Appendicular Muscles Lecture Notes

Appendicular Muscles

Previous Lecture Review (Axial Muscles)

• Axial Muscles
  • Head & neck.
  • Vertebral column.
  • Respiration
  • Abdominal wall.
  • Pelvic floor.

Review Questions (From Previous Lecture)

• Function of axial muscles:
  • Support & move head & spinal cord.
  • Function in nonverbal communication (affect facial features).
  • Move lower jaw during chewing.
  • Assist in food processing & swallowing.
  • Aid breathing.
  • Support & protect abdominal & pelvic region.
• The orbicularis oculi, zygomaticus major & minor, & orbicularis oris are sphincter muscles.
  • TRUE
• The risorius and platysma are involved with smiling.
  • TRUE
• Muscle associated w/ chewing:
  • Temporalis, masseter, lateral & medial pterygoids, & buccinator.
• Common insertion of all the tongue muscles:
  • Inferior aspect of the tongue in some regard.
• Common origin structure that the erector spinae muscles attach to:
  • Spinous processes.
• Muscle not involved w/ respiration:
  • Transversospinalis
• Muscle not of the abdominal wall or the pelvic floor:
  • E. All the above are muscles of the abdominal wall or the pelvic floor.
• The trapezius muscles are considered part of the axial muscles.
  • FALSE

Upcoming Quizzes and Exams

• Quiz 3 is on 6/9
• Quiz 4 is on 6/11
• Exam 2 & practical 2 are on 6/16

Introduction to Appendicular Muscles

• Appendicular muscles are muscles that move:
  • Pectoral girdle.
  • Glenohumeral joint/arm.
  • Elbow joint/forearm.
  • Wrist joint, hand, & fingers.
  • Hip joint/thigh.
  • Knee joint/leg.
  • Leg & foot.
• Control movement of pectoral & pelvic girdles, as well as the upper & lower limbs.

Organization of Appendicular Muscles

• Broken up into 5 groups:
  1. Move pectoral girdle.
  2. Move glenohumeral joint/arm.
  3. Brachial & antebrachial muscles.
     • What do those anatomical region names mean again?
  4. Antebrachial muscles that move the wrist joint, hand, & fingers.
  5. Intrinsic hand muscles.

Muscles That Move Pectoral Girdle

• Originate on axial skeleton & insert on clavicle & scapula.
• Function to stabilize & move scapula.
  • Help increase arm’s angle of movements.
• Divided into anterior & posterior thoracic sections.
  • Some muscles are grouped by scapular movement; they are responsible for:
    • Elevation, depression, protraction, or retraction.
• Examples:
  • Pectoralis minor
    • Origin: anterior surface of ribs.
    • Insertion: coracoid process of scapula.
    • Function: draws scapula forward & downward.
  • Serratus anterior
    • Origin: ribs 1-8 (anterior & superior margins).
    • Insertion: entire anterior surface of vertebral border of scapula.
    • Function: rotates scapula so that its inferior angle moves laterally & upward; pushing & punching, “boxers muscle.”
    • Both of these muscles contribute to protracting scapulae…if serratus anterior is agonist, what would pectoralis minor be considered?
  • Subclavius
    • Stabilize & depress clavicle.
  • Trapezius
    • Origin: occipital bone, spines of C7 & all thoracic vertebrae…
    • Insertion: continuous insertion along acromion & spine of scapula & lateral 3rd of clavicle.
    • Function: stabilizes, raises, retracts, & rotates scapula.
  • Rhomboid major & minor
    • Elevates & retracts (adducts) scapula; inferiorly rotates scapula.
  • Levator scapulae
    • Elevates scapula; inferiorly rotates scapula.
    • Pulls glenoid cavity inferiorly.

Muscles That Move Glenohumeral Joint/Arm

• Synonymous w/ “moving arm or humerus.”
• Glenohumeral joint consists of 11 muscles.
  • Insert on humerus, radius, or ulna.
• Examples:
  • Latissimus dorsi
    • Origins: ribs (8-12), thoracic vertebrae (T7-T12)…
    • Insertion: humerus (intertubercular groove).
    • Function: prime mover of arm extension; adduction & medial rotation at shoulder.
    • “Swimmer’s muscle”
  • Teres major: synergist of latissimus dorsi (so performs same functions).
  • Pectoralis major
    • Origin: sternal end of clavicle, sternum & rib cartilage.
    • Insertion: greater tubercle of humerus.
    • Function: prime mover of arm flexion, rotates arm medially, adducts arm (climbing, throwing, pushing).
    • What is the relationship between latissimus dorsi and pectoralis major?
  • Deltoid
    • Origin: trapezius, clavicle, scapula.
    • Insertion: humerus (deltoid tuberosity).
    • Function: prime mover of arm abduction when all its fibers contract simultaneously.
    • Site for intramuscular injections (tetanus shots, etc.).
  • Rotor cuff = supraspinatus, infraspinatus, subscapularis & teres minor
    • Surrounds shoulder joint.
    • Provide strength & stability to shoulder joint.
    • Attach scapula to humerus.
    • Actions of these muscles & pitching:
      • Subscapularis – used when winding up for a pitch (medially rotates arm).
      • Supraspinatus – used when you start to execute pitch, by fully abducting arm.
      • Infraspinatus & teres minor – help slow down pitching arm upon completion of pitch (adduct & laterally rotate arm).

