Muscular System

• Skeletal Muscles and associated connective tissue– Skeletal muscle cells=muscle fibers

FUNCTIONS• Produces movement

– (through contraction of cells)• Stabilizes joints and maintains posture

• (through contraction of cells)• Communication

– (through contraction of cells)– Enhances interpersonal communication through facial expression

• Produces body heat – (through high levels of cellular respiration)

Figure 10.2

Figure 10.1

Figure 10.3

Table 10.2

Dark DarkLightLight

striations

Figure 10.8

Figure 10.9

Figure 10.9:

Summary of events initiating and causing contraction

Motor Unit:A motor neuron and all the muscle fibers it innervates

Figure 10.10

Figure 12.10 showing deep fascial compartments

Figure 12.16 showing deep fascial compartments

Figure 12.19 showing deep fascial compartments

Trauma/infection inflammation/swelling + confined space/compartment build up of pressure

a. Pressure on nerves pain & tenderness

b. Compression/obstruction of blood vessels disrupts blood flow

Tissue death (infarction/necrosis)

The following slide has an image of a fasciotomy performed to relieve pressure within an inflamed fascial compartment and diagrams used in lecture to explain the similar basis of carple

tunnel syndrome

Prolonged compromised blood flow

http://en.wikipedia.org/wiki/File:Fasciotomy_leg.jpg

Following slides are descriptions of motor innervations of selected nerves

Motor Cortex: Frontal LobeControls conscious/volunatary muscle activity

Figure 15.11

Figure 15.12

Somatomotor homunculus -- on precentral gyrus -- primary somatomotor cortex

Frontal Lobe

• Primary Somatic Motor Center:– Precentral gyrus /primary motor cortex: – Origin of motor neurons to specific muscles– Contralateral– Contains the motor homunculus, a ‘motor map’ of

the body• Premotor area: anterior to primary motor cortex.

– Motor functions organized before initiation of activity– Including frontal eye field for eye movement

• Broca's area: motor speech- muscle to vocalize

• Frontal lobe and motor control is contralateral: e.g., the right frontral lobe controls movement on the left side of the body

Motor innervations for selected Cranial Nerves V, VII, & XI

Trigeminal Nerve (V)

• Motor Innervation:– Muscles of mastication

(and some of palate and throat)

– Through: • Foramen ovale• Foramen rotundum• Superior orbital fissure

Facial Nerve (VII)• Motor:

– Muscles of facial expression– (and some throat muscles)

– Bell’s (Facial) Palsy– Some branches pass through internal

acoustic meatus and stylomastoid foramen

Accessory Nerve (XI) / a.k.a. spinal accessory nerve

• Motor:– Sternocleidomastoi

d and trapezius– Some pharynx muscles

– Passes through the jugular foramen

Radial Nerve:

Course:• Through axilla, then deep

along posterior humerus then along radius

Motor innervation: • All upper limb extensor

muscles + brachioradialis and

supinator

Factoid: Wrist drop (crutch paralysis):

constant pressure on/in axillary or region or other pressure on nerve can cause damage to nerve preventing wrist extensors from working resulting in “drop” of wrist.

Median Nerve:

Course• Along medial,

anterior humerus, across antecubital region (i.e., elbow pit) into wrist

Motor Innervation: • Pronators, flexors of

wrist and digits & most thumb muscles

• Flex carp rad and deep muscle• Does not innervate brachiorad.

Factoid:Involved with Carple

tunnel Syndrome

Ulnar NerveCourse: • runs on medial arm

and forearm (along ulna)

Motor: • Some wrist flexors

(flexor carpi ulnaris) and intrinsic digit flexors

• And most digit ab/adductors

Factoid:Association w/ “funny

bone”

Femoral Nerve

Course, from lumbar region/plexus across front of iliacus muscle and over the top/front of pubic bone

Motor: • iliopsoas, pectineus,

quadriceps group, & sartorius– Flexion of thigh

and/or extension of knee

Sciatic nerve = tibial nerve + common fibular nerve

Posterior view

anterior view

Tibial (sciatic) Nerve

Course: from sacral plexus, through greater sciatic notch to pass behind the pubis and enter posterior thigh and leg and most of foot

Motor:• Posterior thigh

(hamstrings) and posterior leg

muscles; muscles (those that plantar flex foot and flex toes) flexors

Common Fibular (sciatic) Nerve

Course:• Separates from tibial in

popliteal fossa (knee pit) and innervates anterior and lateral leg and foot

Motor:• Anterior and

lateral leg muscles and to extensors of toes