg) (a) Muscles of the thigh

Figure 10.25b Summary of actions of muscles of the thigh and leg. Posterior compartment muscles Gastrocnemius and soleus Anterior compartment muscle Fibula Medial compartment muscles of thigh and lateral muscles of leg Fibularis muscles Posterior compartment of leg (plantar flexes foot, flexes toes) (b) Tibialis anterior Tibia Lateral compartment of leg (plantar flexes and everts foot); innervation Anterior compartment of leg (dorsiflexes foot, extends toes) (b) Muscles of the leg

Figure 15.3a Extrinsic eye muscles. Superior oblique muscle Superior oblique tendon Superior rectus muscle Lateral rectus muscle Inferior rectus muscle Inferior oblique muscle (a) Lateral view of the right eye

Figure 15.3b Extrinsic eye muscles. Trochlea Superior oblique muscle Superior oblique tendon Superior rectus muscle Inferior rectus muscle Medial rectus muscle Lateral rectus muscle (b) Superior view of the right eye