Arm & Forearm Muscles that Move Elbow Joint/Forearm

• “Flexing elbow joint” & “flexing forearm” are synonymous.
• Muscles of arm are subdivided into 2 compartments:
  • Anterior/flexor compartment.
  • Posterior/extensor compartment.
• Examples:
  • Biceps brachii
    • Origin: coracoid process & supraglenoid tubercle of scapula.
    • Insertion: radial tuberosity & bicipital aponeurosis.
    • Function: flexes elbow joint & supinates forearm.
  • Brachialis
    • Origin: front of distal humerus.
    • Insertion: coronoid process of ulna.
    • Function: major forearm flexor.
  • Brachioradialis
    • Origin: supracondylar ridge on humerus.
    • Insertion: base of styloid process on radius.
    • Function: synergist in forearm flexion.
  • Triceps brachii (long, lateral, & medial heads)
    • Origins: long head, infraglenoid tubercle of scapula; lateral & medial head, posterior of humerus (above & below radial groove respectively).
    • Insertion: olecranon of ulna.
    • Function: primary extensor of forearm.
  • Anconeus – also extends forearm.
  • Supination vs. Pronation
    • Supination
      • supinator
      • biceps brachii
      • brachioradialis
    • Pronation
      • pronator teres
      • pronator quadratus

Forearm Muscles That Move Wrist Joint, Hand, & Fingers

• Flexor carpi radialis & flexor carpi ulnaris
  • Flex wrist & abduct hand.
• Palmaris longus
  • Weak wrist flexor.
• Extensor carpi radialis longus & brevis, as well as extensor carpi ulnaris.
  • Extends wrist & adducts hand.
• Extensor digitorum
  • Extends wrist, extends 2nd - 5th MP joints, PIP joints, & DIP joints.
• Extensor digiti minimi
  • Extends wrist, MP, & PIP joints of finger 5.

Hand: Dorsal Aspect

• Extensor tendons
  • Most are fleshy proximally & long tendons distally, almost all of which insert in hand.
  • At wrist, these tendons are anchored firmly by band-like thickenings of deep fascia called flexor & extensor retinacula (retainers).
• Extensor retinaculum
  • These “wrist bands” keep tendons from jumping outward when tensed.
  • Crowded together in wrist & palm, muscle tendons are surrounded by slippery tendon sheaths that minimize friction as they slide against one another.

Function of Forearm Muscles

• Many muscles in forearm perform several basic functions:
  • Some move hand at wrist.
  • Some move fingers.
  • Help supinate & pronate forearm.
• At wrist joint, forearm muscles bring about flexion, extension, abduction & adduction of hand.
• At finger joints these muscles mostly just flex & extend fingers.
• Finer movements are from muscles in hand itself.
• Flexor Retinaculum -Transverse carpal ligament.
• Carpal Tunnel
  • Irritates the median nerve running through carpal tunnel (carpal ligament), rubbed together, causing inflammation & swelling – puts pressure on median nerve, which serves hand, which results in pain & numbness.

Muscles That Move Hip Joint/Thigh

• “Moving thigh” = “moving hip joint”
• Fascia lata – deep fascia of thigh which surrounds thigh muscles like a “supportive stocking” & tightly binds them.
• Thigh partitioned into compartments via fascia lata.
  • Anterior, medial, lateral, & posterior.
• Most muscles that act on thigh originate on os coxae & insert on femur.

Anterior Compartment

• These muscles either extend knee or flex thigh.
• Iliopsoas (psoas major & iliacus)
  • Origins: T12-L5 vertebrae & iliac fossa.
  • Insertion: Lesser trochanter of femur.
  • Function: Flexes thigh.
• Sartorius
  • Origin: iliac spine
  • Insertion: winds around medial knee into proximal tibia (tibial tuberosity).
  • Function: flexes, abducts & laterally rotates thigh; flexes & medially rotates leg.
  • Longest muscle in body!

Medial Compartment

• 6 muscles.
• 5 adduct thigh.
• 4 of those 5 also flex thigh.
  • Adductor longus & brevis, gracilis, & pectineus.
• 5th 1, adductor magnus, extends & laterally rotates thigh.
• 6th muscle, obturator externus, laterally rotates thigh (does not adduct).

Lateral Compartment

• Consists of 1 muscle that _ the thigh.
• Tensor fasciae latae
  • Origin: Iliac crest & spine (lateral surface of anterior superior iliac spine).
  • Insertion: Iliotibial band/tract.
  • Function: _ & medially rotates thigh.

Posterior Compartment

• These muscles act as both flexors of knee & extensors of thigh.
• Consist of 3 gluteal muscles, 5 muscles that laterally rotate thigh, & 3 hamstring muscles.
• Gluteus maximus
  • Origin: iliac crest, sacrum & coccyx.
  • Insertion: gluteal tuberosity on femur…
  • Function: major extensor of thigh; complex & powerful, climbing stairs & running; inactive during standing & walking.
• Gluteus medius
  • Origin: ilium
  • Insertion: anterior border of greater trochanter on femur.
  • Function: abducts & medially rotates thigh; steadies pelvis; extremely important in walking – keeps pelvis up so foot in air does not drag.
• Gluteus minimus
  • Origin: ilium
  • Insertion: short tendon into greater trochanter on femur.
  • Function: same as gluteus medius.