Anatomy Block 1 (Skeletal Muscle)

What is skeletal muscle?

Muscles anchored to skeleton, when muscles contract they facilitate movement.

Prime mover muscles do what?

Drive a specific movement

Muscles that are synergist do what?

Help one another to perform a specific function.

Muscles that are fixators do what?

A muscle that is fixated or holding joints steady, causing no damage.

What is the muscle belly/ body?

Outside of muscle

What is the Epimysium?

The outer membrane of skeletal muscle

What are the bundles of structures within a muscle called?

Fascicles

The fascicles in the muscle are wrapped or protected by?

Perimysium

When cutting the Perimysium in a muscle we find what?

Individual muscle fibers/cells

What is the membrane wrapped around muscle fibers/cells?

Endomysium

What are Tendons?

Anchoring points from muscle to bone.

What is a motor unit?

Muscle fiber in contact with branch of an axon (neuron).

The individual branch of neuron communicates with muscle fiber for it to do what?

This causes it to move.

What is Nerve Innervation?

Terminal ends of a neuronal axon branch controlling muscle fibers and telling them what to do.

Every muscle fiber/ cell has a?

Motor end plate (interacts with axons terminal boutons)

1 neuron will control how many muscle fibers?

150 muscle fibers, if a large muscle it can control up to 2000 fibers.

What is the Neuromuscular Junction?

The area that the nervous tissue meets with the muscle fiber. The terminal end of the axon interacts with the motor end plate of the sarcolemma that surrounds individuals fibers.

The neurotransmitter gated channels have to connect with?

The appropriate key which is the receptor.

The pre-synaptic component is?

The neuron

The post-synaptic component is the?

Muscle fiber

What is a Synapse?

The process of the release of acetylcholine and it binding to its appropriate receptor. Leading to muscle contraction.

How does Muscle Contraction end?

Acetylcholine is stopped and terminal end of neuron attracts acetylcholine and brings it back inside and packs it into packages.

Acetylcholinesterase is what?

Breakdown of acetylcholine

What are the Mimetic Muscles?

Radiate into the skin of the face and the head; their contraction causes displacement of the skin. (Expressive Muscles)

What muscle is innervated (motor) by cranial nerve VII (facial nerve)?

Mimetic Muscles

What are the 4 muscle groups of the Mimetic Muscles?

1. Scalp

2. Eyelid

3. Nasal region (only nasalis)

4. Mouth region

What are the Muscles of the Scalp?

Epicranius

2 Bellies: Frontal and Occipital, connected by a flat sheet like tendon.

What is the tendon connecting the frontal and occipital muscles of the scalp?

Epicranial aponeurosis.

What are the Muscles of the Eyelid Region?

• Orbicularis Oculi

• Corrugator Supercilli

What is the muscle Orbicularis Oculi?

Produces folds in lateral angle of the eye, expression of Worry and Concern.

What is the muscle Corrugator Supercilli?

Pulls the skin and eyebrow down and medially. Produces vertical folds. Protects against light. Thinker Brow Expression.

What is the Nasalis?

Muscle in the nasal region, flares nostrils.

What are the muscles in the Mouth Region?

• Orbicularis Oris

• Buccinator

• Zygomaticus Major and Minor

• Risorius

• Levator Labil Superior

• Lavator Anguli Oris

• Depressor Anguli Oris

• Depressor Labil Inferioris

• Mentalis

• Platysma

What is the muscle Orbicularis Oris?

Contraction closes the mouth, strong contraction gives sucking shape.

What is the muscle Buccinator?

Enables air to be blown out of mouth. Keeps mucus membrane of the cheek free of folds

What is the Zygomaticus Major and Minor?

Lifts the corner of the mouth upward giving laughter or pleasure expression.

What is the Risorius muscle?

Together with zygomatic major it produces the nasolabial folds.

What is the Levator Labil Superioris muscle?

Infraorbital margin to skin of upper lip.

What is the Lavator Anguli Oris?

Lifts the angle of the mouth, giving expression of self confidence.

What is the Depressor Anguli Oris?

Pulls the angle of the mouth downwards and produces expression of sadness.

