Muscles

Muscles

Direction of Muscle Fibers

Fig. 11-1

Sites of Muscle Attachment

• _________ attach bone to bone. ________ attach muscle to bone.Ligaments Tendons

. . or cartilage or connective tissue.

• Origin = stationary point of muscle attachment

• Insertion = mobile point of muscle attachment

• Belly = fleshy part of the muscle

• Aponeurosis = large, flat tendon

Special Tendons

Galea aponeurotica

Coordination of Muscle Action

Agonist (prime mover) – a muscle whose contraction is chiefly responsible for a particular movement Synergist – assist the agonist; may provide additional pull near the insertion or may stabilize the point of origin Antagonist – contraction opposes the action of the agonist

e.g. Biceps brachii and Triceps brachii are antagonists

Muscles Work as LeversLever = a rigid structure that moves on a fixed point, or fulcrum, when a force is applied to it. This force overcomes resistance.

Components of a Lever System

• Applied Force = muscle contraction • Lever = bone• Fulcrum = joint• Resistance = weight of body parts, gravity, objects

point of attachment

F

AF

R

Classes of Levers(determined by position of fulcrum)

First Class Lever - fulcrum lies between the AF & resistance

e.g. hyperextension of neck (Fig 11-2a)

Classes of LeversSecond Class Lever – resistance lies between AF & fulcrum

e.g. plantar flexion (Fig 11-2b)

Classes of LeversThird Class Lever – AF lies between resistance & fulcrum

e.g. flexion of elbow (Fig 11-2c)

Naming of Muscles

• Orientation of muscle fibers- Rectus (straight)- Transverse (horizontal)- Oblique (angled)

• Body region (review Fig 1-6)

- Brachialis - Gluteus

Naming of Muscles

• Relative position- External / Internus- Superficialis (superficial) / Profundus (deep) - Supra / Infra

• Size- Maximus / Minimus- Major / Minor- Longus (long) / Brevis (short)

Naming of Muscles

• Shape - Deltoid (triangle; D)

- Trapezius (trapezoid)

• Number of origins (heads)- Biceps- Triceps- Quadriceps

Naming of Muscles

• Location of origin & insertion - Coracobrachialis- Iliotibial tract

• Action- Abductor / Adductor- Pronator / Supinator- Flexor / Extensor

Head & Neck

Platysma

insertion

origin

What is its action? ___________________depresses mandible

Head & Neck

Digastric muscle

Neck muscles

1. Digastric 5. Sternohyoid 6. Sternothyroid

Neck Muscles

Chest, Shoulder, & Back

Chest, Shoulder, & Back

Chest, Shoulder, & Back

Chest, Shoulder, & Back

Arm Muscles

Orbicularis oris

TrapeziusSCM

Pectoralis major

Serratus anterior

Deltoid

Biceps brachii

BrachioradialisPronator teres

Flexor carpi radialisFlexor carpi ulnaris

Arm Muscles

Coracobrachialis

Brachialis

Pronator teresFlexor carpi radialis

Palmarus longusFlexor carpi ulnaris

Arm MusclesSemispinalis capitus

SCM

Splenius capitus

Levator scapulaeTrapezius

Triceps brachii

Deltoid

InfraspinatusTeres minor

Teres major

Arm Muscles

Triceps brachii

Aconeus

Extensor carpi radialis longus

Extensor carpi radialis brevis

Extensor carpi ulnaris

Extensor digitorum

Trunk & Abdominal Muscles

External abdominalobliques

Serratus anterior

Linea alba

Trunk & Abdominal Muscles

External intercostals

Rectus abdominis

Internal abdominal obliques

Trunk & Abdominal Muscles

Serratus anterior

External intercostals

Rectus abdominis

Linea alba

Transverse abdominis

External oblique

Internal oblique

Trunk & Abdominal Muscles

Linea alba

Trunk & Abdominal Muscles

Internal intercostals

Trunk & Abdominal Muscles

Diaphragm

Central tendonof diaphragm

Trunk & Abdominal Muscles

Erector Spinae (sacrospinalis)

Origin: transverse & spinous process of C, T, and L

Insertion: same as origin

Action: extends the spine

Trunk & Abdominal Muscles

Quadratus lumborum

Origin: Iliac crest

Insertion: transverse processes upper L (1 -4)

Action: flexes spine

Hips, Buttocks, & Groin

Tensor Fascia Latae

Origin: iliac crest of the illium

Insertion: iliotibial tract

Action: flexes & abducts the thigh

Hips, Buttocks, & Groin

Iliopsoas - Iliacus

Origin: iliac crest

Insertion: lesser trochanter of femur

Iliopsoas – psoas major

Origin: transverse processes of L

Insertion: lesser trochanter of femur

Action of both iliopsoas: flexes thigh

Hips, Buttocks, & Groin

Inguinal ligament

Hips, Buttocks, & Groin

Gluteus Maximus

Origin: gluteal line of illium

Insertion: gluteal tuberosity of femur

Action: extends and laterally rotates thigh

Gluteus Medius

Origin: outer surface of the illium

Insertion: greater trochanter of femur

Action: abducts and medially rotates thigh

Leg Muscles

IT tract

Tensor fasciae latae

Sartorius

Quadriceps

Rectus femoris

Vastus lateralis

Vastus medialis

Leg Muscles

Vastus lateralis

Vastus medialis

Vastus intermedius

Adductor longus

Adductor magnus

Leg Muscles

Gracilis

Leg Muscles

Biceps femoris(long head)

Biceps femoris(short head)

Semitendonosis

Semimembranosis

Adductor magnus Gracilis

Leg Muscles

Fibularis longus

Tibialis anterior

Soleus

Extensor digitorum longus

Leg Muscles

Tibialis anterior

Fibularis longus

Extensor digitorum longus

Soleus

Gastrocnemius

Leg Muscles

Gatrocnemius

Calcaneal tendon

Leg Muscles

Tibialis posterior

Flexor digitorum longus