What is the Depressor Labil Inferious?

Pulls the lower lip down, giving expression of perseverance.

What is the Mentalis muscle?

Chin-lip furrow, giving expression of doubt and indecision.

What is the muscle Platysma?

Tenses the skin in the anterior neck

Sensory Innervation of the face occurs with which cranial nerve?

Cranial Nerve 5 - Trigeminal Nerve (Ophthalmic, Maxillary and Mandibular Branch)

What is the Maxillary Branch?

Supplies lower eyelid, cheek, lateral nasal, upper lip, and anterior temporal regions by its tertiary branch, infraorbital nerve. (Sensory Functions)

What is Bells Palsy?

An acute, unilateral idiopathic palsy of cranial nerve 7 (facial nerve) resulting in muscle weakness and cranial neuropathy. Commonly caused by Herpes Simplex Virus.

What are the Muscles of Mastication?

CN V = Trigeminal Nerve (Ophthalmic, Maxillary, and Mandibular)

• Masseter: Powerfully closes the jaw by elevating the mandible

• Temporalis: Strongest elevator of lower jaw.

• Lateral pterygoid: Mandibular movements

• Medial pterygoid: Elevates mandible pushing forward, rotational movements

What are the pterygoid plates?

Processes that are projecting inferior from sphenoid bone.

The lateral pterygoid is also attached to the?

Tempormandibular joint

The lateral and medial pterygoid nerve are innervated by which nerve?

The five,in Al nerve ( cranial nerve 5)

What is the temporomandibular joint (TMJ)?

Head of mandible interacting with head of temporal joint of temporal bone.

What is TMJ Syndrome?

Umbrella term to describe acute or chronic pain in mastication muscle’s or temporomandibular joint

What is the Sternocleidomastoid?

Unilateral contractions turns the head to opposite side and bends it ipsilaterally, bilateral contractions lifts the head.

• Participates in respiration by elevating thoracic cage.

• Innervation: Accessory Nerve (CN XI) + Spinal Nerve C2-C3

What are the Infrahyoid Muscles?

• Omohyoid (Superior and Inferior)

• Thyrohyoid

• Sternothyroid

• Sternohyoid

What is the Omohyoid (Superior/ Inferior Belly)?

• Dilate internal jugular vein, aids to return of blood to heart.

• Opening mouth and lateral flexion of head

Innervation: C1-C3 (Cervical Ansa)

What 3 muscles are innervated by Spinal Nerve C1 before entering cervical ansa?

• Sternohyoid

• Sternothyroid

• Thyrohyoid

All infrahyoid muscles work together to do what?

Opening mouth, stabilizing anterior aspect of throat, and swallowing.

What are the suprahyoid muscles?

• Mylohyoid

• Stylohyoid

• Digastric

What is the Digastric Muscle?

Helps with stabilizing the mouth when speaking, hyoid bone, and swallowing helps with depression of mandible.

Innervation: Anterior Belly: CN V/3 and Posterior Belly CN VII

What is the Stylohyoid Muscle?

Elevates and retracts hyoid bone, elongate floor of mouth.

Innervation: CN VII

All suprahyoid muscles are?

Synergists

What is the Mylohyoid?

Elevates hyoid and floor of mouth and tongue when swallowing and speaking.

Innervation: CN V/3

What is the Geniohyoid Muscle?

Pulls the hyoid bone, shortens floor of the mouth and widens pharynx.

Innervation: Spinal Nerve C1

What are the Paravertebral Muscles?

• Rectus Capitis

• Longus Capitis

• Longus Colli

What is the Rectus Capitis?

Helps to flex the head

Innervation: Spinal Nerve C1

What is the Longus Capitis?

Bends the head forward and unilateral action turns the head sideways.

Innervation: Spinal Nerves C1-4

What is Longus Colli?

Unilateral contraction of bends cervical spine.

What are the Scalene Muscles?

• Anterior

• Medius

• Posterior

30% of population have what present?

Scalenus minimus

The Scalene muscles are important muscles for?

Reparation

Scalene Muscles innervation are?

C4-C8